linux-toradex.git/drivers/nvme, branch v5.7-rc2 Linux kernel for Apalis and Colibri modules Merge tag 'block-5.7-2020-04-10' of git://git.kernel.dk/linux-block 2020-04-10T17:06:54+00:00 Linus Torvalds torvalds@linux-foundation.org 2020-04-10T17:06:54+00:00 8df2a0a6da450b0fc28f1fed110817c1d98b84c2 Pull block fixes from Jens Axboe: "Here's a set of fixes that should go into this merge window. This contains: - NVMe pull request from Christoph with various fixes - Better discard support for loop (Evan) - Only call ->commit_rqs() if we have queued IO (Keith) - blkcg offlining fixes (Tejun) - fix (and fix the fix) for busy partitions" * tag 'block-5.7-2020-04-10' of git://git.kernel.dk/linux-block: block: fix busy device checking in blk_drop_partitions again block: fix busy device checking in blk_drop_partitions nvmet-rdma: fix double free of rdma queue blk-mq: don't commit_rqs() if none were queued nvme-fc: Revert "add module to ops template to allow module references" nvme: fix deadlock caused by ANA update wrong locking nvmet-rdma: fix bonding failover possible NULL deref loop: Better discard support for block devices loop: Report EOPNOTSUPP properly nvmet: fix NULL dereference when removing a referral nvme: inherit stable pages constraint in the mpath stack device blkcg: don't offline parent blkcg first blkcg: rename blkcg->cgwb_refcnt to ->online_pin and always use it nvme-tcp: fix possible crash in recv error flow nvme-tcp: don't poll a non-live queue nvme-tcp: fix possible crash in write_zeroes processing nvmet-fc: fix typo in comment nvme-rdma: Replace comma with a semicolon nvme-fcloop: fix deallocation of working context nvme: fix compat address handling in several ioctls 
Pull block fixes from Jens Axboe:
 "Here's a set of fixes that should go into this merge window. This
  contains:

   - NVMe pull request from Christoph with various fixes

   - Better discard support for loop (Evan)

   - Only call ->commit_rqs() if we have queued IO (Keith)

   - blkcg offlining fixes (Tejun)

   - fix (and fix the fix) for busy partitions"

* tag 'block-5.7-2020-04-10' of git://git.kernel.dk/linux-block:
  block: fix busy device checking in blk_drop_partitions again
  block: fix busy device checking in blk_drop_partitions
  nvmet-rdma: fix double free of rdma queue
  blk-mq: don't commit_rqs() if none were queued
  nvme-fc: Revert "add module to ops template to allow module references"
  nvme: fix deadlock caused by ANA update wrong locking
  nvmet-rdma: fix bonding failover possible NULL deref
  loop: Better discard support for block devices
  loop: Report EOPNOTSUPP properly
  nvmet: fix NULL dereference when removing a referral
  nvme: inherit stable pages constraint in the mpath stack device
  blkcg: don't offline parent blkcg first
  blkcg: rename blkcg->cgwb_refcnt to ->online_pin and always use it
  nvme-tcp: fix possible crash in recv error flow
  nvme-tcp: don't poll a non-live queue
  nvme-tcp: fix possible crash in write_zeroes processing
  nvmet-fc: fix typo in comment
  nvme-rdma: Replace comma with a semicolon
  nvme-fcloop: fix deallocation of working context
  nvme: fix compat address handling in several ioctls
nvmet-rdma: fix double free of rdma queue 2020-04-07T16:33:45+00:00 Israel Rukshin israelr@mellanox.com 2020-04-07T11:02:28+00:00 21f9024355e58772ec5d7fc3534aa5e29d72a8b6 In case rdma accept fails at nvmet_rdma_queue_connect(), release work is scheduled. Later on, a new RDMA CM event may arrive since we didn't destroy the cm-id and call nvmet_rdma_queue_connect_fail(), which schedule another release work. This will cause calling nvmet_rdma_free_queue twice. To fix this we implicitly destroy the cm_id with non-zero ret code, which guarantees that new rdma_cm events will not arrive afterwards. Also add a qp pointer to nvmet_rdma_queue structure, so we can use it when the cm_id pointer is NULL or was destroyed. Signed-off-by: Israel Rukshin <israelr@mellanox.com> Suggested-by: Sagi Grimberg <sagi@grimberg.me> Reviewed-by: Max Gurtovoy <maxg@mellanox.com> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Christoph Hellwig <hch@lst.de> 
In case rdma accept fails at nvmet_rdma_queue_connect(), release work is
scheduled. Later on, a new RDMA CM event may arrive since we didn't
destroy the cm-id and call nvmet_rdma_queue_connect_fail(), which
schedule another release work. This will cause calling
nvmet_rdma_free_queue twice. To fix this we implicitly destroy the cm_id
with non-zero ret code, which guarantees that new rdma_cm events will
not arrive afterwards. Also add a qp pointer to nvmet_rdma_queue
structure, so we can use it when the cm_id pointer is NULL or was
destroyed.

Signed-off-by: Israel Rukshin <israelr@mellanox.com>
Suggested-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
nvme-fc: Revert "add module to ops template to allow module references" 2020-04-04T07:09:39+00:00 James Smart jsmart2021@gmail.com 2020-04-03T14:33:20+00:00 8c5c660529209a0e324c1c1a35ce3f83d67a2aa5 The original patch was to resolve the lldd being able to be unloaded while being used to talk to the boot device of the system. However, the end result of the original patch is that any driver unload while a nvme controller is live via the lldd is now being prohibited. Given the module reference, the module teardown routine can't be called, thus there's no way, other than manual actions to terminate the controllers. Fixes: 863fbae929c7 ("nvme_fc: add module to ops template to allow module references") Cc: <stable@vger.kernel.org> # v5.4+ Signed-off-by: James Smart <jsmart2021@gmail.com> Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com> Signed-off-by: Christoph Hellwig <hch@lst.de> 
The original patch was to resolve the lldd being able to be unloaded
while being used to talk to the boot device of the system. However, the
end result of the original patch is that any driver unload while a nvme
controller is live via the lldd is now being prohibited. Given the module
reference, the module teardown routine can't be called, thus there's no
way, other than manual actions to terminate the controllers.

Fixes: 863fbae929c7 ("nvme_fc: add module to ops template to allow module references")
Cc: <stable@vger.kernel.org> # v5.4+
Signed-off-by: James Smart <jsmart2021@gmail.com>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
nvme: fix deadlock caused by ANA update wrong locking 2020-04-04T07:07:03+00:00 Sagi Grimberg sagi@grimberg.me 2020-04-02T16:34:54+00:00 657f1975e9d9c880fa13030e88ba6cc84964f1db The deadlock combines 4 flows in parallel: - ns scanning (triggered from reconnect) - request timeout - ANA update (triggered from reconnect) - I/O coming into the mpath device (1) ns scanning triggers disk revalidation -> update disk info -> freeze queue -> but blocked, due to (2) (2) timeout handler reference the g_usage_counter - > but blocks in the transport .timeout() handler, due to (3) (3) the transport timeout handler (indirectly) calls nvme_stop_queue() -> which takes the (down_read) namespaces_rwsem - > but blocks, due to (4) (4) ANA update takes the (down_write) namespaces_rwsem -> calls nvme_mpath_set_live() -> which synchronize the ns_head srcu (see commit 504db087aacc) -> but blocks, due to (5) (5) I/O came into nvme_mpath_make_request -> took srcu_read_lock -> direct_make_request > blk_queue_enter -> but blocked, due to (1) ==> the request queue is under freeze -> deadlock. The fix is making ANA update take a read lock as the namespaces list is not manipulated, it is just the ns and ns->head that are being updated (which is protected with the ns->head lock). Fixes: 0d0b660f214dc ("nvme: add ANA support") Signed-off-by: Sagi Grimberg <sagi@grimberg.me> Reviewed-by: Keith Busch <kbusch@kernel.org> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Christoph Hellwig <hch@lst.de> 
The deadlock combines 4 flows in parallel:
- ns scanning (triggered from reconnect)
- request timeout
- ANA update (triggered from reconnect)
- I/O coming into the mpath device

(1) ns scanning triggers disk revalidation -> update disk info ->
    freeze queue -> but blocked, due to (2)

(2) timeout handler reference the g_usage_counter - > but blocks in
    the transport .timeout() handler, due to (3)

(3) the transport timeout handler (indirectly) calls nvme_stop_queue() ->
    which takes the (down_read) namespaces_rwsem - > but blocks, due to (4)

(4) ANA update takes the (down_write) namespaces_rwsem -> calls
    nvme_mpath_set_live() -> which synchronize the ns_head srcu
    (see commit 504db087aacc) -> but blocks, due to (5)

(5) I/O came into nvme_mpath_make_request -> took srcu_read_lock ->
    direct_make_request > blk_queue_enter -> but blocked, due to (1)

==> the request queue is under freeze -> deadlock.

The fix is making ANA update take a read lock as the namespaces list
is not manipulated, it is just the ns and ns->head that are being
updated (which is protected with the ns->head lock).

Fixes: 0d0b660f214dc ("nvme: add ANA support")
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
nvmet-rdma: fix bonding failover possible NULL deref 2020-04-04T07:06:55+00:00 Sagi Grimberg sagi@grimberg.me 2020-04-02T15:48:53+00:00 a032e4f6d60d0aca4f6570d2ad33105a2b9ba385 RDMA_CM_EVENT_ADDR_CHANGE event occur in the case of bonding failover on normal as well as on listening cm_ids. Hence this event will immediately trigger a NULL dereference trying to disconnect a queue for a cm_id that actually belongs to the port. To fix this we provide a different handler for the listener cm_ids that will defer a work to disable+(re)enable the port which essentially destroys and setups another listener cm_id Reported-by: Alex Lyakas <alex@zadara.com> Signed-off-by: Sagi Grimberg <sagi@grimberg.me> Reviewed-by: Max Gurtovoy <maxg@mellanox.com> Tested-by: Alex Lyakas <alex@zadara.com> Signed-off-by: Christoph Hellwig <hch@lst.de> 
RDMA_CM_EVENT_ADDR_CHANGE event occur in the case of bonding failover
on normal as well as on listening cm_ids. Hence this event will
immediately trigger a NULL dereference trying to disconnect a queue
for a cm_id that actually belongs to the port.

To fix this we provide a different handler for the listener cm_ids
that will defer a work to disable+(re)enable the port which essentially
destroys and setups another listener cm_id

Reported-by: Alex Lyakas <alex@zadara.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Tested-by: Alex Lyakas <alex@zadara.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Merge tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi 2020-04-03T00:03:53+00:00 Linus Torvalds torvalds@linux-foundation.org 2020-04-03T00:03:53+00:00 79f51b7b9c4719303f758ae8406c4e5997ed6aa3 Pull SCSI updates from James Bottomley: "This series has a huge amount of churn because it pulls in Mauro's doc update changing all our txt files to rst ones. Excluding that, we have the usual driver updates (qla2xxx, ufs, lpfc, zfcp, ibmvfc, pm80xx, aacraid), a treewide update for scnprintf and some other minor updates. The major core change is Hannes moving functions out of the aacraid driver and into the core" * tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (223 commits) scsi: aic7xxx: aic97xx: Remove FreeBSD-specific code scsi: ufs: Do not rely on prefetched data scsi: dc395x: remove dc395x_bios_param scsi: libiscsi: Fix error count for active session scsi: hpsa: correct race condition in offload enabled scsi: message: fusion: Replace zero-length array with flexible-array member scsi: qedi: Add PCI shutdown handler support scsi: qedi: Add MFW error recovery process scsi: ufs: Enable block layer runtime PM for well-known logical units scsi: ufs-qcom: Override devfreq parameters scsi: ufshcd: Let vendor override devfreq parameters scsi: ufshcd: Update the set frequency to devfreq scsi: ufs: Resume ufs host before accessing ufs device scsi: ufs-mediatek: customize the delay for enabling host scsi: ufs: make HCE polling more compact to improve initialization latency scsi: ufs: allow custom delay prior to host enabling scsi: ufs-mediatek: use common delay function scsi: ufs: introduce common and flexible delay function scsi: ufs: use an enum for host capabilities scsi: ufs: fix uninitialized tx_lanes in ufshcd_disable_tx_lcc() ... 
Pull SCSI updates from James Bottomley:
 "This series has a huge amount of churn because it pulls in Mauro's doc
  update changing all our txt files to rst ones.

  Excluding that, we have the usual driver updates (qla2xxx, ufs, lpfc,
  zfcp, ibmvfc, pm80xx, aacraid), a treewide update for scnprintf and
  some other minor updates.

  The major core change is Hannes moving functions out of the aacraid
  driver and into the core"

* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (223 commits)
  scsi: aic7xxx: aic97xx: Remove FreeBSD-specific code
  scsi: ufs: Do not rely on prefetched data
  scsi: dc395x: remove dc395x_bios_param
  scsi: libiscsi: Fix error count for active session
  scsi: hpsa: correct race condition in offload enabled
  scsi: message: fusion: Replace zero-length array with flexible-array member
  scsi: qedi: Add PCI shutdown handler support
  scsi: qedi: Add MFW error recovery process
  scsi: ufs: Enable block layer runtime PM for well-known logical units
  scsi: ufs-qcom: Override devfreq parameters
  scsi: ufshcd: Let vendor override devfreq parameters
  scsi: ufshcd: Update the set frequency to devfreq
  scsi: ufs: Resume ufs host before accessing ufs device
  scsi: ufs-mediatek: customize the delay for enabling host
  scsi: ufs: make HCE polling more compact to improve initialization latency
  scsi: ufs: allow custom delay prior to host enabling
  scsi: ufs-mediatek: use common delay function
  scsi: ufs: introduce common and flexible delay function
  scsi: ufs: use an enum for host capabilities
  scsi: ufs: fix uninitialized tx_lanes in ufshcd_disable_tx_lcc()
  ...
nvmet: fix NULL dereference when removing a referral 2020-04-02T08:51:56+00:00 Sagi Grimberg sagi@grimberg.me 2020-04-01T23:16:27+00:00 f0e656e4f253120eb871a53ffab7664530c1d9f4 When item release is called, the parent is already null. We need the parent to pass to nvmet_referral_disable so hook it up to ->disconnect_notify. Reported-by: Tony Asleson <tasleson@redhat.com> Signed-off-by: Sagi Grimberg <sagi@grimberg.me> Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Signed-off-by: Christoph Hellwig <hch@lst.de> 
When item release is called, the parent is already null.  We need the
parent to pass to nvmet_referral_disable so hook it up to
->disconnect_notify.

Reported-by: Tony Asleson <tasleson@redhat.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
nvme: inherit stable pages constraint in the mpath stack device 2020-04-02T08:51:46+00:00 Sagi Grimberg sagi@grimberg.me 2020-04-02T05:44:43+00:00 74e4d20e2f43cf09a35543d960ac8f7a1ffcbbb5 If the backing device require stable pages, we need to set it on the stack mpath device as well. This applies to rdma/fc transports when doing data integrity and tcp transport calculating digests. Signed-off-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Christoph Hellwig <hch@lst.de> 
If the backing device require stable pages, we need to set it on the
stack mpath device as well. This applies to rdma/fc transports when
doing data integrity and tcp transport calculating digests.

Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
nvme-tcp: fix possible crash in recv error flow 2020-04-01T09:07:13+00:00 Sagi Grimberg sagi@grimberg.me 2020-04-01T05:44:23+00:00 39d06079a50fe2a651091b38e311e605de0788cb If the target misbehaves and sends us unexpected payload we need to make sure to fail the controller and stop processing the input stream. We clear the rd_enabled flag and stop the io_work, but we may still requeue it if we still have pending sends and then in the next invocation we will process the input stream as the check is only in the .data_ready upcall. To fix this we need to make sure not to self-requeue io_work upon a recv flow error. This fixes the crash: nvme nvme2: receive failed: -22 BUG: unable to handle page fault for address: ffffbeb5816c3b48 nvme_ns_head_make_request: 29 callbacks suppressed block nvme0n5: no usable path - requeuing I/O block nvme0n5: no usable path - requeuing I/O block nvme0n7: no usable path - requeuing I/O block nvme0n7: no usable path - requeuing I/O block nvme0n3: no usable path - requeuing I/O block nvme0n3: no usable path - requeuing I/O block nvme0n3: no usable path - requeuing I/O block nvme0n7: no usable path - requeuing I/O block nvme0n3: no usable path - requeuing I/O block nvme0n3: no usable path - requeuing I/O #PF: supervisor read access inkernel mode #PF: error_code(0x0000) - not-present page PGD 1039157067 P4D 1039157067 PUD 103915a067 PMD 102719f067 PTE 0 Oops: 0000 [#1] SMP PTI CPU: 8 PID: 411 Comm: kworker/8:1H Not tainted 5.3.0-40-generic #32~18.04.1-Ubuntu Hardware name: Supermicro Super Server/X10SRi-F, BIOS 2.0 12/17/2015 Workqueue: nvme_tcp_wq nvme_tcp_io_work [nvme_tcp] RIP: 0010:nvme_tcp_recv_skb+0x2ae/0xb50 [nvme_tcp] RSP: 0018:ffffbeb5806cfd10 EFLAGS: 00010246 RAX: ffffbeb5816c3b48 RBX: 00000000000003d0 RCX: 0000000000000008 RDX: 00000000000003d0 RSI: 0000000000000001 RDI: ffff9a3040684b40 RBP: ffffbeb5806cfd90 R08: 0000000000000000 R09: ffffffff946e6900 R10: ffffbeb5806cfce0 R11: 0000000000000001 R12: 0000000000000000 R13: ffff9a2ff86501c0 R14: 00000000000003d0 R15: ffff9a30b85f2798 FS: 0000000000000000(0000) GS:ffff9a30bf800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffbeb5816c3b48 CR3: 000000088400a006 CR4: 00000000003626e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: tcp_read_sock+0x8c/0x290 ? __release_sock+0x9d/0xe0 ? nvme_tcp_write_space+0xb0/0xb0 [nvme_tcp] nvme_tcp_io_work+0x4b4/0x830 [nvme_tcp] ? finish_task_switch+0x163/0x270 process_one_work+0x1fd/0x3f0 worker_thread+0x34/0x410 kthread+0x121/0x140 ? process_one_work+0x3f0/0x3f0 ? kthread_park+0xb0/0xb0 ret_from_fork+0x35/0x40 Reported-by: Roy Shterman <roys@lightbitslabs.com> Signed-off-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Christoph Hellwig <hch@lst.de> 
If the target misbehaves and sends us unexpected payload we
need to make sure to fail the controller and stop processing
the input stream. We clear the rd_enabled flag and stop
the io_work, but we may still requeue it if we still have pending
sends and then in the next invocation we will process the input
stream as the check is only in the .data_ready upcall.

To fix this we need to make sure not to self-requeue io_work
upon a recv flow error.

This fixes the crash:
 nvme nvme2: receive failed:  -22
 BUG: unable to handle page fault for address: ffffbeb5816c3b48
 nvme_ns_head_make_request: 29 callbacks suppressed
 block nvme0n5: no usable path - requeuing I/O
 block nvme0n5: no usable path - requeuing I/O
 block nvme0n7: no usable path - requeuing I/O
 block nvme0n7: no usable path - requeuing I/O
 block nvme0n3: no usable path - requeuing I/O
 block nvme0n3: no usable path - requeuing I/O
 block nvme0n3: no usable path - requeuing I/O
 block nvme0n7: no usable path - requeuing I/O
 block nvme0n3: no usable path - requeuing I/O
 block nvme0n3: no usable path - requeuing I/O
 #PF: supervisor read access inkernel mode
 #PF: error_code(0x0000) - not-present page
 PGD 1039157067 P4D 1039157067 PUD 103915a067 PMD 102719f067 PTE 0
 Oops: 0000 [#1] SMP PTI
 CPU: 8 PID: 411 Comm: kworker/8:1H Not tainted 5.3.0-40-generic #32~18.04.1-Ubuntu
 Hardware name: Supermicro Super Server/X10SRi-F, BIOS 2.0 12/17/2015
 Workqueue: nvme_tcp_wq nvme_tcp_io_work [nvme_tcp]
 RIP: 0010:nvme_tcp_recv_skb+0x2ae/0xb50 [nvme_tcp]
 RSP: 0018:ffffbeb5806cfd10 EFLAGS: 00010246
 RAX: ffffbeb5816c3b48 RBX: 00000000000003d0 RCX: 0000000000000008
 RDX: 00000000000003d0 RSI: 0000000000000001 RDI: ffff9a3040684b40
 RBP: ffffbeb5806cfd90 R08: 0000000000000000 R09: ffffffff946e6900
 R10: ffffbeb5806cfce0 R11: 0000000000000001 R12: 0000000000000000
 R13: ffff9a2ff86501c0 R14: 00000000000003d0 R15: ffff9a30b85f2798
 FS:  0000000000000000(0000) GS:ffff9a30bf800000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: ffffbeb5816c3b48 CR3: 000000088400a006 CR4: 00000000003626e0
 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
 Call Trace:
  tcp_read_sock+0x8c/0x290
  ? __release_sock+0x9d/0xe0
  ? nvme_tcp_write_space+0xb0/0xb0 [nvme_tcp]
  nvme_tcp_io_work+0x4b4/0x830 [nvme_tcp]
  ? finish_task_switch+0x163/0x270
  process_one_work+0x1fd/0x3f0
  worker_thread+0x34/0x410
  kthread+0x121/0x140
  ? process_one_work+0x3f0/0x3f0
  ? kthread_park+0xb0/0xb0
  ret_from_fork+0x35/0x40

Reported-by: Roy Shterman <roys@lightbitslabs.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
nvme-tcp: don't poll a non-live queue 2020-03-31T15:57:32+00:00 Sagi Grimberg sagi@grimberg.me 2020-03-23T23:43:52+00:00 f86e5bf817a57c7e6538dafee2fc65a525bb9935 In error recovery we might be removing the queue so check we can actually poll before we do. Reported-by: Mark Wunderlich <mark.wunderlich@intel.com> Tested-by: Mark Wunderlich <mark.wunderlich@intel.com> Signed-off-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Keith Busch <kbusch@kernel.org> Signed-off-by: Christoph Hellwig <hch@lst.de> 
In error recovery we might be removing the queue so check we
can actually poll before we do.

Reported-by: Mark Wunderlich <mark.wunderlich@intel.com>
Tested-by: Mark Wunderlich <mark.wunderlich@intel.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>