The PCI interrupt vectors intended to be associated with a queue may
not start at 0; a driver may allocate pre_vectors for special use. This
patch adds an offset parameter so blk-mq may find the intended affinity
mask and updates all drivers using this API accordingly.
Cc: Don Brace <don.brace@microsemi.com>
Cc: <qla2xxx-upstream@qlogic.com>
Cc: <linux-scsi@vger.kernel.org>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If a storage device handled by BFQ happens to be slower than 7.5 KB/s
for a certain amount of time (in the order of a second), then the
estimated peak rate of the device, maintained in BFQ, becomes equal to
0. The reason is the limited precision with which the rate is
represented (details on the range of representable values in the
comments introduced by this commit). This leads to a division-by-zero
error where the estimated peak rate is used as divisor. Such a type of
failure has been reported in [1].
This commit addresses this issue by:
1. Lower-bounding the estimated peak rate to 1
2. Adding and improving comments on the range of rates representable
[1] https://www.spinics.net/lists/kernel/msg2739205.html
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
I'm getting a slab named "biovec-(1<<(21-12))". It is caused by unintended
expansion of the macro BIO_MAX_PAGES. This patch renames it to biovec-max.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org # v4.14+
Signed-off-by: Jens Axboe <axboe@kernel.dk>
scsi_device_quiesce() uses synchronize_rcu() to guarantee that the
effect of blk_set_preempt_only() will be visible for percpu_ref_tryget()
calls that occur after the queue unfreeze by using the approach
explained in https://lwn.net/Articles/573497/. The rcu read lock and
unlock calls in blk_queue_enter() form a pair with the synchronize_rcu()
call in scsi_device_quiesce(). Both scsi_device_quiesce() and
blk_queue_enter() must either use regular RCU or RCU-sched.
Since neither the RCU-protected code in blk_queue_enter() nor
blk_queue_usage_counter_release() sleeps, regular RCU protection
is sufficient. Note: scsi_device_quiesce() does not have to be
modified since it already uses synchronize_rcu().
Reported-by: Tejun Heo <tj@kernel.org>
Fixes: 3a0a529971 ("block, scsi: Make SCSI quiesce and resume work reliably")
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Oleksandr Natalenko <oleksandr@natalenko.name>
Cc: Martin Steigerwald <martin@lichtvoll.de>
Cc: stable@vger.kernel.org # v4.15
Signed-off-by: Jens Axboe <axboe@kernel.dk>
bio_check_eod() should check partition size not the whole disk if
bio->bi_partno is non-zero. Do this by moving the call
to bio_check_eod() into blk_partition_remap().
Based on an earlier patch from Jiufei Xue.
Fixes: 74d46992e0 ("block: replace bi_bdev with a gendisk pointer and partitions index")
Reported-by: Jiufei Xue <jiufei.xue@linux.alibaba.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Since commit 634f9e4631 ("blk-mq: remove REQ_ATOM_COMPLETE usages
from blk-mq") blk_rq_is_complete() only reports whether or not a
request has completed for legacy queues. Hence modify the
blk-mq-debugfs code such that it shows the blk-mq request state
again.
Fixes: 634f9e4631 ("blk-mq: remove REQ_ATOM_COMPLETE usages from blk-mq")
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We've triggered a WARNING in blk_throtl_bio() when throttling writeback
io, which complains blkg->refcnt is already 0 when calling blkg_get(),
and then kernel crashes with invalid page request.
After investigating this issue, we've found it is caused by a race
between blkcg_bio_issue_check() and cgroup_rmdir(), which is described
below:
writeback kworker cgroup_rmdir
cgroup_destroy_locked
kill_css
css_killed_ref_fn
css_killed_work_fn
offline_css
blkcg_css_offline
blkcg_bio_issue_check
rcu_read_lock
blkg_lookup
spin_trylock(q->queue_lock)
blkg_destroy
spin_unlock(q->queue_lock)
blk_throtl_bio
spin_lock_irq(q->queue_lock)
...
spin_unlock_irq(q->queue_lock)
rcu_read_unlock
Since rcu can only prevent blkg from releasing when it is being used,
the blkg->refcnt can be decreased to 0 during blkg_destroy() and schedule
blkg release.
Then trying to blkg_get() in blk_throtl_bio() will complains the WARNING.
And then the corresponding blkg_put() will schedule blkg release again,
which result in double free.
This race is introduced by commit ae11889636 ("blkcg: consolidate blkg
creation in blkcg_bio_issue_check()"). Before this commit, it will
lookup first and then try to lookup/create again with queue_lock. Since
revive this logic is a bit drastic, so fix it by only offlining pd during
blkcg_css_offline(), and move the rest destruction (especially
blkg_put()) into blkcg_css_free(), which should be the right way as
discussed.
Fixes: ae11889636 ("blkcg: consolidate blkg creation in blkcg_bio_issue_check()")
Reported-by: Jiufei Xue <jiufei.xue@linux.alibaba.com>
Signed-off-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The length must be given as bytes and not as 4 bit tuples.
Reviewed-by: Scott Bauer <scott.bauer@intel.com>
Signed-off-by: Jonas Rabenstein <jonas.rabenstein@studium.uni-erlangen.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The current BSG design tries to shoe-horn the transport-specific
passthrough commands into the overall framework for SCSI passthrough
requests. This has a couple problems:
- each passthrough queue has to set the QUEUE_FLAG_SCSI_PASSTHROUGH flag
despite not dealing with SCSI commands at all. Because of that these
queues could also incorrectly accept SCSI commands from in-kernel
users or through the legacy SCSI_IOCTL_SEND_COMMAND ioctl.
- the real SCSI bsg queues also incorrectly accept bsg requests of the
BSG_SUB_PROTOCOL_SCSI_TRANSPORT type
- the bsg transport code is almost unredable because it tries to reuse
different SCSI concepts for its own purpose.
This patch instead adds a new bsg_ops structure to handle the two cases
differently, and thus solves all of the above problems. Another side
effect is that the bsg-lib queues also don't need to embedd a
struct scsi_request anymore.
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>
Users of the bsg-lib interface should only use the bsg_job data structure
and not know about implementation details of it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Benjamin Block <bblock@linux.vnet.ibm.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The zfcp driver wants to know the timeout for a bsg job, so add a field
to struct bsg_job for it in preparation of not exposing the request
to the bsg-lib users.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Benjamin Block <bblock@linux.vnet.ibm.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Avoid that building with W=1 causes the kernel-doc tool to complain
about undocumented function arguments for the blk-zoned.c source file.
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This patch helps to avoid that new code gets introduced in block drivers
that manipulates queue flags without holding the queue lock when that
lock should be held.
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>
This patch has been generated as follows:
for verb in set_unlocked clear_unlocked set clear; do
replace-in-files queue_flag_${verb} blk_queue_flag_${verb%_unlocked} \
$(git grep -lw queue_flag_${verb} drivers block/bsg*)
done
Except for protecting all queue flag changes with the queue lock
this patch does not change any functionality.
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Shaohua Li <shli@fb.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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>
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>
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>
Tokens are prefixed by a variable length of bytes. If a bytestring is
not stored in an tiny or short atom, we have to skip more than one byte
in order to have the actual bytes not prefixed by the bytes describing
the actual length of the string.
Acked-by: Jonathan Derrick <jonathan.derrick@intel.com>
Signed-off-by: Jonas Rabenstein <jonas.rabenstein@studium.uni-erlangen.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Avoid that the following race can occur:
blk_cleanup_queue() blkcg_print_blkgs()
spin_lock_irq(lock) (1) spin_lock_irq(blkg->q->queue_lock) (2,5)
q->queue_lock = &q->__queue_lock (3)
spin_unlock_irq(lock) (4)
spin_unlock_irq(blkg->q->queue_lock) (6)
(1) take driver lock;
(2) busy loop for driver lock;
(3) override driver lock with internal lock;
(4) unlock driver lock;
(5) can take driver lock now;
(6) but unlock internal lock.
This change is safe because only the SCSI core and the NVME core keep
a reference on a request queue after having called blk_cleanup_queue().
Neither driver accesses any of the removed data structures between its
blk_cleanup_queue() and blk_put_queue() calls.
Reported-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Jan Kara <jack@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Initialize the request queue lock earlier such that the following
race can no longer occur:
blk_init_queue_node() blkcg_print_blkgs()
blk_alloc_queue_node (1)
q->queue_lock = &q->__queue_lock (2)
blkcg_init_queue(q) (3)
spin_lock_irq(blkg->q->queue_lock) (4)
q->queue_lock = lock (5)
spin_unlock_irq(blkg->q->queue_lock) (6)
(1) allocate an uninitialized queue;
(2) initialize queue_lock to its default internal lock;
(3) initialize blkcg part of request queue, which will create blkg and
then insert it to blkg_list;
(4) traverse blkg_list and find the created blkg, and then take its
queue lock, here it is the default *internal lock*;
(5) *race window*, now queue_lock is overridden with *driver specified
lock*;
(6) now unlock *driver specified lock*, not the locked *internal lock*,
unlock balance breaks.
The changes in this patch are as follows:
- Move the .queue_lock initialization from blk_init_queue_node() into
blk_alloc_queue_node().
- Only override the .queue_lock pointer for legacy queues because it
is not useful for blk-mq queues to override this pointer.
- For all all block drivers that initialize .queue_lock explicitly,
change the blk_alloc_queue() call in the driver into a
blk_alloc_queue_node() call and remove the explicit .queue_lock
initialization. Additionally, initialize the spin lock that will
be used as queue lock earlier if necessary.
Reported-by: Joseph Qi <joseph.qi@linux.alibaba.com>
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>
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>
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>
When debugging the ZBC code in the mq-deadline scheduler it is very
important to know which zones are locked and which zones are not
locked. Hence this patch that exports the zone locking information
through debugfs.
Cc: Omar Sandoval <osandov@fb.com>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Tested-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Make sure that the queue show and store methods are contiguous and
also that these appear in alphabetical order.
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Damien Le Moal <damien.lemoal@wdc.com>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When two blkdev_open() calls for a partition race with device removal
and recreation, we can hit BUG_ON(!bd_may_claim(bdev, whole, holder)) in
blkdev_open(). The race can happen as follows:
CPU0 CPU1 CPU2
del_gendisk()
bdev_unhash_inode(part1);
blkdev_open(part1, O_EXCL) blkdev_open(part1, O_EXCL)
bdev = bd_acquire() bdev = bd_acquire()
blkdev_get(bdev)
bd_start_claiming(bdev)
- finds old inode 'whole'
bd_prepare_to_claim() -> 0
bdev_unhash_inode(whole);
<device removed>
<new device under same
number created>
blkdev_get(bdev);
bd_start_claiming(bdev)
- finds new inode 'whole'
bd_prepare_to_claim()
- this also succeeds as we have
different 'whole' here...
- bad things happen now as we
have two exclusive openers of
the same bdev
The problem here is that block device opens can see various intermediate
states while gendisk is shutting down and then being recreated.
We fix the problem by introducing new lookup_sem in gendisk that
synchronizes gendisk deletion with get_gendisk() and furthermore by
making sure that get_gendisk() does not return gendisk that is being (or
has been) deleted. This makes sure that once we ever manage to look up
newly created bdev inode, we are also guaranteed that following
get_gendisk() will either return failure (and we fail open) or it
returns gendisk for the new device and following bdget_disk() will
return new bdev inode (i.e., blkdev_open() follows the path as if it is
completely run after new device is created).
Reported-and-analyzed-by: Hou Tao <houtao1@huawei.com>
Tested-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add a proper counterpart to get_disk_and_module() -
put_disk_and_module(). Currently it is opencoded in several places.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Rename get_disk() to get_disk_and_module() to make sure what the
function does. It's not a great name but at least it is now clear that
put_disk() is not it's counterpart.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Commit 8ddcd65325 "block: introduce GENHD_FL_HIDDEN" added handling of
hidden devices to get_gendisk() but forgot to drop module reference
which is also acquired by get_disk(). Drop the reference as necessary.
Arguably the function naming here is misleading as put_disk() is *not*
the counterpart of get_disk() but let's fix that in the follow up
commit since that will be more intrusive.
Fixes: 8ddcd65325
CC: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When requeuing request, the domain token should have been freed
before re-inserting the request to io scheduler. Otherwise, the
assigned domain token will be leaked, and IO hang can be caused.
Cc: Paolo Valente <paolo.valente@linaro.org>
Cc: Omar Sandoval <osandov@fb.com>
Cc: stable@vger.kernel.org
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
__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>
The 'lend' parameter of truncate_inode_pages_range is required to be
inclusive, so follow the rule.
This patch fixes one memory corruption triggered by discard.
Cc: <stable@vger.kernel.org>
Cc: Dmitry Monakhov <dmonakhov@openvz.org>
Fixes: 351499a172 ("block: Invalidate cache on discard v2")
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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>
This is the mindless scripted replacement of kernel use of POLL*
variables as described by Al, done by this script:
for V in IN OUT PRI ERR RDNORM RDBAND WRNORM WRBAND HUP RDHUP NVAL MSG; do
L=`git grep -l -w POLL$V | grep -v '^t' | grep -v /um/ | grep -v '^sa' | grep -v '/poll.h$'|grep -v '^D'`
for f in $L; do sed -i "-es/^\([^\"]*\)\(\<POLL$V\>\)/\\1E\\2/" $f; done
done
with de-mangling cleanups yet to come.
NOTE! On almost all architectures, the EPOLL* constants have the same
values as the POLL* constants do. But they keyword here is "almost".
For various bad reasons they aren't the same, and epoll() doesn't
actually work quite correctly in some cases due to this on Sparc et al.
The next patch from Al will sort out the final differences, and we
should be all done.
Scripted-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 'a6a252e64914 ("blk-mq-sched: decide how to handle flush rq via
RQF_FLUSH_SEQ")' makes all non-flush re-prepared requests for a device
be re-inserted into the active I/O scheduler for that device. As a
consequence, I/O schedulers may get the same request inserted again,
even several times, without a finish_request invoked on that request
before each re-insertion.
This fact is the cause of the failure reported in [1]. For an I/O
scheduler, every re-insertion of the same re-prepared request is
equivalent to the insertion of a new request. For schedulers like
mq-deadline or kyber, this fact causes no harm. In contrast, it
confuses a stateful scheduler like BFQ, which keeps state for an I/O
request, until the finish_request hook is invoked on the request. In
particular, BFQ may get stuck, waiting forever for the number of
request dispatches, of the same request, to be balanced by an equal
number of request completions (while there will be one completion for
that request). In this state, BFQ may refuse to serve I/O requests
from other bfq_queues. The hang reported in [1] then follows.
However, the above re-prepared requests undergo a requeue, thus the
requeue_request hook of the active elevator is invoked for these
requests, if set. This commit then addresses the above issue by
properly implementing the hook requeue_request in BFQ.
[1] https://marc.info/?l=linux-block&m=151211117608676
Reported-by: Ivan Kozik <ivan@ludios.org>
Reported-by: Alban Browaeys <alban.browaeys@gmail.com>
Tested-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Serena Ziviani <ziviani.serena@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The classic error injection mechanism, should_fail_request() does not
support use cases where more information is required (from the entire
struct bio, for example).
To that end, this patch introduces should_fail_bio(), which calls
should_fail_request() under the hood but provides a convenient
place for kprobes to hook into if they require the entire struct bio.
This patch also replaces some existing calls to should_fail_request()
with should_fail_bio() with no degradation in performance.
Signed-off-by: Howard McLauchlan <hmclauchlan@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Mikulas reported a workload that saw bad performance, and figured
out what it was due to various other types of requests being
accounted as reads. Flush requests, for instance. Due to the
high latency of those, we heavily throttle the writes to keep
the latencies in balance. But they really should be accounted
as writes.
Fix this by checking the exact type of the request. If it's a
read, account as a read, if it's a write or a flush, account
as a write. Any other request we disregard. Previously everything
would have been mistakenly accounted as reads.
Reported-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org # v4.12+
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Merge tag 'for-linus-20180204' of git://git.kernel.dk/linux-block
Pull more block updates from Jens Axboe:
"Most of this is fixes and not new code/features:
- skd fix from Arnd, fixing a build error dependent on sla allocator
type.
- blk-mq scheduler discard merging fixes, one from me and one from
Keith. This fixes a segment miscalculation for blk-mq-sched, where
we mistakenly think two segments are physically contigious even
though the request isn't carrying real data. Also fixes a bio-to-rq
merge case.
- Don't re-set a bit on the buffer_head flags, if it's already set.
This can cause scalability concerns on bigger machines and
workloads. From Kemi Wang.
- Add BLK_STS_DEV_RESOURCE return value to blk-mq, allowing us to
distuingish between a local (device related) resource starvation
and a global one. The latter might happen without IO being in
flight, so it has to be handled a bit differently. From Ming"
* tag 'for-linus-20180204' of git://git.kernel.dk/linux-block:
block: skd: fix incorrect linux/slab_def.h inclusion
buffer: Avoid setting buffer bits that are already set
blk-mq-sched: Enable merging discard bio into request
blk-mq: fix discard merge with scheduler attached
blk-mq: introduce BLK_STS_DEV_RESOURCE
I ran into an issue on my laptop that triggered a bug on the
discard path:
WARNING: CPU: 2 PID: 207 at drivers/nvme/host/core.c:527 nvme_setup_cmd+0x3d3/0x430
Modules linked in: rfcomm fuse ctr ccm bnep arc4 binfmt_misc snd_hda_codec_hdmi nls_iso8859_1 nls_cp437 vfat snd_hda_codec_conexant fat snd_hda_codec_generic iwlmvm snd_hda_intel snd_hda_codec snd_hwdep mac80211 snd_hda_core snd_pcm snd_seq_midi snd_seq_midi_event snd_rawmidi snd_seq x86_pkg_temp_thermal intel_powerclamp kvm_intel uvcvideo iwlwifi btusb snd_seq_device videobuf2_vmalloc btintel videobuf2_memops kvm snd_timer videobuf2_v4l2 bluetooth irqbypass videobuf2_core aesni_intel aes_x86_64 crypto_simd cryptd snd glue_helper videodev cfg80211 ecdh_generic soundcore hid_generic usbhid hid i915 psmouse e1000e ptp pps_core xhci_pci xhci_hcd intel_gtt
CPU: 2 PID: 207 Comm: jbd2/nvme0n1p7- Tainted: G U 4.15.0+ #176
Hardware name: LENOVO 20FBCTO1WW/20FBCTO1WW, BIOS N1FET59W (1.33 ) 12/19/2017
RIP: 0010:nvme_setup_cmd+0x3d3/0x430
RSP: 0018:ffff880423e9f838 EFLAGS: 00010217
RAX: 0000000000000000 RBX: ffff880423e9f8c8 RCX: 0000000000010000
RDX: ffff88022b200010 RSI: 0000000000000002 RDI: 00000000327f0000
RBP: ffff880421251400 R08: ffff88022b200000 R09: 0000000000000009
R10: 0000000000000000 R11: 0000000000000000 R12: 000000000000ffff
R13: ffff88042341e280 R14: 000000000000ffff R15: ffff880421251440
FS: 0000000000000000(0000) GS:ffff880441500000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055b684795030 CR3: 0000000002e09006 CR4: 00000000001606e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
nvme_queue_rq+0x40/0xa00
? __sbitmap_queue_get+0x24/0x90
? blk_mq_get_tag+0xa3/0x250
? wait_woken+0x80/0x80
? blk_mq_get_driver_tag+0x97/0xf0
blk_mq_dispatch_rq_list+0x7b/0x4a0
? deadline_remove_request+0x49/0xb0
blk_mq_do_dispatch_sched+0x4f/0xc0
blk_mq_sched_dispatch_requests+0x106/0x170
__blk_mq_run_hw_queue+0x53/0xa0
__blk_mq_delay_run_hw_queue+0x83/0xa0
blk_mq_run_hw_queue+0x6c/0xd0
blk_mq_sched_insert_request+0x96/0x140
__blk_mq_try_issue_directly+0x3d/0x190
blk_mq_try_issue_directly+0x30/0x70
blk_mq_make_request+0x1a4/0x6a0
generic_make_request+0xfd/0x2f0
? submit_bio+0x5c/0x110
submit_bio+0x5c/0x110
? __blkdev_issue_discard+0x152/0x200
submit_bio_wait+0x43/0x60
ext4_process_freed_data+0x1cd/0x440
? account_page_dirtied+0xe2/0x1a0
ext4_journal_commit_callback+0x4a/0xc0
jbd2_journal_commit_transaction+0x17e2/0x19e0
? kjournald2+0xb0/0x250
kjournald2+0xb0/0x250
? wait_woken+0x80/0x80
? commit_timeout+0x10/0x10
kthread+0x111/0x130
? kthread_create_worker_on_cpu+0x50/0x50
? do_group_exit+0x3a/0xa0
ret_from_fork+0x1f/0x30
Code: 73 89 c1 83 ce 10 c1 e1 10 09 ca 83 f8 04 0f 87 0f ff ff ff 8b 4d 20 48 8b 7d 00 c1 e9 09 48 01 8c c7 00 08 00 00 e9 f8 fe ff ff <0f> ff 4c 89 c7 41 bc 0a 00 00 00 e8 0d 78 d6 ff e9 a1 fc ff ff
---[ end trace 50d361cc444506c8 ]---
print_req_error: I/O error, dev nvme0n1, sector 847167488
Decoding the assembly, the request claims to have 0xffff segments,
while nvme counts two. This turns out to be because we don't check
for a data carrying request on the mq scheduler path, and since
blk_phys_contig_segment() returns true for a non-data request,
we decrement the initial segment count of 0 and end up with
0xffff in the unsigned short.
There are a few issues here:
1) We should initialize the segment count for a discard to 1.
2) The discard merging is currently using the data limits for
segments and sectors.
Fix this up by having attempt_merge() correctly identify the
request, and by initializing the segment count correctly
for discards.
This can only be triggered with mq-deadline on discard capable
devices right now, which isn't a common configuration.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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>
Pull poll annotations from Al Viro:
"This introduces a __bitwise type for POLL### bitmap, and propagates
the annotations through the tree. Most of that stuff is as simple as
'make ->poll() instances return __poll_t and do the same to local
variables used to hold the future return value'.
Some of the obvious brainos found in process are fixed (e.g. POLLIN
misspelled as POLL_IN). At that point the amount of sparse warnings is
low and most of them are for genuine bugs - e.g. ->poll() instance
deciding to return -EINVAL instead of a bitmap. I hadn't touched those
in this series - it's large enough as it is.
Another problem it has caught was eventpoll() ABI mess; select.c and
eventpoll.c assumed that corresponding POLL### and EPOLL### were
equal. That's true for some, but not all of them - EPOLL### are
arch-independent, but POLL### are not.
The last commit in this series separates userland POLL### values from
the (now arch-independent) kernel-side ones, converting between them
in the few places where they are copied to/from userland. AFAICS, this
is the least disruptive fix preserving poll(2) ABI and making epoll()
work on all architectures.
As it is, it's simply broken on sparc - try to give it EPOLLWRNORM and
it will trigger only on what would've triggered EPOLLWRBAND on other
architectures. EPOLLWRBAND and EPOLLRDHUP, OTOH, are never triggered
at all on sparc. With this patch they should work consistently on all
architectures"
* 'misc.poll' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (37 commits)
make kernel-side POLL... arch-independent
eventpoll: no need to mask the result of epi_item_poll() again
eventpoll: constify struct epoll_event pointers
debugging printk in sg_poll() uses %x to print POLL... bitmap
annotate poll(2) guts
9p: untangle ->poll() mess
->si_band gets POLL... bitmap stored into a user-visible long field
ring_buffer_poll_wait() return value used as return value of ->poll()
the rest of drivers/*: annotate ->poll() instances
media: annotate ->poll() instances
fs: annotate ->poll() instances
ipc, kernel, mm: annotate ->poll() instances
net: annotate ->poll() instances
apparmor: annotate ->poll() instances
tomoyo: annotate ->poll() instances
sound: annotate ->poll() instances
acpi: annotate ->poll() instances
crypto: annotate ->poll() instances
block: annotate ->poll() instances
x86: annotate ->poll() instances
...
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
...
Use pr_debug instead of hand crafted macros. This way it is not needed to
re-compile the kernel to enable bsg debug outputs and it's possible to
selectively enable specific prints.
Cc: Joe Perches <joe@perches.com>
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Attributes that only implement .seq_ops are read-only, any write to
them should be rejected. But currently kernel would crash when
writing to such debugfs entries, e.g.
chmod +w /sys/kernel/debug/block/<dev>/requeue_list
echo 0 > /sys/kernel/debug/block/<dev>/requeue_list
chmod -w /sys/kernel/debug/block/<dev>/requeue_list
Fix it by returning -EPERM in blk_mq_debugfs_write() when writing to
such attributes.
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We inadvertently set it again on the source bio, but we need
to set it on the new split bio instead.
Fixes: fbbaf700e7 ("block: trace completion of all bios.")
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The previous patch removed all users of these two functions. Hence
also remove the functions themselves.
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>
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>
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>
In mixed read/write workload on SSD, write latency is much lower than
read. But now we only track and record read latency and then use it as
threshold base for both read and write io latency accounting. As a
result, write io latency will always be considered as good and
bad_bio_cnt is much smaller than 20% of bio_cnt. That is to mean, the
tg to be checked will be treated as idle most of the time and still let
others dispatch more ios, even it is truly running under low limit and
wants its low limit to be guaranteed, which is not we expected in fact.
So track read and write request individually, which can bring more
precise latency control for low limit idle detection.
Signed-off-by: Joseph Qi <qijiang.qj@alibaba-inc.com>
Reviewed-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
