Now that we are protected against lookup vs free races for the namespace
by using kref_get_unless_zero we don't need the hack of NULLing out the
disk private data during removal.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
For kref_get_unless_zero to protect against lookup vs free races we need
to use it in all places where we aren't guaranteed to already hold a
reference. There is no such guarantee in nvme_find_get_ns, so switch to
kref_get_unless_zero in this function.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
The scheduler framework now supports looking up the appropriate
scheduler with the {name,mq} tupple. We can register mq-deadline
with the alias of 'deadline', so that switching to 'deadline'
will do the right thing based on the type of driver attached to
it.
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Since we now lookup elevator types with the appropriate multiqueue
capability, allow schedulers to register with an alias alongside
the real name. This is in preparation for allowing 'mq-deadline'
to register an alias of 'deadline' as well.
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If an IO scheduler is selected via elevator= and it doesn't match
the driver in question wrt blk-mq support, then we fail to boot.
The elevator= parameter is deprecated and only supported for
non-mq devices. Augment the elevator lookup API so that we
pass in if we're looking for an mq capable scheduler or not,
so that we only ever return a valid type for the queue in
question.
Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=196695
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
sd_config_write_same() ignores ->max_ws_blocks == 0 and resets it to
permit trying WRITE SAME on older SCSI devices, unless ->no_write_same
is set. Because REQ_OP_WRITE_ZEROES is implemented in terms of WRITE
SAME, blkdev_issue_zeroout() may fail with -EREMOTEIO:
$ fallocate -zn -l 1k /dev/sdg
fallocate: fallocate failed: Remote I/O error
$ fallocate -zn -l 1k /dev/sdg # OK
$ fallocate -zn -l 1k /dev/sdg # OK
The following calls succeed because sd_done() sets ->no_write_same in
response to a sense that would become BLK_STS_TARGET/-EREMOTEIO, causing
__blkdev_issue_zeroout() to fall back to generating ZERO_PAGE bios.
This means blkdev_issue_zeroout() must cope with WRITE ZEROES failing
and fall back to manually zeroing, unless BLKDEV_ZERO_NOFALLBACK is
specified. For BLKDEV_ZERO_NOFALLBACK case, return -EOPNOTSUPP if
sd_done() has just set ->no_write_same thus indicating lack of offload
support.
Fixes: c20cfc27a4 ("block: stop using blkdev_issue_write_same for zeroing")
Cc: Hannes Reinecke <hare@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
blkdev_issue_zeroout() will use this in !BLKDEV_ZERO_NOFALLBACK case.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Check for CAP_SYS_ADMIN before calling into the driver, similar to
blkdev_flushbuf(). This is safer and can spare a check in the driver.
(Currently BLKROSET is overridden by md and rbd, rbd is missing the
check. md has the check, but it covers a lot more than BLKROSET.)
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
It is reasonable drop page cache on discard, otherwise that pages may
be written by writeback second later, so thin provision devices will
not be happy. This seems to be a security leak in case of secure discard case.
Also add check for queue_discard flag on early stage.
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
A previous patch inadvertently left an unused test function in the
header, kill it.
Fixes: 8bd400204b ("lightnvm: pblk: cleanup unused and static functions")
Signed-off-by: Javier González <javier@cnexlabs.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The transport io timeout behavior wasn't quite correct. It ignored
that the io error handler is supposed to be synchronous so it possibly
allowed the blk request to be restarted while the io associated was
still aborting. Timeouts on reserved commands, those used for
association create, were never timing out thus they hung out forever.
To correct:
If an io is times out while a remoteport is not connected, just
restart the io timer. The lack of connectivity will simultaneously
be resetting the controller, so the reset path will abort and terminate
the io.
If an io is times out while it was marked for transport abort, just
reset the io timer. The abort process is underway and will complete
the io.
Otherwise, if an io times out, abort the io. If the abort was
unsuccessful (unlikely) give up and return not handled.
If the abort was successful, as the abort process is underway it will
terminate the io, so rather than synchronously waiting, just restart
the io timer.
Signed-off-by: James Smart <james.smart@broadcom.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
The io completion handling for i/o's that are failing due to
to a transport error or association termination had issues, causing
io failures (DNR set so retries didn't kick in) or long stalls.
Change the io completion handler for the following items:
When an io has been completed due to a transport abort (based on an
exchange error) or when marked as aborted as part of an association
termination (FCOP_FLAGS_TERMIO), set the NVME completion status to
NVME_SC_ABORTED. By default, do not set DNR on the status so that a
retry can be attempted after association recreate.
In cases where an io is failed (non-successful nvme status including
aborted), if the controller is being deleted (blk_queue_dying) or
the io was part of the ios used for association creation (ctrl state
is NEW or RECONNECTING), then additionally set the DNR bit so the io
will not be retried. If the failed io was part of association creation,
the failure will tear down the partially completioned association and
typically restart a new reconnect attempt (another create association
later).
Rearranged code flow to remove a largely unneeded local variable.
Signed-off-by: James Smart <james.smart@broadcom.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This adds SGL support for NVMe PCIe driver, based on an earlier patch
from Rajiv Shanmugam Madeswaran <smrajiv15 at gmail.com>. This patch
refactors the original code and adds new module parameter sgl_threshold
to determine whether to use SGL or PRP for IOs.
The usage of SGLs is controlled by the sgl_threshold module parameter,
which allows to conditionally use SGLs if average request segment
size (avg_seg_size) is greater than sgl_threshold. In the original patch,
the decision of using SGLs was dependent only on the IO size,
with the new approach we consider not only IO size but also the
number of physical segments present in the IO.
We calculate avg_seg_size based on request payload bytes and number
of physical segments present in the request.
For e.g.:-
1. blk_rq_nr_phys_segments = 2 blk_rq_payload_bytes = 8k
avg_seg_size = 4K use sgl if avg_seg_size >= sgl_threshold.
2. blk_rq_nr_phys_segments = 2 blk_rq_payload_bytes = 64k
avg_seg_size = 32K use sgl if avg_seg_size >= sgl_threshold.
3. blk_rq_nr_phys_segments = 16 blk_rq_payload_bytes = 64k
avg_seg_size = 4K use sgl if avg_seg_size >= sgl_threshold.
Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Switch to the ida_simple_* helpers instead of opencoding them.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
In case we disable namespaces which has the nsid like
subsystem max_nsid we need to search for the next largest nsid
in this subsystem. If the subsystem don't has more namespaces
we set it to 0, else we take nsid from the last namespace in
namespaces list because the list is sorted while inserting.
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Roy Shterman <roys@lightbitslabs.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
[hch: slight refactor]
Signed-off-by: Christoph Hellwig <hch@lst.de>
This flag is useful for admin queues that aren't used for normal IO.
Signed-off-by: Israel Rukshin <israelr@mellanox.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Since commit b86dd81
"block: get rid of blk-mq default scheduler choice Kconfig entries",
when setting nr_hw_queues to 1 the admin tag set uses mq-deadline scheduler.
This flag is useful for admin queues that aren't used for normal IO.
Signed-off-by: Israel Rukshin <israelr@mellanox.com>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: James Smart <james.smart@broadcom.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Since commit b86dd81
"block: get rid of blk-mq default scheduler choice Kconfig entries",
when setting nr_hw_queues to 1 the admin tag set uses mq-deadline scheduler.
This flag is useful for admin queues that aren't used for normal IO.
Signed-off-by: Israel Rukshin <israelr@mellanox.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
fixed comment typos in adapter_alloc_cq() and adapter_alloc_sq().
'the the' duplications are replaced with 'that the'.
Signed-off-by: Minwoo Im <dn3108@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
If the controller is deleting (in case the user decided to delete it), we
have no point to continue reset sequence.
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Instead of marking we are deleting, mark we are allocated and check that
instead. This makes the logic symmetrical to connected mark check.
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
No chance for the local invalidate to succeed if the queue-pair
is in error state. Most likely the target will do a remote
invalidation of our mr so not a big loss on the test_bit.
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Relying on the queue state while tearing down on every reconnect
attempt is not a good design. We should do it once in err_work
and simply try to establish the queues for each reconnect attempt.
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Warn if req->mr is NULL as it should never happen.
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
No need for the extra line for trivial assignments.
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Instead of flagging admin/io.
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Move blk_mq_reinit_tagset from blk-mq to nvme core
as the only user of it. Current transports that use
it (rdma, fc) simply implement .reinit_request op.
This patch does not change any functionality.
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Iterator helper to apply a function on all the
tags in a given tagset. export it as it will be used
outside the block layer later on.
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
When we're getting a domain token, if we fail to get a token on our
first attempt, we put the current hardware queue on a wait queue and
then try again just in case a token was freed after our initial attempt
but before we got on the wait queue. If this second attempt succeeds, we
currently leave the hardware queue on the wait queue. Usually this is
okay; we'll just run the hardware queue one extra time when another
token is freed. However, if the hardware queue doesn't have any other
requests waiting, then when it it gets the extra wakeup, it won't have
anything to free and therefore won't wake up any other hardware queues.
If tokens are limited, then we won't make forward progress and the
device will hang.
Reported-by: Bin Zha <zhabin.zb@alibaba-inc.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Fix to return error code -ENOMEM from the null_alloc_dev() error
handling case instead of 0, as done elsewhere in this function.
Fixes: 2984c8684f ("nullb: factor disk parameters")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Sphinx treats symbols that end with '_' as a kind of special
documentation indicator, so fix that by adding an ending '*'
to it.
../block/bio.c:404: ERROR: Unknown target name: "gfp".
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Sorry this got through to linux-block, was detected by the kbuilds test
robot. NSEC_PER_SEC is a long constant; 2.5 * 10^9 doesn't fit in a
signed long constant.
Fixes: e41166c5c4 ("bcache: writeback rate shouldn't artifically clamp")
Reviewed-by: Coly Li <colyli@suse.de>
Signed-off-by: Michael Lyle <mlyle@lyle.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The use of the union reduces the size of closure struct by taking advantage
of the current size of its members. The offset of func in work_struct
equals the size of the first three members, so that work.work_func will
just reference the forth member - fn.
This is smart but dangerous. It can be broken if work_struct or the other
structs get changed, and can be a bit difficult to debug.
Signed-off-by: Liang Chen <liangchen.linux@gmail.com>
Reviewed-by: Michael Lyle <mlyle@lyle.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The time spent searching for things to write back "counts" for the
actual rate achieved, so don't flush the accumulated rate with each
chunk.
This will maintain better fidelity to user-commanded rates, but it
may slightly increase the burstiness of writeback. The writeback
lock needs improvement to help mitigate this.
Signed-off-by: Michael Lyle <mlyle@lyle.org>
Reviewed-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The previous code artificially limited writeback rate to 1000000
blocks/second (NSEC_PER_MSEC), which is a rate that can be met on fast
hardware. The rate limiting code works fine (though with decreased
precision) up to 3 orders of magnitude faster, so use NSEC_PER_SEC.
Additionally, ensure that uint32_t is used as a type for rate throughout
the rate management so that type checking/clamp_t can work properly.
bch_next_delay should be rewritten for increased precision and better
handling of high rates and long sleep periods, but this is adequate for
now.
Signed-off-by: Michael Lyle <mlyle@lyle.org>
Reported-by: Coly Li <colyli@suse.de>
Reviewed-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This works in conjunction with the new PI controller. Currently, in
real-world workloads, the rate controller attempts to write back 1
sector per second. In practice, these minimum-rate writebacks are
between 4k and 60k in test scenarios, since bcache aggregates and
attempts to do contiguous writes and because filesystems on top of
bcachefs typically write 4k or more.
Previously, bcache used to guarantee to write at least once per second.
This means that the actual writeback rate would exceed the configured
amount by a factor of 8-120 or more.
This patch adjusts to be willing to sleep up to 2.5 seconds, and to
target writing 4k/second. On the smallest writes, it will sleep 1
second like before, but many times it will sleep longer and load the
backing device less. This keeps the loading on the cache and backing
device related to writeback more consistent when writing back at low
rates.
Signed-off-by: Michael Lyle <mlyle@lyle.org>
Reviewed-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
bcache uses a control system to attempt to keep the amount of dirty data
in cache at a user-configured level, while not responding excessively to
transients and variations in write rate. Previously, the system was a
PD controller; but the output from it was integrated, turning the
Proportional term into an Integral term, and turning the Derivative term
into a crude Proportional term. Performance of the controller has been
uneven in production, and it has tended to respond slowly, oscillate,
and overshoot.
This patch set replaces the current control system with an explicit PI
controller and tuning that should be correct for most hardware. By
default, it attempts to write at a rate that would retire 1/40th of the
current excess blocks per second. An integral term in turn works to
remove steady state errors.
IMO, this yields benefits in simplicity (removing weighted average
filtering, etc) and system performance.
Another small change is a tunable parameter is introduced to allow the
user to specify a minimum rate at which dirty blocks are retired.
There is a slight difference from earlier versions of the patch in
integral handling to prevent excessive negative integral windup.
Signed-off-by: Michael Lyle <mlyle@lyle.org>
Reviewed-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If an IO operation fails, and we didn't successfully read data from the
cache, don't writeback invalid/partial data to the backing disk.
Signed-off-by: Michael Lyle <mlyle@lyle.org>
Reviewed-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Parameter bio is no longer used, clean it.
Signed-off-by: Yijing Wang <wangyijing@huawei.com>
Reviewed-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Flag for bypass if the IO is for read-ahead or background, unless the
read-ahead request is for metadata (eg, from gfs2).
Bypass if:
bio->bi_opf & (REQ_RAHEAD|REQ_BACKGROUND) &&
!(bio->bi_opf & REQ_META))
Writeback if:
op_is_sync(bio->bi_opf) ||
bio->bi_opf & (REQ_META|REQ_PRIO)
Signed-off-by: Eric Wheeler <bcache@linux.ewheeler.net>
Reviewed-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
set_capacity() has been called in bcache_device_init(),
remove the redundant one.
Signed-off-by: Yijing Wang <wangyijing@huawei.com>
Reviewed-by: Eric Wheeler <bcache@linux.ewheeler.net>
Acked-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Current partition support of bcache is confusing and buggy. It tries to
trace non-continuous device minor numbers by an ida bit string, and
mistakenly mixed bcache device index with minor numbers. This design
generates several negative results,
- Index of bcache device name is not consecutive under /dev/. If there are
3 bcache devices, they name will be,
/dev/bcache0, /dev/bcache16, /dev/bcache32
Only bcache code indexes bcache device name is such an interesting way.
- First minor number of each bcache device is traced by ida bit string.
One bcache device will occupy 16 bits, this is not a good idea. Indeed
only one bit is enough.
- Because minor number and bcache device index are mixed, a device index
is allocated by ida_simple_get(), but an first minor number is sent into
ida_simple_remove() to release the device. It confused original author
too.
Root cause of the above errors is, bcache code should not handle device
minor numbers at all! A standard process to support multiple partitions in
Linux kernel is,
- Device driver provides major device number, and indexes multiple device
instances.
- Device driver does not allocat nor trace device minor number, only
provides a first minor number of a given device instance, and sets how
many minor numbers (paritions) the device instance may have.
All rested stuffs are handled by block layer code, most of the details can
be found from block/{genhd, partition-generic}.c files.
This patch re-writes multiple partitions support for bcache. It makes
whole things to be more clear, and uses ida bit string in a more efficeint
way.
- Ida bit string only traces bcache device index, not minor number. For a
bcache device with 128 partitions, only one bit in ida bit string is
enough.
- Device minor number and device index are separated in concept. Device
index is used for /dev node naming, and ida bit string trace. Minor
number is calculated from device index and only used to initialize
first_minor of a bcache device.
- It does not follow any standard for 16 partitions on a bcache device.
This patch sets 128 partitions on single bcache device at max, this is
the limitation from GPT (GUID Partition Table) and supported by fdisk.
Considering a typical device minor number is 20 bits width, each bcache
device may have 128 partitions (7 bits), there can be 8192 bcache devices
existing on system. For most common deployment for a single server in
now days, it should be enough.
[minor spelling fixes in commit message by Michael Lyle]
Signed-off-by: Coly Li <colyli@suse.de>
Cc: Eric Wheeler <bcache@lists.ewheeler.net>
Cc: Junhui Tang <tang.junhui@zte.com.cn>
Reviewed-by: Michael Lyle <mlyle@lyle.org>
Signed-off-by: Michael Lyle <mlyle@lyle.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Code comments in alloc.c:bch_alloc_sectors() mentions a function
name find_data_bucket(), the correct function name should be
pick_data_bucket() indeed. bch_alloc_sectors() is a quite important
function in bcache allocation code, fixing the typo may help
other people to have less confusion.
Signed-off-by: Coly Li <colyli@suse.de>
Reviewed-by: Tang Junhui <tang.junhui@zte.com.cn>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In bcache code, sysfs entries are created before all resources get
allocated, e.g. allocation thread of a cache set.
There is posibility for NULL pointer deference if a resource is accessed
but which is not initialized yet. Indeed Jorg Bornschein catches one on
cache set allocation thread and gets a kernel oops.
The reason for this bug is, when bch_bucket_alloc() is called during
cache set registration and attaching, ca->alloc_thread is not properly
allocated and initialized yet, call wake_up_process() on ca->alloc_thread
triggers NULL pointer deference failure. A simple and fast fix is, before
waking up ca->alloc_thread, checking whether it is allocated, and only
wake up ca->alloc_thread when it is not NULL.
Signed-off-by: Coly Li <colyli@suse.de>
Reported-by: Jorg Bornschein <jb@capsec.org>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Cc: stable@vger.kernel.org
Reviewed-by: Michael Lyle <mlyle@lyle.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
