Commit Graph

865 Commits

Author SHA1 Message Date
Jianchao Wang
d6a51a97c0 blk-mq: replace and kill blk_mq_request_issue_directly
Replace blk_mq_request_issue_directly with blk_mq_try_issue_directly
in blk_insert_cloned_request and kill it as nobody uses it any more.

Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-16 08:33:58 -07:00
Jianchao Wang
5b7a6f128a blk-mq: issue directly with bypass 'false' in blk_mq_sched_insert_requests
It is not necessary to issue request directly with bypass 'true'
in blk_mq_sched_insert_requests and handle the non-issued requests
itself. Just set bypass to 'false' and let blk_mq_try_issue_directly
handle them totally. Remove the blk_rq_can_direct_dispatch check,
because blk_mq_try_issue_directly can handle it well.If request is
direct-issued unsuccessfully, insert the reset.

Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-16 08:33:57 -07:00
Jianchao Wang
7f556a44e6 blk-mq: refactor the code of issue request directly
Merge blk_mq_try_issue_directly and __blk_mq_try_issue_directly
into one interface to unify the interfaces to issue requests
directly. The merged interface takes over the requests totally,
it could insert, end or do nothing based on the return value of
.queue_rq and 'bypass' parameter. Then caller needn't any other
handling any more and then code could be cleaned up.

And also the commit c616cbee ( blk-mq: punt failed direct issue
to dispatch list ) always inserts requests to hctx dispatch list
whenever get a BLK_STS_RESOURCE or BLK_STS_DEV_RESOURCE, this is
overkill and will harm the merging. We just need to do that for
the requests that has been through .queue_rq. This patch also
could fix this.

Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-16 08:33:57 -07:00
Mikulas Patocka
e016b78201 block: return just one value from part_in_flight
The previous patches deleted all the code that needed the second value
returned from part_in_flight - now the kernel only uses the first value.

Consequently, part_in_flight (and blk_mq_in_flight) may be changed so that
it only returns one value.

This patch just refactors the code, there's no functional change.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-10 08:30:38 -07:00
Jens Axboe
96f774106e Linux 4.20-rc6
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Merge tag 'v4.20-rc6' into for-4.21/block

Pull in v4.20-rc6 to resolve the conflict in NVMe, but also to get the
two corruption fixes. We're going to be overhauling the direct dispatch
path, and we need to do that on top of the changes we made for that
in mainline.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-09 17:45:40 -07:00
Ming Lei
5938870247 blk-mq: re-build queue map in case of kdump kernel
Now almost all .map_queues() implementation based on managed irq
affinity doesn't update queue mapping and it just retrieves the
old built mapping, so if nr_hw_queues is changed, the mapping talbe
includes stale mapping. And only blk_mq_map_queues() may rebuild
the mapping talbe.

One case is that we limit .nr_hw_queues as 1 in case of kdump kernel.
However, drivers often builds queue mapping before allocating tagset
via pci_alloc_irq_vectors_affinity(), but set->nr_hw_queues can be set
as 1 in case of kdump kernel, so wrong queue mapping is used, and
kernel panic[1] is observed during booting.

This patch fixes the kernel panic triggerd on nvme by rebulding the
mapping table via blk_mq_map_queues().

[1] kernel panic log
[    4.438371] nvme nvme0: 16/0/0 default/read/poll queues
[    4.443277] BUG: unable to handle kernel NULL pointer dereference at 0000000000000098
[    4.444681] PGD 0 P4D 0
[    4.445367] Oops: 0000 [#1] SMP NOPTI
[    4.446342] CPU: 3 PID: 201 Comm: kworker/u33:10 Not tainted 4.20.0-rc5-00664-g5eb02f7ee1eb-dirty #459
[    4.447630] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.10.2-2.fc27 04/01/2014
[    4.448689] Workqueue: nvme-wq nvme_scan_work [nvme_core]
[    4.449368] RIP: 0010:blk_mq_map_swqueue+0xfb/0x222
[    4.450596] Code: 04 f5 20 28 ef 81 48 89 c6 39 55 30 76 93 89 d0 48 c1 e0 04 48 03 83 f8 05 00 00 48 8b 00 42 8b 3c 28 48 8b 43 58 48 8b 04 f8 <48> 8b b8 98 00 00 00 4c 0f a3 37 72 42 f0 4c 0f ab 37 66 8b b8 f6
[    4.453132] RSP: 0018:ffffc900023b3cd8 EFLAGS: 00010286
[    4.454061] RAX: 0000000000000000 RBX: ffff888174448000 RCX: 0000000000000001
[    4.456480] RDX: 0000000000000001 RSI: ffffe8feffc506c0 RDI: 0000000000000001
[    4.458750] RBP: ffff88810722d008 R08: ffff88817647a880 R09: 0000000000000002
[    4.464580] R10: ffffc900023b3c10 R11: 0000000000000004 R12: ffff888174448538
[    4.467803] R13: 0000000000000004 R14: 0000000000000001 R15: 0000000000000001
[    4.469220] FS:  0000000000000000(0000) GS:ffff88817bac0000(0000) knlGS:0000000000000000
[    4.471554] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    4.472464] CR2: 0000000000000098 CR3: 0000000174e4e001 CR4: 0000000000760ee0
[    4.474264] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[    4.476007] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[    4.477061] PKRU: 55555554
[    4.477464] Call Trace:
[    4.478731]  blk_mq_init_allocated_queue+0x36a/0x3ad
[    4.479595]  blk_mq_init_queue+0x32/0x4e
[    4.480178]  nvme_validate_ns+0x98/0x623 [nvme_core]
[    4.480963]  ? nvme_submit_sync_cmd+0x1b/0x20 [nvme_core]
[    4.481685]  ? nvme_identify_ctrl.isra.8+0x70/0xa0 [nvme_core]
[    4.482601]  nvme_scan_work+0x23a/0x29b [nvme_core]
[    4.483269]  ? _raw_spin_unlock_irqrestore+0x25/0x38
[    4.483930]  ? try_to_wake_up+0x38d/0x3b3
[    4.484478]  ? process_one_work+0x179/0x2fc
[    4.485118]  process_one_work+0x1d3/0x2fc
[    4.485655]  ? rescuer_thread+0x2ae/0x2ae
[    4.486196]  worker_thread+0x1e9/0x2be
[    4.486841]  kthread+0x115/0x11d
[    4.487294]  ? kthread_park+0x76/0x76
[    4.487784]  ret_from_fork+0x3a/0x50
[    4.488322] Modules linked in: nvme nvme_core qemu_fw_cfg virtio_scsi ip_tables
[    4.489428] Dumping ftrace buffer:
[    4.489939]    (ftrace buffer empty)
[    4.490492] CR2: 0000000000000098
[    4.491052] ---[ end trace 03cd268ad5a86ff7 ]---

Cc: Christoph Hellwig <hch@lst.de>
Cc: linux-nvme@lists.infradead.org
Cc: David Milburn <dmilburn@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-07 22:26:38 -07:00
Jens Axboe
c616cbee97 blk-mq: punt failed direct issue to dispatch list
After the direct dispatch corruption fix, we permanently disallow direct
dispatch of non read/write requests. This works fine off the normal IO
path, as they will be retried like any other failed direct dispatch
request. But for the blk_insert_cloned_request() that only DM uses to
bypass the bottom level scheduler, we always first attempt direct
dispatch. For some types of requests, that's now a permanent failure,
and no amount of retrying will make that succeed. This results in a
livelock.

Instead of making special cases for what we can direct issue, and now
having to deal with DM solving the livelock while still retaining a BUSY
condition feedback loop, always just add a request that has been through
->queue_rq() to the hardware queue dispatch list. These are safe to use
as no merging can take place there. Additionally, if requests do have
prepped data from drivers, we aren't dependent on them not sharing space
in the request structure to safely add them to the IO scheduler lists.

This basically reverts ffe81d4532 and is based on a patch from Ming,
but with the list insert case covered as well.

Fixes: ffe81d4532 ("blk-mq: fix corruption with direct issue")
Cc: stable@vger.kernel.org
Suggested-by: Ming Lei <ming.lei@redhat.com>
Reported-by: Bart Van Assche <bvanassche@acm.org>
Tested-by: Ming Lei <ming.lei@redhat.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-07 08:16:11 -07:00
Jens Axboe
ffe81d4532 blk-mq: fix corruption with direct issue
If we attempt a direct issue to a SCSI device, and it returns BUSY, then
we queue the request up normally. However, the SCSI layer may have
already setup SG tables etc for this particular command. If we later
merge with this request, then the old tables are no longer valid. Once
we issue the IO, we only read/write the original part of the request,
not the new state of it.

This causes data corruption, and is most often noticed with the file
system complaining about the just read data being invalid:

[  235.934465] EXT4-fs error (device sda1): ext4_iget:4831: inode #7142: comm dpkg-query: bad extra_isize 24937 (inode size 256)

because most of it is garbage...

This doesn't happen from the normal issue path, as we will simply defer
the request to the hardware queue dispatch list if we fail. Once it's on
the dispatch list, we never merge with it.

Fix this from the direct issue path by flagging the request as
REQ_NOMERGE so we don't change the size of it before issue.

See also:
  https://bugzilla.kernel.org/show_bug.cgi?id=201685

Tested-by: Guenter Roeck <linux@roeck-us.net>
Fixes: 6ce3dd6eec ("blk-mq: issue directly if hw queue isn't busy in case of 'none'")
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-04 20:06:48 -07:00
Christoph Hellwig
6544d229bf block: enable polling by default if a poll map is initalized
If the user did setup polling in the driver we should not require
another know in the block layer to enable it.

Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-04 11:38:19 -07:00
Christoph Hellwig
529262d56d block: remove ->poll_fn
This was intended to support users like nvme multipath, but is just
getting in the way and adding another indirect call.

Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-04 11:38:19 -07:00
Jens Axboe
fe1f452640 blk-mq: don't call ktime_get_ns() if we don't need it
We only need the request fields and the end_io time if we have
stats enabled, or if we have a scheduler attached as those may
use it for completion time stats.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-03 14:59:16 -07:00
Jens Axboe
b2c5d16b72 blk-mq: use plug for devices that implement ->commits_rqs()
If we have that hook, we know the driver handles bd->last == true in
a smart fashion. If it does, even for multiple hardware queues, it's
a good idea to flush batches of requests to the device, if we have
batches of requests from the submitter.

Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-29 10:12:37 -07:00
Jens Axboe
be94f058f2 blk-mq: use bd->last == true for list inserts
If we are issuing a list of requests, we know if we're at the last one.
If we fail issuing, ensure that we call ->commits_rqs() to flush any
potential previous requests.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-29 10:12:32 -07:00
Jens Axboe
d666ba98f8 blk-mq: add mq_ops->commit_rqs()
blk-mq passes information to the hardware about any given request being
the last that we will issue in this sequence. The point is that hardware
can defer costly doorbell type writes to the last request. But if we run
into errors issuing a sequence of requests, we may never send the request
with bd->last == true set. For that case, we need a hook that tells the
hardware that nothing else is coming right now.

For failures returned by the drivers ->queue_rq() hook, the driver is
responsible for flushing pending requests, if it uses bd->last to
optimize that part. This works like before, no changes there.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-29 10:11:56 -07:00
Jens Axboe
ce5b009cff block: improve logic around when to sort a plug list
Only do it if we have requests for multiple queues in the same
plug.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-29 10:11:45 -07:00
Dan Carpenter
4e6db0f21c blk-mq: Add a NULL check in blk_mq_free_map_and_requests()
I recently found some code which called blk_mq_free_map_and_requests()
with a NULL set->tags pointer.  I fixed the caller, but it seems like a
good idea to add a NULL check here as well.  Now we can call:

	blk_mq_free_tag_set(set);
	blk_mq_free_tag_set(set);

twice in a row and it's harmless.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-29 08:16:08 -07:00
Jens Axboe
4711b57317 blk-mq: fix failure to decrement plug count on single rq removal
If we yank a 'same_queue_rq' request off the plug list, we should
also decrement the cached request count.

Fixes: 5f0ed774ed ("block: sum requests in the plug structure")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-28 06:29:23 -07:00
Jens Axboe
5f0ed774ed block: sum requests in the plug structure
This isn't exactly the same as the previous count, as it includes
requests for all devices. But that really doesn't matter, if we have
more than the threshold (16) queued up, flush it. It's not worth it
to have an expensive list loop for this.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-26 10:35:22 -07:00
Keith Busch
af78ff7c6e blk-mq: Simplify request completion state
There are no more users relying on blk-mq request states to prevent
double completions, so replace the relatively expensive cmpxchg operation
with WRITE_ONCE.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-26 10:34:27 -07:00
Keith Busch
16c15eb16a blk-mq: Return true if request was completed
A driver may have internal state to cleanup if we're pretending a request
didn't complete. Return 'false' if the command wasn't actually completed
due to the timeout error injection, and true otherwise.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-26 10:34:24 -07:00
Jens Axboe
4ab32bf330 blk-mq: never redirect polled IO completions
It's pointless to do so, we are by definition on the CPU we want/need
to be, as that's the one waiting for a completion event.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-26 08:26:04 -07:00
Jens Axboe
aa61bec30e blk-mq: ensure mq_ops ->poll() is entered at least once
Right now we immediately bail if need_resched() is true, but
we need to do at least one loop in case we have entries waiting.
So just invert the need_resched() check, putting it at the
bottom of the loop.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-26 08:25:57 -07:00
Jens Axboe
0a1b8b87d0 block: make blk_poll() take a parameter on whether to spin or not
blk_poll() has always kept spinning until it found an IO. This is
fine for SYNC polling, since we need to find one request we have
pending, but in preparation for ASYNC polling it can be beneficial
to just check if we have any entries available or not.

Existing callers are converted to pass in 'spin == true', to retain
the old behavior.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-26 08:25:53 -07:00
Jens Axboe
9743139c5d blk-mq: remove 'tag' parameter from mq_ops->poll()
We always pass in -1 now and none of the callers use the tag value,
remove the parameter.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-26 08:25:44 -07:00
Jens Axboe
1052b8ac52 blk-mq: when polling for IO, look for any completion
If we want to support async IO polling, then we have to allow finding
completions that aren't just for the one we are looking for. Always pass
in -1 to the mq_ops->poll() helper, and have that return how many events
were found in this poll loop.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-26 08:25:40 -07:00
Ming Lei
1db4909e76 blk-mq: not embed .mq_kobj and ctx->kobj into queue instance
Even though .mq_kobj, ctx->kobj and q->kobj share same lifetime
from block layer's view, actually they don't because userspace may
grab one kobject anytime via sysfs.

This patch fixes the issue by the following approach:

1) introduce 'struct blk_mq_ctxs' for holding .mq_kobj and managing
all ctxs

2) free all allocated ctxs and the 'blk_mq_ctxs' instance in release
handler of .mq_kobj

3) grab one ref of .mq_kobj before initializing each ctx->kobj, so that
.mq_kobj is always released after all ctxs are freed.

This patch fixes kernel panic issue during booting when DEBUG_KOBJECT_RELEASE
is enabled.

Reported-by: Guenter Roeck <linux@roeck-us.net>
Cc: "jianchao.wang" <jianchao.w.wang@oracle.com>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-21 05:57:56 -07:00
Damien Le Moal
e2b3fa5af7 block: Remove bio->bi_ioc
bio->bi_ioc is never set so always NULL. Remove references to it in
bio_disassociate_task() and in rq_ioc() and delete this field from
struct bio. With this change, rq_ioc() always returns
current->io_context without the need for a bio argument. Further
simplify the code and make it more readable by also removing this
helper, which also allows to simplify blk_mq_sched_assign_ioc() by
removing its bio argument.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Adam Manzanares <adam.manzanares@wdc.com>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-19 19:03:44 -07:00
Jens Axboe
85f4d4b65f block: have ->poll_fn() return number of entries polled
We currently only really support sync poll, ie poll with 1 IO in flight.
This prepares us for supporting async poll.

Note that the returned value isn't necessarily 100% accurate. If poll
races with IRQ completion, we assume that the fact that the task is now
runnable means we found at least one entry. In reality it could be more
than 1, or not even 1. This is fine, the caller will just need to take
this into account.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-19 08:34:50 -07:00
Jens Axboe
849a370016 block: avoid ordered task state change for polled IO
For the core poll helper, the task state setting don't need to imply any
atomics, as it's the current task itself that is being modified and
we're not going to sleep.

For IRQ driven, the wakeup path have the necessary barriers to not need
us using the heavy handed version of the task state setting.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-19 08:34:49 -07:00
Jens Axboe
344e9ffcbd block: add queue_is_mq() helper
Various spots check for q->mq_ops being non-NULL, but provide
a helper to do this instead.

Where the ->mq_ops != NULL check is redundant, remove it.

Since mq == rq-based now that legacy is gone, get rid of the
queue_is_rq_based() and just use queue_is_mq() everywhere.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-16 08:34:06 -07:00
Christoph Hellwig
6d46964230 block: remove the lock argument to blk_alloc_queue_node
With the legacy request path gone there is no real need to override the
queue_lock.

Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-15 12:13:35 -07:00
Christoph Hellwig
d53375608e block: remove the unused lock argument to rq_qos_throttle
Unused now that the legacy request path is gone.

Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-15 12:13:22 -07:00
Christoph Hellwig
57d74df907 block: use atomic bitops for ->queue_flags
->queue_flags is generally not set or cleared in the fast path, and also
generally set or cleared one flag at a time.  Make use of the normal
atomic bitops for it so that we don't need to take the queue_lock,
which is otherwise mostly unused in the core block layer now.

Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-15 12:13:19 -07:00
Christoph Hellwig
079076b341 block: remove deadline __deadline manipulation helpers
No users left since the removal of the legacy request interface, we can
remove all the magic bit stealing now and make it a normal field.

But use WRITE_ONCE/READ_ONCE on the new deadline field, given that we
don't seem to have any mechanism to guarantee a new value actually
gets seen by other threads.

Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-15 12:13:16 -07:00
Christoph Hellwig
9d037ad707 block: remove req->timeout_list
Unused now that the legacy request path is gone.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-09 11:44:10 -07:00
Jens Axboe
ae8799125d blk-mq: provide a helper to check if a queue is busy
Returns true if the queue currently has requests pending,
false if not.

DM can use this to replace the atomic_inc/dec they do per device
to see if a device is busy.

Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-08 10:24:23 -07:00
Jens Axboe
7baa85727d blk-mq-tag: change busy_iter_fn to return whether to continue or not
We have this functionality in sbitmap, but we don't export it in
blk-mq for users of the tags busy iteration. This can be useful
for stopping the iteration, if the caller doesn't need to find
more requests.

Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-08 10:24:07 -07:00
Jens Axboe
3110fc7960 blk-mq: improve plug list sorting
Currently we only look at the software queue, but with support
for multiple maps, we should also look at the hardware queue.
This is important since we'll flush out the request list if
either the software queue or hardware queue don't match.

This sorts by software queue first, then hardware queue if
that differs. Finally we sort by request location like before.
This minimizes the flush points per plug list.

Reviewed-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07 13:45:00 -07:00
Jens Axboe
67cae4c948 blk-mq: cleanup and improve list insertion
It's somewhat strange to have a list insertion function that
relies on the fact that the caller has mapped things correctly.
Pass in the hardware queue directly for insertion, which makes
for a much cleaner interface and implementation.

Reviewed-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07 13:44:59 -07:00
Jens Axboe
ea4f995ee8 blk-mq: cache request hardware queue mapping
We call blk_mq_map_queue() a lot, at least two times for each
request per IO, sometimes more. Since we now have an indirect
call as well in that function. cache the mapping so we don't
have to re-call blk_mq_map_queue() for the same request
multiple times.

Reviewed-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07 13:44:59 -07:00
Jens Axboe
392546aed2 blk-mq: separate number of hardware queues from nr_cpu_ids
With multiple maps, nr_cpu_ids is no longer the maximum number of
hardware queues we support on a given devices. The initializer of
the tag_set can have set ->nr_hw_queues larger than the available
number of CPUs, since we can exceed that with multiple queue maps.

Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07 13:44:59 -07:00
Jens Axboe
b3c661b15d blk-mq: support multiple hctx maps
Add support for the tag set carrying multiple queue maps, and
for the driver to inform blk-mq how many it wishes to support
through setting set->nr_maps.

This adds an mq_ops helper for drivers that support more than 1
map, mq_ops->rq_flags_to_type(). The function takes request/bio
flags and CPU, and returns a queue map index for that. We then
use the type information in blk_mq_map_queue() to index the map
set.

Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07 13:44:59 -07:00
Jens Axboe
f31967f0e4 blk-mq: allow software queue to map to multiple hardware queues
The mapping used to be dependent on just the CPU location, but
now it's a tuple of (type, cpu) instead. This is a prep patch
for allowing a single software queue to map to multiple hardware
queues. No functional changes in this patch.

This changes the software queue count to an unsigned short
to save a bit of space. We can still support 64K-1 CPUs,
which should be enough. Add a check to catch a wrap.

Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07 13:44:59 -07:00
Jens Axboe
f9afca4d36 blk-mq: pass in request/bio flags to queue mapping
Prep patch for being able to place request based not just on
CPU location, but also on the type of request.

Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07 13:44:59 -07:00
Jens Axboe
ed76e329d7 blk-mq: abstract out queue map
This is in preparation for allowing multiple sets of maps per
queue, if so desired.

Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07 13:44:59 -07:00
Jens Axboe
a8908939af blk-mq: kill q->mq_map
It's just a pointer to set->mq_map, use that instead. Move the
assignment a bit earlier, so we always know it's valid.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07 13:44:59 -07:00
Jens Axboe
9cf2bab630 block: kill request ->cpu member
This was used for completion placement for the legacy path,
but for mq we have rq->mq_ctx->cpu for that. Add a helper
to get the request CPU assignment, as the mq_ctx type is
private to blk-mq.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07 13:42:33 -07:00
Jens Axboe
c7bb9ad174 block: get rid of q->softirq_done_fn()
With the legacy path gone, all we do is funnel it through the
mq_ops->complete() operation.

Tested-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07 13:42:33 -07:00
Jens Axboe
7d692330e7 block: get rid of blk_queued_rq()
No point in hiding what this does, just open code it in the
one spot where we are still using it.

Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07 13:42:33 -07:00
Jens Axboe
db6d995235 block: remove request_list code
It's now dead code, nobody uses it.

Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07 13:42:33 -07:00
Jens Axboe
f9cd4bfe96 block: get rid of MQ scheduler ops union
This is a remnant of when we had ops for both SQ and MQ
schedulers. Now it's just MQ, so get rid of the union.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07 13:42:32 -07:00
Jens Axboe
ba7b443422 blk-mq: remove legacy check in queue blk_freeze_queue()
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07 13:42:31 -07:00
Jens Axboe
7ac257b862 blk-mq: remove the request_list usage
We don't do anything with it, that's just the legacy path.

Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07 13:42:31 -07:00
Xiaoguang Wang
d6f1dda272 blk-mq: place trace_block_getrq() in correct place
trace_block_getrq() is to indicate a request struct has been allocated
for queue, so put it in right place.

Reviewed-by: Jianchao Wang <jianchao.w.wang@oracle.com>
Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-10-25 11:17:40 -06:00
Jens Axboe
9316a9ed68 blk-mq: provide helper for setting up an SQ queue and tag set
This pattern is repeated throughout all the blk-mq conversions.
Provide a basic helper to get it done.

Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-10-15 20:05:18 -06:00
Jianchao Wang
e01ad46d53 blk-mq: fallback to previous nr_hw_queues when updating fails
When we try to increate the nr_hw_queues, we may fail due to
shortage of memory or other reason, then blk_mq_realloc_hw_ctxs stops
and some entries in q->queue_hw_ctx are left with NULL. However,
because queue map has been updated with new nr_hw_queues, some cpus
have been mapped to hw queue which just encounters allocation failure,
thus blk_mq_map_queue could return NULL. This will cause panic in
following blk_mq_map_swqueue.

To fix it, when increase nr_hw_queues fails, fallback to previous
nr_hw_queues and post warning. At the same time, driver's .map_queues
usually use completion irq affinity to map hw and cpu, fallback
nr_hw_queues will cause lack of some cpu's map to hw, so use default
blk_mq_map_queues to do that.

Reported-by: syzbot+83e8cbe702263932d9d4@syzkaller.appspotmail.com
Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-10-13 15:42:04 -06:00
Jianchao Wang
34d11ffac1 blk-mq: realloc hctx when hw queue is mapped to another node
When the hw queues and mq_map are updated, a hctx could be mapped
to a different numa node. At this moment, we need to realloc the
hctx. If fail to do that, go on using previous hctx.

Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-10-13 15:42:02 -06:00
Jianchao Wang
5b202853ff blk-mq: change gfp flags to GFP_NOIO in blk_mq_realloc_hw_ctxs
blk_mq_realloc_hw_ctxs could be invoked during update hw queues.
At the momemt, IO is blocked. Change the gfp flags from GFP_KERNEL
to GFP_NOIO to avoid forever hang during memory allocation in
blk_mq_realloc_hw_ctxs.

Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-10-13 15:42:01 -06:00
Jianchao Wang
477e19dedc blk-mq: adjust debugfs and sysfs register when updating nr_hw_queues
blk-mq debugfs and sysfs entries need to be removed before updating
queue map, otherwise, we get get wrong result there. This patch fixes
it and remove the redundant debugfs and sysfs register/unregister
operations during __blk_mq_update_nr_hw_queues.

Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-10-13 15:41:59 -06:00
Ming Lei
36e765392e blk-mq: complete req in softirq context in case of single queue
Lot of controllers may have only one irq vector for completing IO
request. And usually affinity of the only irq vector is all possible
CPUs, however, on most of ARCH, there may be only one specific CPU
for handling this interrupt.

So if all IOs are completed in hardirq context, it is inevitable to
degrade IO performance because of increased irq latency.

This patch tries to address this issue by allowing to complete request
in softirq context, like the legacy IO path.

IOPS is observed as ~13%+ in the following randread test on raid0 over
virtio-scsi.

mdadm --create --verbose /dev/md0 --level=0 --chunk=1024 --raid-devices=8 /dev/sdb /dev/sdc /dev/sdd /dev/sde /dev/sdf /dev/sdg /dev/sdh /dev/sdi

fio --time_based --name=benchmark --runtime=30 --filename=/dev/md0 --nrfiles=1 --ioengine=libaio --iodepth=32 --direct=1 --invalidate=1 --verify=0 --verify_fatal=0 --numjobs=32 --rw=randread --blocksize=4k

Cc: Dongli Zhang <dongli.zhang@oracle.com>
Cc: Zach Marano <zmarano@google.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Jianchao Wang <jianchao.w.wang@oracle.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-10-08 10:50:43 -06:00
Jens Axboe
c0aac682fa This is the 4.19-rc6 release
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Merge tag 'v4.19-rc6' into for-4.20/block

Merge -rc6 in, for two reasons:

1) Resolve a trivial conflict in the blk-mq-tag.c documentation
2) A few important regression fixes went into upstream directly, so
   they aren't in the 4.20 branch.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

* tag 'v4.19-rc6': (780 commits)
  Linux 4.19-rc6
  MAINTAINERS: fix reference to moved drivers/{misc => auxdisplay}/panel.c
  cpufreq: qcom-kryo: Fix section annotations
  perf/core: Add sanity check to deal with pinned event failure
  xen/blkfront: correct purging of persistent grants
  Revert "xen/blkfront: When purging persistent grants, keep them in the buffer"
  selftests/powerpc: Fix Makefiles for headers_install change
  blk-mq: I/O and timer unplugs are inverted in blktrace
  dax: Fix deadlock in dax_lock_mapping_entry()
  x86/boot: Fix kexec booting failure in the SEV bit detection code
  bcache: add separate workqueue for journal_write to avoid deadlock
  drm/amd/display: Fix Edid emulation for linux
  drm/amd/display: Fix Vega10 lightup on S3 resume
  drm/amdgpu: Fix vce work queue was not cancelled when suspend
  Revert "drm/panel: Add device_link from panel device to DRM device"
  xen/blkfront: When purging persistent grants, keep them in the buffer
  clocksource/drivers/timer-atmel-pit: Properly handle error cases
  block: fix deadline elevator drain for zoned block devices
  ACPI / hotplug / PCI: Don't scan for non-hotplug bridges if slot is not bridge
  drm/syncobj: Don't leak fences when WAIT_FOR_SUBMIT is set
  ...

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-10-01 08:58:57 -06:00
Omar Sandoval
ed88660a53 block: move call of scheduler's ->completed_request() hook
Commit 4bc6339a58 ("block: move blk_stat_add() to
__blk_mq_end_request()") consolidated some calls using ktime_get() so
we'd only need to call it once. Kyber's ->completed_request() hook also
calls ktime_get(), so let's move it to the same place, too.

Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-27 17:34:52 -06:00
Ilya Dryomov
587562d0c7 blk-mq: I/O and timer unplugs are inverted in blktrace
trace_block_unplug() takes true for explicit unplugs and false for
implicit unplugs.  schedule() unplugs are implicit and should be
reported as timer unplugs.  While correct in the legacy code, this has
been inverted in blk-mq since 4.11.

Cc: stable@vger.kernel.org
Fixes: bd166ef183 ("blk-mq-sched: add framework for MQ capable IO schedulers")
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-27 13:12:44 -06:00
Bart Van Assche
986d413b7c blk-mq: Enable support for runtime power management
Now that the blk-mq core processes power management requests
(marked with RQF_PREEMPT) in other states than RPM_ACTIVE, enable
runtime power management for blk-mq.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Jianchao Wang <jianchao.w.wang@oracle.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-26 15:11:29 -06:00
Bart Van Assche
bdd6316094 block: Allow unfreezing of a queue while requests are in progress
A later patch will call blk_freeze_queue_start() followed by
blk_mq_unfreeze_queue() without waiting for q_usage_counter to drop
to zero. Make sure that this doesn't cause a kernel warning to appear
by switching from percpu_ref_reinit() to percpu_ref_resurrect(). The
former namely requires that the refcount it operates on is zero.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Jianchao Wang <jianchao.w.wang@oracle.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-26 15:11:29 -06:00
Linus Torvalds
5bed49adfe for-4.19/post-20180822
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Merge tag 'for-4.19/post-20180822' of git://git.kernel.dk/linux-block

Pull more block updates from Jens Axboe:

 - Set of bcache fixes and changes (Coly)

 - The flush warn fix (me)

 - Small series of BFQ fixes (Paolo)

 - wbt hang fix (Ming)

 - blktrace fix (Steven)

 - blk-mq hardware queue count update fix (Jianchao)

 - Various little fixes

* tag 'for-4.19/post-20180822' of git://git.kernel.dk/linux-block: (31 commits)
  block/DAC960.c: make some arrays static const, shrinks object size
  blk-mq: sync the update nr_hw_queues with blk_mq_queue_tag_busy_iter
  blk-mq: init hctx sched after update ctx and hctx mapping
  block: remove duplicate initialization
  tracing/blktrace: Fix to allow setting same value
  pktcdvd: fix setting of 'ret' error return for a few cases
  block: change return type to bool
  block, bfq: return nbytes and not zero from struct cftype .write() method
  block, bfq: improve code of bfq_bfqq_charge_time
  block, bfq: reduce write overcharge
  block, bfq: always update the budget of an entity when needed
  block, bfq: readd missing reset of parent-entity service
  blk-wbt: fix IO hang in wbt_wait()
  block: don't warn for flush on read-only device
  bcache: add the missing comments for smp_mb()/smp_wmb()
  bcache: remove unnecessary space before ioctl function pointer arguments
  bcache: add missing SPDX header
  bcache: move open brace at end of function definitions to next line
  bcache: add static const prefix to char * array declarations
  bcache: fix code comments style
  ...
2018-08-22 13:38:05 -07:00
Jianchao Wang
f5bbbbe4d6 blk-mq: sync the update nr_hw_queues with blk_mq_queue_tag_busy_iter
For blk-mq, part_in_flight/rw will invoke blk_mq_in_flight/rw to
account the inflight requests. It will access the queue_hw_ctx and
nr_hw_queues w/o any protection. When updating nr_hw_queues and
blk_mq_in_flight/rw occur concurrently, panic comes up.

Before update nr_hw_queues, the q will be frozen. So we could use
q_usage_counter to avoid the race. percpu_ref_is_zero is used here
so that we will not miss any in-flight request. The access to
nr_hw_queues and queue_hw_ctx in blk_mq_queue_tag_busy_iter are
under rcu critical section, __blk_mq_update_nr_hw_queues could use
synchronize_rcu to ensure the zeroed q_usage_counter to be globally
visible.

Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-08-21 09:02:56 -06:00
Jianchao Wang
d48ece209f blk-mq: init hctx sched after update ctx and hctx mapping
Currently, when update nr_hw_queues, IO scheduler's init_hctx will
be invoked before the mapping between ctx and hctx is adapted
correctly by blk_mq_map_swqueue. The IO scheduler init_hctx (kyber)
may depend on this mapping and get wrong result and panic finally.
A simply way to fix this is that switch the IO scheduler to 'none'
before update the nr_hw_queues, and then switch it back after
update nr_hw_queues. blk_mq_sched_init_/exit_hctx are removed due
to nobody use them any more.

Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-08-21 09:02:55 -06:00
Linus Torvalds
73ba2fb33c for-4.19/block-20180812
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Merge tag 'for-4.19/block-20180812' of git://git.kernel.dk/linux-block

Pull block updates from Jens Axboe:
 "First pull request for this merge window, there will also be a
  followup request with some stragglers.

  This pull request contains:

   - Fix for a thundering heard issue in the wbt block code (Anchal
     Agarwal)

   - A few NVMe pull requests:
      * Improved tracepoints (Keith)
      * Larger inline data support for RDMA (Steve Wise)
      * RDMA setup/teardown fixes (Sagi)
      * Effects log suppor for NVMe target (Chaitanya Kulkarni)
      * Buffered IO suppor for NVMe target (Chaitanya Kulkarni)
      * TP4004 (ANA) support (Christoph)
      * Various NVMe fixes

   - Block io-latency controller support. Much needed support for
     properly containing block devices. (Josef)

   - Series improving how we handle sense information on the stack
     (Kees)

   - Lightnvm fixes and updates/improvements (Mathias/Javier et al)

   - Zoned device support for null_blk (Matias)

   - AIX partition fixes (Mauricio Faria de Oliveira)

   - DIF checksum code made generic (Max Gurtovoy)

   - Add support for discard in iostats (Michael Callahan / Tejun)

   - Set of updates for BFQ (Paolo)

   - Removal of async write support for bsg (Christoph)

   - Bio page dirtying and clone fixups (Christoph)

   - Set of bcache fix/changes (via Coly)

   - Series improving blk-mq queue setup/teardown speed (Ming)

   - Series improving merging performance on blk-mq (Ming)

   - Lots of other fixes and cleanups from a slew of folks"

* tag 'for-4.19/block-20180812' of git://git.kernel.dk/linux-block: (190 commits)
  blkcg: Make blkg_root_lookup() work for queues in bypass mode
  bcache: fix error setting writeback_rate through sysfs interface
  null_blk: add lock drop/acquire annotation
  Blk-throttle: reduce tail io latency when iops limit is enforced
  block: paride: pd: mark expected switch fall-throughs
  block: Ensure that a request queue is dissociated from the cgroup controller
  block: Introduce blk_exit_queue()
  blkcg: Introduce blkg_root_lookup()
  block: Remove two superfluous #include directives
  blk-mq: count the hctx as active before allocating tag
  block: bvec_nr_vecs() returns value for wrong slab
  bcache: trivial - remove tailing backslash in macro BTREE_FLAG
  bcache: make the pr_err statement used for ENOENT only in sysfs_attatch section
  bcache: set max writeback rate when I/O request is idle
  bcache: add code comments for bset.c
  bcache: fix mistaken comments in request.c
  bcache: fix mistaken code comments in bcache.h
  bcache: add a comment in super.c
  bcache: avoid unncessary cache prefetch bch_btree_node_get()
  bcache: display rate debug parameters to 0 when writeback is not running
  ...
2018-08-14 10:23:25 -07:00
Jianchao Wang
d263ed9926 blk-mq: count the hctx as active before allocating tag
Currently, we count the hctx as active after allocate driver tag
successfully. If a previously inactive hctx try to get tag first
time, it may fails and need to wait. However, due to the stale tag
->active_queues, the other shared-tags users are still able to
occupy all driver tags while there is someone waiting for tag.
Consequently, even if the previously inactive hctx is waked up, it
still may not be able to get a tag and could be starved.

To fix it, we count the hctx as active before try to allocate driver
tag, then when it is waiting the tag, the other shared-tag users
will reserve budget for it.

Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-08-09 08:34:17 -06:00
Linus Torvalds
eb181a814c for-linus-20180727
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Merge tag 'for-linus-20180727' of git://git.kernel.dk/linux-block

Pull block fixes from Jens Axboe:
 "Bigger than usual at this time, mostly due to the O_DIRECT corruption
  issue and the fact that I was on vacation last week. This contains:

   - NVMe pull request with two fixes for the FC code, and two target
     fixes (Christoph)

   - a DIF bio reset iteration fix (Greg Edwards)

   - two nbd reply and requeue fixes (Josef)

   - SCSI timeout fixup (Keith)

   - a small series that fixes an issue with bio_iov_iter_get_pages(),
     which ended up causing corruption for larger sized O_DIRECT writes
     that ended up racing with buffered writes (Martin Wilck)"

* tag 'for-linus-20180727' of git://git.kernel.dk/linux-block:
  block: reset bi_iter.bi_done after splitting bio
  block: bio_iov_iter_get_pages: pin more pages for multi-segment IOs
  blkdev: __blkdev_direct_IO_simple: fix leak in error case
  block: bio_iov_iter_get_pages: fix size of last iovec
  nvmet: only check for filebacking on -ENOTBLK
  nvmet: fixup crash on NULL device path
  scsi: set timed out out mq requests to complete
  blk-mq: export setting request completion state
  nvme: if_ready checks to fail io to deleting controller
  nvmet-fc: fix target sgl list on large transfers
  nbd: handle unexpected replies better
  nbd: don't requeue the same request twice.
2018-07-27 12:51:00 -07:00
Keith Busch
0fc09f9209 blk-mq: export setting request completion state
This is preparing for drivers that want to directly alter the state of
their requests. No functional change here.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-07-24 14:41:50 -06:00
Ming Lei
8824f62246 blk-mq: fail the request in case issue failure
Inside blk_mq_try_issue_list_directly(), if the request is issued as
failed, we shouldn't try to do it again, otherwise the warning in
blk_mq_start_request() will be triggered. This change is aligned to
behaviour of other ways of request issue & dispatch.

Fixes: 6ce3dd6eec ("blk-mq: issue directly if hw queue isn't busy in case of 'none'")
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: kernel test robot <rong.a.chen@intel.com>
Cc: LKP <lkp@01.org>
Reported-by: kernel test robot <rong.a.chen@intel.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-07-22 17:31:18 -06:00
Ming Lei
6ce3dd6eec blk-mq: issue directly if hw queue isn't busy in case of 'none'
In case of 'none' io scheduler, when hw queue isn't busy, it isn't
necessary to enqueue request to sw queue and dequeue it from
sw queue because request may be submitted to hw queue asap without
extra cost, meantime there shouldn't be much request in sw queue,
and we don't need to worry about effect on IO merge.

There are still some single hw queue SCSI HBAs(HPSA, megaraid_sas, ...)
which may connect high performance devices, so 'none' is often required
for obtaining good performance.

This patch improves IOPS and decreases CPU unilization on megaraid_sas,
per Kashyap's test.

Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Hannes Reinecke <hare@suse.de>
Reported-by: Kashyap Desai <kashyap.desai@broadcom.com>
Tested-by: Kashyap Desai <kashyap.desai@broadcom.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-07-17 16:04:00 -06:00
Josef Bacik
c1c80384c8 block: remove external dependency on wbt_flags
We don't really need to save this stuff in the core block code, we can
just pass the bio back into the helpers later on to derive the same
flags and update the rq->wbt_flags appropriately.

Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-07-09 09:07:54 -06:00
Josef Bacik
a79050434b blk-rq-qos: refactor out common elements of blk-wbt
blkcg-qos is going to do essentially what wbt does, only on a cgroup
basis.  Break out the common code that will be shared between blkcg-qos
and wbt into blk-rq-qos.* so they can both utilize the same
infrastructure.

Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-07-09 09:07:54 -06:00
Ming Lei
6e76871730 blk-mq: dequeue request one by one from sw queue if hctx is busy
It won't be efficient to dequeue request one by one from sw queue,
but we have to do that when queue is busy for better merge performance.

This patch takes the Exponential Weighted Moving Average(EWMA) to figure
out if queue is busy, then only dequeue request one by one from sw queue
when queue is busy.

Fixes: b347689ffb ("blk-mq-sched: improve dispatching from sw queue")
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Hannes Reinecke <hare@suse.de>
Reported-by: Kashyap Desai <kashyap.desai@broadcom.com>
Tested-by: Kashyap Desai <kashyap.desai@broadcom.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-07-09 09:07:53 -06:00
Ming Lei
3f0cedc7e9 blk-mq: use list_splice_tail_init() to insert requests
list_splice_tail_init() is much more faster than inserting each
request one by one, given all requets in 'list' belong to
same sw queue and ctx->lock is required to insert requests.

Cc: Laurence Oberman <loberman@redhat.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Bart Van Assche <bart.vanassche@wdc.com>
Tested-by: Kashyap Desai <kashyap.desai@broadcom.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-07-09 09:07:53 -06:00
Minwoo Im
c018c84fdb blk-mq: fix typo in a function comment
Fix typo in a function blk_mq_alloc_tag_set() comment.
if if it too large -> if it's too large.

Signed-off-by: Minwoo Im <minwoo.im.dev@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-07-09 09:07:53 -06:00
Minwoo Im
0da73d00ca blk-mq: code clean-up by adding an API to clear set->mq_map
set->mq_map is now currently cleared if something goes wrong when
establishing a queue map in blk-mq-pci.c.  It's also cleared before
updating a queue map in blk_mq_update_queue_map().

This patch provides an API to clear set->mq_map to make it clear.

Signed-off-by: Minwoo Im <minwoo.im.dev@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-07-09 09:07:53 -06:00
Ming Lei
97889f9ac2 blk-mq: remove synchronize_rcu() from blk_mq_del_queue_tag_set()
We have to remove synchronize_rcu() from blk_queue_cleanup(),
otherwise long delay can be caused during lun probe. For removing
it, we have to avoid to iterate the set->tag_list in IO path, eg,
blk_mq_sched_restart().

This patch reverts 5b79413946d (Revert "blk-mq: don't handle
TAG_SHARED in restart"). Given we have fixed enough IO hang issue,
and there isn't any reason to restart all queues in one tags any more,
see the following reasons:

1) blk-mq core can deal with shared-tags case well via blk_mq_get_driver_tag(),
which can wake up queues waiting for driver tag.

2) SCSI is a bit special because it may return BLK_STS_RESOURCE if queue,
target or host is ready, but SCSI built-in restart can cover all these well,
see scsi_end_request(), queue will be rerun after any request initiated from
this host/target is completed.

In my test on scsi_debug(8 luns), this patch may improve IOPS by 20% ~ 30%
when running I/O on these 8 luns concurrently.

Fixes: 705cda97ee ("blk-mq: Make it safe to use RCU to iterate over blk_mq_tag_set.tag_list")
Cc: Omar Sandoval <osandov@fb.com>
Cc: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: linux-scsi@vger.kernel.org
Reported-by: Andrew Jones <drjones@redhat.com>
Tested-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-07-09 09:07:52 -06:00
Ming Lei
5815839b3c blk-mq: introduce new lock for protecting hctx->dispatch_wait
Now hctx->lock is only acquired when adding hctx->dispatch_wait to
one wait queue, but not held when removing it from the wait queue.

IO hang can be observed easily if SCHED RESTART is disabled, that means
now RESTART exits just for fixing the issue in blk_mq_mark_tag_wait().

This patch fixes the issue by introducing hctx->dispatch_wait_lock and
holding it for removing hctx->dispatch_wait in blk_mq_dispatch_wake(),
since we need to avoid acquiring hctx->lock in irq context.

Fixes: eb619fdb2d ("blk-mq: fix issue with shared tag queue re-running")
Cc: Christoph Hellwig <hch@lst.de>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Bart Van Assche <bart.vanassche@wdc.com>
Tested-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-07-09 09:07:52 -06:00
Ming Lei
2278d69f03 blk-mq: don't pass **hctx to blk_mq_mark_tag_wait()
'hctx' won't be changed at all, so not necessary to pass
'**hctx' to blk_mq_mark_tag_wait().

Cc: Christoph Hellwig <hch@lst.de>
Cc: Bart Van Assche <bart.vanassche@wdc.com>
Tested-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-07-09 09:07:52 -06:00
Ming Lei
8ab6bb9ee8 blk-mq: cleanup blk_mq_get_driver_tag()
We never pass 'wait' as true to blk_mq_get_driver_tag(), and hence
we never change '**hctx' as well. The last use of these went away
with the flush cleanup, commit 0c2a6fe4dc.

So cleanup the usage and remove the two extra parameters.

Cc: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Tested-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-07-09 09:07:52 -06:00
Linus Torvalds
e6e5bec43c for-linus-20180629
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Merge tag 'for-linus-20180629' of git://git.kernel.dk/linux-block

Pull block fixes from Jens Axboe:
 "Small set of fixes for this series. Mostly just minor fixes, the only
  oddball in here is the sg change.

  The sg change came out of the stall fix for NVMe, where we added a
  mempool and limited us to a single page allocation. CONFIG_SG_DEBUG
  sort-of ruins that, since we'd need to account for that. That's
  actually a generic problem, since lots of drivers need to allocate SG
  lists. So this just removes support for CONFIG_SG_DEBUG, which I added
  back in 2007 and to my knowledge it was never useful.

  Anyway, outside of that, this pull contains:

   - clone of request with special payload fix (Bart)

   - drbd discard handling fix (Bart)

   - SATA blk-mq stall fix (me)

   - chunk size fix (Keith)

   - double free nvme rdma fix (Sagi)"

* tag 'for-linus-20180629' of git://git.kernel.dk/linux-block:
  sg: remove ->sg_magic member
  drbd: Fix drbd_request_prepare() discard handling
  blk-mq: don't queue more if we get a busy return
  block: Fix cloning of requests with a special payload
  nvme-rdma: fix possible double free of controller async event buffer
  block: Fix transfer when chunk sectors exceeds max
2018-06-30 10:47:46 -07:00
Jens Axboe
1f57f8d442 blk-mq: don't queue more if we get a busy return
Some devices have different queue limits depending on the type of IO. A
classic case is SATA NCQ, where some commands can queue, but others
cannot. If we have NCQ commands inflight and encounter a non-queueable
command, the driver returns busy. Currently we attempt to dispatch more
from the scheduler, if we were able to queue some commands. But for the
case where we ended up stopping due to BUSY, we should not attempt to
retrieve more from the scheduler. If we do, we can get into a situation
where we attempt to queue a non-queueable command, get BUSY, then
successfully retrieve more commands from that scheduler and queue those.
This can repeat forever, starving the non-queuable command indefinitely.

Fix this by NOT attempting to pull more commands from the scheduler, if
we get a BUSY return. This should also be more optimal in terms of
letting requests stay in the scheduler for as long as possible, if we
get a BUSY due to the regular out-of-tags condition.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-06-29 07:52:31 -06:00
Linus Torvalds
77072ca59f for-linus-20180623
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Merge tag 'for-linus-20180623' of git://git.kernel.dk/linux-block

Pull block fixes from Jens Axboe:

 - Further timeout fixes. We aren't quite there yet, so expect another
   round of fixes for that to completely close some of the IRQ vs
   completion races. (Christoph/Bart)

 - Set of NVMe fixes from the usual suspects, mostly error handling

 - Two off-by-one fixes (Dan)

 - Another bdi race fix (Jan)

 - Fix nbd reconfigure with NBD_DISCONNECT_ON_CLOSE (Doron)

* tag 'for-linus-20180623' of git://git.kernel.dk/linux-block:
  blk-mq: Fix timeout handling in case the timeout handler returns BLK_EH_DONE
  bdi: Fix another oops in wb_workfn()
  lightnvm: Remove depends on HAS_DMA in case of platform dependency
  nvme-pci: limit max IO size and segments to avoid high order allocations
  nvme-pci: move nvme_kill_queues to nvme_remove_dead_ctrl
  nvme-fc: release io queues to allow fast fail
  nbd: Add the nbd NBD_DISCONNECT_ON_CLOSE config flag.
  block: sed-opal: Fix a couple off by one bugs
  blk-mq-debugfs: Off by one in blk_mq_rq_state_name()
  nvmet: reset keep alive timer in controller enable
  nvme-rdma: don't override opts->queue_size
  nvme-rdma: Fix command completion race at error recovery
  nvme-rdma: fix possible free of a non-allocated async event buffer
  nvme-rdma: fix possible double free condition when failing to create a controller
  Revert "block: Add warning for bi_next not NULL in bio_endio()"
  block: fix timeout changes for legacy request drivers
2018-06-24 06:33:54 +08:00
Bart Van Assche
f5e350f021 blk-mq: Fix timeout handling in case the timeout handler returns BLK_EH_DONE
Make sure that RQF_TIMED_OUT is cleared when a request is reused
after a block driver timeout handler has returned BLK_EH_DONE.

Fixes: da66126739 ("blk-mq: don't time out requests again that are in the timeout handler")
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jianchao Wang <jianchao.w.wang@oracle.com>
Cc: Andrew Randrianasulu <randrianasulu@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-06-23 10:25:45 -06:00
Linus Torvalds
265c5596da for-linus-20180616
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Merge tag 'for-linus-20180616' of git://git.kernel.dk/linux-block

Pull block fixes from Jens Axboe:
 "A collection of fixes that should go into -rc1. This contains:

   - bsg_open vs bsg_unregister race fix (Anatoliy)

   - NVMe pull request from Christoph, with fixes for regressions in
     this window, FC connect/reconnect path code unification, and a
     trace point addition.

   - timeout fix (Christoph)

   - remove a few unused functions (Christoph)

   - blk-mq tag_set reinit fix (Roman)"

* tag 'for-linus-20180616' of git://git.kernel.dk/linux-block:
  bsg: fix race of bsg_open and bsg_unregister
  block: remov blk_queue_invalidate_tags
  nvme-fabrics: fix and refine state checks in __nvmf_check_ready
  nvme-fabrics: handle the admin-only case properly in nvmf_check_ready
  nvme-fabrics: refactor queue ready check
  blk-mq: remove blk_mq_tagset_iter
  nvme: remove nvme_reinit_tagset
  nvme-fc: fix nulling of queue data on reconnect
  nvme-fc: remove reinit_request routine
  blk-mq: don't time out requests again that are in the timeout handler
  nvme-fc: change controllers first connect to use reconnect path
  nvme: don't rely on the changed namespace list log
  nvmet: free smart-log buffer after use
  nvme-rdma: fix error flow during mapping request data
  nvme: add bio remapping tracepoint
  nvme: fix NULL pointer dereference in nvme_init_subsystem
  blk-mq: reinit q->tag_set_list entry only after grace period
2018-06-17 05:37:55 +09:00
Christoph Hellwig
da66126739 blk-mq: don't time out requests again that are in the timeout handler
We can currently call the timeout handler again on a request that has
already been handed over to the timeout handler.  Prevent that with a new
flag.

Fixes: 12f5b931 ("blk-mq: Remove generation seqeunce")
Reported-by: Andrew Randrianasulu <randrianasulu@gmail.com>
Tested-by: Andrew Randrianasulu <randrianasulu@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-06-14 08:39:46 -06:00
Kees Cook
590b5b7d86 treewide: kzalloc_node() -> kcalloc_node()
The kzalloc_node() function has a 2-factor argument form, kcalloc_node(). This
patch replaces cases of:

        kzalloc_node(a * b, gfp, node)

with:
        kcalloc_node(a * b, gfp, node)

as well as handling cases of:

        kzalloc_node(a * b * c, gfp, node)

with:

        kzalloc_node(array3_size(a, b, c), gfp, node)

as it's slightly less ugly than:

        kcalloc_node(array_size(a, b), c, gfp, node)

This does, however, attempt to ignore constant size factors like:

        kzalloc_node(4 * 1024, gfp, node)

though any constants defined via macros get caught up in the conversion.

Any factors with a sizeof() of "unsigned char", "char", and "u8" were
dropped, since they're redundant.

The Coccinelle script used for this was:

// Fix redundant parens around sizeof().
@@
type TYPE;
expression THING, E;
@@

(
  kzalloc_node(
-	(sizeof(TYPE)) * E
+	sizeof(TYPE) * E
  , ...)
|
  kzalloc_node(
-	(sizeof(THING)) * E
+	sizeof(THING) * E
  , ...)
)

// Drop single-byte sizes and redundant parens.
@@
expression COUNT;
typedef u8;
typedef __u8;
@@

(
  kzalloc_node(
-	sizeof(u8) * (COUNT)
+	COUNT
  , ...)
|
  kzalloc_node(
-	sizeof(__u8) * (COUNT)
+	COUNT
  , ...)
|
  kzalloc_node(
-	sizeof(char) * (COUNT)
+	COUNT
  , ...)
|
  kzalloc_node(
-	sizeof(unsigned char) * (COUNT)
+	COUNT
  , ...)
|
  kzalloc_node(
-	sizeof(u8) * COUNT
+	COUNT
  , ...)
|
  kzalloc_node(
-	sizeof(__u8) * COUNT
+	COUNT
  , ...)
|
  kzalloc_node(
-	sizeof(char) * COUNT
+	COUNT
  , ...)
|
  kzalloc_node(
-	sizeof(unsigned char) * COUNT
+	COUNT
  , ...)
)

// 2-factor product with sizeof(type/expression) and identifier or constant.
@@
type TYPE;
expression THING;
identifier COUNT_ID;
constant COUNT_CONST;
@@

(
- kzalloc_node
+ kcalloc_node
  (
-	sizeof(TYPE) * (COUNT_ID)
+	COUNT_ID, sizeof(TYPE)
  , ...)
|
- kzalloc_node
+ kcalloc_node
  (
-	sizeof(TYPE) * COUNT_ID
+	COUNT_ID, sizeof(TYPE)
  , ...)
|
- kzalloc_node
+ kcalloc_node
  (
-	sizeof(TYPE) * (COUNT_CONST)
+	COUNT_CONST, sizeof(TYPE)
  , ...)
|
- kzalloc_node
+ kcalloc_node
  (
-	sizeof(TYPE) * COUNT_CONST
+	COUNT_CONST, sizeof(TYPE)
  , ...)
|
- kzalloc_node
+ kcalloc_node
  (
-	sizeof(THING) * (COUNT_ID)
+	COUNT_ID, sizeof(THING)
  , ...)
|
- kzalloc_node
+ kcalloc_node
  (
-	sizeof(THING) * COUNT_ID
+	COUNT_ID, sizeof(THING)
  , ...)
|
- kzalloc_node
+ kcalloc_node
  (
-	sizeof(THING) * (COUNT_CONST)
+	COUNT_CONST, sizeof(THING)
  , ...)
|
- kzalloc_node
+ kcalloc_node
  (
-	sizeof(THING) * COUNT_CONST
+	COUNT_CONST, sizeof(THING)
  , ...)
)

// 2-factor product, only identifiers.
@@
identifier SIZE, COUNT;
@@

- kzalloc_node
+ kcalloc_node
  (
-	SIZE * COUNT
+	COUNT, SIZE
  , ...)

// 3-factor product with 1 sizeof(type) or sizeof(expression), with
// redundant parens removed.
@@
expression THING;
identifier STRIDE, COUNT;
type TYPE;
@@

(
  kzalloc_node(
-	sizeof(TYPE) * (COUNT) * (STRIDE)
+	array3_size(COUNT, STRIDE, sizeof(TYPE))
  , ...)
|
  kzalloc_node(
-	sizeof(TYPE) * (COUNT) * STRIDE
+	array3_size(COUNT, STRIDE, sizeof(TYPE))
  , ...)
|
  kzalloc_node(
-	sizeof(TYPE) * COUNT * (STRIDE)
+	array3_size(COUNT, STRIDE, sizeof(TYPE))
  , ...)
|
  kzalloc_node(
-	sizeof(TYPE) * COUNT * STRIDE
+	array3_size(COUNT, STRIDE, sizeof(TYPE))
  , ...)
|
  kzalloc_node(
-	sizeof(THING) * (COUNT) * (STRIDE)
+	array3_size(COUNT, STRIDE, sizeof(THING))
  , ...)
|
  kzalloc_node(
-	sizeof(THING) * (COUNT) * STRIDE
+	array3_size(COUNT, STRIDE, sizeof(THING))
  , ...)
|
  kzalloc_node(
-	sizeof(THING) * COUNT * (STRIDE)
+	array3_size(COUNT, STRIDE, sizeof(THING))
  , ...)
|
  kzalloc_node(
-	sizeof(THING) * COUNT * STRIDE
+	array3_size(COUNT, STRIDE, sizeof(THING))
  , ...)
)

// 3-factor product with 2 sizeof(variable), with redundant parens removed.
@@
expression THING1, THING2;
identifier COUNT;
type TYPE1, TYPE2;
@@

(
  kzalloc_node(
-	sizeof(TYPE1) * sizeof(TYPE2) * COUNT
+	array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2))
  , ...)
|
  kzalloc_node(
-	sizeof(TYPE1) * sizeof(THING2) * (COUNT)
+	array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2))
  , ...)
|
  kzalloc_node(
-	sizeof(THING1) * sizeof(THING2) * COUNT
+	array3_size(COUNT, sizeof(THING1), sizeof(THING2))
  , ...)
|
  kzalloc_node(
-	sizeof(THING1) * sizeof(THING2) * (COUNT)
+	array3_size(COUNT, sizeof(THING1), sizeof(THING2))
  , ...)
|
  kzalloc_node(
-	sizeof(TYPE1) * sizeof(THING2) * COUNT
+	array3_size(COUNT, sizeof(TYPE1), sizeof(THING2))
  , ...)
|
  kzalloc_node(
-	sizeof(TYPE1) * sizeof(THING2) * (COUNT)
+	array3_size(COUNT, sizeof(TYPE1), sizeof(THING2))
  , ...)
)

// 3-factor product, only identifiers, with redundant parens removed.
@@
identifier STRIDE, SIZE, COUNT;
@@

(
  kzalloc_node(
-	(COUNT) * STRIDE * SIZE
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kzalloc_node(
-	COUNT * (STRIDE) * SIZE
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kzalloc_node(
-	COUNT * STRIDE * (SIZE)
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kzalloc_node(
-	(COUNT) * (STRIDE) * SIZE
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kzalloc_node(
-	COUNT * (STRIDE) * (SIZE)
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kzalloc_node(
-	(COUNT) * STRIDE * (SIZE)
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kzalloc_node(
-	(COUNT) * (STRIDE) * (SIZE)
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kzalloc_node(
-	COUNT * STRIDE * SIZE
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
)

// Any remaining multi-factor products, first at least 3-factor products,
// when they're not all constants...
@@
expression E1, E2, E3;
constant C1, C2, C3;
@@

(
  kzalloc_node(C1 * C2 * C3, ...)
|
  kzalloc_node(
-	(E1) * E2 * E3
+	array3_size(E1, E2, E3)
  , ...)
|
  kzalloc_node(
-	(E1) * (E2) * E3
+	array3_size(E1, E2, E3)
  , ...)
|
  kzalloc_node(
-	(E1) * (E2) * (E3)
+	array3_size(E1, E2, E3)
  , ...)
|
  kzalloc_node(
-	E1 * E2 * E3
+	array3_size(E1, E2, E3)
  , ...)
)

// And then all remaining 2 factors products when they're not all constants,
// keeping sizeof() as the second factor argument.
@@
expression THING, E1, E2;
type TYPE;
constant C1, C2, C3;
@@

(
  kzalloc_node(sizeof(THING) * C2, ...)
|
  kzalloc_node(sizeof(TYPE) * C2, ...)
|
  kzalloc_node(C1 * C2 * C3, ...)
|
  kzalloc_node(C1 * C2, ...)
|
- kzalloc_node
+ kcalloc_node
  (
-	sizeof(TYPE) * (E2)
+	E2, sizeof(TYPE)
  , ...)
|
- kzalloc_node
+ kcalloc_node
  (
-	sizeof(TYPE) * E2
+	E2, sizeof(TYPE)
  , ...)
|
- kzalloc_node
+ kcalloc_node
  (
-	sizeof(THING) * (E2)
+	E2, sizeof(THING)
  , ...)
|
- kzalloc_node
+ kcalloc_node
  (
-	sizeof(THING) * E2
+	E2, sizeof(THING)
  , ...)
|
- kzalloc_node
+ kcalloc_node
  (
-	(E1) * E2
+	E1, E2
  , ...)
|
- kzalloc_node
+ kcalloc_node
  (
-	(E1) * (E2)
+	E1, E2
  , ...)
|
- kzalloc_node
+ kcalloc_node
  (
-	E1 * E2
+	E1, E2
  , ...)
)

Signed-off-by: Kees Cook <keescook@chromium.org>
2018-06-12 16:19:22 -07:00
Roman Pen
a347c7ad8e blk-mq: reinit q->tag_set_list entry only after grace period
It is not allowed to reinit q->tag_set_list list entry while RCU grace
period has not completed yet, otherwise the following soft lockup in
blk_mq_sched_restart() happens:

[ 1064.252652] watchdog: BUG: soft lockup - CPU#12 stuck for 23s! [fio:9270]
[ 1064.254445] task: ffff99b912e8b900 task.stack: ffffa6d54c758000
[ 1064.254613] RIP: 0010:blk_mq_sched_restart+0x96/0x150
[ 1064.256510] Call Trace:
[ 1064.256664]  <IRQ>
[ 1064.256824]  blk_mq_free_request+0xea/0x100
[ 1064.256987]  msg_io_conf+0x59/0xd0 [ibnbd_client]
[ 1064.257175]  complete_rdma_req+0xf2/0x230 [ibtrs_client]
[ 1064.257340]  ? ibtrs_post_recv_empty+0x4d/0x70 [ibtrs_core]
[ 1064.257502]  ibtrs_clt_rdma_done+0xd1/0x1e0 [ibtrs_client]
[ 1064.257669]  ib_create_qp+0x321/0x380 [ib_core]
[ 1064.257841]  ib_process_cq_direct+0xbd/0x120 [ib_core]
[ 1064.258007]  irq_poll_softirq+0xb7/0xe0
[ 1064.258165]  __do_softirq+0x106/0x2a2
[ 1064.258328]  irq_exit+0x92/0xa0
[ 1064.258509]  do_IRQ+0x4a/0xd0
[ 1064.258660]  common_interrupt+0x7a/0x7a
[ 1064.258818]  </IRQ>

Meanwhile another context frees other queue but with the same set of
shared tags:

[ 1288.201183] INFO: task bash:5910 blocked for more than 180 seconds.
[ 1288.201833] bash            D    0  5910   5820 0x00000000
[ 1288.202016] Call Trace:
[ 1288.202315]  schedule+0x32/0x80
[ 1288.202462]  schedule_timeout+0x1e5/0x380
[ 1288.203838]  wait_for_completion+0xb0/0x120
[ 1288.204137]  __wait_rcu_gp+0x125/0x160
[ 1288.204287]  synchronize_sched+0x6e/0x80
[ 1288.204770]  blk_mq_free_queue+0x74/0xe0
[ 1288.204922]  blk_cleanup_queue+0xc7/0x110
[ 1288.205073]  ibnbd_clt_unmap_device+0x1bc/0x280 [ibnbd_client]
[ 1288.205389]  ibnbd_clt_unmap_dev_store+0x169/0x1f0 [ibnbd_client]
[ 1288.205548]  kernfs_fop_write+0x109/0x180
[ 1288.206328]  vfs_write+0xb3/0x1a0
[ 1288.206476]  SyS_write+0x52/0xc0
[ 1288.206624]  do_syscall_64+0x68/0x1d0
[ 1288.206774]  entry_SYSCALL_64_after_hwframe+0x3d/0xa2

What happened is the following:

1. There are several MQ queues with shared tags.
2. One queue is about to be freed and now task is in
   blk_mq_del_queue_tag_set().
3. Other CPU is in blk_mq_sched_restart() and loops over all queues in
   tag list in order to find hctx to restart.

Because linked list entry was modified in blk_mq_del_queue_tag_set()
without proper waiting for a grace period, blk_mq_sched_restart()
never ends, spining in list_for_each_entry_rcu_rr(), thus soft lockup.

Fix is simple: reinit list entry after an RCU grace period elapsed.

Fixes: Fixes: 705cda97ee ("blk-mq: Make it safe to use RCU to iterate over blk_mq_tag_set.tag_list")
Cc: stable@vger.kernel.org
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: linux-block@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Roman Pen <roman.penyaev@profitbricks.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-06-11 08:13:41 -06:00
Jianchao Wang
0196d6b408 blk-mq: return when hctx is stopped in blk_mq_run_work_fn
If a hardware queue is stopped, it should not be run again before
explicitly started. Ignore stopped queues in blk_mq_run_work_fn(),
fixing a regression recently introduced when the START_ON_RUN bit
was removed.

Fixes: 15fe8a90bb ("blk-mq: remove blk_mq_delay_queue()")
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-06-04 12:10:40 -06:00
Christoph Hellwig
131d08e122 block: split the blk-mq case from elevator_init
There is almost no shared logic, which leads to a very confusing code
flow.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Tested-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-06-01 07:38:21 -06:00
Christoph Hellwig
acddf3b308 block: move sysfs_lock into elevator_init
Both callers take just around so function call, so move it in.
Also remove the now pointless blk_mq_sched_init wrapper.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Tested-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-06-01 07:38:19 -06:00
Christoph Hellwig
d1210d5afb blk-mq: simplify blk_mq_rq_timed_out
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-05-29 08:59:21 -06:00
Christoph Hellwig
f6e7d48a78 block: remove BLK_EH_HANDLED
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-05-29 08:59:21 -06:00
Christoph Hellwig
6600593cbd block: rename BLK_EH_NOT_HANDLED to BLK_EH_DONE
The BLK_EH_NOT_HANDLED implies nothing happen, but very often that
is not what is happening - instead the driver already completed the
command.  Fix the symbolic name to reflect that a little better.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-05-29 08:59:21 -06:00
Keith Busch
12f5b93145 blk-mq: Remove generation seqeunce
This patch simplifies the timeout handling by relying on the request
reference counting to ensure the iterator is operating on an inflight
and truly timed out request. Since the reference counting prevents the
tag from being reallocated, the block layer no longer needs to prevent
drivers from completing their requests while the timeout handler is
operating on it: a driver completing a request is allowed to proceed to
the next state without additional syncronization with the block layer.

This also removes any need for generation sequence numbers since the
request lifetime is prevented from being reallocated as a new sequence
while timeout handling is operating on it.

To enables this a refcount is added to struct request so that request
users can be sure they're operating on the same request without it
changing while they're processing it.  The request's tag won't be
released for reuse until both the timeout handler and the completion
are done with it.

Signed-off-by: Keith Busch <keith.busch@intel.com>
[hch: slight cleanups, added back submission side hctx lock, use cmpxchg
 for completions]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-05-29 08:59:21 -06:00
Keith Busch
ad103e7983 blk-mq: Fix timeout and state order
The block layer had been setting the state to in-flight prior to updating
the timer. This is the wrong order since the timeout handler could observe
the in-flight state with the older timeout, believing the request had
expired when in fact it is just getting started.

Signed-off-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-05-29 08:47:40 -06:00
huhai
b4f6f38d9f blk-mq: remove wrong 'unlikely' check
When dispatch_rq_from_ctx is called, in the vast majority of cases
the ctx->rq_list is not empty.

Signed-off-by: huhai <huhai@kylinos.cn>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-05-22 08:38:04 -06:00
huhai
d416c92c5d blk-mq: clear hctx->dispatch_from when mappings change
When the number of hardware queues is changed, the drivers will call
blk_mq_update_nr_hw_queues() to remap hardware queues. This changes
the ctx mappings, but the current code doesn't clear the
->dispatch_from hint. This can result in dispatch_from pointing to
a ctx that isn't mapped to the hctx anymore.

Fixes: b347689ffb ("blk-mq-sched: improve dispatching from sw queue")
Signed-off-by: huhai <huhai@kylinos.cn>
Reviewed-by: Ming Lei <ming.lei@redhat.com>

Moved the placement of the clearing to where we clear other items
pertaining to the existing mapping, added Fixes line, and reworded
the commit message.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-05-18 08:35:38 -06:00
huhai
8fa9f55645 blk-mq: remove redundant insert case in blk_mq_make_request()
We can use blk_mq_sched_insert_request() even if we don't have
an IO scheduler attached, since that case will end up being
exactly the same as what blk_mq_queue_io() was doing now.

Signed-off-by: huhai <huhai@kylinos.cn>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-05-16 08:22:47 -06:00
Jens Axboe
17a5119932 blk-mq: don't call into depth limiting for reserved tags
It's not useful, they are internal and/or error handling recovery
commands.

Acked-by: Paolo Valente <paolo.valente@linaro.org>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-05-10 11:27:12 -06:00
Omar Sandoval
522a777566 block: consolidate struct request timestamp fields
Currently, struct request has four timestamp fields:

- A start time, set at get_request time, in jiffies, used for iostats
- An I/O start time, set at start_request time, in ktime nanoseconds,
  used for blk-stats (i.e., wbt, kyber, hybrid polling)
- Another start time and another I/O start time, used for cfq and bfq

These can all be consolidated into one start time and one I/O start
time, both in ktime nanoseconds, shaving off up to 16 bytes from struct
request depending on the kernel config.

Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-05-09 08:33:09 -06:00
Omar Sandoval
4bc6339a58 block: move blk_stat_add() to __blk_mq_end_request()
We want this next to blk_account_io_done() for the next change so that
we can call ktime_get() only once for both.

Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-05-09 08:33:07 -06:00
Omar Sandoval
544ccc8dc9 block: get rid of struct blk_issue_stat
struct blk_issue_stat squashes three things into one u64:

- The time the driver started working on a request
- The original size of the request (for the io.low controller)
- Flags for writeback throttling

It turns out that on x86_64, we have a 4 byte hole in struct request
which we can fill with the non-timestamp fields from blk_issue_stat,
simplifying things quite a bit.

Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-05-09 08:33:05 -06:00
Omar Sandoval
a8a4594170 block: pass struct request instead of struct blk_issue_stat to wbt
issue_stat is going to go away, so first make writeback throttling take
the containing request, update the internal wbt helpers accordingly, and
change rwb->sync_cookie to be the request pointer instead of the
issue_stat pointer. No functional change.

Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-05-09 08:33:02 -06:00
Omar Sandoval
bf0ddaba65 blk-mq: fix sysfs inflight counter
When the blk-mq inflight implementation was added, /proc/diskstats was
converted to use it, but /sys/block/$dev/inflight was not. Fix it by
adding another helper to count in-flight requests by data direction.

Fixes: f299b7c7a9 ("blk-mq: provide internal in-flight variant")
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-04-26 09:02:01 -06:00
Omar Sandoval
6131837b1d blk-mq: count allocated but not started requests in iostats inflight
In the legacy block case, we increment the counter right after we
allocate the request, not when the driver handles it. In both the legacy
and blk-mq cases, part_inc_in_flight() is called from
blk_account_io_start() right after we've allocated the request. blk-mq
only considers requests started requests as inflight, but this is
inconsistent with the legacy definition and the intention in the code.
This removes the started condition and instead counts all allocated
requests.

Fixes: f299b7c7a9 ("blk-mq: provide internal in-flight variant")
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-04-26 09:02:00 -06:00
Ming Lei
4412efecf7 Revert "blk-mq: remove code for dealing with remapping queue"
This reverts commit 37c7c6c76d.

Turns out some drivers(most are FC drivers) may not use managed
IRQ affinity, and has their customized .map_queues meantime, so
still keep this code for avoiding regression.

Reported-by: Laurence Oberman <loberman@redhat.com>
Tested-by: Laurence Oberman <loberman@redhat.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Tested-by: Stefan Haberland <sth@linux.vnet.ibm.com>
Cc: Ewan Milne <emilne@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-04-25 09:49:22 -06:00
Jianchao Wang
f4560231ec blk-mq: start request gstate with gen 1
rq->gstate and rq->aborted_gstate both are zero before rqs are
allocated. If we have a small timeout, when the timer fires,
there could be rqs that are never allocated, and also there could
be rq that has been allocated but not initialized and started. At
the moment, the rq->gstate and rq->aborted_gstate both are 0, thus
the blk_mq_terminate_expired will identify the rq is timed out and
invoke .timeout early.

For scsi, this will cause scsi_times_out to be invoked before the
scsi_cmnd is not initialized, scsi_cmnd->device is still NULL at
the moment, then we will get crash.

Cc: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Martin Steigerwald <Martin@Lichtvoll.de>
Cc: stable@vger.kernel.org
Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-04-16 21:56:41 -06:00
Ming Lei
37c7c6c76d blk-mq: remove code for dealing with remapping queue
Firstly, from commit 4b855ad371 ("blk-mq: Create hctx for each present CPU),
blk-mq doesn't remap queue any more after CPU topo is changed.

Secondly, set->nr_hw_queues can't be bigger than nr_cpu_ids, and now we map
all possible CPUs to hw queues, so at least one CPU is mapped to each hctx.

So queue mapping has became static and fixed just like percpu variable, and
we don't need to handle queue remapping any more.

Cc: Stefan Haberland <sth@linux.vnet.ibm.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-04-10 08:38:46 -06:00
Ming Lei
efea8450c3 blk-mq: don't check queue mapped in __blk_mq_delay_run_hw_queue()
There are several reasons for removing the check:

1) blk_mq_hw_queue_mapped() returns true always now since each hctx
may be mapped by one CPU at least

2) when there isn't any online CPU mapped to this hctx, there won't
be any IO queued to this CPU, blk_mq_run_hw_queue() only runs queue
if there is IO queued to this hctx

3) If __blk_mq_delay_run_hw_queue() is called by blk_mq_delay_run_hw_queue(),
which is run from blk_mq_dispatch_rq_list() or scsi_mq_get_budget(), and
the hctx to be handled has to be mapped.

Cc: Stefan Haberland <sth@linux.vnet.ibm.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-04-10 08:38:46 -06:00
Ming Lei
15fe8a90bb blk-mq: remove blk_mq_delay_queue()
No driver uses this interface any more, so remove it.

Cc: Stefan Haberland <sth@linux.vnet.ibm.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-04-10 08:38:46 -06:00
Ming Lei
f82ddf1923 blk-mq: introduce blk_mq_hw_queue_first_cpu() to figure out first cpu
This patch introduces helper of blk_mq_hw_queue_first_cpu() for
figuring out the hctx's first cpu, and code duplication can be
avoided.

Cc: Stefan Haberland <sth@linux.vnet.ibm.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-04-10 08:38:46 -06:00
Ming Lei
476f8c98a9 blk-mq: avoid to write intermediate result to hctx->next_cpu
This patch figures out the final selected CPU, then writes
it to hctx->next_cpu once, then we can avoid to intermediate
next cpu observed from other dispatch paths.

Cc: Stefan Haberland <sth@linux.vnet.ibm.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-04-10 08:38:46 -06:00
Ming Lei
a1c735fb79 blk-mq: make sure that correct hctx->next_cpu is set
From commit 20e4d81393 (blk-mq: simplify queue mapping & schedule
with each possisble CPU), one hctx can be mapped from all offline CPUs,
then hctx->next_cpu can be set as wrong.

This patch fixes this issue by making hctx->next_cpu pointing to the
first CPU in hctx->cpumask if all CPUs in hctx->cpumask are offline.

Cc: Stefan Haberland <sth@linux.vnet.ibm.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Fixes: 20e4d81393 ("blk-mq: simplify queue mapping & schedule with each possisble CPU")
Cc: stable@vger.kernel.org
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-04-10 08:38:46 -06:00
Ming Lei
0bca799b92 blk-mq: order getting budget and driver tag
This patch orders getting budget and driver tag by making sure to acquire
driver tag after budget is got, this way can help to avoid the following
race:

1) before dispatch request from scheduler queue, get one budget first, then
dequeue a request, call it request A.

2) in another IO path for dispatching request B which is from hctx->dispatch,
driver tag is got, then try to get budget in blk_mq_dispatch_rq_list(),
unfortunately the budget is held by request A.

3) meantime blk_mq_dispatch_rq_list() is called for dispatching request
A, and try to get driver tag first, unfortunately no driver tag is
available because the driver tag is held by request B

4) both two IO pathes can't move on, and IO stall is caused.

This issue can be observed when running dbench on USB storage.

This patch fixes this issue by always getting budget before getting
driver tag.

Cc: stable@vger.kernel.org
Fixes: de14829740 ("blk-mq: introduce .get_budget and .put_budget in blk_mq_ops")
Cc: Christoph Hellwig <hch@lst.de>
Cc: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Omar Sandoval <osandov@fb.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-04-10 08:38:46 -06:00
Bart Van Assche
7dfdbc7367 block: Protect queue flag changes with the queue lock
Since the queue flags may be changed concurrently from multiple
contexts after a queue becomes visible in sysfs, make these changes
safe by protecting these with the queue lock.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-03-08 14:13:48 -07:00
Bart Van Assche
8814ce8a0f block: Introduce blk_queue_flag_{set,clear,test_and_{set,clear}}()
Introduce functions that modify the queue flags and that protect
these modifications with the request queue lock. Except for moving
one wake_up_all() call from inside to outside a critical section,
this patch does not change any functionality.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-03-08 14:13:48 -07:00
Bart Van Assche
f78bac2c8e block: Use the queue_flag_*() functions instead of open-coding these
Except for changing the atomic queue flag manipulations that are
protected by the queue lock into non-atomic manipulations, this
patch does not change any functionality.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-03-08 14:13:48 -07:00
Bart Van Assche
5ee0524ba1 block: Add 'lock' as third argument to blk_alloc_queue_node()
This patch does not change any functionality.

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Philipp Reisner <philipp.reisner@linbit.com>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-02-28 12:23:35 -07:00
Omar Sandoval
e9a99a6388 block: clear ctx pending bit under ctx lock
When we insert a request, we set the software queue pending bit while
holding the software queue lock. However, we clear it outside of the
lock, so it's possible that a concurrent insert could reset the bit
after we clear it but before we empty the request list. Afterwards, the
bit would still be set but the software queue wouldn't have any requests
in it, leading us to do a spurious run in the future. This is mostly a
benign/theoretical issue, but it makes the following change easier to
justify.

Signed-off-by: Omar Sandoval <osandov@fb.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-02-28 12:23:35 -07:00
Ming Lei
105976f517 blk-mq: don't call io sched's .requeue_request when requeueing rq to ->dispatch
__blk_mq_requeue_request() covers two cases:

- one is that the requeued request is added to hctx->dispatch, such as
blk_mq_dispatch_rq_list()

- another case is that the request is requeued to io scheduler, such as
blk_mq_requeue_request().

We should call io sched's .requeue_request callback only for the 2nd
case.

Cc: Paolo Valente <paolo.valente@linaro.org>
Cc: Omar Sandoval <osandov@fb.com>
Fixes: bd166ef183 ("blk-mq-sched: add framework for MQ capable IO schedulers")
Cc: stable@vger.kernel.org
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Acked-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-02-24 15:55:54 -07:00
Nitesh Shetty
67b4110f8c blk: optimization for classic polling
This removes the dependency on interrupts to wake up task. Set task
state as TASK_RUNNING, if need_resched() returns true,
while polling for IO completion.
Earlier, polling task used to sleep, relying on interrupt to wake it up.
This made some IO take very long when interrupt-coalescing is enabled in
NVMe.

Reference:
http://lists.infradead.org/pipermail/linux-nvme/2018-February/015435.html

Changes since v2->v3:
	-using __set_current_state() instead of set_current_state()

Changes since v1->v2:
	-setting task state once in blk_poll, instead of multiple
callers.

Signed-off-by: Nitesh Shetty <nj.shetty@samsung.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-02-13 09:12:04 -07:00
Ming Lei
86ff7c2a80 blk-mq: introduce BLK_STS_DEV_RESOURCE
This status is returned from driver to block layer if device related
resource is unavailable, but driver can guarantee that IO dispatch
will be triggered in future when the resource is available.

Convert some drivers to return BLK_STS_DEV_RESOURCE.  Also, if driver
returns BLK_STS_RESOURCE and SCHED_RESTART is set, rerun queue after
a delay (BLK_MQ_DELAY_QUEUE) to avoid IO stalls.  BLK_MQ_DELAY_QUEUE is
3 ms because both scsi-mq and nvmefc are using that magic value.

If a driver can make sure there is in-flight IO, it is safe to return
BLK_STS_DEV_RESOURCE because:

1) If all in-flight IOs complete before examining SCHED_RESTART in
blk_mq_dispatch_rq_list(), SCHED_RESTART must be cleared, so queue
is run immediately in this case by blk_mq_dispatch_rq_list();

2) if there is any in-flight IO after/when examining SCHED_RESTART
in blk_mq_dispatch_rq_list():
- if SCHED_RESTART isn't set, queue is run immediately as handled in 1)
- otherwise, this request will be dispatched after any in-flight IO is
  completed via blk_mq_sched_restart()

3) if SCHED_RESTART is set concurently in context because of
BLK_STS_RESOURCE, blk_mq_delay_run_hw_queue() will cover the above two
cases and make sure IO hang can be avoided.

One invariant is that queue will be rerun if SCHED_RESTART is set.

Suggested-by: Jens Axboe <axboe@kernel.dk>
Tested-by: Laurence Oberman <loberman@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-30 20:18:28 -07:00
Linus Torvalds
0a4b6e2f80 Merge branch 'for-4.16/block' of git://git.kernel.dk/linux-block
Pull block updates from Jens Axboe:
 "This is the main pull request for block IO related changes for the
  4.16 kernel. Nothing major in this pull request, but a good amount of
  improvements and fixes all over the map. This contains:

   - BFQ improvements, fixes, and cleanups from Angelo, Chiara, and
     Paolo.

   - Support for SMR zones for deadline and mq-deadline from Damien and
     Christoph.

   - Set of fixes for bcache by way of Michael Lyle, including fixes
     from himself, Kent, Rui, Tang, and Coly.

   - Series from Matias for lightnvm with fixes from Hans Holmberg,
     Javier, and Matias. Mostly centered around pblk, and the removing
     rrpc 1.2 in preparation for supporting 2.0.

   - A couple of NVMe pull requests from Christoph. Nothing major in
     here, just fixes and cleanups, and support for command tracing from
     Johannes.

   - Support for blk-throttle for tracking reads and writes separately.
     From Joseph Qi. A few cleanups/fixes also for blk-throttle from
     Weiping.

   - Series from Mike Snitzer that enables dm to register its queue more
     logically, something that's alwways been problematic on dm since
     it's a stacked device.

   - Series from Ming cleaning up some of the bio accessor use, in
     preparation for supporting multipage bvecs.

   - Various fixes from Ming closing up holes around queue mapping and
     quiescing.

   - BSD partition fix from Richard Narron, fixing a problem where we
     can't mount newer (10/11) FreeBSD partitions.

   - Series from Tejun reworking blk-mq timeout handling. The previous
     scheme relied on atomic bits, but it had races where we would think
     a request had timed out if it to reused at the wrong time.

   - null_blk now supports faking timeouts, to enable us to better
     exercise and test that functionality separately. From me.

   - Kill the separate atomic poll bit in the request struct. After
     this, we don't use the atomic bits on blk-mq anymore at all. From
     me.

   - sgl_alloc/free helpers from Bart.

   - Heavily contended tag case scalability improvement from me.

   - Various little fixes and cleanups from Arnd, Bart, Corentin,
     Douglas, Eryu, Goldwyn, and myself"

* 'for-4.16/block' of git://git.kernel.dk/linux-block: (186 commits)
  block: remove smart1,2.h
  nvme: add tracepoint for nvme_complete_rq
  nvme: add tracepoint for nvme_setup_cmd
  nvme-pci: introduce RECONNECTING state to mark initializing procedure
  nvme-rdma: remove redundant boolean for inline_data
  nvme: don't free uuid pointer before printing it
  nvme-pci: Suspend queues after deleting them
  bsg: use pr_debug instead of hand crafted macros
  blk-mq-debugfs: don't allow write on attributes with seq_operations set
  nvme-pci: Fix queue double allocations
  block: Set BIO_TRACE_COMPLETION on new bio during split
  blk-throttle: use queue_is_rq_based
  block: Remove kblockd_schedule_delayed_work{,_on}()
  blk-mq: Avoid that blk_mq_delay_run_hw_queue() introduces unintended delays
  blk-mq: Rename blk_mq_request_direct_issue() into blk_mq_request_issue_directly()
  lib/scatterlist: Fix chaining support in sgl_alloc_order()
  blk-throttle: track read and write request individually
  block: add bdev_read_only() checks to common helpers
  block: fail op_is_write() requests to read-only partitions
  blk-throttle: export io_serviced_recursive, io_service_bytes_recursive
  ...
2018-01-29 11:51:49 -08:00
Bart Van Assche
ae943d2062 blk-mq: Avoid that blk_mq_delay_run_hw_queue() introduces unintended delays
Make sure that calling blk_mq_run_hw_queue() or
blk_mq_kick_requeue_list() triggers a queue run without delay even
if blk_mq_delay_run_hw_queue() has been called recently and if its
delay has not yet expired.

Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-19 12:52:01 -07:00
Bart Van Assche
c77ff7fd03 blk-mq: Rename blk_mq_request_direct_issue() into blk_mq_request_issue_directly()
Most blk-mq functions have a name that follows the pattern blk_mq_${action}.
However, the function name blk_mq_request_direct_issue is an exception.
Hence rename this function. This patch does not change any functionality.

Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-19 12:51:59 -07:00
Ming Lei
23d4ee19e7 blk-mq: don't dispatch request in blk_mq_request_direct_issue if queue is busy
If we run into blk_mq_request_direct_issue(), when queue is busy, we
don't want to dispatch this request into hctx->dispatch_list, and
what we need to do is to return the queue busy info to caller, so
that caller can deal with it well.

Fixes: 396eaf21ee ("blk-mq: improve DM's blk-mq IO merging via blk_insert_cloned_request feedback")
Reported-by: Laurence Oberman <loberman@redhat.com>
Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-17 21:38:52 -07:00
Mike Snitzer
9e97d2951a blk-mq-sched: remove unused 'can_block' arg from blk_mq_sched_insert_request
After commit:

923218f616 ("blk-mq: don't allocate driver tag upfront for flush rq")

we no longer use the 'can_block' argument in
blk_mq_sched_insert_request(). Kill it.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Added actual commit message as to why it's being removed.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-17 09:49:21 -07:00
Ming Lei
396eaf21ee blk-mq: improve DM's blk-mq IO merging via blk_insert_cloned_request feedback
blk_insert_cloned_request() is called in the fast path of a dm-rq driver
(e.g. blk-mq request-based DM mpath).  blk_insert_cloned_request() uses
blk_mq_request_bypass_insert() to directly append the request to the
blk-mq hctx->dispatch_list of the underlying queue.

1) This way isn't efficient enough because the hctx spinlock is always
used.

2) With blk_insert_cloned_request(), we completely bypass underlying
queue's elevator and depend on the upper-level dm-rq driver's elevator
to schedule IO.  But dm-rq currently can't get the underlying queue's
dispatch feedback at all.  Without knowing whether a request was issued
or not (e.g. due to underlying queue being busy) the dm-rq elevator will
not be able to provide effective IO merging (as a side-effect of dm-rq
currently blindly destaging a request from its elevator only to requeue
it after a delay, which kills any opportunity for merging).  This
obviously causes very bad sequential IO performance.

Fix this by updating blk_insert_cloned_request() to use
blk_mq_request_direct_issue().  blk_mq_request_direct_issue() allows a
request to be issued directly to the underlying queue and returns the
dispatch feedback (blk_status_t).  If blk_mq_request_direct_issue()
returns BLK_SYS_RESOURCE the dm-rq driver will now use DM_MAPIO_REQUEUE
to _not_ destage the request.  Whereby preserving the opportunity to
merge IO.

With this, request-based DM's blk-mq sequential IO performance is vastly
improved (as much as 3X in mpath/virtio-scsi testing).

Signed-off-by: Ming Lei <ming.lei@redhat.com>
[blk-mq.c changes heavily influenced by Ming Lei's initial solution, but
they were refactored to make them less fragile and easier to read/review]
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-17 09:46:54 -07:00
Mike Snitzer
0f95549c0e blk-mq: factor out a few helpers from __blk_mq_try_issue_directly
No functional change.  Just makes code flow more logically.

In following commit, __blk_mq_try_issue_directly() will be used to
return the dispatch result (blk_status_t) to DM.  DM needs this
information to improve IO merging.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-17 09:46:50 -07:00
Ming Lei
7df938fbc4 blk-mq: turn WARN_ON in __blk_mq_run_hw_queue into printk
We know this WARN_ON is harmless and in reality it may be trigged,
so convert it to printk() and dump_stack() to avoid to confusing
people.

Also add comment about two releated races here.

Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Stefan Haberland <sth@linux.vnet.ibm.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "jianchao.wang" <jianchao.w.wang@oracle.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-17 09:46:27 -07:00
Ming Lei
7bed45954b blk-mq: make sure hctx->next_cpu is set correctly
When hctx->next_cpu is set from possible online CPUs, there is one
race in which hctx->next_cpu may be set as >= nr_cpu_ids, and finally
break workqueue.

The race can be triggered in the following two sitations:

1) when one CPU is becoming DEAD, blk_mq_hctx_notify_dead() is called
to dispatch requests from the DEAD cpu context, but at that
time, this DEAD CPU has been cleared from 'cpu_online_mask', so all
CPUs in hctx->cpumask may become offline, and cause hctx->next_cpu set
a bad value.

2) blk_mq_delay_run_hw_queue() is called from CPU B, and found the queue
should be run on the other CPU A, then CPU A may become offline at the
same time and all CPUs in hctx->cpumask become offline.

This patch deals with this issue by re-selecting next CPU, and making
sure it is set correctly.

Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Stefan Haberland <sth@linux.vnet.ibm.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Reported-by: "jianchao.wang" <jianchao.w.wang@oracle.com>
Tested-by: "jianchao.wang" <jianchao.w.wang@oracle.com>
Fixes: 20e4d81393 ("blk-mq: simplify queue mapping & schedule with each possisble CPU")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-17 09:46:26 -07:00
Jens Axboe
bf9ae8c532 blk-mq: fix bad clear of RQF_MQ_INFLIGHT in blk_mq_ct_ctx_init()
A previous commit moved the clearing of rq->rq_flags later,
but we may have already set RQF_MQ_INFLIGHT when that happens.
Ensure that we correctly initialize rq->rq_flags to the
right value.

This is based on an original fix by Ming, just rewritten to not
require a conditional.

Fixes: 7c3fb70f03 ("block: rearrange a few request fields for better cache layout")
Reviewed-by:  Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-14 10:46:24 -07:00
Christoph Hellwig
20e4d81393 blk-mq: simplify queue mapping & schedule with each possisble CPU
The previous patch assigns interrupt vectors to all possible CPUs, so
now hctx can be mapped to possible CPUs, this patch applies this fact
to simplify queue mapping & schedule so that we don't need to handle
CPU hotplug for dealing with physical CPU plug & unplug. With this
simplication, we can work well on physical CPU plug & unplug, which
is a normal use case for VM at least.

Make sure we allocate blk_mq_ctx structures for all possible CPUs, and
set hctx->numa_node for possible CPUs which are mapped to this hctx. And
only choose the online CPUs for schedule.

Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Tested-by: Stefan Haberland <sth@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Fixes: 4b855ad371 ("blk-mq: Create hctx for each present CPU")
(merged the three into one because any single one may not work, and fix
selecting online CPUs for scheduler)
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-12 11:01:40 -07:00
Bart Van Assche
c27d53fb44 blk-mq: Reduce the number of if-statements in blk_mq_mark_tag_wait()
This patch does not change any functionality but makes the
blk_mq_mark_tag_wait() code slightly easier to read.

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-11 09:59:35 -07:00
Bart Van Assche
b7435db8b8 blk-mq: Add locking annotations to hctx_lock() and hctx_unlock()
This patch avoids that sparse reports the following:

block/blk-mq.c:637:33: warning: context imbalance in 'hctx_unlock' - unexpected unlock
block/blk-mq.c:642:9: warning: context imbalance in 'hctx_lock' - wrong count at exit

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-10 12:36:02 -07:00
Jens Axboe
7c3fb70f03 block: rearrange a few request fields for better cache layout
Move completion related items (like the call single data) near the
end of the struct, instead of mixing them in with the initial
queueing related fields.

Move queuelist below the bio structures. Then we have all
queueing related bits in the first cache line.

This yields a 1.5-2% increase in IOPS for a null_blk test, both for
sync and for high thread count access. Sync test goes form 975K to
992K, 32-thread case from 20.8M to 21.2M IOPS.

Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-10 11:47:58 -07:00
Jens Axboe
e14575b3d4 block: convert REQ_ATOM_COMPLETE to stealing rq->__deadline bit
We only have one atomic flag left. Instead of using an entire
unsigned long for that, steal the bottom bit of the deadline
field that we already reserved.

Remove ->atomic_flags, since it's now unused.

Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-10 11:47:53 -07:00
Jens Axboe
0a72e7f449 block: add accessors for setting/querying request deadline
We reduce the resolution of request expiry, but since we're already
using jiffies for this where resolution depends on the kernel
configuration and since the timeout resolution is coarse anyway,
that should be fine.

Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-10 11:47:47 -07:00
Jens Axboe
76a86f9d02 block: remove REQ_ATOM_POLL_SLEPT
We don't need this to be an atomic flag, it can be a regular
flag. We either end up on the same CPU for the polling, in which
case the state is sane, or we did the sleep which would imply
the needed barrier to ensure we see the right state.

Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-10 11:47:43 -07:00
Bart Van Assche
fcd36c36f3 blk-mq: Explain when 'active_queues' is decremented
It is nontrivial to derive from the blk-mq source code when
blk_mq_tags.active_queues is decremented. Hence add a comment that
explains this.

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-10 09:45:29 -07:00
Bart Van Assche
ee3e4de525 blk-mq: Fix spelling in a source code comment
Change "nedeing" into "needing" and "caes" into "cases".

Fixes: commit f906a6a0f4 ("blk-mq: improve tag waiting setup for non-shared tags")
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-09 11:15:15 -07:00
Jens Axboe
08b5a6e2a7 blk-mq: silence false positive warnings in hctx_unlock()
In some stupider versions of gcc, it complains:

block/blk-mq.c: In function ‘blk_mq_complete_request’:
./include/linux/srcu.h:175:2: warning: ‘srcu_idx’ may be used uninitialized in this function [-Wmaybe-uninitialized]
  __srcu_read_unlock(sp, idx);
  ^
block/blk-mq.c:620:6: note: ‘srcu_idx’ was declared here
  int srcu_idx;
      ^

which is completely bogus, since we only use srcu_idx when
hctx->flags & BLK_MQ_F_BLOCKING is set, and that's the case where
hctx_lock() has initialized it.

Just set it to '0' in the normal path in hctx_lock() to silence
this annoying warning.

Fixes: 04ced159ce ("blk-mq: move hctx lock/unlock into a helper")
Fixes: 5197c05e16 ("blk-mq: protect completion path with RCU")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-09 09:32:25 -07:00
Tejun Heo
05707b64ae blk-mq: rename blk_mq_hw_ctx->queue_rq_srcu to ->srcu
The RCU protection has been expanded to cover both queueing and
completion paths making ->queue_rq_srcu a misnomer.  Rename it to
->srcu as suggested by Bart.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Bart Van Assche <Bart.VanAssche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-09 09:31:15 -07:00
Tejun Heo
5a61c36398 blk-mq: remove REQ_ATOM_STARTED
After the recent updates to use generation number and state based
synchronization, we can easily replace REQ_ATOM_STARTED usages by
adding an extra state to distinguish completed but not yet freed
state.

Add MQ_RQ_COMPLETE and replace REQ_ATOM_STARTED usages with
blk_mq_rq_state() tests.  REQ_ATOM_STARTED no longer has any users
left and is removed.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-09 09:31:15 -07:00
Tejun Heo
634f9e4631 blk-mq: remove REQ_ATOM_COMPLETE usages from blk-mq
After the recent updates to use generation number and state based
synchronization, blk-mq no longer depends on REQ_ATOM_COMPLETE except
to avoid firing the same timeout multiple times.

Remove all REQ_ATOM_COMPLETE usages and use a new rq_flags flag
RQF_MQ_TIMEOUT_EXPIRED to avoid firing the same timeout multiple
times.  This removes atomic bitops from hot paths too.

v2: Removed blk_clear_rq_complete() from blk_mq_rq_timed_out().

v3: Added RQF_MQ_TIMEOUT_EXPIRED flag.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: "jianchao.wang" <jianchao.w.wang@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-09 09:31:15 -07:00
Tejun Heo
358f70da49 blk-mq: make blk_abort_request() trigger timeout path
With issue/complete and timeout paths now using the generation number
and state based synchronization, blk_abort_request() is the only one
which depends on REQ_ATOM_COMPLETE for arbitrating completion.

There's no reason for blk_abort_request() to be a completely separate
path.  This patch makes blk_abort_request() piggyback on the timeout
path instead of trying to terminate the request directly.

This removes the last dependency on REQ_ATOM_COMPLETE in blk-mq.

Note that this makes blk_abort_request() asynchronous - it initiates
abortion but the actual termination will happen after a short while,
even when the caller owns the request.  AFAICS, SCSI and ATA should be
fine with that and I think mtip32xx and dasd should be safe but not
completely sure.  It'd be great if people who know the drivers take a
look.

v2: - Add comment explaining the lack of synchronization around
      ->deadline update as requested by Bart.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Asai Thambi SP <asamymuthupa@micron.com>
Cc: Stefan Haberland <sth@linux.vnet.ibm.com>
Cc: Jan Hoeppner <hoeppner@linux.vnet.ibm.com>
Cc: Bart Van Assche <Bart.VanAssche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-09 09:31:15 -07:00
Tejun Heo
67818d2573 blk-mq: use blk_mq_rq_state() instead of testing REQ_ATOM_COMPLETE
blk_mq_check_inflight() and blk_mq_poll_hybrid_sleep() test
REQ_ATOM_COMPLETE to determine the request state.  Both uses are
speculative and we can test REQ_ATOM_STARTED and blk_mq_rq_state() for
equivalent results.  Replace the tests.  This will allow removing
REQ_ATOM_COMPLETE usages from blk-mq.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-09 09:31:15 -07:00
Tejun Heo
1d9bd5161b blk-mq: replace timeout synchronization with a RCU and generation based scheme
Currently, blk-mq timeout path synchronizes against the usual
issue/completion path using a complex scheme involving atomic
bitflags, REQ_ATOM_*, memory barriers and subtle memory coherence
rules.  Unfortunately, it contains quite a few holes.

There's a complex dancing around REQ_ATOM_STARTED and
REQ_ATOM_COMPLETE between issue/completion and timeout paths; however,
they don't have a synchronization point across request recycle
instances and it isn't clear what the barriers add.
blk_mq_check_expired() can easily read STARTED from N-2'th iteration,
deadline from N-1'th, blk_mark_rq_complete() against Nth instance.

In fact, it's pretty easy to make blk_mq_check_expired() terminate a
later instance of a request.  If we induce 5 sec delay before
time_after_eq() test in blk_mq_check_expired(), shorten the timeout to
2s, and issue back-to-back large IOs, blk-mq starts timing out
requests spuriously pretty quickly.  Nothing actually timed out.  It
just made the call on a recycle instance of a request and then
terminated a later instance long after the original instance finished.
The scenario isn't theoretical either.

This patch replaces the broken synchronization mechanism with a RCU
and generation number based one.

1. Each request has a u64 generation + state value, which can be
   updated only by the request owner.  Whenever a request becomes
   in-flight, the generation number gets bumped up too.  This provides
   the basis for the timeout path to distinguish different recycle
   instances of the request.

   Also, marking a request in-flight and setting its deadline are
   protected with a seqcount so that the timeout path can fetch both
   values coherently.

2. The timeout path fetches the generation, state and deadline.  If
   the verdict is timeout, it records the generation into a dedicated
   request abortion field and does RCU wait.

3. The completion path is also protected by RCU (from the previous
   patch) and checks whether the current generation number and state
   match the abortion field.  If so, it skips completion.

4. The timeout path, after RCU wait, scans requests again and
   terminates the ones whose generation and state still match the ones
   requested for abortion.

   By now, the timeout path knows that either the generation number
   and state changed if it lost the race or the completion will yield
   to it and can safely timeout the request.

While it's more lines of code, it's conceptually simpler, doesn't
depend on direct use of subtle memory ordering or coherence, and
hopefully doesn't terminate the wrong instance.

While this change makes REQ_ATOM_COMPLETE synchronization unnecessary
between issue/complete and timeout paths, REQ_ATOM_COMPLETE isn't
removed yet as it's still used in other places.  Future patches will
move all state tracking to the new mechanism and remove all bitops in
the hot paths.

Note that this patch adds a comment explaining a race condition in
BLK_EH_RESET_TIMER path.  The race has always been there and this
patch doesn't change it.  It's just documenting the existing race.

v2: - Fixed BLK_EH_RESET_TIMER handling as pointed out by Jianchao.
    - s/request->gstate_seqc/request->gstate_seq/ as suggested by Peter.
    - READ_ONCE() added in blk_mq_rq_update_state() as suggested by Peter.

v3: - Fixed possible extended seqcount / u64_stats_sync read looping
      spotted by Peter.
    - MQ_RQ_IDLE was incorrectly being set in complete_request instead
      of free_request.  Fixed.

v4: - Rebased on top of hctx_lock() refactoring patch.
    - Added comment explaining the use of hctx_lock() in completion path.

v5: - Added comments requested by Bart.
    - Note the addition of BLK_EH_RESET_TIMER race condition in the
      commit message.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: "jianchao.wang" <jianchao.w.wang@oracle.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Bart Van Assche <Bart.VanAssche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-09 09:31:15 -07:00
Tejun Heo
5197c05e16 blk-mq: protect completion path with RCU
Currently, blk-mq protects only the issue path with RCU.  This patch
puts the completion path under the same RCU protection.  This will be
used to synchronize issue/completion against timeout by later patches,
which will also add the comments.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-09 09:31:15 -07:00
Jens Axboe
04ced159ce blk-mq: move hctx lock/unlock into a helper
Move the RCU vs SRCU logic into lock/unlock helpers, which makes
the actual functional bits within the locked region much easier
to read.

tj: Reordered in front of timeout revamp patches and added the missing
    blk_mq_run_hw_queue() conversion.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-09 09:31:15 -07:00
Ming Lei
8ab0b7dc73 blk-mq: fix kernel oops in blk_mq_tag_idle()
HW queues may be unmapped in some cases, such as blk_mq_update_nr_hw_queues(),
then we need to check it before calling blk_mq_tag_idle(), otherwise
the following kernel oops can be triggered, so fix it by checking if
the hw queue is unmapped since it doesn't make sense to idle the tags
any more after hw queues are unmapped.

[  440.771298] Workqueue: nvme-wq nvme_rdma_del_ctrl_work [nvme_rdma]
[  440.779104] task: ffff894bae755ee0 ti: ffff893bf9bc8000 task.ti: ffff893bf9bc8000
[  440.788359] RIP: 0010:[<ffffffffb730e2b4>]  [<ffffffffb730e2b4>] __blk_mq_tag_idle+0x24/0x40
[  440.798697] RSP: 0018:ffff893bf9bcbd10  EFLAGS: 00010286
[  440.805538] RAX: 0000000000000000 RBX: ffff895bb131dc00 RCX: 000000000000011f
[  440.814426] RDX: 00000000ffffffff RSI: 0000000000000120 RDI: ffff895bb131dc00
[  440.823301] RBP: ffff893bf9bcbd10 R08: 000000000001b860 R09: 4a51d361c00c0000
[  440.832193] R10: b5907f32b4cc7003 R11: ffffd6cabfb57000 R12: ffff894bafd1e008
[  440.841091] R13: 0000000000000001 R14: ffff895baf770000 R15: 0000000000000080
[  440.849988] FS:  0000000000000000(0000) GS:ffff894bbdcc0000(0000) knlGS:0000000000000000
[  440.859955] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  440.867274] CR2: 0000000000000008 CR3: 000000103d098000 CR4: 00000000001407e0
[  440.876169] Call Trace:
[  440.879818]  [<ffffffffb7309d68>] blk_mq_exit_hctx+0xd8/0xe0
[  440.887051]  [<ffffffffb730dc40>] blk_mq_free_queue+0xf0/0x160
[  440.894465]  [<ffffffffb72ff679>] blk_cleanup_queue+0xd9/0x150
[  440.901881]  [<ffffffffc08a802b>] nvme_ns_remove+0x5b/0xb0 [nvme_core]
[  440.910068]  [<ffffffffc08a811b>] nvme_remove_namespaces+0x3b/0x60 [nvme_core]
[  440.919026]  [<ffffffffc08b817b>] __nvme_rdma_remove_ctrl+0x2b/0xb0 [nvme_rdma]
[  440.928079]  [<ffffffffc08b8237>] nvme_rdma_del_ctrl_work+0x17/0x20 [nvme_rdma]
[  440.937126]  [<ffffffffb70ab58a>] process_one_work+0x17a/0x440
[  440.944517]  [<ffffffffb70ac3a8>] worker_thread+0x278/0x3c0
[  440.951607]  [<ffffffffb70ac130>] ? manage_workers.isra.24+0x2a0/0x2a0
[  440.959760]  [<ffffffffb70b352f>] kthread+0xcf/0xe0
[  440.966055]  [<ffffffffb70b3460>] ? insert_kthread_work+0x40/0x40
[  440.973715]  [<ffffffffb76d8658>] ret_from_fork+0x58/0x90
[  440.980586]  [<ffffffffb70b3460>] ? insert_kthread_work+0x40/0x40
[  440.988229] Code: 5b 41 5c 5d c3 66 90 0f 1f 44 00 00 48 8b 87 20 01 00 00 f0 0f ba 77 40 01 19 d2 85 d2 75 08 c3 0f 1f 80 00 00 00 00 55 48 89 e5 <f0> ff 48 08 48 8d 78 10 e8 7f 0f 05 00 5d c3 0f 1f 00 66 2e 0f
[  441.011620] RIP  [<ffffffffb730e2b4>] __blk_mq_tag_idle+0x24/0x40
[  441.019301]  RSP <ffff893bf9bcbd10>
[  441.024052] CR2: 0000000000000008

Reported-by: Zhang Yi <yizhan@redhat.com>
Tested-by: Zhang Yi <yizhan@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-09 08:39:31 -07:00
Ming Lei
fb350e0ad9 blk-mq: fix race between updating nr_hw_queues and switching io sched
In both elevator_switch_mq() and blk_mq_update_nr_hw_queues(), sched tags
can be allocated, and q->nr_hw_queue is used, and race is inevitable, for
example: blk_mq_init_sched() may trigger use-after-free on hctx, which is
freed in blk_mq_realloc_hw_ctxs() when nr_hw_queues is decreased.

This patch fixes the race be holding q->sysfs_lock.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reported-by: Yi Zhang <yi.zhang@redhat.com>
Tested-by: Yi Zhang <yi.zhang@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-06 09:25:36 -07:00
Ming Lei
7d4901a90d blk-mq: avoid to map CPU into stale hw queue
blk_mq_pci_map_queues() may not map one CPU into any hw queue, but its
previous map isn't cleared yet, and may point to one stale hw queue
index.

This patch fixes the following issue by clearing the mapping table before
setting it up in blk_mq_pci_map_queues().

This patches fixes this following issue reported by Zhang Yi:

[  101.202734] BUG: unable to handle kernel NULL pointer dereference at 0000000094d3013f
[  101.211487] IP: blk_mq_map_swqueue+0xbc/0x200
[  101.216346] PGD 0 P4D 0
[  101.219171] Oops: 0000 [#1] SMP
[  101.222674] Modules linked in: sunrpc ipmi_ssif vfat fat intel_rapl sb_edac x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm irqbypass crct10dif_pclmul crc32_pclmul ghash_clmulni_intel intel_cstate intel_uncore mxm_wmi intel_rapl_perf iTCO_wdt ipmi_si ipmi_devintf pcspkr iTCO_vendor_support sg dcdbas ipmi_msghandler wmi mei_me lpc_ich shpchp mei acpi_power_meter dm_multipath ip_tables xfs libcrc32c sd_mod mgag200 i2c_algo_bit drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm drm ahci libahci crc32c_intel libata tg3 nvme nvme_core megaraid_sas ptp i2c_core pps_core dm_mirror dm_region_hash dm_log dm_mod
[  101.284881] CPU: 0 PID: 504 Comm: kworker/u25:5 Not tainted 4.15.0-rc2 #1
[  101.292455] Hardware name: Dell Inc. PowerEdge R730xd/072T6D, BIOS 2.5.5 08/16/2017
[  101.301001] Workqueue: nvme-wq nvme_reset_work [nvme]
[  101.306636] task: 00000000f2c53190 task.stack: 000000002da874f9
[  101.313241] RIP: 0010:blk_mq_map_swqueue+0xbc/0x200
[  101.318681] RSP: 0018:ffffc9000234fd70 EFLAGS: 00010282
[  101.324511] RAX: ffff88047ffc9480 RBX: ffff88047e130850 RCX: 0000000000000000
[  101.332471] RDX: ffffe8ffffd40580 RSI: ffff88047e509b40 RDI: ffff88046f37a008
[  101.340432] RBP: 000000000000000b R08: ffff88046f37a008 R09: 0000000011f94280
[  101.348392] R10: ffff88047ffd4d00 R11: 0000000000000000 R12: ffff88046f37a008
[  101.356353] R13: ffff88047e130f38 R14: 000000000000000b R15: ffff88046f37a558
[  101.364314] FS:  0000000000000000(0000) GS:ffff880277c00000(0000) knlGS:0000000000000000
[  101.373342] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  101.379753] CR2: 0000000000000098 CR3: 000000047f409004 CR4: 00000000001606f0
[  101.387714] Call Trace:
[  101.390445]  blk_mq_update_nr_hw_queues+0xbf/0x130
[  101.395791]  nvme_reset_work+0x6f4/0xc06 [nvme]
[  101.400848]  ? pick_next_task_fair+0x290/0x5f0
[  101.405807]  ? __switch_to+0x1f5/0x430
[  101.409988]  ? put_prev_entity+0x2f/0xd0
[  101.414365]  process_one_work+0x141/0x340
[  101.418836]  worker_thread+0x47/0x3e0
[  101.422921]  kthread+0xf5/0x130
[  101.426424]  ? rescuer_thread+0x380/0x380
[  101.430896]  ? kthread_associate_blkcg+0x90/0x90
[  101.436048]  ret_from_fork+0x1f/0x30
[  101.440034] Code: 48 83 3c ca 00 0f 84 2b 01 00 00 48 63 cd 48 8b 93 10 01 00 00 8b 0c 88 48 8b 83 20 01 00 00 4a 03 14 f5 60 04 af 81 48 8b 0c c8 <48> 8b 81 98 00 00 00 f0 4c 0f ab 30 8b 81 f8 00 00 00 89 42 44
[  101.461116] RIP: blk_mq_map_swqueue+0xbc/0x200 RSP: ffffc9000234fd70
[  101.468205] CR2: 0000000000000098
[  101.471907] ---[ end trace 5fe710f98228a3ca ]---
[  101.482489] Kernel panic - not syncing: Fatal exception
[  101.488505] Kernel Offset: disabled
[  101.497752] ---[ end Kernel panic - not syncing: Fatal exception

Reviewed-by: Christoph Hellwig <hch@lst.de>
Suggested-by: Christoph Hellwig <hch@lst.de>
Reported-by: Yi Zhang <yi.zhang@redhat.com>
Tested-by: Yi Zhang <yi.zhang@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-06 09:25:36 -07:00
Ming Lei
24f5a90f0d blk-mq: quiesce queue during switching io sched and updating nr_requests
Dispatch may still be in-progress after queue is frozen, so we have to
quiesce queue before switching IO scheduler and updating nr_requests.

Also when switching io schedulers, blk_mq_run_hw_queue() may still be
called somewhere(such as from nvme_reset_work()), and io scheduler's
per-hctx data may not be setup yet, so cause oops even inside
blk_mq_hctx_has_pending(), such as it can be run just between:

        ret = e->ops.mq.init_sched(q, e);
AND
        ret = e->ops.mq.init_hctx(hctx, i)

inside blk_mq_init_sched().

This reverts commit 7a148c2fcff8330(block: don't call blk_mq_quiesce_queue()
after queue is frozen) basically, and makes sure blk_mq_hctx_has_pending
won't be called if queue is quiesced.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Fixes: 7a148c2fcff83309(block: don't call blk_mq_quiesce_queue() after queue is frozen)
Reported-by: Yi Zhang <yi.zhang@redhat.com>
Tested-by: Yi Zhang <yi.zhang@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-06 09:25:36 -07:00
Ming Lei
454be724f6 block: drain queue before waiting for q_usage_counter becoming zero
Now we track legacy requests with .q_usage_counter in commit 055f6e18e0
("block: Make q_usage_counter also track legacy requests"), but that
commit never runs and drains legacy queue before waiting for this counter
becoming zero, then IO hang is caused in the test of pulling disk during IO.

This patch fixes the issue by draining requests before waiting for
q_usage_counter becoming zero, both Mauricio and chenxiang reported this
issue, and observed that it can be fixed by this patch.

Link: https://marc.info/?l=linux-block&m=151192424731797&w=2
Fixes: 055f6e18e08f("block: Make q_usage_counter also track legacy requests")
Cc: Wen Xiong <wenxiong@us.ibm.com>
Tested-by: "chenxiang (M)" <chenxiang66@hisilicon.com>
Tested-by: Mauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-05 09:09:48 -07:00
Johannes Thumshirn
d904bfa79f block/blk-mq.c: use kmalloc_array_node()
Now that we have a NUMA-aware version of kmalloc_array() we can use it
instead of kmalloc_node() without an overflow check in the size
calculation.

Link: http://lkml.kernel.org/r/20170927082038.3782-3-jthumshirn@suse.de
Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Damien Le Moal <damien.lemoal@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Doug Ledford <dledford@redhat.com>
Cc: Hal Rosenstock <hal.rosenstock@gmail.com>
Cc: Mike Marciniszyn <infinipath@intel.com>
Cc: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Cc: Sean Hefty <sean.hefty@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-15 18:21:02 -08:00
Jens Axboe
ff821d2714 blk-mq: fixup some comment typos and lengths
Various typos and/or spelling errors in comments. Fixes a few > 80 char
lines as well.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-11-10 22:05:12 -07:00
Jens Axboe
f906a6a0f4 blk-mq: improve tag waiting setup for non-shared tags
If we run out of driver tags, we currently treat shared and non-shared
tags the same - both cases hook into the tag waitqueue. This is a bit
more costly than it needs to be on unshared tags, since we have to both
grab the hctx lock, and the waitqueue lock (and disable interrupts).
For the non-shared case, we can simply mark the queue as needing a
restart.

Split blk_mq_dispatch_wait_add() to account for both cases, and
rename it to blk_mq_mark_tag_wait() to better reflect what it
does now.

Without this patch, shared and non-shared performance is about the same
with 4 fio thread hammering on a single null_blk device (~410K, at 75%
sys). With the patch, the shared case is the same, but the non-shared
tags case runs at 431K at 71% sys.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-11-10 19:55:57 -07:00
Jens Axboe
79f720a751 blk-mq: only run the hardware queue if IO is pending
Currently we are inconsistent in when we decide to run the queue. Using
blk_mq_run_hw_queues() we check if the hctx has pending IO before
running it, but we don't do that from the individual queue run function,
blk_mq_run_hw_queue(). This results in a lot of extra and pointless
queue runs, potentially, on flush requests and (much worse) on tag
starvation situations. This is observable just looking at top output,
with lots of kworkers active. For the !async runs, it just adds to the
CPU overhead of blk-mq.

Move the has-pending check into the run function instead of having
callers do it.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-11-10 19:55:57 -07:00
Bart Van Assche
9a95e4ef70 block, nvme: Introduce blk_mq_req_flags_t
Several block layer and NVMe core functions accept a combination
of BLK_MQ_REQ_* flags through the 'flags' argument but there is
no verification at compile time whether the right type of block
layer flags is passed. Make it possible for sparse to verify this.
This patch does not change any functionality.

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Cc: linux-nvme@lists.infradead.org
Cc: Christoph Hellwig <hch@lst.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-11-10 19:53:25 -07:00
Bart Van Assche
3a0a529971 block, scsi: Make SCSI quiesce and resume work reliably
The contexts from which a SCSI device can be quiesced or resumed are:
* Writing into /sys/class/scsi_device/*/device/state.
* SCSI parallel (SPI) domain validation.
* The SCSI device power management methods. See also scsi_bus_pm_ops.

It is essential during suspend and resume that neither the filesystem
state nor the filesystem metadata in RAM changes. This is why while
the hibernation image is being written or restored that SCSI devices
are quiesced. The SCSI core quiesces devices through scsi_device_quiesce()
and scsi_device_resume(). In the SDEV_QUIESCE state execution of
non-preempt requests is deferred. This is realized by returning
BLKPREP_DEFER from inside scsi_prep_state_check() for quiesced SCSI
devices. Avoid that a full queue prevents power management requests
to be submitted by deferring allocation of non-preempt requests for
devices in the quiesced state. This patch has been tested by running
the following commands and by verifying that after each resume the
fio job was still running:

for ((i=0; i<10; i++)); do
  (
    cd /sys/block/md0/md &&
    while true; do
      [ "$(<sync_action)" = "idle" ] && echo check > sync_action
      sleep 1
    done
  ) &
  pids=($!)
  for d in /sys/class/block/sd*[a-z]; do
    bdev=${d#/sys/class/block/}
    hcil=$(readlink "$d/device")
    hcil=${hcil#../../../}
    echo 4 > "$d/queue/nr_requests"
    echo 1 > "/sys/class/scsi_device/$hcil/device/queue_depth"
    fio --name="$bdev" --filename="/dev/$bdev" --buffered=0 --bs=512 \
      --rw=randread --ioengine=libaio --numjobs=4 --iodepth=16       \
      --iodepth_batch=1 --thread --loops=$((2**31)) &
    pids+=($!)
  done
  sleep 1
  echo "$(date) Hibernating ..." >>hibernate-test-log.txt
  systemctl hibernate
  sleep 10
  kill "${pids[@]}"
  echo idle > /sys/block/md0/md/sync_action
  wait
  echo "$(date) Done." >>hibernate-test-log.txt
done

Reported-by: Oleksandr Natalenko <oleksandr@natalenko.name>
References: "I/O hangs after resuming from suspend-to-ram" (https://marc.info/?l=linux-block&m=150340235201348).
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Martin Steigerwald <martin@lichtvoll.de>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-11-10 19:53:25 -07:00
Bart Van Assche
1b6d65a0bf block: Introduce BLK_MQ_REQ_PREEMPT
Set RQF_PREEMPT if BLK_MQ_REQ_PREEMPT is passed to
blk_get_request_flags().

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Martin Steigerwald <martin@lichtvoll.de>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-11-10 19:53:25 -07:00
Ming Lei
055f6e18e0 block: Make q_usage_counter also track legacy requests
This patch makes it possible to pause request allocation for
the legacy block layer by calling blk_mq_freeze_queue() and
blk_mq_unfreeze_queue().

Signed-off-by: Ming Lei <ming.lei@redhat.com>
[ bvanassche: Combined two patches into one, edited a comment and made sure
  REQ_NOWAIT is handled properly in blk_old_get_request() ]
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Martin Steigerwald <martin@lichtvoll.de>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-11-10 19:53:25 -07:00
Jens Axboe
eb619fdb2d blk-mq: fix issue with shared tag queue re-running
This patch attempts to make the case of hctx re-running on driver tag
failure more robust. Without this patch, it's pretty easy to trigger a
stall condition with shared tags. An example is using null_blk like
this:

modprobe null_blk queue_mode=2 nr_devices=4 shared_tags=1 submit_queues=1 hw_queue_depth=1

which sets up 4 devices, sharing the same tag set with a depth of 1.
Running a fio job ala:

[global]
bs=4k
rw=randread
norandommap
direct=1
ioengine=libaio
iodepth=4

[nullb0]
filename=/dev/nullb0
[nullb1]
filename=/dev/nullb1
[nullb2]
filename=/dev/nullb2
[nullb3]
filename=/dev/nullb3

will inevitably end with one or more threads being stuck waiting for a
scheduler tag. That IO is then stuck forever, until someone else
triggers a run of the queue.

Ensure that we always re-run the hardware queue, if the driver tag we
were waiting for got freed before we added our leftover request entries
back on the dispatch list.

Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Tested-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-11-10 19:53:25 -07:00
Ming Lei
0c6af1ccd5 blk-mq: put driver tag if dispatch budget can't be got
We have to put the driver tag if dispatch budget can't be got, otherwise
it might cause IO deadlock, especially in case that size of tags is very
small.

Fixes: de1482974080(blk-mq: introduce .get_budget and .put_budget in blk_mq_ops)
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-11-10 19:53:25 -07:00
Ming Lei
923218f616 blk-mq: don't allocate driver tag upfront for flush rq
The idea behind it is simple:

1) for none scheduler, driver tag has to be borrowed for flush rq,
   otherwise we may run out of tag, and that causes an IO hang. And
   get/put driver tag is actually noop for none, so reordering tags
   isn't necessary at all.

2) for a real I/O scheduler, we need not allocate a driver tag upfront
   for flush rq. It works just fine to follow the same approach as
   normal requests: allocate driver tag for each rq just before calling
   ->queue_rq().

One driver visible change is that the driver tag isn't shared in the
flush request sequence. That won't be a problem, since we always do that
in legacy path.

Then flush rq need not be treated specially wrt. get/put driver tag.
This cleans up the code - for instance, reorder_tags_to_front() can be
removed, and we needn't worry about request ordering in dispatch list
for avoiding I/O deadlock.

Also we have to put the driver tag before requeueing.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-11-04 12:40:13 -06:00
Ming Lei
244c65a3cc blk-mq: move blk_mq_put_driver_tag*() into blk-mq.h
We need this helper to put the driver tag for flush rq, since we will
not share tag in the flush request sequence in the following patch
in case that I/O scheduler is applied.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-11-04 12:39:57 -06:00
Ming Lei
b0850297c7 block: pass 'run_queue' to blk_mq_request_bypass_insert
Block flush need this function without running the queue, so add a
parameter controlling whether we run it or not.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-11-04 12:38:40 -06:00
Jianchao Wang
6d6f167ce7 blk-mq: put the driver tag of nxt rq before first one is requeued
When freeing the driver tag of the next rq with an I/O scheduler
configured, we get the first entry of the list. However, this can
race with requeue of a request, and we end up getting the wrong request
from the head of the list. Free the driver tag of next rq before the
failed one is requeued in the failure branch of queue_rq callback.

Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-11-04 12:38:40 -06:00
Ming Lei
88022d7201 blk-mq: don't handle failure in .get_budget
It is enough to just check if we can get the budget via .get_budget().
And we don't need to deal with device state change in .get_budget().

For SCSI, one issue to be fixed is that we have to call
scsi_mq_uninit_cmd() to free allocated ressources if SCSI device fails
to handle the request. And it isn't enough to simply call
blk_mq_end_request() to do that if this request is marked as
RQF_DONTPREP.

Fixes: 0df21c86bdbf(scsi: implement .get_budget and .put_budget for blk-mq)
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-11-04 12:31:08 -06:00
Bart Van Assche
21e768b442 blk-mq: Make blk_mq_get_request() error path less confusing
blk_mq_get_tag() can modify data->ctx. This means that in the
error path of blk_mq_get_request() data->ctx should be passed to
blk_mq_put_ctx() instead of local_ctx. Note: since blk_mq_put_ctx()
ignores its argument, this patch does not change any functionality.

References: commit 1ad43c0078 ("blk-mq: don't leak preempt counter/q_usage_counter when allocating rq failed")
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-11-03 12:33:56 -06:00
weiping zhang
c2e82a2348 blk-mq: fix nr_requests wrong value when modify it from sysfs
if blk-mq use "none" io scheduler, nr_request get a wrong value when
input a number > tag_set->queue_depth. blk_mq_tag_update_depth will get
the smaller one min(nr, set->queue_depth), and then q->nr_request get a
wrong value.

Reproduce:

echo none > /sys/block/nvme0n1/queue/scheduler
echo 1000000 > /sys/block/nvme0n1/queue/nr_requests
cat /sys/block/nvme0n1/queue/nr_requests
1000000

Signed-off-by: weiping zhang <zhangweiping@didichuxing.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-11-03 12:21:06 -06:00
Christoph Hellwig
ea435e1b93 block: add a poll_fn callback to struct request_queue
That we we can also poll non blk-mq queues.  Mostly needed for
the NVMe multipath code, but could also be useful elsewhere.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-11-03 10:31:48 -06:00
Ming Lei
1f460b63d4 blk-mq: don't restart queue when .get_budget returns BLK_STS_RESOURCE
SCSI restarts its queue in scsi_end_request() automatically, so we don't
need to handle this case in blk-mq.

Especailly any request won't be dequeued in this case, we needn't to
worry about IO hang caused by restart vs. dispatch.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-11-01 08:20:34 -06:00
Ming Lei
b347689ffb blk-mq-sched: improve dispatching from sw queue
SCSI devices use host-wide tagset, and the shared driver tag space is
often quite big. However, there is also a queue depth for each lun(
.cmd_per_lun), which is often small, for example, on both lpfc and
qla2xxx, .cmd_per_lun is just 3.

So lots of requests may stay in sw queue, and we always flush all
belonging to same hw queue and dispatch them all to driver.
Unfortunately it is easy to cause queue busy because of the small
.cmd_per_lun.  Once these requests are flushed out, they have to stay in
hctx->dispatch, and no bio merge can happen on these requests, and
sequential IO performance is harmed.

This patch introduces blk_mq_dequeue_from_ctx for dequeuing a request
from a sw queue, so that we can dispatch them in scheduler's way. We can
then avoid dequeueing too many requests from sw queue, since we don't
flush ->dispatch completely.

This patch improves dispatching from sw queue by using the .get_budget
and .put_budget callbacks.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-11-01 08:20:02 -06:00
Ming Lei
de14829740 blk-mq: introduce .get_budget and .put_budget in blk_mq_ops
For SCSI devices, there is often a per-request-queue depth, which needs
to be respected before queuing one request.

Currently blk-mq always dequeues the request first, then calls
.queue_rq() to dispatch the request to lld. One obvious issue with this
approach is that I/O merging may not be successful, because when the
per-request-queue depth can't be respected, .queue_rq() has to return
BLK_STS_RESOURCE, and then this request has to stay in hctx->dispatch
list. This means it never gets a chance to be merged with other IO.

This patch introduces .get_budget and .put_budget callback in blk_mq_ops,
then we can try to get reserved budget first before dequeuing request.
If the budget for queueing I/O can't be satisfied, we don't need to
dequeue request at all. Hence the request can be left in the IO
scheduler queue, for more merging opportunities.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-11-01 08:20:02 -06:00
Shaohua Li
85acb3ba2f block: set request_list for request
Legacy queue sets request's request_list, mq doesn't. This makes mq does
the same thing, so we can find cgroup of a request. Note, we really
only use blkg field of request_list, it's pointless to allocate mempool
for request_list in mq case.

Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-10-10 13:48:16 -06:00
Jens Axboe
fc13457f74 blk-mq: document the need to have STARTED and COMPLETED share a byte
For memory ordering guarantees on stores, we need to ensure that
these two bits share the same byte of storage in the unsigned
long. Add a comment as to why, and a BUILD_BUG_ON() to ensure that
we don't violate this requirement.

Suggested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-10-04 11:22:24 -06:00
Peter Zijlstra
a7af0af321 blk-mq: attempt to fix atomic flag memory ordering
Attempt to untangle the ordering in blk-mq. The patch introducing the
single smp_mb__before_atomic() is obviously broken in that it doesn't
clearly specify a pairing barrier and an obtained guarantee.

The comment is further misleading in that it hints that the
deadline store and the COMPLETE store also need to be ordered, but
AFAICT there is no such dependency. However what does appear to be
important is the clear happening _after_ the store, and that worked by
pure accident.

This clarifies blk_mq_start_request() -- we should not get there with
STARTING set -- this simplifies the code and makes the barrier usage
sane (the old code could be read to allow not having _any_ atomic after
the barrier, in which case the barrier hasn't got anything to order). We
then also introduce the missing pairing barrier for it.

Also down-grade the barrier to smp_wmb(), this is cheaper for
PowerPC/ARM and doesn't cost anything extra on x86.

And it documents the STARTING vs COMPLETE ordering. Although I've not
been entirely successful in reverse engineering the blk-mq state
machine so there might still be more funnies around timeout vs
requeue.

If I got anything wrong, feel free to educate me by adding comments to
clarify things ;-)

Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Ming Lei <tom.leiming@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Andrea Parri <parri.andrea@gmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Bart Van Assche <bart.vanassche@wdc.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Fixes: 538b753418 ("blk-mq: request deadline must be visible before marking rq as started")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-10-04 11:20:11 -06:00
Jens Axboe
7beb2f845b blk-mq: wire up completion notifier for laptop mode
For some reason, the laptop mode IO completion notified was never wired
up for blk-mq. Ensure that we trigger the callback appropriately, to arm
the laptop mode flush timer.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <Bart.VanAssche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-10-03 08:38:17 -06:00
weiping zhang
547248736a blk-mq: remove unused function hctx_allow_merges
since 9bddeb2a5b "blk-mq: make per-sw-queue bio merge as default .bio_merge"
there is no caller for this function.

Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: weiping zhang <zhangweiping@didichuxing.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-09-30 02:17:37 -06:00
Jens Axboe
157f377beb block: directly insert blk-mq request from blk_insert_cloned_request()
A NULL pointer crash was reported for the case of having the BFQ IO
scheduler attached to the underlying blk-mq paths of a DM multipath
device.  The crash occured in blk_mq_sched_insert_request()'s call to
e->type->ops.mq.insert_requests().

Paolo Valente correctly summarized why the crash occured with:
"the call chain (dm_mq_queue_rq -> map_request -> setup_clone ->
blk_rq_prep_clone) creates a cloned request without invoking
e->type->ops.mq.prepare_request for the target elevator e.  The cloned
request is therefore not initialized for the scheduler, but it is
however inserted into the scheduler by blk_mq_sched_insert_request."

All said, a request-based DM multipath device's IO scheduler should be
the only one used -- when the original requests are issued to the
underlying paths as cloned requests they are inserted directly in the
underlying dispatch queue(s) rather than through an additional elevator.

But commit bd166ef18 ("blk-mq-sched: add framework for MQ capable IO
schedulers") switched blk_insert_cloned_request() from using
blk_mq_insert_request() to blk_mq_sched_insert_request().  Which
incorrectly added elevator machinery into a call chain that isn't
supposed to have any.

To fix this introduce a blk-mq private blk_mq_request_bypass_insert()
that blk_insert_cloned_request() calls to insert the request without
involving any elevator that may be attached to the cloned request's
request_queue.

Fixes: bd166ef183 ("blk-mq-sched: add framework for MQ capable IO schedulers")
Cc: stable@vger.kernel.org
Reported-by: Bart Van Assche <Bart.VanAssche@wdc.com>
Tested-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-09-11 16:43:57 -06:00
Linus Torvalds
a0725ab0c7 Merge branch 'for-4.14/block' of git://git.kernel.dk/linux-block
Pull block layer updates from Jens Axboe:
 "This is the first pull request for 4.14, containing most of the code
  changes. It's a quiet series this round, which I think we needed after
  the churn of the last few series. This contains:

   - Fix for a registration race in loop, from Anton Volkov.

   - Overflow complaint fix from Arnd for DAC960.

   - Series of drbd changes from the usual suspects.

   - Conversion of the stec/skd driver to blk-mq. From Bart.

   - A few BFQ improvements/fixes from Paolo.

   - CFQ improvement from Ritesh, allowing idling for group idle.

   - A few fixes found by Dan's smatch, courtesy of Dan.

   - A warning fixup for a race between changing the IO scheduler and
     device remova. From David Jeffery.

   - A few nbd fixes from Josef.

   - Support for cgroup info in blktrace, from Shaohua.

   - Also from Shaohua, new features in the null_blk driver to allow it
     to actually hold data, among other things.

   - Various corner cases and error handling fixes from Weiping Zhang.

   - Improvements to the IO stats tracking for blk-mq from me. Can
     drastically improve performance for fast devices and/or big
     machines.

   - Series from Christoph removing bi_bdev as being needed for IO
     submission, in preparation for nvme multipathing code.

   - Series from Bart, including various cleanups and fixes for switch
     fall through case complaints"

* 'for-4.14/block' of git://git.kernel.dk/linux-block: (162 commits)
  kernfs: checking for IS_ERR() instead of NULL
  drbd: remove BIOSET_NEED_RESCUER flag from drbd_{md_,}io_bio_set
  drbd: Fix allyesconfig build, fix recent commit
  drbd: switch from kmalloc() to kmalloc_array()
  drbd: abort drbd_start_resync if there is no connection
  drbd: move global variables to drbd namespace and make some static
  drbd: rename "usermode_helper" to "drbd_usermode_helper"
  drbd: fix race between handshake and admin disconnect/down
  drbd: fix potential deadlock when trying to detach during handshake
  drbd: A single dot should be put into a sequence.
  drbd: fix rmmod cleanup, remove _all_ debugfs entries
  drbd: Use setup_timer() instead of init_timer() to simplify the code.
  drbd: fix potential get_ldev/put_ldev refcount imbalance during attach
  drbd: new disk-option disable-write-same
  drbd: Fix resource role for newly created resources in events2
  drbd: mark symbols static where possible
  drbd: Send P_NEG_ACK upon write error in protocol != C
  drbd: add explicit plugging when submitting batches
  drbd: change list_for_each_safe to while(list_first_entry_or_null)
  drbd: introduce drbd_recv_header_maybe_unplug
  ...
2017-09-07 11:59:42 -07:00
Bart Van Assche
4d6062193b block: Fix two comments that refer to .queue_rq() return values
Since patch "blk-mq: switch .queue_rq return value to blk_status_t"
.queue_rq() returns a BLK_STS_* value instead of a BLK_MQ_RQ_*
value. Hence refer to the former in comments about .queue_rq()
return values.

Fixes: commit 39a70c76b8 ("blk-mq: clarify dispatch may not be drained/blocked by stopping queue")
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-08-18 08:36:58 -06:00
Keith Busch
3280d66a63 blk-mq: Fix queue usage on failed request allocation
blk_mq_get_request() does not release the callers queue usage counter
when allocation fails. The caller still needs to account for its own
queue usage when it is unable to allocate a request.

Fixes: 1ad43c0078 ("blk-mq: don't leak preempt counter/q_usage_counter when allocating rq failed")

Reported-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Tested-by: Max Gurtovoy <maxg@mellanox.com>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-08-15 07:22:34 -06:00
Bart Van Assche
d4acf3650c block: Make blk_mq_delay_kick_requeue_list() rerun the queue at a quiet time
The blk_mq_delay_kick_requeue_list() function is used by the device
mapper and only by the device mapper to rerun the queue and requeue
list after a delay. This function is called once per request that
gets requeued. Modify this function such that the queue is run once
per path change event instead of once per request that is requeued.

Fixes: commit 2849450ad3 ("blk-mq: introduce blk_mq_delay_kick_requeue_list()")
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-08-09 20:24:38 -06:00
Jens Axboe
b8d62b3a9c blk-mq: enable checking two part inflight counts at the same time
Modify blk_mq_in_flight() to count both a partition and root at
the same time. Then we only have to call it once, instead of
potentially looping the tags twice.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-08-09 13:09:33 -06:00
Jens Axboe
f299b7c7a9 blk-mq: provide internal in-flight variant
We don't have to inc/dec some counter, since we can just
iterate the tags. That makes inc/dec a noop, but means we
have to iterate busy tags to get an in-flight count.

Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-08-09 13:09:28 -06:00
Ming Lei
1ad43c0078 blk-mq: don't leak preempt counter/q_usage_counter when allocating rq failed
When blk_mq_get_request() failed, preempt counter isn't
released, and blk_mq_make_request() doesn't release the counter
too.

This patch fixes the issue, and makes sure that preempt counter
is only held if rq is allocated successfully. The same policy is
applied on .q_usage_counter too.

Signed-off-by: Ming Lei <minlei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-08-02 08:23:57 -06:00
Jens Axboe
b7a71e66d4 blk-mq: add warning to __blk_mq_run_hw_queue() for ints disabled
We recently had a bug in the IPR SCSI driver, where it would end up
making the SCSI mid layer run the mq hardware queue with interrupts
disabled. This isn't legal, since the software queue locking relies
on never being grabbed from interrupt context. Additionally, drivers
that set BLK_MQ_F_BLOCKING may schedule from this context.

Add a WARN_ON_ONCE() to catch bad users up front.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-08-01 09:28:24 -06:00
Jens Axboe
18e9781d44 blk-mq: blk_mq_requeue_work() doesn't need to save IRQ flags
We know we're in process context, so don't bother using the
IRQ safe versions of the spin lock.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-07-29 09:00:03 -06:00
Linus Torvalds
130568d5ea Merge branch 'for-linus' of git://git.kernel.dk/linux-block
Pull more block updates from Jens Axboe:
 "This is a followup for block changes, that didn't make the initial
  pull request. It's a bit of a mixed bag, this contains:

   - A followup pull request from Sagi for NVMe. Outside of fixups for
     NVMe, it also includes a series for ensuring that we properly
     quiesce hardware queues when browsing live tags.

   - Set of integrity fixes from Dmitry (mostly), fixing various issues
     for folks using DIF/DIX.

   - Fix for a bug introduced in cciss, with the req init changes. From
     Christoph.

   - Fix for a bug in BFQ, from Paolo.

   - Two followup fixes for lightnvm/pblk from Javier.

   - Depth fix from Ming for blk-mq-sched.

   - Also from Ming, performance fix for mtip32xx that was introduced
     with the dynamic initialization of commands"

* 'for-linus' of git://git.kernel.dk/linux-block: (44 commits)
  block: call bio_uninit in bio_endio
  nvmet: avoid unneeded assignment of submit_bio return value
  nvme-pci: add module parameter for io queue depth
  nvme-pci: compile warnings in nvme_alloc_host_mem()
  nvmet_fc: Accept variable pad lengths on Create Association LS
  nvme_fc/nvmet_fc: revise Create Association descriptor length
  lightnvm: pblk: remove unnecessary checks
  lightnvm: pblk: control I/O flow also on tear down
  cciss: initialize struct scsi_req
  null_blk: fix error flow for shared tags during module_init
  block: Fix __blkdev_issue_zeroout loop
  nvme-rdma: unconditionally recycle the request mr
  nvme: split nvme_uninit_ctrl into stop and uninit
  virtio_blk: quiesce/unquiesce live IO when entering PM states
  mtip32xx: quiesce request queues to make sure no submissions are inflight
  nbd: quiesce request queues to make sure no submissions are inflight
  nvme: kick requeue list when requeueing a request instead of when starting the queues
  nvme-pci: quiesce/unquiesce admin_q instead of start/stop its hw queues
  nvme-loop: quiesce/unquiesce admin_q instead of start/stop its hw queues
  nvme-fc: quiesce/unquiesce admin_q instead of start/stop its hw queues
  ...
2017-07-11 15:36:52 -07:00
Linus Torvalds
03ffbcdd78 Merge branch 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull irq updates from Thomas Gleixner:
 "The irq department delivers:

   - Expand the generic infrastructure handling the irq migration on CPU
     hotplug and convert X86 over to it. (Thomas Gleixner)

     Aside of consolidating code this is a preparatory change for:

   - Finalizing the affinity management for multi-queue devices. The
     main change here is to shut down interrupts which are affine to a
     outgoing CPU and reenabling them when the CPU comes online again.
     That avoids moving interrupts pointlessly around and breaking and
     reestablishing affinities for no value. (Christoph Hellwig)

     Note: This contains also the BLOCK-MQ and NVME changes which depend
     on the rework of the irq core infrastructure. Jens acked them and
     agreed that they should go with the irq changes.

   - Consolidation of irq domain code (Marc Zyngier)

   - State tracking consolidation in the core code (Jeffy Chen)

   - Add debug infrastructure for hierarchical irq domains (Thomas
     Gleixner)

   - Infrastructure enhancement for managing generic interrupt chips via
     devmem (Bartosz Golaszewski)

   - Constification work all over the place (Tobias Klauser)

   - Two new interrupt controller drivers for MVEBU (Thomas Petazzoni)

   - The usual set of fixes, updates and enhancements all over the
     place"

* 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (112 commits)
  irqchip/or1k-pic: Fix interrupt acknowledgement
  irqchip/irq-mvebu-gicp: Allocate enough memory for spi_bitmap
  irqchip/gic-v3: Fix out-of-bound access in gic_set_affinity
  nvme: Allocate queues for all possible CPUs
  blk-mq: Create hctx for each present CPU
  blk-mq: Include all present CPUs in the default queue mapping
  genirq: Avoid unnecessary low level irq function calls
  genirq: Set irq masked state when initializing irq_desc
  genirq/timings: Add infrastructure for estimating the next interrupt arrival time
  genirq/timings: Add infrastructure to track the interrupt timings
  genirq/debugfs: Remove pointless NULL pointer check
  irqchip/gic-v3-its: Don't assume GICv3 hardware supports 16bit INTID
  irqchip/gic-v3-its: Add ACPI NUMA node mapping
  irqchip/gic-v3-its-platform-msi: Make of_device_ids const
  irqchip/gic-v3-its: Make of_device_ids const
  irqchip/irq-mvebu-icu: Add new driver for Marvell ICU
  irqchip/irq-mvebu-gicp: Add new driver for Marvell GICP
  dt-bindings/interrupt-controller: Add DT binding for the Marvell ICU
  genirq/irqdomain: Remove auto-recursive hierarchy support
  irqchip/MSI: Use irq_domain_update_bus_token instead of an open coded access
  ...
2017-07-03 16:50:31 -07:00
Dmitry Monakhov
e23947bd76 bio-integrity: fold bio_integrity_enabled to bio_integrity_prep
Currently all integrity prep hooks are open-coded, and if prepare fails
we ignore it's code and fail bio with EIO. Let's return real error to
upper layer, so later caller may react accordingly.

In fact no one want to use bio_integrity_prep() w/o bio_integrity_enabled,
so it is reasonable to fold it in to one function.

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
[hch: merged with the latest block tree,
	return bool from bio_integrity_prep]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-07-03 16:56:24 -06:00
Linus Torvalds
9bd42183b9 Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
 "The main changes in this cycle were:

   - Add the SYSTEM_SCHEDULING bootup state to move various scheduler
     debug checks earlier into the bootup. This turns silent and
     sporadically deadly bugs into nice, deterministic splats. Fix some
     of the splats that triggered. (Thomas Gleixner)

   - A round of restructuring and refactoring of the load-balancing and
     topology code (Peter Zijlstra)

   - Another round of consolidating ~20 of incremental scheduler code
     history: this time in terms of wait-queue nomenclature. (I didn't
     get much feedback on these renaming patches, and we can still
     easily change any names I might have misplaced, so if anyone hates
     a new name, please holler and I'll fix it.) (Ingo Molnar)

   - sched/numa improvements, fixes and updates (Rik van Riel)

   - Another round of x86/tsc scheduler clock code improvements, in hope
     of making it more robust (Peter Zijlstra)

   - Improve NOHZ behavior (Frederic Weisbecker)

   - Deadline scheduler improvements and fixes (Luca Abeni, Daniel
     Bristot de Oliveira)

   - Simplify and optimize the topology setup code (Lauro Ramos
     Venancio)

   - Debloat and decouple scheduler code some more (Nicolas Pitre)

   - Simplify code by making better use of llist primitives (Byungchul
     Park)

   - ... plus other fixes and improvements"

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (103 commits)
  sched/cputime: Refactor the cputime_adjust() code
  sched/debug: Expose the number of RT/DL tasks that can migrate
  sched/numa: Hide numa_wake_affine() from UP build
  sched/fair: Remove effective_load()
  sched/numa: Implement NUMA node level wake_affine()
  sched/fair: Simplify wake_affine() for the single socket case
  sched/numa: Override part of migrate_degrades_locality() when idle balancing
  sched/rt: Move RT related code from sched/core.c to sched/rt.c
  sched/deadline: Move DL related code from sched/core.c to sched/deadline.c
  sched/cpuset: Only offer CONFIG_CPUSETS if SMP is enabled
  sched/fair: Spare idle load balancing on nohz_full CPUs
  nohz: Move idle balancer registration to the idle path
  sched/loadavg: Generalize "_idle" naming to "_nohz"
  sched/core: Drop the unused try_get_task_struct() helper function
  sched/fair: WARN() and refuse to set buddy when !se->on_rq
  sched/debug: Fix SCHED_WARN_ON() to return a value on !CONFIG_SCHED_DEBUG as well
  sched/wait: Disambiguate wq_entry->task_list and wq_head->task_list naming
  sched/wait: Move bit_wait_table[] and related functionality from sched/core.c to sched/wait_bit.c
  sched/wait: Split out the wait_bit*() APIs from <linux/wait.h> into <linux/wait_bit.h>
  sched/wait: Re-adjust macro line continuation backslashes in <linux/wait.h>
  ...
2017-07-03 13:08:04 -07:00
Christoph Hellwig
4b855ad371 blk-mq: Create hctx for each present CPU
Currently we only create hctx for online CPUs, which can lead to a lot
of churn due to frequent soft offline / online operations.  Instead
allocate one for each present CPU to avoid this and dramatically simplify
the code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Cc: Keith Busch <keith.busch@intel.com>
Cc: linux-block@vger.kernel.org
Cc: linux-nvme@lists.infradead.org
Link: http://lkml.kernel.org/r/20170626102058.10200-3-hch@lst.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-06-28 23:00:07 +02:00
Christoph Hellwig
46685d1a95 blk-mq: don't bounce by default
For historical reasons we default to bouncing highmem pages for all block
queues.  But the blk-mq drivers are easy to audit to ensure that we don't
need this - scsi and mtip32xx set explicit limits and everyone else doesn't
have any particular ones.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-27 12:13:45 -06:00
Christoph Hellwig
0b0bcacc3b block: don't bother with bounce limits for make_request drivers
We only call blk_queue_bounce for request-based drivers, so stop messing
with it for make_request based drivers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-27 12:13:45 -06:00
Ingo Molnar
1bc3cd4dfa Merge branch 'linus' into sched/core, to pick up fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-24 08:57:20 +02:00
Jens Axboe
f95a0d6a95 Merge commit '8e8320c9315c' into for-4.13/block
Pull in the fix for shared tags, as it conflicts with the pending
changes in for-4.13/block. We already pulled in v4.12-rc5 to solve
other conflicts or get fixes that went into 4.12, so not a lot
of changes in this merge.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-22 21:55:24 -06:00
weiping
a9590fe148 blk-mq: remove double set queue_num
hwctx's queue_num has been set prior call blk_mq_init_hctx, so no need
set it again.

Signed-off-by: weiping <zhangweiping@didichuxing.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-22 09:18:25 -06:00
Bart Van Assche
852ec80983 blk-mq: Make it safe to quiesce and unquiesce from an interrupt handler
Since blk_mq_quiesce_queue_nowait() can be called from interrupt
context, make this safe. Since this function is not in the hot
path, uninline it.

Fixes: commit f4560ffe8c ("blk-mq: use QUEUE_FLAG_QUIESCED to quiesce queue")
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-21 12:01:15 -06:00
Jens Axboe
8e8320c931 blk-mq: fix performance regression with shared tags
If we have shared tags enabled, then every IO completion will trigger
a full loop of every queue belonging to a tag set, and every hardware
queue for each of those queues, even if nothing needs to be done.
This causes a massive performance regression if you have a lot of
shared devices.

Instead of doing this huge full scan on every IO, add an atomic
counter to the main queue that tracks how many hardware queues have
been marked as needing a restart. With that, we can avoid looking for
restartable queues, if we don't have to.

Max reports that this restores performance. Before this patch, 4K
IOPS was limited to 22-23K IOPS. With the patch, we are running at
950-970K IOPS.

Fixes: 6d8c6c0f97 ("blk-mq: Restart a single queue if tag sets are shared")
Reported-by: Max Gurtovoy <maxg@mellanox.com>
Tested-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
Tested-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-21 10:17:49 -06:00
Bart Van Assche
5435c023b9 blk-mq: Warn when attempting to run a hardware queue that is not mapped
A queue must be frozen while the mapped state of a hardware queue
is changed. Additionally, any change of the mapped state is
followed by a call to blk_mq_map_swqueue() (see also
blk_mq_init_allocated_queue() and blk_mq_update_nr_hw_queues()).
Since blk_mq_map_swqueue() does not map any unmapped hardware
queue onto any software queue, no attempt will be made to run
an unmapped hardware queue. Hence issue a warning upon attempts
to run an unmapped hardware queue.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-20 19:27:14 -06:00
Bart Van Assche
7b6078146c blk-mq: Document locking assumptions
Document the locking assumptions in functions that modify
blk_mq_ctx.rq_list to make it easier for humans to verify
this code.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-20 19:27:14 -06:00
Bart Van Assche
c3a148d20a blk-mq: Initialize .rq_flags in blk_mq_rq_ctx_init()
Initialization of blk-mq requests is a bit weird: blk_mq_rq_ctx_init()
is called after a value has been assigned to .rq_flags and .rq_flags
is initialized in __blk_mq_finish_request(). Initialize .rq_flags in
blk_mq_rq_ctx_init() instead of relying on __blk_mq_finish_request().
Moving the initialization of .rq_flags is fine because all changes
and tests of .rq_flags occur between blk_get_request() and finishing
a request.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-20 19:27:14 -06:00
Bart Van Assche
cd6ce1482f block: Make request operation type argument declarations consistent
Instead of declaring the second argument of blk_*_get_request()
as int and passing it to functions that expect an unsigned int,
declare that second argument as unsigned int. Also because of
consistency, rename that second argument from 'rw' into 'op'.
This patch does not change any functionality.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-20 19:27:14 -06:00
Bart Van Assche
0731967877 blk-mq: Reduce blk_mq_hw_ctx size
Since the srcu structure is rather large (184 bytes on an x86-64
system with kernel debugging disabled), only allocate it if needed.

Reported-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-20 19:27:14 -06:00
Goldwyn Rodrigues
03a07c92a9 block: return on congested block device
A new bio operation flag REQ_NOWAIT is introduced to identify bio's
orignating from iocb with IOCB_NOWAIT. This flag indicates
to return immediately if a request cannot be made instead
of retrying.

Stacked devices such as md (the ones with make_request_fn hooks)
currently are not supported because it may block for housekeeping.
For example, an md can have a part of the device suspended.
For this reason, only request based devices are supported.
In the future, this feature will be expanded to stacked devices
by teaching them how to handle the REQ_NOWAIT flags.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-20 07:12:03 -06:00
Ingo Molnar
2055da9738 sched/wait: Disambiguate wq_entry->task_list and wq_head->task_list naming
So I've noticed a number of instances where it was not obvious from the
code whether ->task_list was for a wait-queue head or a wait-queue entry.

Furthermore, there's a number of wait-queue users where the lists are
not for 'tasks' but other entities (poll tables, etc.), in which case
the 'task_list' name is actively confusing.

To clear this all up, name the wait-queue head and entry list structure
fields unambiguously:

	struct wait_queue_head::task_list	=> ::head
	struct wait_queue_entry::task_list	=> ::entry

For example, this code:

	rqw->wait.task_list.next != &wait->task_list

... is was pretty unclear (to me) what it's doing, while now it's written this way:

	rqw->wait.head.next != &wait->entry

... which makes it pretty clear that we are iterating a list until we see the head.

Other examples are:

	list_for_each_entry_safe(pos, next, &x->task_list, task_list) {
	list_for_each_entry(wq, &fence->wait.task_list, task_list) {

... where it's unclear (to me) what we are iterating, and during review it's
hard to tell whether it's trying to walk a wait-queue entry (which would be
a bug), while now it's written as:

	list_for_each_entry_safe(pos, next, &x->head, entry) {
	list_for_each_entry(wq, &fence->wait.head, entry) {

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-20 12:19:14 +02:00
Ingo Molnar
ac6424b981 sched/wait: Rename wait_queue_t => wait_queue_entry_t
Rename:

	wait_queue_t		=>	wait_queue_entry_t

'wait_queue_t' was always a slight misnomer: its name implies that it's a "queue",
but in reality it's a queue *entry*. The 'real' queue is the wait queue head,
which had to carry the name.

Start sorting this out by renaming it to 'wait_queue_entry_t'.

This also allows the real structure name 'struct __wait_queue' to
lose its double underscore and become 'struct wait_queue_entry',
which is the more canonical nomenclature for such data types.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-20 12:18:27 +02:00
Ming Lei
641a9ed60f Revert "blk-mq: don't use sync workqueue flushing from drivers"
This patch reverts commit 2719aa217e0d02(blk-mq: don't use
sync workqueue flushing from drivers) because only
blk_mq_quiesce_queue() need the sync flush, and now
we don't need to stop queue any more, so revert it.

Also changes to cancel_delayed_work() in blk_mq_stop_hw_queue().

Reviewed-by: Bart Van Assche <Bart.VanAssche@sandisk.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-18 14:24:48 -06:00
Ming Lei
39a70c76b8 blk-mq: clarify dispatch may not be drained/blocked by stopping queue
BLK_MQ_S_STOPPED may not be observed in other concurrent I/O paths,
we can't guarantee that dispatching won't happen after returning
from the APIs of stopping queue.

So clarify the fact and avoid potential misuse.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Bart Van Assche <Bart.VanAssche@sandisk.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-18 14:24:48 -06:00
Ming Lei
1d9e9bc6b5 blk-mq: don't stop queue for quiescing
Queue can be started by other blk-mq APIs and can be used in
different cases, this limits uses of blk_mq_quiesce_queue()
if it is based on stopping queue, and make its usage very
difficult, especially users have to use the stop queue APIs
carefully for avoiding to break blk_mq_quiesce_queue().

We have applied the QUIESCED flag for draining and blocking
dispatch, so it isn't necessary to stop queue any more.

After stopping queue is removed, blk_mq_quiesce_queue() can
be used safely and easily, then users won't worry about queue
restarting during quiescing at all.

Reviewed-by: Bart Van Assche <Bart.VanAssche@sandisk.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-18 14:24:48 -06:00
Ming Lei
69e07c4adb blk-mq: update comments on blk_mq_quiesce_queue()
Actually what we want to get from blk_mq_quiesce_queue()
isn't only to wait for completion of all ongoing .queue_rq().

In the typical context of canceling requests, we need to
make sure that the following is done in the dispatch path
before starting to cancel requests:

	- failed dispatched request is finished
	- busy dispatched request is requeued, and the STARTED
	flag is cleared

So update comment to keep code, doc and our expection consistent.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-18 14:24:48 -06:00
Ming Lei
f4560ffe8c blk-mq: use QUEUE_FLAG_QUIESCED to quiesce queue
It is required that no dispatch can happen any more once
blk_mq_quiesce_queue() returns, and we don't have such requirement
on APIs of stopping queue.

But blk_mq_quiesce_queue() still may not block/drain dispatch in the
the case of BLK_MQ_S_START_ON_RUN, so use the new introduced flag of
QUEUE_FLAG_QUIESCED and evaluate it inside RCU read-side critical
sections for fixing this issue.

Also blk_mq_quiesce_queue() is implemented via stopping queue, which
limits its uses, and easy to cause race, because any queue restart in
other paths may break blk_mq_quiesce_queue(). With the introduced
flag of QUEUE_FLAG_QUIESCED, we don't need to depend on stopping queue
for quiescing any more.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Bart Van Assche <Bart.VanAssche@sandisk.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-18 14:24:27 -06:00
Ming Lei
e4e739131a blk-mq: introduce blk_mq_unquiesce_queue
blk_mq_start_stopped_hw_queues() is used implictly
as counterpart of blk_mq_quiesce_queue() for unquiescing queue,
so we introduce blk_mq_unquiesce_queue() and make it
as counterpart of blk_mq_quiesce_queue() explicitly.

This function is for improving the current quiescing mechanism
in the following patches.

Reviewed-by: Bart Van Assche <Bart.VanAssche@sandisk.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-18 14:20:04 -06:00
NeilBrown
af67c31fba blk: remove bio_set arg from blk_queue_split()
blk_queue_split() is always called with the last arg being q->bio_split,
where 'q' is the first arg.

Also blk_queue_split() sometimes uses the passed-in 'bs' and sometimes uses
q->bio_split.

This is inconsistent and unnecessary.  Remove the last arg and always use
q->bio_split inside blk_queue_split()

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Credit-to: Javier González <jg@lightnvm.io> (Noticed that lightnvm was missed)
Reviewed-by: Javier González <javier@cnexlabs.com>
Tested-by: Javier González <javier@cnexlabs.com>
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-18 12:40:59 -06:00
Christoph Hellwig
e4cdf1a1cb blk-mq: remove __blk_mq_alloc_request
Move most code into blk_mq_rq_ctx_init, and the rest into
blk_mq_get_request.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-18 10:08:55 -06:00
Christoph Hellwig
5bbf4e5a8e blk-mq-sched: unify request prepare methods
This patch makes sure we always allocate requests in the core blk-mq
code and use a common prepare_request method to initialize them for
both mq I/O schedulers.  For Kyber and additional limit_depth method
is added that is called before allocating the request.

Also because none of the intializations can really fail the new method
does not return an error - instead the bfq finish method is hardened
to deal with the no-IOC case.

Last but not least this removes the abuse of RQF_QUEUE by the blk-mq
scheduling code as RQF_ELFPRIV is all that is needed now.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-18 10:08:55 -06:00
Christoph Hellwig
44e8c2bff8 blk-mq: refactor blk_mq_sched_assign_ioc
blk_mq_sched_assign_ioc now only handles the assigned of the ioc if
the schedule needs it (bfq only at the moment).  The caller to the
per-request initializer is moved out so that it can be merged with
a similar call for the kyber I/O scheduler.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-18 10:08:55 -06:00
Christoph Hellwig
037cebb85b blk-mq: streamline blk_mq_get_request
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-18 10:08:55 -06:00
Christoph Hellwig
6af54051a0 blk-mq: simplify blk_mq_free_request
Merge three functions only tail-called by blk_mq_free_request into
blk_mq_free_request.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-18 10:08:55 -06:00
Christoph Hellwig
7b9e936163 blk-mq-sched: unify request finished methods
No need to have two different callouts of bfq vs kyber.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-18 10:08:55 -06:00
Christoph Hellwig
ea511e3c28 blk-mq: remove blk_mq_sched_{get,put}_rq_priv
Having these as separate helpers in a header really does not help
readability, or my chances to refactor this code sanely.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-18 10:08:55 -06:00
Christoph Hellwig
d2c0d38324 blk-mq: move blk_mq_sched_{get,put}_request to blk-mq.c
Having them out of line in blk-mq-sched.c just makes the code flow
unnecessarily complicated.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-18 10:08:55 -06:00
Christoph Hellwig
6e15cf2a0b blk-mq: mark blk_mq_rq_ctx_init static
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-18 10:08:55 -06:00
Jens Axboe
f06345add9 blk-mq: fixup type of 'ret' in __blk_mq_try_issue_directly()
Should be a blk_status_t type, not an integer.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-12 11:22:46 -06:00
Jens Axboe
8f66439eec Linux 4.12-rc5
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Merge tag 'v4.12-rc5' into for-4.13/block

We've already got a few conflicts and upcoming work depends on some of the
changes that have gone into mainline as regression fixes for this series.

Pull in 4.12-rc5 to resolve these conflicts and make it easier on down stream
trees to continue working on 4.13 changes.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-12 08:30:13 -06:00
Christoph Hellwig
fc17b6534e blk-mq: switch ->queue_rq return value to blk_status_t
Use the same values for use for request completion errors as the return
value from ->queue_rq.  BLK_STS_RESOURCE is special cased to cause
a requeue, and all the others are completed as-is.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
2017-06-09 09:27:32 -06:00
Christoph Hellwig
2a842acab1 block: introduce new block status code type
Currently we use nornal Linux errno values in the block layer, and while
we accept any error a few have overloaded magic meanings.  This patch
instead introduces a new  blk_status_t value that holds block layer specific
status codes and explicitly explains their meaning.  Helpers to convert from
and to the previous special meanings are provided for now, but I suspect
we want to get rid of them in the long run - those drivers that have a
errno input (e.g. networking) usually get errnos that don't know about
the special block layer overloads, and similarly returning them to userspace
will usually return somethings that strictly speaking isn't correct
for file system operations, but that's left as an exercise for later.

For now the set of errors is a very limited set that closely corresponds
to the previous overloaded errno values, but there is some low hanging
fruite to improve it.

blk_status_t (ab)uses the sparse __bitwise annotations to allow for sparse
typechecking, so that we can easily catch places passing the wrong values.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
2017-06-09 09:27:32 -06:00
Ming Lei
d964f04a8f blk-mq: fix direct issue
If queue is stopped, we shouldn't dispatch request into driver and
hardware, unfortunately the check is removed in bd166ef183c2(blk-mq-sched:
add framework for MQ capable IO schedulers).

This patch fixes the issue by moving the check back into
__blk_mq_try_issue_directly().

This patch fixes request use-after-free[1][2] during canceling requets
of NVMe in nvme_dev_disable(), which can be triggered easily during
NVMe reset & remove test.

[1] oops kernel log when CONFIG_BLK_DEV_INTEGRITY is on
[  103.412969] BUG: unable to handle kernel NULL pointer dereference at 000000000000000a
[  103.412980] IP: bio_integrity_advance+0x48/0xf0
[  103.412981] PGD 275a88067
[  103.412981] P4D 275a88067
[  103.412982] PUD 276c43067
[  103.412983] PMD 0
[  103.412984]
[  103.412986] Oops: 0000 [#1] SMP
[  103.412989] Modules linked in: vfat fat intel_rapl sb_edac x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm irqbypass crct10dif_pclmul crc32_pclmul ghash_clmulni_intel pcbc aesni_intel crypto_simd cryptd ipmi_ssif iTCO_wdt iTCO_vendor_support mxm_wmi glue_helper dcdbas ipmi_si mei_me pcspkr mei sg ipmi_devintf lpc_ich ipmi_msghandler shpchp acpi_power_meter wmi nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables xfs libcrc32c sd_mod mgag200 i2c_algo_bit drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm drm crc32c_intel nvme ahci nvme_core libahci libata tg3 i2c_core megaraid_sas ptp pps_core dm_mirror dm_region_hash dm_log dm_mod
[  103.413035] CPU: 0 PID: 102 Comm: kworker/0:2 Not tainted 4.11.0+ #1
[  103.413036] Hardware name: Dell Inc. PowerEdge R730xd/072T6D, BIOS 2.2.5 09/06/2016
[  103.413041] Workqueue: events nvme_remove_dead_ctrl_work [nvme]
[  103.413043] task: ffff9cc8775c8000 task.stack: ffffc033c252c000
[  103.413045] RIP: 0010:bio_integrity_advance+0x48/0xf0
[  103.413046] RSP: 0018:ffffc033c252fc10 EFLAGS: 00010202
[  103.413048] RAX: 0000000000000000 RBX: ffff9cc8720a8cc0 RCX: ffff9cca72958240
[  103.413049] RDX: ffff9cca72958000 RSI: 0000000000000008 RDI: ffff9cc872537f00
[  103.413049] RBP: ffffc033c252fc28 R08: 0000000000000000 R09: ffffffffb963a0d5
[  103.413050] R10: 000000000000063e R11: 0000000000000000 R12: ffff9cc8720a8d18
[  103.413051] R13: 0000000000001000 R14: ffff9cc872682e00 R15: 00000000fffffffb
[  103.413053] FS:  0000000000000000(0000) GS:ffff9cc877c00000(0000) knlGS:0000000000000000
[  103.413054] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  103.413055] CR2: 000000000000000a CR3: 0000000276c41000 CR4: 00000000001406f0
[  103.413056] Call Trace:
[  103.413063]  bio_advance+0x2a/0xe0
[  103.413067]  blk_update_request+0x76/0x330
[  103.413072]  blk_mq_end_request+0x1a/0x70
[  103.413074]  blk_mq_dispatch_rq_list+0x370/0x410
[  103.413076]  ? blk_mq_flush_busy_ctxs+0x94/0xe0
[  103.413080]  blk_mq_sched_dispatch_requests+0x173/0x1a0
[  103.413083]  __blk_mq_run_hw_queue+0x8e/0xa0
[  103.413085]  __blk_mq_delay_run_hw_queue+0x9d/0xa0
[  103.413088]  blk_mq_start_hw_queue+0x17/0x20
[  103.413090]  blk_mq_start_hw_queues+0x32/0x50
[  103.413095]  nvme_kill_queues+0x54/0x80 [nvme_core]
[  103.413097]  nvme_remove_dead_ctrl_work+0x1f/0x40 [nvme]
[  103.413103]  process_one_work+0x149/0x360
[  103.413105]  worker_thread+0x4d/0x3c0
[  103.413109]  kthread+0x109/0x140
[  103.413111]  ? rescuer_thread+0x380/0x380
[  103.413113]  ? kthread_park+0x60/0x60
[  103.413120]  ret_from_fork+0x2c/0x40
[  103.413121] Code: 08 4c 8b 63 50 48 8b 80 80 00 00 00 48 8b 90 d0 03 00 00 31 c0 48 83 ba 40 02 00 00 00 48 8d 8a 40 02 00 00 48 0f 45 c1 c1 ee 09 <0f> b6 48 0a 0f b6 40 09 41 89 f5 83 e9 09 41 d3 ed 44 0f af e8
[  103.413145] RIP: bio_integrity_advance+0x48/0xf0 RSP: ffffc033c252fc10
[  103.413146] CR2: 000000000000000a
[  103.413157] ---[ end trace cd6875d16eb5a11e ]---
[  103.455368] Kernel panic - not syncing: Fatal exception
[  103.459826] Kernel Offset: 0x37600000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)
[  103.850916] ---[ end Kernel panic - not syncing: Fatal exception
[  103.857637] sched: Unexpected reschedule of offline CPU#1!
[  103.863762] ------------[ cut here ]------------

[2] kernel hang in blk_mq_freeze_queue_wait() when CONFIG_BLK_DEV_INTEGRITY is off
[  247.129825] INFO: task nvme-test:1772 blocked for more than 120 seconds.
[  247.137311]       Not tainted 4.12.0-rc2.upstream+ #4
[  247.142954] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  247.151704] Call Trace:
[  247.154445]  __schedule+0x28a/0x880
[  247.158341]  schedule+0x36/0x80
[  247.161850]  blk_mq_freeze_queue_wait+0x4b/0xb0
[  247.166913]  ? remove_wait_queue+0x60/0x60
[  247.171485]  blk_freeze_queue+0x1a/0x20
[  247.175770]  blk_cleanup_queue+0x7f/0x140
[  247.180252]  nvme_ns_remove+0xa3/0xb0 [nvme_core]
[  247.185503]  nvme_remove_namespaces+0x32/0x50 [nvme_core]
[  247.191532]  nvme_uninit_ctrl+0x2d/0xa0 [nvme_core]
[  247.196977]  nvme_remove+0x70/0x110 [nvme]
[  247.201545]  pci_device_remove+0x39/0xc0
[  247.205927]  device_release_driver_internal+0x141/0x200
[  247.211761]  device_release_driver+0x12/0x20
[  247.216531]  pci_stop_bus_device+0x8c/0xa0
[  247.221104]  pci_stop_and_remove_bus_device_locked+0x1a/0x30
[  247.227420]  remove_store+0x7c/0x90
[  247.231320]  dev_attr_store+0x18/0x30
[  247.235409]  sysfs_kf_write+0x3a/0x50
[  247.239497]  kernfs_fop_write+0xff/0x180
[  247.243867]  __vfs_write+0x37/0x160
[  247.247757]  ? selinux_file_permission+0xe5/0x120
[  247.253011]  ? security_file_permission+0x3b/0xc0
[  247.258260]  vfs_write+0xb2/0x1b0
[  247.261964]  ? syscall_trace_enter+0x1d0/0x2b0
[  247.266924]  SyS_write+0x55/0xc0
[  247.270540]  do_syscall_64+0x67/0x150
[  247.274636]  entry_SYSCALL64_slow_path+0x25/0x25
[  247.279794] RIP: 0033:0x7f5c96740840
[  247.283785] RSP: 002b:00007ffd00e87ee8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[  247.292238] RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007f5c96740840
[  247.300194] RDX: 0000000000000002 RSI: 00007f5c97060000 RDI: 0000000000000001
[  247.308159] RBP: 00007f5c97060000 R08: 000000000000000a R09: 00007f5c97059740
[  247.316123] R10: 0000000000000001 R11: 0000000000000246 R12: 00007f5c96a14400
[  247.324087] R13: 0000000000000002 R14: 0000000000000001 R15: 0000000000000000
[  370.016340] INFO: task nvme-test:1772 blocked for more than 120 seconds.

Fixes: 12d70958a2e8(blk-mq: don't fail allocating driver tag for stopped hw queue)
Cc: stable@vger.kernel.org
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Bart Van Assche <Bart.VanAssche@sandisk.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2017-06-06 10:00:35 -06:00
Ming Lei
dad7a3be49 blk-mq: pass correct hctx to blk_mq_try_issue_directly
When direct issue is done on request picked up from plug list,
the hctx need to be updated with the actual hw queue, otherwise
wrong hctx is used and may hurt performance, especially when
wrong SRCU readlock is acquired/released

Reported-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2017-06-06 10:00:33 -06:00
Keith Busch
e4dc2b32df blk-mq: Take tagset lock when updating hw queues
The tagset lock needs to be held when iterating the tag_list, so a
lockdep assert was added when updating number of hardware queues. The
drivers calling this API, however, were unaware of the new requirement,
so are failing the assertion.

This patch takes the lock within the blk-mq function so the drivers do
not have to be modified in order to be safe.

Fixes: 705cda97e ("blk-mq: Make it safe to use RCU to iterate over blk_mq_tag_set.tag_list")
Reported-by: Gabriel Krisman Bertazi <krisman@collabora.co.uk>
Reviewed-by: Bart Van Assche <Bart.VanAssche@sandisk.com>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2017-05-30 12:32:37 -06:00
Ming Lei
9bddeb2a5b blk-mq: make per-sw-queue bio merge as default .bio_merge
Because what the per-sw-queue bio merge does is basically same with
scheduler's .bio_merge(), this patch makes per-sw-queue bio merge
as the default .bio_merge if no scheduler is used or io scheduler
doesn't provide .bio_merge().

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2017-05-26 14:12:04 -06:00
Ming Lei
ab42f35d9c blk-mq: merge bio into sw queue before plugging
Before blk-mq is introduced, I/O is merged to elevator
before being putted into plug queue, but blk-mq changed the
order and makes merging to sw queue basically impossible.
Then it is observed that throughput of sequential I/O is degraded
about 10%~20% on virtio-blk in the test[1] if mq-deadline isn't used.

This patch moves the bio merging per sw queue before plugging,
like what blk_queue_bio() does, and the performance regression is
fixed under this situation.

[1]. test script:
sudo fio --direct=1 --size=128G --bsrange=4k-4k --runtime=40 --numjobs=16 --ioengine=libaio --iodepth=64 --group_reporting=1 --filename=/dev/vdb --name=virtio_blk-test-$RW --rw=$RW --output-format=json

RW=read or write

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2017-05-26 14:12:03 -06:00
Ming Lei
7254a50a5d blk-mq: remove blk_mq_abort_requeue_list()
No one uses it any more, so remove it.

Reviewed-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
2017-05-22 20:50:11 +02:00
Wen Xiong
f36ea50ca0 blk-mq: NVMe 512B/4K+T10 DIF/DIX format returns I/O error on dd with split op
When formatting NVMe to 512B/4K + T10 DIf/DIX, dd with split op returns
"Input/output error". Looks block layer split the bio after calling
bio_integrity_prep(bio). This patch fixes the issue.

Below is how we debug this issue:
(1)format nvme to 4K block # size with type 2 DIF
(2)dd with block size bigger than 1024k.
oflag=direct
dd: error writing '/dev/nvme0n1': Input/output error

We added some debug code in nvme device driver. It showed us the first
op and the second op have the same bi and pi address. This is not
correct.

1st op: nvme0n1 Op:Wr slba 0x505 length 0x100, PI ctrl=0x1400,
	dsmgmt=0x0, AT=0x0 & RT=0x505
	Guard 0x00b1, AT 0x0000, RT physical 0x00000505 RT virtual 0x00002828

2nd op: nvme0n1 Op:Wr slba 0x605 length 0x1, PI ctrl=0x1400, dsmgmt=0x0,
	AT=0x0 & RT=0x605  ==> This op fails and subsequent 5 retires..
	Guard 0x00b1, AT 0x0000, RT physical 0x00000605 RT virtual 0x00002828

With the fix, It showed us both of the first op and the second op have
correct bi and pi address.

1st op: nvme2n1 Op:Wr slba 0x505 length 0x100, PI ctrl=0x1400,
	dsmgmt=0x0, AT=0x0 & RT=0x505
	Guard 0x5ccb, AT 0x0000, RT physical 0x00000505 RT virtual
	0x00002828
2nd op: nvme2n1 Op:Wr slba 0x605 length 0x1, PI ctrl=0x1400, dsmgmt=0x0,
	AT=0x0 & RT=0x605
	Guard 0xab4c, AT 0x0000, RT physical 0x00000605 RT virtual
	0x00003028

Signed-off-by: Wen Xiong <wenxiong@linux.vnet.ibm.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2017-05-10 08:02:58 -06:00
Colin Ian King
ebd7685795 blk-mq: make __blk_mq_stop_hw_queues static
Making __blk_mq_stop_hw_queues static fixes sparse warning:

  block/blk-mq.c:6: warning: symbol '__blk_mq_stop_hw_queues' was not
  declared. Should it be static?

Fixes: 2719aa217e ("blk-mq: don't use sync workqueue flushing from drivers")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2017-05-08 08:09:39 -06:00
Wanpeng Li
51d638b1f5 block/mq: fix potential deadlock during cpu hotplug
This can be triggered by hot-unplug one cpu.

======================================================
 [ INFO: possible circular locking dependency detected ]
 4.11.0+ #17 Not tainted
 -------------------------------------------------------
 step_after_susp/2640 is trying to acquire lock:
  (all_q_mutex){+.+...}, at: [<ffffffffb33f95b8>] blk_mq_queue_reinit_work+0x18/0x110

 but task is already holding lock:
  (cpu_hotplug.lock){+.+.+.}, at: [<ffffffffb306d04f>] cpu_hotplug_begin+0x7f/0xe0

 which lock already depends on the new lock.

 the existing dependency chain (in reverse order) is:

 -> #1 (cpu_hotplug.lock){+.+.+.}:
        lock_acquire+0x11c/0x230
        __mutex_lock+0x92/0x990
        mutex_lock_nested+0x1b/0x20
        get_online_cpus+0x64/0x80
        blk_mq_init_allocated_queue+0x3a0/0x4e0
        blk_mq_init_queue+0x3a/0x60
        loop_add+0xe5/0x280
        loop_init+0x124/0x177
        do_one_initcall+0x53/0x1c0
        kernel_init_freeable+0x1e3/0x27f
        kernel_init+0xe/0x100
        ret_from_fork+0x31/0x40

 -> #0 (all_q_mutex){+.+...}:
        __lock_acquire+0x189a/0x18a0
        lock_acquire+0x11c/0x230
        __mutex_lock+0x92/0x990
        mutex_lock_nested+0x1b/0x20
        blk_mq_queue_reinit_work+0x18/0x110
        blk_mq_queue_reinit_dead+0x1c/0x20
        cpuhp_invoke_callback+0x1f2/0x810
        cpuhp_down_callbacks+0x42/0x80
        _cpu_down+0xb2/0xe0
        freeze_secondary_cpus+0xb6/0x390
        suspend_devices_and_enter+0x3b3/0xa40
        pm_suspend+0x129/0x490
        state_store+0x82/0xf0
        kobj_attr_store+0xf/0x20
        sysfs_kf_write+0x45/0x60
        kernfs_fop_write+0x135/0x1c0
        __vfs_write+0x37/0x160
        vfs_write+0xcd/0x1d0
        SyS_write+0x58/0xc0
        do_syscall_64+0x8f/0x710
        return_from_SYSCALL_64+0x0/0x7a

 other info that might help us debug this:

  Possible unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock(cpu_hotplug.lock);
                                lock(all_q_mutex);
                                lock(cpu_hotplug.lock);
   lock(all_q_mutex);

  *** DEADLOCK ***

 8 locks held by step_after_susp/2640:
  #0:  (sb_writers#6){.+.+.+}, at: [<ffffffffb3244aed>] vfs_write+0x1ad/0x1d0
  #1:  (&of->mutex){+.+.+.}, at: [<ffffffffb32d3a51>] kernfs_fop_write+0x101/0x1c0
  #2:  (s_active#166){.+.+.+}, at: [<ffffffffb32d3a59>] kernfs_fop_write+0x109/0x1c0
  #3:  (pm_mutex){+.+...}, at: [<ffffffffb30d2ecd>] pm_suspend+0x21d/0x490
  #4:  (acpi_scan_lock){+.+.+.}, at: [<ffffffffb34dc3d7>] acpi_scan_lock_acquire+0x17/0x20
  #5:  (cpu_add_remove_lock){+.+.+.}, at: [<ffffffffb306d6d7>] freeze_secondary_cpus+0x27/0x390
  #6:  (cpu_hotplug.dep_map){++++++}, at: [<ffffffffb306cfd5>] cpu_hotplug_begin+0x5/0xe0
  #7:  (cpu_hotplug.lock){+.+.+.}, at: [<ffffffffb306d04f>] cpu_hotplug_begin+0x7f/0xe0

 stack backtrace:
 CPU: 3 PID: 2640 Comm: step_after_susp Not tainted 4.11.0+ #17
 Hardware name: Dell Inc. OptiPlex 7040/0JCTF8, BIOS 1.4.9 09/12/2016
 Call Trace:
  dump_stack+0x99/0xce
  print_circular_bug+0x1fa/0x270
  __lock_acquire+0x189a/0x18a0
  lock_acquire+0x11c/0x230
  ? lock_acquire+0x11c/0x230
  ? blk_mq_queue_reinit_work+0x18/0x110
  ? blk_mq_queue_reinit_work+0x18/0x110
  __mutex_lock+0x92/0x990
  ? blk_mq_queue_reinit_work+0x18/0x110
  ? kmem_cache_free+0x2cb/0x330
  ? anon_transport_class_unregister+0x20/0x20
  ? blk_mq_queue_reinit_work+0x110/0x110
  mutex_lock_nested+0x1b/0x20
  ? mutex_lock_nested+0x1b/0x20
  blk_mq_queue_reinit_work+0x18/0x110
  blk_mq_queue_reinit_dead+0x1c/0x20
  cpuhp_invoke_callback+0x1f2/0x810
  ? __flow_cache_shrink+0x160/0x160
  cpuhp_down_callbacks+0x42/0x80
  _cpu_down+0xb2/0xe0
  freeze_secondary_cpus+0xb6/0x390
  suspend_devices_and_enter+0x3b3/0xa40
  ? rcu_read_lock_sched_held+0x79/0x80
  pm_suspend+0x129/0x490
  state_store+0x82/0xf0
  kobj_attr_store+0xf/0x20
  sysfs_kf_write+0x45/0x60
  kernfs_fop_write+0x135/0x1c0
  __vfs_write+0x37/0x160
  ? rcu_read_lock_sched_held+0x79/0x80
  ? rcu_sync_lockdep_assert+0x2f/0x60
  ? __sb_start_write+0xd9/0x1c0
  ? vfs_write+0x1ad/0x1d0
  vfs_write+0xcd/0x1d0
  SyS_write+0x58/0xc0
  ? rcu_read_lock_sched_held+0x79/0x80
  do_syscall_64+0x8f/0x710
  ? trace_hardirqs_on_thunk+0x1a/0x1c
  entry_SYSCALL64_slow_path+0x25/0x25

The cpu hotplug path will hold cpu_hotplug.lock and then reinit all exiting
queues for blk mq w/ all_q_mutex, however, blk_mq_init_allocated_queue() will
contend these two locks in the inversion order. This is due to commit eabe06595d
(blk/mq: Cure cpu hotplug lock inversion), it fixes a cpu hotplug lock inversion
issue because of hotplug rework, however the hotplug rework is still work-in-progress
and lives in a -tip branch and mainline cannot yet trigger that splat. The commit
breaks the linus's tree in the merge window, so this patch reverts the lock order
and avoids to splat linus's tree.

Cc: Jens Axboe <axboe@kernel.dk>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2017-05-07 19:50:11 -06:00
Omar Sandoval
9c1051aacd blk-mq: untangle debugfs and sysfs
Originally, I tied debugfs registration/unregistration together with
sysfs. There's no reason to do this, and it's getting in the way of
letting schedulers define their own debugfs attributes. Instead, tie the
debugfs registration to the lifetime of the structures themselves.

The saner lifetimes mean we can also get rid of the extra mq directory
and move everything one level up. I.e., nvme0n1/mq/hctx0/tags is now
just nvme0n1/hctx0/tags.

Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2017-05-04 08:24:13 -06:00
Peter Zijlstra
eabe06595d block/mq: Cure cpu hotplug lock inversion
By poking at /debug/sched_features I triggered the following splat:

 [] ======================================================
 [] WARNING: possible circular locking dependency detected
 [] 4.11.0-00873-g964c8b7-dirty #694 Not tainted
 [] ------------------------------------------------------
 [] bash/2109 is trying to acquire lock:
 []  (cpu_hotplug_lock.rw_sem){++++++}, at: [<ffffffff8120cb8b>] static_key_slow_dec+0x1b/0x50
 []
 [] but task is already holding lock:
 []  (&sb->s_type->i_mutex_key#4){+++++.}, at: [<ffffffff81140216>] sched_feat_write+0x86/0x170
 []
 [] which lock already depends on the new lock.
 []
 []
 [] the existing dependency chain (in reverse order) is:
 []
 [] -> #2 (&sb->s_type->i_mutex_key#4){+++++.}:
 []        lock_acquire+0x100/0x210
 []        down_write+0x28/0x60
 []        start_creating+0x5e/0xf0
 []        debugfs_create_dir+0x13/0x110
 []        blk_mq_debugfs_register+0x21/0x70
 []        blk_mq_register_dev+0x64/0xd0
 []        blk_register_queue+0x6a/0x170
 []        device_add_disk+0x22d/0x440
 []        loop_add+0x1f3/0x280
 []        loop_init+0x104/0x142
 []        do_one_initcall+0x43/0x180
 []        kernel_init_freeable+0x1de/0x266
 []        kernel_init+0xe/0x100
 []        ret_from_fork+0x31/0x40
 []
 [] -> #1 (all_q_mutex){+.+.+.}:
 []        lock_acquire+0x100/0x210
 []        __mutex_lock+0x6c/0x960
 []        mutex_lock_nested+0x1b/0x20
 []        blk_mq_init_allocated_queue+0x37c/0x4e0
 []        blk_mq_init_queue+0x3a/0x60
 []        loop_add+0xe5/0x280
 []        loop_init+0x104/0x142
 []        do_one_initcall+0x43/0x180
 []        kernel_init_freeable+0x1de/0x266
 []        kernel_init+0xe/0x100
 []        ret_from_fork+0x31/0x40

 []  *** DEADLOCK ***
 []
 [] 3 locks held by bash/2109:
 []  #0:  (sb_writers#11){.+.+.+}, at: [<ffffffff81292bcd>] vfs_write+0x17d/0x1a0
 []  #1:  (debugfs_srcu){......}, at: [<ffffffff8155a90d>] full_proxy_write+0x5d/0xd0
 []  #2:  (&sb->s_type->i_mutex_key#4){+++++.}, at: [<ffffffff81140216>] sched_feat_write+0x86/0x170
 []
 [] stack backtrace:
 [] CPU: 9 PID: 2109 Comm: bash Not tainted 4.11.0-00873-g964c8b7-dirty #694
 [] Hardware name: Intel Corporation S2600GZ/S2600GZ, BIOS SE5C600.86B.02.02.0002.122320131210 12/23/2013
 [] Call Trace:

 []  lock_acquire+0x100/0x210
 []  get_online_cpus+0x2a/0x90
 []  static_key_slow_dec+0x1b/0x50
 []  static_key_disable+0x20/0x30
 []  sched_feat_write+0x131/0x170
 []  full_proxy_write+0x97/0xd0
 []  __vfs_write+0x28/0x120
 []  vfs_write+0xb5/0x1a0
 []  SyS_write+0x49/0xa0
 []  entry_SYSCALL_64_fastpath+0x23/0xc2

This is because of the cpu hotplug lock rework. Break the chain at #1
by reversing the lock acquisition order. This way i_mutex_key#4 no
longer depends on cpu_hotplug_lock and things are good.

Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
2017-05-04 07:57:13 -06:00
Jens Axboe
2719aa217e blk-mq: don't use sync workqueue flushing from drivers
A previous commit introduced the sync flush, which we need from
internal callers like blk_mq_quiesce_queue(). However, we also
call the stop helpers from drivers, particularly from ->queue_rq()
when we have to stop processing for a bit. We can't block from
those locations, and we don't have to guarantee that we're
fully flushed.

Fixes: 9f99373790 ("blk-mq: unify hctx delayed_run_work and run_work")
Reviewed-by: Bart Van Assche <Bart.VanAssche@sandisk.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2017-05-03 11:44:43 -06:00
Ming Lei
7a148c2fcf block: don't call blk_mq_quiesce_queue() after queue is frozen
After queue is frozen, no request in this queue can be in use at all, so
there can't be any .queue_rq() running on this queue.  It isn't
necessary to call blk_mq_quiesce_queue() any more, so remove it in both
elevator_switch_mq() and blk_mq_update_nr_requests().

Cc: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>

Fixed up the description a bit.

Signed-off-by: Jens Axboe <axboe@fb.com>
2017-05-02 11:33:08 -06:00
Christoph Hellwig
d6296d39e9 blk-mq: update ->init_request and ->exit_request prototypes
Remove the request_idx parameter, which can't be used safely now that we
support I/O schedulers with blk-mq.  Except for a superflous check in
mtip32xx it was unused anyway.

Also pass the tag_set instead of just the driver data - this allows drivers
to avoid some code duplication in a follow on cleanup.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
2017-05-02 07:52:08 -06:00