commit f1be1788a3 ("block: model freeze & enter queue as lock for
supporting lockdep") tries to apply lockdep for verifying freeze &
unfreeze. However, the verification is only done the outmost freeze and
unfreeze. This way is actually not correct because q->mq_freeze_depth
still may drop to zero on other task instead of the freeze owner task.
Fix this issue by always verifying the last unfreeze lock on the owner
task context, and make sure both the outmost freeze & unfreeze are
verified in the current task.
Fixes: f1be1788a3 ("block: model freeze & enter queue as lock for supporting lockdep")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20241031133723.303835-4-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
No one use blk_freeze_queue(), so remove it and the obsolete comment.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20241031133723.303835-2-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Recently we got several deadlock report[1][2][3] caused by
blk_mq_freeze_queue and blk_enter_queue().
Turns out the two are just like acquiring read/write lock, so model them
as read/write lock for supporting lockdep:
1) model q->q_usage_counter as two locks(io and queue lock)
- queue lock covers sync with blk_enter_queue()
- io lock covers sync with bio_enter_queue()
2) make the lockdep class/key as per-queue:
- different subsystem has very different lock use pattern, shared lock
class causes false positive easily
- freeze_queue degrades to no lock in case that disk state becomes DEAD
because bio_enter_queue() won't be blocked any more
- freeze_queue degrades to no lock in case that request queue becomes dying
because blk_enter_queue() won't be blocked any more
3) model blk_mq_freeze_queue() as acquire_exclusive & try_lock
- it is exclusive lock, so dependency with blk_enter_queue() is covered
- it is trylock because blk_mq_freeze_queue() are allowed to run
concurrently
4) model blk_enter_queue() & bio_enter_queue() as acquire_read()
- nested blk_enter_queue() are allowed
- dependency with blk_mq_freeze_queue() is covered
- blk_queue_exit() is often called from other contexts(such as irq), and
it can't be annotated as lock_release(), so simply do it in
blk_enter_queue(), this way still covered cases as many as possible
With lockdep support, such kind of reports may be reported asap and
needn't wait until the real deadlock is triggered.
For example, lockdep report can be triggered in the report[3] with this
patch applied.
[1] occasional block layer hang when setting 'echo noop > /sys/block/sda/queue/scheduler'
https://bugzilla.kernel.org/show_bug.cgi?id=219166
[2] del_gendisk() vs blk_queue_enter() race condition
https://lore.kernel.org/linux-block/20241003085610.GK11458@google.com/
[3] queue_freeze & queue_enter deadlock in scsi
https://lore.kernel.org/linux-block/ZxG38G9BuFdBpBHZ@fedora/T/#u
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20241025003722.3630252-4-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add non_owner variant of start_freeze/unfreeze queue APIs, so that the
caller knows that what they are doing, and we can skip lockdep support
for non_owner variant in per-call level.
Prepare for supporting lockdep for freezing/unfreezing queue.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20241025003722.3630252-2-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Commit a6088845c2 ("block: kyber: make kyber more friendly with merging")
removed the only blk_mq_flush_busy_ctxs() call from outside the block layer
core. Hence unexport blk_mq_flush_busy_ctxs().
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20241023202850.3469279-1-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Make sure that the tag_list_lock mutex is not held any longer than
necessary. This change reduces latency if e.g. blk_mq_quiesce_tagset()
is called concurrently from more than one thread. This function is used
by the NVMe core and also by the UFS driver.
Reported-by: Peter Wang <peter.wang@mediatek.com>
Cc: Chao Leng <lengchao@huawei.com>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: stable@vger.kernel.org
Fixes: 414dd48e88 ("blk-mq: add tagset quiesce interface")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20241022181617.2716173-1-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Supposing first scenario with a virtio_blk driver.
CPU0 CPU1
blk_mq_try_issue_directly()
__blk_mq_issue_directly()
q->mq_ops->queue_rq()
virtio_queue_rq()
blk_mq_stop_hw_queue()
virtblk_done()
blk_mq_request_bypass_insert() 1) store
blk_mq_start_stopped_hw_queue()
clear_bit(BLK_MQ_S_STOPPED) 3) store
blk_mq_run_hw_queue()
if (!blk_mq_hctx_has_pending()) 4) load
return
blk_mq_sched_dispatch_requests()
blk_mq_run_hw_queue()
if (!blk_mq_hctx_has_pending())
return
blk_mq_sched_dispatch_requests()
if (blk_mq_hctx_stopped()) 2) load
return
__blk_mq_sched_dispatch_requests()
Supposing another scenario.
CPU0 CPU1
blk_mq_requeue_work()
blk_mq_insert_request() 1) store
virtblk_done()
blk_mq_start_stopped_hw_queue()
blk_mq_run_hw_queues() clear_bit(BLK_MQ_S_STOPPED) 3) store
blk_mq_run_hw_queue()
if (!blk_mq_hctx_has_pending()) 4) load
return
blk_mq_sched_dispatch_requests()
if (blk_mq_hctx_stopped()) 2) load
continue
blk_mq_run_hw_queue()
Both scenarios are similar, the full memory barrier should be inserted
between 1) and 2), as well as between 3) and 4) to make sure that either
CPU0 sees BLK_MQ_S_STOPPED is cleared or CPU1 sees dispatch list.
Otherwise, either CPU will not rerun the hardware queue causing
starvation of the request.
The easy way to fix it is to add the essential full memory barrier into
helper of blk_mq_hctx_stopped(). In order to not affect the fast path
(hardware queue is not stopped most of the time), we only insert the
barrier into the slow path. Actually, only slow path needs to care about
missing of dispatching the request to the low-level device driver.
Fixes: 320ae51fee ("blk-mq: new multi-queue block IO queueing mechanism")
Cc: stable@vger.kernel.org
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20241014092934.53630-4-songmuchun@bytedance.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Supposing the following scenario.
CPU0 CPU1
blk_mq_insert_request() 1) store
blk_mq_unquiesce_queue()
blk_queue_flag_clear() 3) store
blk_mq_run_hw_queues()
blk_mq_run_hw_queue()
if (!blk_mq_hctx_has_pending()) 4) load
return
blk_mq_run_hw_queue()
if (blk_queue_quiesced()) 2) load
return
blk_mq_sched_dispatch_requests()
The full memory barrier should be inserted between 1) and 2), as well as
between 3) and 4) to make sure that either CPU0 sees QUEUE_FLAG_QUIESCED
is cleared or CPU1 sees dispatch list or setting of bitmap of software
queue. Otherwise, either CPU will not rerun the hardware queue causing
starvation.
So the first solution is to 1) add a pair of memory barrier to fix the
problem, another solution is to 2) use hctx->queue->queue_lock to
synchronize QUEUE_FLAG_QUIESCED. Here, we chose 2) to fix it since
memory barrier is not easy to be maintained.
Fixes: f4560ffe8c ("blk-mq: use QUEUE_FLAG_QUIESCED to quiesce queue")
Cc: stable@vger.kernel.org
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20241014092934.53630-3-songmuchun@bytedance.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Supposing the following scenario with a virtio_blk driver.
CPU0 CPU1 CPU2
blk_mq_try_issue_directly()
__blk_mq_issue_directly()
q->mq_ops->queue_rq()
virtio_queue_rq()
blk_mq_stop_hw_queue()
virtblk_done()
blk_mq_try_issue_directly()
if (blk_mq_hctx_stopped())
blk_mq_request_bypass_insert() blk_mq_run_hw_queue()
blk_mq_run_hw_queue() blk_mq_run_hw_queue()
blk_mq_insert_request()
return
After CPU0 has marked the queue as stopped, CPU1 will see the queue is
stopped. But before CPU1 puts the request on the dispatch list, CPU2
receives the interrupt of completion of request, so it will run the
hardware queue and marks the queue as non-stopped. Meanwhile, CPU1 also
runs the same hardware queue. After both CPU1 and CPU2 complete
blk_mq_run_hw_queue(), CPU1 just puts the request to the same hardware
queue and returns. It misses dispatching a request. Fix it by running
the hardware queue explicitly. And blk_mq_request_issue_directly()
should handle a similar situation. Fix it as well.
Fixes: d964f04a8f ("blk-mq: fix direct issue")
Cc: stable@vger.kernel.org
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20241014092934.53630-2-songmuchun@bytedance.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Applications using the passthrough interfaces for IO want to continue
seeing the disk stats. These requests had been fenced off from this
block layer feature. While the block layer doesn't necessarily know what
a passthrough command does, we do know the data size and direction,
which is enough to account for the command's stats.
Since tracking these has the potential to produce unexpected results,
the passthrough stats are locked behind a new queue flag that needs to
be enabled with the /sys/block/<dev>/queue/iostats_passthrough
attribute.
Signed-off-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20241007153236.2818562-1-kbusch@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
It's known needed at that point, and it's cleaner to just assign it
there rather than rely on it being reliably set before hitting the
IO accounting. Hence, move it out of blk_mq_rq_time_init(), which is
now only doing the allocation side timing.
While at it, get rid of the '0' time passing to blk_mq_rq_time_init(),
just pass in blk_time_get_ns() for the two cases where 0 is being
explicitly passed in. The rest pass in the previously cached allocation
time.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
A previous commit moved RQF_IO_STAT into blk_account_io_done(), where
it's being set rather than at allocation time. Unfortunately we do check
for that flag in blk_mq_rq_time_init(), and hence setting the
start_time_ns wasn't being done. This lead to unwieldy inflight IO counts
and times, as IO completion accounting would a 0 value rather than the
issue time for it's subtraction math.
Fix this by switching the blk_mq_rq_time_init() check to use the queue
state rather than the request state.
Fixes: b8f762400ae8 ("block: move iostat check into blk_acount_io_start()")
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202410062110.512391df-oliver.sang@intel.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
It's now just checking whether or not RQF_IO_STAT is set, so let's get
rid of it and just open-code the specific flag that is being checked.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If RQF_IO_STAT is set, then accounting is enabled. There's no need to
further gate this on req->part being set or not, RQF_IO_STAT should
never be set if accounting is not being done for this request.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Rather than have blk_do_io_stat() check for both RQF_IO_STAT and whether
the request is a passthrough requests every time, move both of those
checks into blk_account_io_start(). Then blk_do_io_stat() can be reduced
to just checking for RQF_IO_STAT.
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Anuj Gupta <anuj20.g@samsung.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Commit 7b815817aa ("blk-mq: add helper for checking if one CPU is mapped to specified hctx")
needs to check queue mapping via tag set in hctx's cpuhp handler.
However, q->tag_set may not be setup yet when the cpuhp handler is
enabled, then kernel oops is triggered.
Fix the issue by setup queue tag_set before initializing hctx.
Cc: stable@vger.kernel.org
Reported-and-tested-by: Rick Koch <mr.rickkoch@gmail.com>
Closes: https://lore.kernel.org/linux-block/CANa58eeNDozLaBHKPLxSAhEy__FPfJT_F71W=sEQw49UCrC9PQ@mail.gmail.com
Fixes: 7b815817aa ("blk-mq: add helper for checking if one CPU is mapped to specified hctx")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20241014005115.2699642-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Merge tag 'for-6.12/block-20240925' of git://git.kernel.dk/linux
Pull more block updates from Jens Axboe:
- Improve blk-integrity segment counting and merging (Keith)
- NVMe pull request via Keith:
- Multipath fixes (Hannes)
- Sysfs attribute list NULL terminate fix (Shin'ichiro)
- Remove problematic read-back (Keith)
- Fix for a regression with the IO scheduler switching freezing from
6.11 (Damien)
- Use a raw spinlock for sbitmap, as it may get called from preempt
disabled context (Ming)
- Cleanup for bd_claiming waiting, using var_waitqueue() rather than
the bit waitqueues, as that more accurately describes that it does
(Neil)
- Various cleanups (Kanchan, Qiu-ji, David)
* tag 'for-6.12/block-20240925' of git://git.kernel.dk/linux:
nvme: remove CC register read-back during enabling
nvme: null terminate nvme_tls_attrs
nvme-multipath: avoid hang on inaccessible namespaces
nvme-multipath: system fails to create generic nvme device
lib/sbitmap: define swap_lock as raw_spinlock_t
block: Remove unused blk_limits_io_{min,opt}
drbd: Fix atomicity violation in drbd_uuid_set_bm()
block: Fix elv_iosched_local_module handling of "none" scheduler
block: remove bogus union
block: change wait on bd_claiming to use a var_waitqueue
blk-integrity: improved sg segment mapping
block: unexport blk_rq_count_integrity_sg
nvme-rdma: use request to get integrity segments
scsi: use request to get integrity segments
block: provide a request helper for user integrity segments
blk-integrity: consider entire bio list for merging
blk-integrity: properly account for segments
blk-mq: set the nr_integrity_segments from bio
blk-mq: unconditional nr_integrity_segments
- Core:
- Remove a global lock in the affinity setting code
The lock protects a cpumask for intermediate results and the lock
causes a bottleneck on simultaneous start of multiple virtual
machines. Replace the lock and the static cpumask with a per CPU
cpumask which is nicely serialized by raw spinlock held when
executing this code.
- Provide support for giving a suffix to interrupt domain names.
That's required to support devices with subfunctions so that the
domain names are distinct even if they originate from the same
device node.
- The usual set of cleanups and enhancements all over the place
- Drivers:
- Support for longarch AVEC interrupt chip
- Refurbishment of the Armada driver so it can be extended for new
variants.
- The usual set of cleanups and enhancements all over the place
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Merge tag 'irq-core-2024-09-16' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull irq updates from Thomas Gleixner:
"Core:
- Remove a global lock in the affinity setting code
The lock protects a cpumask for intermediate results and the lock
causes a bottleneck on simultaneous start of multiple virtual
machines. Replace the lock and the static cpumask with a per CPU
cpumask which is nicely serialized by raw spinlock held when
executing this code.
- Provide support for giving a suffix to interrupt domain names.
That's required to support devices with subfunctions so that the
domain names are distinct even if they originate from the same
device node.
- The usual set of cleanups and enhancements all over the place
Drivers:
- Support for longarch AVEC interrupt chip
- Refurbishment of the Armada driver so it can be extended for new
variants.
- The usual set of cleanups and enhancements all over the place"
* tag 'irq-core-2024-09-16' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (73 commits)
genirq: Use cpumask_intersects()
genirq/cpuhotplug: Use cpumask_intersects()
irqchip/apple-aic: Only access system registers on SoCs which provide them
irqchip/apple-aic: Add a new "Global fast IPIs only" feature level
irqchip/apple-aic: Skip unnecessary enabling of use_fast_ipi
dt-bindings: apple,aic: Document A7-A11 compatibles
irqdomain: Use IS_ERR_OR_NULL() in irq_domain_trim_hierarchy()
genirq/msi: Use kmemdup_array() instead of kmemdup()
genirq/proc: Change the return value for set affinity permission error
genirq/proc: Use irq_move_pending() in show_irq_affinity()
genirq/proc: Correctly set file permissions for affinity control files
genirq: Get rid of global lock in irq_do_set_affinity()
genirq: Fix typo in struct comment
irqchip/loongarch-avec: Add AVEC irqchip support
irqchip/loongson-pch-msi: Prepare get_pch_msi_handle() for AVECINTC
irqchip/loongson-eiointc: Rename CPUHP_AP_IRQ_LOONGARCH_STARTING
LoongArch: Architectural preparation for AVEC irqchip
LoongArch: Move irqchip function prototypes to irq-loongson.h
irqchip/loongson-pch-msi: Switch to MSI parent domains
softirq: Remove unused 'action' parameter from action callback
...
This value is used for merging considerations, so it needs to be
accurate.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20240913182854.2445457-3-kbusch@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Always defining the field will make using it easier and less error prone
in future patches.
There shouldn't be any downside to this: the field fits in what would
otherwise be a 2-byte hole, so we're not saving space by conditionally
leaving it out.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20240913182854.2445457-2-kbusch@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The single-queue optimized list flush doesn't have an unplug trace event
to pair with the plug event. Add one.
In the unlikely event an error occurs and falls back to the less
optimized plug flush path, it's possible a 2nd unplug trace event will
be logged, but it will show the remainig count that weren't previously
handled.
Signed-off-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20240906194540.3719642-1-kbusch@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The current setup with bio_may_exceed_limit and __bio_split_to_limits
is a bit of a mess.
Change it so that __bio_split_to_limits does all the work and is just
a variant of bio_split_to_limits that returns nr_segs. This is done
by inlining it and instead have the various bio_split_* helpers directly
submit the potentially split bios.
To support btrfs, the rw version has a lower level helper split out
that just returns the offset to split. This turns out to nicely clean
up the btrfs flow as well.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: David Sterba <dsterba@suse.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Tested-by: Hans Holmberg <hans.holmberg@wdc.com>
Reviewed-by: Hans Holmberg <hans.holmberg@wdc.com>
Link: https://lore.kernel.org/r/20240826173820.1690925-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When soft interrupt actions are called, they are passed a pointer to the
struct softirq action which contains the action's function pointer.
This pointer isn't useful, as the action callback already knows what
function it is. And since each callback handles a specific soft interrupt,
the callback also knows which soft interrupt number is running.
No soft interrupt action callback actually uses this parameter, so remove
it from the function pointer signature. This clarifies that soft interrupt
actions are global routines and makes it slightly cheaper to call them.
Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/all/20240815171549.3260003-1-csander@purestorage.com
Call .limit_depth() after data->hctx has been set such that data->hctx can
be used in .limit_depth() implementations.
Cc: Christoph Hellwig <hch@lst.de>
Cc: Damien Le Moal <dlemoal@kernel.org>
Cc: Zhiguo Niu <zhiguo.niu@unisoc.com>
Fixes: 07757588e5 ("block/mq-deadline: Reserve 25% of scheduler tags for synchronous requests")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Tested-by: Zhiguo Niu <zhiguo.niu@unisoc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240509170149.7639-2-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
IO logical block size is one fundamental queue limit, and every IO has
to be aligned with logical block size because our bio split can't deal
with unaligned bio.
The check has to be done with queue usage counter grabbed because device
reconfiguration may change logical block size, and we can prevent the
reconfiguration from happening by holding queue usage counter.
logical_block_size stays in the 1st cache line of queue_limits, and this
cache line is always fetched in fast path via bio_may_exceed_limits(),
so IO perf won't be affected by this check.
Cc: Yi Zhang <yi.zhang@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ye Bin <yebin10@huawei.com>
Cc: stable@vger.kernel.org
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240620030631.3114026-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Currently blk_queue_get_max_sectors() is passed a enum req_op. In future
the value returned from blk_queue_get_max_sectors() may depend on certain
request flags, so pass a request pointer.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Acked-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20240620125359.2684798-2-john.g.garry@oracle.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Move the poll flag into the queue_limits feature field so that it can
be set atomically with the queue frozen.
Stacking drivers are simplified in that they now can simply set the
flag, and blk_stack_limits will clear it when the features is not
supported by any of the underlying devices.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20240617060532.127975-22-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Move the nowait flag into the queue_limits feature field so that it can
be set atomically with the queue frozen.
Stacking drivers are simplified in that they now can simply set the
flag, and blk_stack_limits will clear it when the features is not
supported by any of the underlying devices.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20240617060532.127975-20-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Move the io_stat flag into the queue_limits feature field so that it can
be set atomically with the queue frozen.
Simplify md and dm to set the flag unconditionally instead of avoiding
setting a simple flag for cases where it already is set by other means,
which is a bit pointless.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20240617060532.127975-17-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
queue_attr_store updates attributes used to control generating I/O, and
can cause malformed bios if changed with I/O in flight. Freeze the queue
in common code instead of adding it to almost every attribute.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20240617060532.127975-12-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Block layer integrity configuration is a bit complex right now, as it
indirects through operation vectors for a simple two-dimensional
configuration:
a) the checksum type of none, ip checksum, crc, crc64
b) the presence or absence of a reference tag
Remove the integrity profile, and instead add a separate csum_type flag
which replaces the existing ip-checksum field and a new flag that
indicates the presence of the reference tag.
This removes up to two layers of indirect calls, remove the need to
offload the no-op verification of non-PI metadata to a workqueue and
generally simplifies the code. The downside is that block/t10-pi.c now
has to be built into the kernel when CONFIG_BLK_DEV_INTEGRITY is
supported. Given that both nvme and SCSI require t10-pi.ko, it is loaded
for all usual configurations that enabled CONFIG_BLK_DEV_INTEGRITY
already, though.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kanchan Joshi <joshi.k@samsung.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240613084839.1044015-6-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Merge tag 'block-6.10-20240523' of git://git.kernel.dk/linux
Pull more block updates from Jens Axboe:
"Followup block updates, mostly due to NVMe being a bit late to the
party. But nothing major in there, so not a big deal.
In detail, this contains:
- NVMe pull request via Keith:
- Fabrics connection retries (Daniel, Hannes)
- Fabrics logging enhancements (Tokunori)
- RDMA delete optimization (Sagi)
- ublk DMA alignment fix (me)
- null_blk sparse warning fixes (Bart)
- Discard support for brd (Keith)
- blk-cgroup list corruption fixes (Ming)
- blk-cgroup stat propagation fix (Waiman)
- Regression fix for plugging stall with md (Yu)
- Misc fixes or cleanups (David, Jeff, Justin)"
* tag 'block-6.10-20240523' of git://git.kernel.dk/linux: (24 commits)
null_blk: fix null-ptr-dereference while configuring 'power' and 'submit_queues'
blk-throttle: remove unused struct 'avg_latency_bucket'
block: fix lost bio for plug enabled bio based device
block: t10-pi: add MODULE_DESCRIPTION()
blk-mq: add helper for checking if one CPU is mapped to specified hctx
blk-cgroup: Properly propagate the iostat update up the hierarchy
blk-cgroup: fix list corruption from reorder of WRITE ->lqueued
blk-cgroup: fix list corruption from resetting io stat
cdrom: rearrange last_media_change check to avoid unintentional overflow
nbd: Fix signal handling
nbd: Remove a local variable from nbd_send_cmd()
nbd: Improve the documentation of the locking assumptions
nbd: Remove superfluous casts
nbd: Use NULL to represent a pointer
brd: implement discard support
null_blk: Fix two sparse warnings
ublk_drv: set DMA alignment mask to 3
nvme-rdma, nvme-tcp: include max reconnects for reconnect logging
nvmet-rdma: Avoid o(n^2) loop in delete_ctrl
nvme: do not retry authentication failures
...
We can easily have up to 24 flags with sane
atomicity, _without_ pushing anything out
of the first cacheline of struct block_device.
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Merge tag 'pull-bd_flags-2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull bdev flags update from Al Viro:
"Compactifying bdev flags.
We can easily have up to 24 flags with sane atomicity, _without_
pushing anything out of the first cacheline of struct block_device"
* tag 'pull-bd_flags-2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
bdev: move ->bd_make_it_fail to ->__bd_flags
bdev: move ->bd_ro_warned to ->__bd_flags
bdev: move ->bd_has_subit_bio to ->__bd_flags
bdev: move ->bd_write_holder into ->__bd_flags
bdev: move ->bd_read_only to ->__bd_flags
bdev: infrastructure for flags
wrapper for access to ->bd_partno
Use bdev_is_paritition() instead of open-coding it
Commit a46c27026d ("blk-mq: don't schedule block kworker on isolated CPUs")
rules out isolated CPUs from hctx->cpumask, and hctx->cpumask should only be
used for scheduling kworker.
Add helper blk_mq_cpu_mapped_to_hctx() and apply it into cpuhp handlers.
This patch avoids to forget clearing INACTIVE of hctx state in case that one
isolated CPU becomes online, and fixes hang issue when allocating request
from this hctx's tags.
Cc: Raju Cheerla <rcheerla@redhat.com>
Fixes: a46c27026d ("blk-mq: don't schedule block kworker on isolated CPUs")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20240517020514.149771-1-ming.lei@redhat.com
Tested-by: Raju Cheerla <rcheerla@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Currently, io_ticks is accounted based on sampling, specifically
update_io_ticks() will always account io_ticks by 1 jiffies from
bdev_start_io_acct()/blk_account_io_start(), and the result can be
inaccurate, for example(HZ is 250):
Test script:
fio -filename=/dev/sda -bs=4k -rw=write -direct=1 -name=test -thinktime=4ms
Test result: util is about 90%, while the disk is really idle.
This behaviour is introduced by commit 5b18b5a737 ("block: delete
part_round_stats and switch to less precise counting"), however, there
was a key point that is missed that this patch also improve performance
a lot:
Before the commit:
part_round_stats:
if (part->stamp != now)
stats |= 1;
part_in_flight()
-> there can be lots of task here in 1 jiffies.
part_round_stats_single()
__part_stat_add()
part->stamp = now;
After the commit:
update_io_ticks:
stamp = part->bd_stamp;
if (time_after(now, stamp))
if (try_cmpxchg())
__part_stat_add()
-> only one task can reach here in 1 jiffies.
Hence in order to account io_ticks precisely, we only need to know if
there are IO inflight at most once in one jiffies. Noted that for
rq-based device, iterating tags should not be used here because
'tags->lock' is grabbed in blk_mq_find_and_get_req(), hence
part_stat_lock_inc/dec() and part_in_flight() is used to trace inflight.
The additional overhead is quite little:
- per cpu add/dec for each IO for rq-based device;
- per cpu sum for each jiffies;
And it's verified by null-blk that there are no performance degration
under heavy IO pressure.
Fixes: 5b18b5a737 ("block: delete part_round_stats and switch to less precise counting")
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20240509123717.3223892-2-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
blk_zone_complete_request() must be called to handle the completion of a
zone write request handled with zone write plugging. This function is
called from blk_complete_request(), blk_update_request() and also in
blk_mq_submit_bio() error path. Improve this by moving this function
call into blk_mq_finish_request() as all requests are processed with
this function when they complete as well as when they are freed without
being executed. This also improves blk_update_request() used by scsi
devices as these may repeatedly call this function to handle partial
completions.
To be consistent with this change, blk_zone_complete_request() is
renamed to blk_zone_finish_request() and
blk_zone_write_plug_complete_request() is renamed to
blk_zone_write_plug_finish_request().
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20240501110907.96950-12-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Zone write plugging ignores empty (no data) flush operations but handles
flush BIOs that have data to ensure that the flush machinery generated
write is processed in order. However, the call to
blk_zone_write_plug_attempt_merge() which sets a request
RQF_ZONE_WRITE_PLUGGING flag is called after blk_insert_flush(), thus
missing indicating that a non empty flush request completion needs
handling by zone write plugging.
Fix this by moving the call to blk_zone_write_plug_attempt_merge()
before blk_insert_flush(). And while at it, rename that function as
blk_zone_write_plug_init_request() to be clear that it is not just about
merging plugged BIOs in the request. While at it, also add a WARN_ONCE()
check that the zone write plug for the request is not NULL.
Fixes: dd291d77cc ("block: Introduce zone write plugging")
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20240501110907.96950-10-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
With the block layer zone write plugging being automatically done for
any write operation to a zone of a zoned block device, a regular request
plugging handled through current->plug can only ever see at most a
single write request per zone. In such case, any potential reordering
of the plugged requests will be harmless. We can thus remove the special
casing for write operations to zones and have these requests plugged as
well. This allows removing the function blk_mq_plug and instead directly
using current->plug where needed.
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Tested-by: Hans Holmberg <hans.holmberg@wdc.com>
Tested-by: Dennis Maisenbacher <dennis.maisenbacher@wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240408014128.205141-29-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The zone append emulation of the scsi disk driver was the only driver
using BLK_STS_ZONE_RESOURCE. With this code removed,
BLK_STS_ZONE_RESOURCE is now unused. Remove this macro definition and
simplify blk_mq_dispatch_rq_list() where this status code was handled.
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Tested-by: Hans Holmberg <hans.holmberg@wdc.com>
Tested-by: Dennis Maisenbacher <dennis.maisenbacher@wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240408014128.205141-20-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Given that zone write plugging manages all writes to zones of a zoned
block device and tracks the write pointer position of all zones that are
not full nor empty, emulating zone append operations using regular
writes can be implemented generically, without relying on the underlying
device driver to implement such emulation. This is needed for devices
that do not natively support the zone append command (e.g. SMR
hard-disks).
A device may request zone append emulation by setting its
max_zone_append_sectors queue limit to 0. For such device, the function
blk_zone_wplug_prepare_bio() changes zone append BIOs into
non-mergeable regular write BIOs. Modified zone append BIOs are flagged
with the new BIO flag BIO_EMULATES_ZONE_APPEND. This flag is checked
on completion of the BIO in blk_zone_write_plug_bio_endio() to restore
the original REQ_OP_ZONE_APPEND operation code of the BIO.
The block layer internal inline helper function bio_is_zone_append() is
added to test if a BIO is either a native zone append operation
(REQ_OP_ZONE_APPEND operation code) or if it is flagged with
BIO_EMULATES_ZONE_APPEND. Given that both native and emulated zone
append BIO completion handling should be similar, The functions
blk_update_request() and blk_zone_complete_request_bio() are modified to
use bio_is_zone_append() to execute blk_zone_update_request_bio() for
both native and emulated zone append operations.
This commit contains contributions from Christoph Hellwig <hch@lst.de>.
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Tested-by: Hans Holmberg <hans.holmberg@wdc.com>
Tested-by: Dennis Maisenbacher <dennis.maisenbacher@wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240408014128.205141-11-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Zone write plugging implements a per-zone "plug" for write operations
to control the submission and execution order of write operations to
sequential write required zones of a zoned block device. Per-zone
plugging guarantees that at any time there is at most only one write
request per zone being executed. This mechanism is intended to replace
zone write locking which implements a similar per-zone write throttling
at the scheduler level, but is implemented only by mq-deadline.
Unlike zone write locking which operates on requests, zone write
plugging operates on BIOs. A zone write plug is simply a BIO list that
is atomically manipulated using a spinlock and a kblockd submission
work. A write BIO to a zone is "plugged" to delay its execution if a
write BIO for the same zone was already issued, that is, if a write
request for the same zone is being executed. The next plugged BIO is
unplugged and issued once the write request completes.
This mechanism allows to:
- Untangle zone write ordering from block IO schedulers. This allows
removing the restriction on using mq-deadline for writing to zoned
block devices. Any block IO scheduler, including "none" can be used.
- Zone write plugging operates on BIOs instead of requests. Plugged
BIOs waiting for execution thus do not hold scheduling tags and thus
are not preventing other BIOs from executing (reads or writes to
other zones). Depending on the workload, this can significantly
improve the device use (higher queue depth operation) and
performance.
- Both blk-mq (request based) zoned devices and BIO-based zoned devices
(e.g. device mapper) can use zone write plugging. It is mandatory
for the former but optional for the latter. BIO-based drivers can
use zone write plugging to implement write ordering guarantees, or
the drivers can implement their own if needed.
- The code is less invasive in the block layer and is mostly limited to
blk-zoned.c with some small changes in blk-mq.c, blk-merge.c and
bio.c.
Zone write plugging is implemented using struct blk_zone_wplug. This
structure includes a spinlock, a BIO list and a work structure to
handle the submission of plugged BIOs. Zone write plugs structures are
managed using a per-disk hash table.
Plugging of zone write BIOs is done using the function
blk_zone_write_plug_bio() which returns false if a BIO execution does
not need to be delayed and true otherwise. This function is called
from blk_mq_submit_bio() after a BIO is split to avoid large BIOs
spanning multiple zones which would cause mishandling of zone write
plugs. This ichange enables by default zone write plugging for any mq
request-based block device. BIO-based device drivers can also use zone
write plugging by expliclty calling blk_zone_write_plug_bio() in their
->submit_bio method. For such devices, the driver must ensure that a
BIO passed to blk_zone_write_plug_bio() is already split and not
straddling zone boundaries.
Only write and write zeroes BIOs are plugged. Zone write plugging does
not introduce any significant overhead for other operations. A BIO that
is being handled through zone write plugging is flagged using the new
BIO flag BIO_ZONE_WRITE_PLUGGING. A request handling a BIO flagged with
this new flag is flagged with the new RQF_ZONE_WRITE_PLUGGING flag.
The completion of BIOs and requests flagged trigger respectively calls
to the functions blk_zone_write_bio_endio() and
blk_zone_write_complete_request(). The latter function is used to
trigger submission of the next plugged BIO using the zone plug work.
blk_zone_write_bio_endio() does the same for BIO-based devices.
This ensures that at any time, at most one request (blk-mq devices) or
one BIO (BIO-based devices) is being executed for any zone. The
handling of zone write plugs using a per-zone plug spinlock maximizes
parallelism and device usage by allowing multiple zones to be writen
simultaneously without lock contention.
Zone write plugging ignores flush BIOs without data. Hovever, any flush
BIO that has data is always plugged so that the write part of the flush
sequence is serialized with other regular writes.
Given that any BIO handled through zone write plugging will be the only
BIO in flight for the target zone when it is executed, the unplugging
and submission of a BIO will have no chance of successfully merging with
plugged requests or requests in the scheduler. To overcome this
potential performance degradation, blk_mq_submit_bio() calls the
function blk_zone_write_plug_attempt_merge() to try to merge other
plugged BIOs with the one just unplugged and submitted. Successful
merging is signaled using blk_zone_write_plug_bio_merged(), called from
bio_attempt_back_merge(). Furthermore, to avoid recalculating the number
of segments of plugged BIOs to attempt merging, the number of segments
of a plugged BIO is saved using the new struct bio field
__bi_nr_segments. To avoid growing the size of struct bio, this field is
added as a union with the bio_cookie field. This is safe to do as
polling is always disabled for plugged BIOs.
When BIOs are plugged in a zone write plug, the device request queue
usage counter is always incremented. This reference is kept and reused
for blk-mq devices when the plugged BIO is unplugged and submitted
again using submit_bio_noacct_nocheck(). For this case, the unplugged
BIO is already flagged with BIO_ZONE_WRITE_PLUGGING and
blk_mq_submit_bio() proceeds directly to allocating a new request for
the BIO, re-using the usage reference count taken when the BIO was
plugged. This extra reference count is dropped in
blk_zone_write_plug_attempt_merge() for any plugged BIO that is
successfully merged. Given that BIO-based devices will not take this
path, the extra reference is dropped after a plugged BIO is unplugged
and submitted.
Zone write plugs are dynamically allocated and managed using a hash
table (an array of struct hlist_head) with RCU protection.
A zone write plug is allocated when a write BIO is received for the
zone and not freed until the zone is fully written, reset or finished.
To detect when a zone write plug can be freed, the write state of each
zone is tracked using a write pointer offset which corresponds to the
offset of a zone write pointer relative to the zone start. Write
operations always increment this write pointer offset. Zone reset
operations set it to 0 and zone finish operations set it to the zone
size.
If a write error happens, the wp_offset value of a zone write plug may
become incorrect and out of sync with the device managed write pointer.
This is handled using the zone write plug flag BLK_ZONE_WPLUG_ERROR.
The function blk_zone_wplug_handle_error() is called from the new disk
zone write plug work when this flag is set. This function executes a
report zone to update the zone write pointer offset to the current
value as indicated by the device. The disk zone write plug work is
scheduled whenever a BIO flagged with BIO_ZONE_WRITE_PLUGGING completes
with an error or when bio_zone_wplug_prepare_bio() detects an unaligned
write. Once scheduled, the disk zone write plugs work keeps running
until all zone errors are handled.
To match the new data structures used for zoned disks, the function
disk_free_zone_bitmaps() is renamed to the more generic
disk_free_zone_resources(). The function disk_init_zone_resources() is
also introduced to initialize zone write plugs resources when a gendisk
is allocated.
In order to guarantee that the user can simultaneously write up to a
number of zones equal to a device max active zone limit or max open zone
limit, zone write plugs are allocated using a mempool sized to the
maximum of these 2 device limits. For a device that does not have
active and open zone limits, 128 is used as the default mempool size.
If a change to the device active and open zone limits is detected, the
disk mempool is resized when blk_revalidate_disk_zones() is executed.
This commit contains contributions from Christoph Hellwig <hch@lst.de>.
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Tested-by: Hans Holmberg <hans.holmberg@wdc.com>
Tested-by: Dennis Maisenbacher <dennis.maisenbacher@wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20240408014128.205141-8-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
On completion of a zone append request, the request sector indicates the
location of the written data. This value must be returned to the user
through the BIO iter sector. This is done in 2 places: in
blk_complete_request() and in blk_update_request(). Introduce the inline
helper function blk_zone_update_request_bio() to avoid duplicating
this BIO update for zone append requests, and to compile out this
helper call when CONFIG_BLK_DEV_ZONED is not enabled.
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Tested-by: Hans Holmberg <hans.holmberg@wdc.com>
Tested-by: Dennis Maisenbacher <dennis.maisenbacher@wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20240408014128.205141-4-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Moving req_bio_endio() code into its only caller, blk_update_request(),
allows reducing accesses to and tests of bio and request fields. Also,
given that partial completions of zone append operations is not
possible and that zone append operations cannot be merged, the update
of the BIO sector using the request sector for these operations can be
moved directly before the call to bio_endio().
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Tested-by: Hans Holmberg <hans.holmberg@wdc.com>
Tested-by: Dennis Maisenbacher <dennis.maisenbacher@wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20240408014128.205141-3-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Kernel parameter of `isolcpus=` or 'nohz_full=' are used to isolate CPUs
for specific task, and it isn't expected to let block IO disturb these CPUs.
blk-mq kworker shouldn't be scheduled on isolated CPUs. Also if isolated
CPUs is run for blk-mq kworker, long block IO latency can be caused.
Kernel workqueue only respects CPU isolation for WQ_UNBOUND, for bound
WQ, the responsibility is on user because CPU is specified as WQ API
parameter, such as mod_delayed_work_on(cpu), queue_delayed_work_on(cpu)
and queue_work_on(cpu).
So not run blk-mq kworker on isolated CPUs by removing isolated CPUs
from hctx->cpumask. Meantime use queue map to check if all CPUs in this
hw queue are offline instead of hctx->cpumask, this way can avoid any
cost in fast IO code path, and is safe since hctx->cpumask are only
used in the two cases.
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Andrew Theurer <atheurer@redhat.com>
Cc: Joe Mario <jmario@redhat.com>
Cc: Sebastian Jug <sejug@redhat.com>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Tejun Heo <tj@kernel.org>
Tesed-by: Joe Mario <jmario@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Ewan D. Milne <emilne@redhat.com>
Link: https://lore.kernel.org/r/20240322021244.1056223-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This reverts commit 748dc0b65e.
Partial zone append completions cannot be supported as there is no
guarantees that the fragmented data will be written sequentially in the
same manner as with a full command. Commit 748dc0b65e ("block: fix
partial zone append completion handling in req_bio_endio()") changed
req_bio_endio() to always advance a partially failed BIO by its full
length, but this can lead to incorrect accounting. So revert this
change and let low level device drivers handle this case by always
failing completely zone append operations. With this revert, users will
still see an IO error for a partially completed zone append BIO.
Fixes: 748dc0b65e ("block: fix partial zone append completion handling in req_bio_endio()")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240328004409.594888-2-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Merge tag 'vfs-6.9.iomap' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull iomap updates from Christian Brauner:
- Restore read-write hints in struct bio through the bi_write_hint
member for the sake of UFS devices in mobile applications. This can
result in up to 40% lower write amplification in UFS devices. The
patch series that builds on this will be coming in via the SCSI
maintainers (Bart)
- Overhaul the iomap writeback code. Afterwards ->map_blocks() is able
to map multiple blocks at once as long as they're in the same folio.
This reduces CPU usage for buffered write workloads on e.g., xfs on
systems with lots of cores (Christoph)
- Record processed bytes in iomap_iter() trace event (Kassey)
- Extend iomap_writepage_map() trace event after Christoph's
->map_block() changes to map mutliple blocks at once (Zhang)
* tag 'vfs-6.9.iomap' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (22 commits)
iomap: Add processed for iomap_iter
iomap: add pos and dirty_len into trace_iomap_writepage_map
block, fs: Restore the per-bio/request data lifetime fields
fs: Propagate write hints to the struct block_device inode
fs: Move enum rw_hint into a new header file
fs: Split fcntl_rw_hint()
fs: Verify write lifetime constants at compile time
fs: Fix rw_hint validation
iomap: pass the length of the dirty region to ->map_blocks
iomap: map multiple blocks at a time
iomap: submit ioends immediately
iomap: factor out a iomap_writepage_map_block helper
iomap: only call mapping_set_error once for each failed bio
iomap: don't chain bios
iomap: move the iomap_sector sector calculation out of iomap_add_to_ioend
iomap: clean up the iomap_alloc_ioend calling convention
iomap: move all remaining per-folio logic into iomap_writepage_map
iomap: factor out a iomap_writepage_handle_eof helper
iomap: move the PF_MEMALLOC check to iomap_writepages
iomap: move the io_folios field out of struct iomap_ioend
...
For most of ARCHs, 'nr_cpus=1' is passed for kdump kernel, so
nr_hw_queues for each mapping is supposed to be 1 already.
More importantly, this way may cause trouble for driver, because blk-mq and
driver see different queue mapping since driver should setup hardware
queue setting before calling into allocating blk-mq tagset.
So not overriding nr_hw_queues and nr_maps for kdump kernel.
Cc: Wen Xiong <wenxiong@us.ibm.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240228040857.306483-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The logic in blk_mq_complete_need_ipi() assumes SMP systems where all
CPUs have equal compute capacities and only LLC cache can make
a different on perceived performance. But this assumption falls apart on
HMP systems where LLC is shared, but the CPUs have different capacities.
Staying local then can have a big performance impact if the IO request
was done from a CPU with higher capacity but the interrupt is serviced
on a lower capacity CPU.
Use the new cpus_equal_capacity() function to check if we need to send
an IPI.
Without the patch I see the BLOCK softirq always running on little cores
(where the hardirq is serviced). With it I can see it running on all
cores.
This was noticed after the topology change [1] where now on a big.LITTLE
we truly get that the LLC is shared between all cores where as in the
past it was being misrepresented for historical reasons. The logic
exposed a missing dependency on capacities for such systems where there
can be a big performance difference between the CPUs.
This of course introduced a noticeable change in behavior depending on
how the topology is presented. Leading to regressions in some workloads
as the performance of the BLOCK softirq on littles can be noticeably
worse on some platforms.
Worth noting that we could have checked for capacities being greater
than or equal instead for equality. This will lead to favouring higher
performance always. But opted for equality instead to match the
performance of the requester without making an assumption that can lead
to power trade-offs which these systems tend to be sensitive about. If
the requester would like to run faster, it's better to rely on the
scheduler to give the IO requester via some facility to run on a faster
core; and then if the interrupt triggered on a CPU with different
capacity we'll make sure to match the performance the requester is
supposed to run at.
[1] https://lpc.events/event/16/contributions/1342/attachments/962/1883/LPC-2022-Android-MC-Phantom-Domains.pdf
Signed-off-by: Qais Yousef <qyousef@layalina.io>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20240223155749.2958009-3-qyousef@layalina.io
Signed-off-by: Jens Axboe <axboe@kernel.dk>
