linux-toradex.git/drivers/md, branch v3.12.43

dm io: deal with wandering queue limits when handling REQ_DISCARD and REQ_WRITE_SAME

2015-04-09T12:14:12+00:00

commit e5db29806b99ce2b2640d2e4d4fcb983cea115c5 upstream.

Since it's possible for the discard and write same queue limits to
change while the upper level command is being sliced and diced, fix up
both of them (a) to reject IO if the special command is unsupported at
the start of the function and (b) read the limits once and let the
commands error out on their own if the status happens to change.

Signed-off-by: Darrick J. Wong 
Signed-off-by: Mikulas Patocka 
Signed-off-by: Mike Snitzer 
Signed-off-by: Jiri Slaby

dm: hold suspend_lock while suspending device during device deletion

2015-04-09T12:14:11+00:00

commit ab7c7bb6f4ab95dbca96fcfc4463cd69843e3e24 upstream.

__dm_destroy() must take the suspend_lock so that its presuspend and
postsuspend calls do not race with an internal suspend.

Signed-off-by: Mikulas Patocka 
Signed-off-by: Mike Snitzer 
Signed-off-by: Jiri Slaby

md/bitmap: always wait for writes on unplug.

2015-04-09T12:13:37+00:00

commit 4b5060ddae2b03c5387321fafc089d242225697a upstream.

If two threads call bitmap_unplug at the same time, then
one might schedule all the writes, and the other might
decide that it doesn't need to wait.  But really it does.

It rarely hurts to wait when it isn't absolutely necessary,
and the current code doesn't really focus on 'absolutely necessary'
anyway.  So just wait always.

This can potentially lead to data corruption if a crash happens
at an awkward time and data was written before the bitmap was
updated.  It is very unlikely, but this should go to -stable
just to be safe.  Appropriate for any -stable.

Signed-off-by: NeilBrown 
Cc: stable@vger.kernel.org (please delay until 3.18 is released)
Signed-off-by: Jiri Slaby

dm snapshot: fix a possible invalid memory access on unload

2015-03-16T13:58:18+00:00

commit 22aa66a3ee5b61e0f4a0bfeabcaa567861109ec3 upstream.

When the snapshot target is unloaded, snapshot_dtr() waits until
pending_exceptions_count drops to zero.  Then, it destroys the snapshot.
Therefore, the function that decrements pending_exceptions_count
should not touch the snapshot structure after the decrement.

pending_complete() calls free_pending_exception(), which decrements
pending_exceptions_count, and then it performs up_write(&s->lock) and it
calls retry_origin_bios() which dereferences  s->origin.  These two
memory accesses to the fields of the snapshot may touch the dm_snapshot
struture after it is freed.

This patch moves the call to free_pending_exception() to the end of
pending_complete(), so that the snapshot will not be destroyed while
pending_complete() is in progress.

Signed-off-by: Mikulas Patocka 
Signed-off-by: Mike Snitzer 
Signed-off-by: Jiri Slaby

dm: fix a race condition in dm_get_md

2015-03-16T13:58:17+00:00

commit 2bec1f4a8832e74ebbe859f176d8a9cb20dd97f4 upstream.

The function dm_get_md finds a device mapper device with a given dev_t,
increases the reference count and returns the pointer.

dm_get_md calls dm_find_md, dm_find_md takes _minor_lock, finds the
device, tests that the device doesn't have DMF_DELETING or DMF_FREEING
flag, drops _minor_lock and returns pointer to the device. dm_get_md then
calls dm_get. dm_get calls BUG if the device has the DMF_FREEING flag,
otherwise it increments the reference count.

There is a possible race condition - after dm_find_md exits and before
dm_get is called, there are no locks held, so the device may disappear or
DMF_FREEING flag may be set, which results in BUG.

To fix this bug, we need to call dm_get while we hold _minor_lock. This
patch renames dm_find_md to dm_get_md and changes it so that it calls
dm_get while holding the lock.

Signed-off-by: Mikulas Patocka 
Signed-off-by: Mike Snitzer 
Signed-off-by: Jiri Slaby

dm io: reject unsupported DISCARD requests with EOPNOTSUPP

2015-03-16T13:58:17+00:00

commit 37527b869207ad4c208b1e13967d69b8bba1fbf9 upstream.

I created a dm-raid1 device backed by a device that supports DISCARD
and another device that does NOT support DISCARD with the following
dm configuration:

 #  echo '0 2048 mirror core 1 512 2 /dev/sda 0 /dev/sdb 0' | dmsetup create moo
 # lsblk -D
 NAME         DISC-ALN DISC-GRAN DISC-MAX DISC-ZERO
 sda                 0        4K       1G         0
 `-moo (dm-0)        0        4K       1G         0
 sdb                 0        0B       0B         0
 `-moo (dm-0)        0        4K       1G         0

Notice that the mirror device /dev/mapper/moo advertises DISCARD
support even though one of the mirror halves doesn't.

If I issue a DISCARD request (via fstrim, mount -o discard, or ioctl
BLKDISCARD) through the mirror, kmirrord gets stuck in an infinite
loop in do_region() when it tries to issue a DISCARD request to sdb.
The problem is that when we call do_region() against sdb, num_sectors
is set to zero because q->limits.max_discard_sectors is zero.
Therefore, "remaining" never decreases and the loop never terminates.

To fix this: before entering the loop, check for the combination of
REQ_DISCARD and no discard and return -EOPNOTSUPP to avoid hanging up
the mirror device.

This bug was found by the unfortunate coincidence of pvmove and a
discard operation in the RHEL 6.5 kernel; upstream is also affected.

Signed-off-by: Darrick J. Wong 
Acked-by: "Martin K. Petersen" 
Signed-off-by: Mike Snitzer 
Signed-off-by: Jiri Slaby

dm mirror: do not degrade the mirror on discard error

2015-03-16T13:58:16+00:00

commit f2ed51ac64611d717d1917820a01930174c2f236 upstream.

It may be possible that a device claims discard support but it rejects
discards with -EOPNOTSUPP.  It happens when using loopback on ext2/ext3
filesystem driven by the ext4 driver.  It may also happen if the
underlying devices are moved from one disk on another.

If discard error happens, we reject the bio with -EOPNOTSUPP, but we do
not degrade the array.

This patch fixes failed test shell/lvconvert-repair-transient.sh in the
lvm2 testsuite if the testsuite is extracted on an ext2 or ext3
filesystem and it is being driven by the ext4 driver.

Signed-off-by: Mikulas Patocka 
Signed-off-by: Mike Snitzer 
Signed-off-by: Jiri Slaby

md/raid1: fix read balance when a drive is write-mostly.

2015-03-05T14:37:07+00:00

commit d1901ef099c38afd11add4cfb3312c02ef21ec4a upstream.

When a drive is marked write-mostly it should only be the
target of reads if there is no other option.

This behaviour was broken by

commit 9dedf60313fa4dddfd5b9b226a0ef12a512bf9dc
    md/raid1: read balance chooses idlest disk for SSD

which causes a write-mostly device to be *preferred* is some cases.

Restore correct behaviour by checking and setting
best_dist_disk and best_pending_disk rather than best_disk.

We only need to test one of these as they are both changed
from -1 or >=0 at the same time.

As we leave min_pending and best_dist unchanged, any non-write-mostly
device will appear better than the write-mostly device.

Reported-by: Tomáš Hodek 
Reported-by: Dark Penguin 
Signed-off-by: NeilBrown 
Link: http://marc.info/?l=linux-raid&m=135982797322422
Fixes: 9dedf60313fa4dddfd5b9b226a0ef12a512bf9dc
Signed-off-by: Jiri Slaby

md/raid5: Fix livelock when array is both resyncing and degraded.

2015-03-05T14:37:06+00:00

commit 26ac107378c4742978216be1005b7291b799c7b2 upstream.

Commit a7854487cd7128a30a7f4f5259de9f67d5efb95f:
  md: When RAID5 is dirty, force reconstruct-write instead of read-modify-write.

Causes an RCW cycle to be forced even when the array is degraded.
A degraded array cannot support RCW as that requires reading all data
blocks, and one may be missing.

Forcing an RCW when it is not possible causes a live-lock and the code
spins, repeatedly deciding to do something that cannot succeed.

So change the condition to only force RCW on non-degraded arrays.

Reported-by: Manibalan P 
Bisected-by: Jes Sorensen 
Tested-by: Jes Sorensen 
Signed-off-by: NeilBrown 
Fixes: a7854487cd7128a30a7f4f5259de9f67d5efb95f
Signed-off-by: Jiri Slaby

dm: do not call dm_sync_table() when creating new devices

2015-02-16T15:10:58+00:00

commit 41abc4e1af369bb5438eaee398e3beee690cc8ca upstream.

When creating new devices dm_sync_table() calls
synchronize_rcu_expedited(), causing _all_ pending RCU pointers to be
flushed. This causes a latency overhead that is especially noticeable
when creating lots of devices.

And all of this is pointless as there are no old maps to be
disconnected, and hence no stale pointers which would need to be
cleared up.

Signed-off-by: Hannes Reinecke 
Reviewed-by: Mikulas Patocka 
Signed-off-by: Mike Snitzer 
Signed-off-by: Jiri Slaby