Mike writes:
  "device mapper fixes

   - Fix a DM thinp __udivdi3 undefined on 32-bit bug introduced during
     4.19 merge window.

   - Fix leak and dangling pointer in DM multipath's scsi_dh related code.

   - A couple stable@ fixes for DM cache's resize support.

   - A DM raid fix to remove "const" from decipher_sync_action()'s return
     type."

* tag 'for-4.19/dm-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
  dm cache: fix resize crash if user doesn't reload cache table
  dm cache metadata: ignore hints array being too small during resize
  dm raid: remove bogus const from decipher_sync_action() return type
  dm mpath: fix attached_handler_name leak and dangling hw_handler_name pointer
  dm thin metadata: fix __udivdi3 undefined on 32-bit

A reload of the cache's DM table is needed during resize because
otherwise a crash will occur when attempting to access smq policy
entries associated with the portion of the cache that was recently
extended.

The reason is cache-size based data structures in the policy will not be
resized, the only way to safely extend the cache is to allow for a
proper cache policy initialization that occurs when the cache table is
loaded.  For example the smq policy's space_init(), init_allocator(),
calc_hotspot_params() must be sized based on the extended cache size.

The fix for this is to disallow cache resizes of this pattern:
1) suspend "cache" target's device
2) resize the fast device used for the cache
3) resume "cache" target's device

Instead, the last step must be a full reload of the cache's DM table.

Fixes: 66a636356 ("dm cache: add stochastic-multi-queue (smq) policy")
Cc: stable@vger.kernel.org
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Commit fd2fa9541 ("dm cache metadata: save in-core policy_hint_size to
on-disk superblock") enabled previously written policy hints to be
used after a cache is reactivated.  But in doing so the cache
metadata's hint array was left exposed to out of bounds access because
on resize the metadata's on-disk hint array wasn't ever extended.

Fix this by ignoring that there are no on-disk hints associated with the
newly added cache blocks.  An expanded on-disk hint array is later
rewritten upon the next clean shutdown of the cache.

Fixes: fd2fa9541 ("dm cache metadata: save in-core policy_hint_size to on-disk superblock")
Cc: stable@vger.kernel.org
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Jens writes:
  "Block fixes for 4.19-rc6

   A set of fixes that should go into this release. This pull request
   contains:

   - A fix (hopefully) for the persistent grants for xen-blkfront. A
     previous fix from this series wasn't complete, hence reverted, and
     this one should hopefully be it. (Boris Ostrovsky)

   - Fix for an elevator drain warning with SMR devices, which is
     triggered when you switch schedulers (Damien)

   - bcache deadlock fix (Guoju Fang)

   - Fix for the block unplug tracepoint, which has had the
     timer/explicit flag reverted since 4.11 (Ilya)

   - Fix a regression in this series where the blk-mq timeout hook is
     invoked with the RCU read lock held, hence preventing it from
     blocking (Keith)

   - NVMe pull from Christoph, with a single multipath fix (Susobhan Dey)"

* tag 'for-linus-20180929' of git://git.kernel.dk/linux-block:
  xen/blkfront: correct purging of persistent grants
  Revert "xen/blkfront: When purging persistent grants, keep them in the buffer"
  blk-mq: I/O and timer unplugs are inverted in blktrace
  bcache: add separate workqueue for journal_write to avoid deadlock
  xen/blkfront: When purging persistent grants, keep them in the buffer
  block: fix deadline elevator drain for zoned block devices
  blk-mq: Allow blocking queue tag iter callbacks
  nvme: properly propagate errors in nvme_mpath_init

After write SSD completed, bcache schedules journal_write work to
system_wq, which is a public workqueue in system, without WQ_MEM_RECLAIM
flag. system_wq is also a bound wq, and there may be no idle kworker on
current processor. Creating a new kworker may unfortunately need to
reclaim memory first, by shrinking cache and slab used by vfs, which
depends on bcache device. That's a deadlock.

This patch create a new workqueue for journal_write with WQ_MEM_RECLAIM
flag. It's rescuer thread will work to avoid the deadlock.

Signed-off-by: Guoju Fang <fangguoju@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

With gcc-4.1.2:

    drivers/md/dm-raid.c:3357: warning: type qualifiers ignored on function return type

Remove the "const" keyword to fix this.

Fixes: 36a240a706d43383 ("dm raid: fix RAID leg rebuild errors")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Commit e8f74a0f0011 ("dm mpath: eliminate need to use
scsi_device_from_queue") introduced 2 regressions:
1) memory leak occurs if attached_handler_name is not assigned to
   m->hw_handler_name
2) m->hw_handler_name can become a dangling pointer if the
   RETAIN_ATTACHED_HW_HANDLER flag is set and scsi_dh_attach() returns
   -EBUSY.

Fix both of these by clearing 'attached_handler_name' pointer passed to
setup_scsi_dh() after it is assigned to m->hw_handler_name.  And if
setup_scsi_dh() doesn't consume 'attached_handler_name' parse_path()
will kfree() it.

Fixes: e8f74a0f0011 ("dm mpath: eliminate need to use scsi_device_from_queue")
Cc: stable@vger.kernel.org # 4.16+
Reported-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

sector_div() is only viable for use with sector_t.
dm_block_t is typedef'd to uint64_t -- so use div_u64() instead.

Fixes: 3ab918281 ("dm thin metadata: try to avoid ever aborting transactions")
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Pull device mapper fixes from Mike Snitzer:

 - DM verity fix for crash due to using vmalloc'd buffers with the
   asynchronous crypto hadsh API.

 - Fix to both DM crypt and DM integrity targets to discontinue using
   CRYPTO_TFM_REQ_MAY_SLEEP because its use of GFP_KERNEL can lead to
   deadlock by recursing back into a filesystem.

 - Various DM raid fixes related to reshape and rebuild races.

 - Fix for DM thin-provisioning to avoid data corruption that was a
   side-effect of needing to abort DM thin metadata transaction due to
   running out of metadata space. Fix is to reserve a small amount of
   metadata space so that once it is used the DM thin-pool can finish
   its active transaction before switching to read-only mode.

* tag 'for-4.19/dm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
  dm thin metadata: try to avoid ever aborting transactions
  dm raid: bump target version, update comments and documentation
  dm raid: fix RAID leg rebuild errors
  dm raid: fix rebuild of specific devices by updating superblock
  dm raid: fix stripe adding reshape deadlock
  dm raid: fix reshape race on small devices
  dm: disable CRYPTO_TFM_REQ_MAY_SLEEP to fix a GFP_KERNEL recursion deadlock
  dm verity: fix crash on bufio buffer that was allocated with vmalloc

Committing a transaction can consume some metadata of it's own, we now
reserve a small amount of metadata to cover this.  Free metadata
reported by the kernel will not include this reserve.

If any of the reserve has been used after a commit we enter a new
internal state PM_OUT_OF_METADATA_SPACE.  This is reported as
PM_READ_ONLY, so no userland changes are needed.  If the metadata
device is resized the pool will move back to PM_WRITE.

These changes mean we never need to abort and rollback a transaction due
to running out of metadata space.  This is particularly important
because there have been a handful of reports of data corruption against
DM thin-provisioning that can all be attributed to the thin-pool having
ran out of metadata space.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>