The reverse-order double lock dance in ioc_release_fn() is using a
retry loop. This is a problem on PREEMPT_RT because it could preempt
the task that would release q->queue_lock and thus live lock in the
retry loop.
RCU is already managing the freeing of the request queue and icq. If
the trylock fails, use RCU to guarantee that the request queue and
icq are not freed and re-acquire the locks in the correct order,
allowing forward progress.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The legacy CFQ IO scheduler could call put_io_context() in its exit_icq()
elevator callback. This led to a lockdep warning, which was fixed in
commit d8c66c5d59 ("block: fix lockdep warning on io_context release
put_io_context()") by using a nested subclass for the ioc spinlock.
However, with commit f382fb0bce ("block: remove legacy IO schedulers")
the CFQ IO scheduler no longer exists.
The BFQ IO scheduler also implements the exit_icq() elevator callback but
does not call put_io_context().
The nested subclass for the ioc spinlock is no longer needed. Since it
existed as an exception and no longer applies, remove the nested subclass
usage.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This reverts commit 826f2f48da.
Qian Cai reports that this commit causes stalls with swap. Revert until
the reason can be figured out.
Reported-by: Qian Cai <cai@lca.pw>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In theory, when GENHD_FL_NO_PART_SCAN is set, no partitions can be created
on one disk. However, ioctl(BLKPG, BLKPG_ADD_PARTITION) doesn't check
GENHD_FL_NO_PART_SCAN, so partitions still can be added even though
GENHD_FL_NO_PART_SCAN is set.
So far blk_drop_partitions() only removes partitions when disk_part_scan_enabled()
return true. This way can make ghost partition on loop device after changing/clearing
FD in case that PARTSCAN is disabled, such as partitions can be added
via 'parted' on loop disk even though GENHD_FL_NO_PART_SCAN is set.
Fix this issue by always removing partitions in blk_drop_partitions(), and
this way is correct because the current code supposes that no partitions
can be added in case of GENHD_FL_NO_PART_SCAN.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In doing high IOPS testing, blk-mq is generally pretty well optimized.
There are a few things that stuck out as using more CPU than what is
really warranted, and one thing is the round_jiffies_up() that we do
twice for each request. That accounts for about 0.8% of the CPU in
my testing.
We can make this cheaper by avoiding an integer division, by just adding
a rough HZ mask that we can AND with instead. The timeouts are only on a
second granularity already, we don't have to be that accurate here and
this patch barely changes that. All we care about is nice grouping.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We've already validated the 'q->elevator' before calling
->ops.completed_request() in blk_mq_sched_completed_request(), thus no
need to validate rq->internal_tag again. Rmove it.
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Remove unnecessary local variable 'ret' in blk_mq_dispatch_hctx_list().
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We never set any congested bits in the group writeback instances of it.
And for the simpler bdi-wide case a simple scalar field is all that
that is needed.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
md is the last driver using the legacy media_changed method. Switch
it over to (not so) new ->clear_events approach, which also removes the
need for the ->revalidate_disk method.
Signed-off-by: Christoph Hellwig <hch@lst.de>
[axboe: remove unused 'bdops' variable in disk_clear_events()]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Move .nr_active update and request assignment into blk_mq_get_driver_tag(),
all are good to do during getting driver tag.
Meantime blk-flush related code is simplified and flush request needn't
to update the request table manually any more.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Current handling of q->mq_ops->queue_rq result is a bit ugly:
- two branches which needs to 'continue' have to check if the
dispatch local list is empty, otherwise one bad request may
be retrieved via 'rq = list_first_entry(list, struct request, queuelist);'
- the branch of 'if (unlikely(ret != BLK_STS_OK))' isn't easy
to follow, since it is actually one error branch.
Streamline this handling, so the code becomes more readable, meantime
potential kernel oops can be avoided in case that the last request in
local dispatch list is failed.
Fixes: fc17b6534e ("blk-mq: switch ->queue_rq return value to blk_status_t")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If blk_mq_submit_bio flushes the plug list, bios for other disks can
show up on current->bio_list. As that doesn't involve any stacking of
block device it is entirely harmless and we should not warn about
this case.
Fixes: ff93ea0ce7 ("block: shortcut __submit_bio_noacct for blk-mq drivers")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
bio_alloc_bioset references current->bio_list[1], so we need to
initialize it for the blk-mq submission path as well.
Fixes: ff93ea0ce7 ("block: shortcut __submit_bio_noacct for blk-mq drivers")
Reported-by: Qian Cai <cai@lca.pw>
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
ktime_to_ns(ktime_get()), which is expensive, does not need to be called
if blk_iolatency_enabled() return false in blkcg_iolatency_done_bio().
Postponing ktime_to_ns(ktime_get()) execution reduces the CPU usage when
blk_iolatency is disabled.
Signed-off-by: Hongnan Li <hongnan.li@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Now that submit_bio_noacct has a decent blk-mq fast path there is no
more need for this bypass.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
For blk-mq drivers bios can only be inserted for the same queue. So
bypass the complicated sorting logic in __submit_bio_noacct with
a blk-mq simpler submission helper.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Split out a __submit_bio_noacct helper for the actual de-recursion
algorithm, and simplify the loop by using a continue when we can't
enter the queue for a bio.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
generic_make_request has always been very confusingly misnamed, so rename
it to submit_bio_noacct to make it clear that it is submit_bio minus
accounting and a few checks.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The make_request_fn is a little weird in that it sits directly in
struct request_queue instead of an operation vector. Replace it with
a block_device_operations method called submit_bio (which describes much
better what it does). Also remove the request_queue argument to it, as
the queue can be derived pretty trivially from the bio.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The variable is only used once, so just open code the bio_sector()
there.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
All registers disks must have a valid queue pointer, so don't bother to
log a warning for that case.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The "generic_make_request: " prefix has no value, and will soon become
stale.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The queue can be trivially derived from the bio, so pass one less
argument.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Just use rq directly, the usage of list_entry_rq() doesn't make any
sense.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
There is a statement that is indented one level too deeply, fix it
by removing a tab.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Move .nr_active update and request assignment into blk_mq_get_driver_tag(),
all are good to do during getting driver tag.
Meantime blk-flush related code is simplified and flush request needn't
to update the request table manually any more.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
It is used by blk-mq.c only, so move it to the source file.
Suggested-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
blk_mq_get_driver_tag() is only used by blk-mq.c and is supposed to
stay in blk-mq.c, so move it and preparing for cleanup code of
get/put driver tag.
Meantime hctx_may_queue() is moved to header file and it is fine
since it is defined as inline always.
No functional change.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
More and more drivers want to get batching requests queued from
block layer, such as mmc, and tcp based storage drivers. Also
current in-tree users have virtio-scsi, virtio-blk and nvme.
For none, we already support batching dispatch.
But for io scheduler, every time we just take one request from scheduler
and pass the single request to blk_mq_dispatch_rq_list(). This way makes
batching dispatch not possible when io scheduler is applied. One reason
is that we don't want to hurt sequential IO performance, becasue IO
merge chance is reduced if more requests are dequeued from scheduler
queue.
Try to support batching dispatch for io scheduler by starting with the
following simple approach:
1) still make sure we can get budget before dequeueing request
2) use hctx->dispatch_busy to evaluate if queue is busy, if it is busy
we fackback to non-batching dispatch, otherwise dequeue as many as
possible requests from scheduler, and pass them to blk_mq_dispatch_rq_list().
Wrt. 2), we use similar policy for none, and turns out that SCSI SSD
performance got improved much.
In future, maybe we can develop more intelligent algorithem for batching
dispatch.
Baolin has tested this patch and found that MMC performance is improved[3].
[1] https://lore.kernel.org/linux-block/20200512075501.GF1531898@T590/#r
[2] https://lore.kernel.org/linux-block/fe6bd8b9-6ed9-b225-f80c-314746133722@grimberg.me/
[3] https://lore.kernel.org/linux-block/CADBw62o9eTQDJ9RvNgEqSpXmg6Xcq=2TxH0Hfxhp29uF2W=TXA@mail.gmail.com/
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Tested-by: Baolin Wang <baolin.wang7@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Baolin Wang <baolin.wang7@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pass obtained budget count to blk_mq_dispatch_rq_list(), and prepare
for supporting fully batching submission.
With the obtained budget count, it is easier to put extra budgets
in case of .queue_rq failure.
Meantime remove the old 'got_budget' parameter.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Tested-by: Baolin Wang <baolin.wang7@gmail.com>
Reviewed-by: Christoph Hellwig <hch@infradead.org>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Baolin Wang <baolin.wang7@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When BLK_STS_RESOURCE or BLK_STS_DEV_RESOURCE is returned from
.queue_rq, the 'list' variable always holds this rq which isn't
queued to LLD successfully.
So blk_mq_dispatch_rq_list() always returns false from the branch
of '!list_empty(list)'.
No functional change.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Tested-by: Baolin Wang <baolin.wang7@gmail.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Christoph Hellwig <hch@infradead.org>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Baolin Wang <baolin.wang7@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Move code for getting driver tag and budget into one helper, so
blk_mq_dispatch_rq_list gets a bit simplified, and easier to read.
Meantime move updating of 'no_tag' and 'no_budget_available' into
the branch for handling partial dispatch because that is exactly
consumer of the two local variables.
Also rename the parameter of 'got_budget' as 'ask_budget'.
No functional change.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Tested-by: Baolin Wang <baolin.wang7@gmail.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Christoph Hellwig <hch@infradead.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Baolin Wang <baolin.wang7@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
All requests in the 'list' of blk_mq_dispatch_rq_list belong to same
hctx, so it is better to pass hctx instead of request queue, because
blk-mq's dispatch target is hctx instead of request queue.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Tested-by: Baolin Wang <baolin.wang7@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Baolin Wang <baolin.wang7@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
blk-mq budget is abstract from scsi's device queue depth, and it is
always per-request-queue instead of hctx.
It can be quite absurd to get a budget from one hctx, then dequeue a
request from scheduler queue, and this request may not belong to this
hctx, at least for bfq and deadline.
So fix the mess and always pass request queue to get/put budget
callback.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Tested-by: Baolin Wang <baolin.wang7@gmail.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Baolin Wang <baolin.wang7@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Just check for a non-NULL elevator directly to make the code more clear.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
It is natural to release driver tag when this request is completed by
LLD or device since its purpose is for LLD use.
One big benefit is that the released tag can be re-used quicker since
bio_endio() may take too long.
Meantime we don't need to release driver tag for flush request.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
bios must have a valid block group by the time they are submitted.
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
blkcg_bio_issue_check is a giant inline function that does three entirely
different things. Factor out the blk-cgroup related bio initalization
into a new helper, and the open code the sequence in the only caller,
relying on the fact that all the actual functionality is stubbed out for
non-cgroup builds.
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The only thing in blkcg_bio_issue_check that needs to be under
rcu_read_lock is blk_throtl_bio, so move the locking there.
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
By moving the initial blkg lookup into blkg_tryget_closest we get
a nicely self contained routines that does all the RCU locking.
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The root_blkg is only torn down at the very end of removing a queue.
So in the I/O submission path is always has a life reference and we
can just grab another one using blkg_get instead of doing a tryget
and parent walk that won't lead anywhere.
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
No good reason to keep these two functions split.
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
bio_associate_blkg_from_page is a special purpose helper for swap bios
that doesn't need access to bio internals. Move it to the swap code
instead of having it in bio.c.
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Merge __bio_associate_blkg into the only caller, which allows to slightly
reduce the RCU crticial section and better explain the code flow.
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
bio_clone_blkg_association is supposed to clone the associatation, but
actually ends up doing a search with a tryget. As we know we have a
reference on the source cgroup just get an unconditional additional
reference to it and call it a day. That also removes the need for
a RCU critical section.
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
bio_disassociate_blkg has two callers, of which one immediately assigns
a new value to >bi_blkg. Just open code the function in the two callers.
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
It is no need do finish_wait twice after acquiring inflight.
Signed-off-by: Guo Xuenan <guoxuenan@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Currently blk-mq does not report any event when two requests get merged
in the elevator. This then results in difficult to understand sequence
of events like:
...
8,0 34 1579 0.608765271 2718 I WS 215023504 + 40 [dbench]
8,0 34 1584 0.609184613 2719 A WS 215023544 + 56 <- (8,4) 2160568
8,0 34 1585 0.609184850 2719 Q WS 215023544 + 56 [dbench]
8,0 34 1586 0.609188524 2719 G WS 215023544 + 56 [dbench]
8,0 3 602 0.609684162 773 D WS 215023504 + 96 [kworker/3:1H]
8,0 34 1591 0.609843593 0 C WS 215023504 + 96 [0]
and you can only guess (after quite some headscratching since the above
excerpt is intermixed with a lot of other IO) that request 215023544+56
got merged to request 215023504+40. Provide proper event for request
merging like we used to do in the legacy block layer.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
