linux.git/drivers/md, branch v3.13-rc4

Merge tag 'dm-3.13-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

2013-12-13T21:22:22+00:00

Pull device mapper fixes from Mike Snitzer:
 "A set of device-mapper fixes for 3.13.

  A fix for possible memory corruption during DM table load, fix a
  possible leak of snapshot space in case of a crash, fix a possible
  deadlock due to a shared workqueue in the delay target, fix to
  initialize read-only module parameters that are used to export metrics
  for dm stats and dm bufio.

  Quite a few stable fixes were identified for both the thin-
  provisioning and caching targets as a result of increased regression
  testing using the device-mapper-test-suite (dmts).  The most notable
  of these are the reference counting fixes for the space map btree that
  is used by the dm-array interface -- without these the dm-cache
  metadata will leak, resulting in dm-cache devices running out of
  metadata blocks.  Also, some important fixes related to the
  thin-provisioning target's transition to read-only mode on error"

* tag 'dm-3.13-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
  dm array: fix a reference counting bug in shadow_ablock
  dm space map: disallow decrementing a reference count below zero
  dm stats: initialize read-only module parameter
  dm bufio: initialize read-only module parameters
  dm cache: actually resize cache
  dm cache: update Documentation for invalidate_cblocks's range syntax
  dm cache policy mq: fix promotions to occur as expected
  dm thin: allow pool in read-only mode to transition to read-write mode
  dm thin: re-establish read-only state when switching to fail mode
  dm thin: always fallback the pool mode if commit fails
  dm thin: switch to read-only mode if metadata space is exhausted
  dm thin: switch to read only mode if a mapping insert fails
  dm space map metadata: return on failure in sm_metadata_new_block
  dm table: fail dm_table_create on dm_round_up overflow
  dm snapshot: avoid snapshot space leak on crash
  dm delay: fix a possible deadlock due to shared workqueue

dm array: fix a reference counting bug in shadow_ablock

2013-12-13T19:22:10+00:00

An old array block could have its reference count decremented below
zero when it is being replaced in the btree by a new array block.

The fix is to increment the old ablock's reference count just before
inserting a new ablock into the btree.

Signed-off-by: Joe Thornber 
Signed-off-by: Mike Snitzer 
Cc: stable@vger.kernel.org # 3.9+

dm space map: disallow decrementing a reference count below zero

2013-12-13T19:22:09+00:00

The old behaviour, returning -EINVAL if a ref_count of 0 would be
decremented, was removed in commit f722063 ("dm space map: optimise
sm_ll_dec and sm_ll_inc").  To fix this regression we return an error
code from the mutator function pointer passed to sm_ll_mutate() and have
dec_ref_count() return -EINVAL if the old ref_count is 0.

Add a DMERR to reflect the potential seriousness of this error.

Also, add missing dm_tm_unlock() to sm_ll_mutate()'s error path.

With this fix the following dmts regression test now passes:
 dmtest run --suite cache -n /metadata_use_kernel/

The next patch fixes the higher-level dm-array code that exposed this
regression.

Signed-off-by: Joe Thornber 
Signed-off-by: Mike Snitzer 
Cc: stable@vger.kernel.org # 3.12+

dm stats: initialize read-only module parameter

2013-12-11T00:13:21+00:00

The module parameter stats_current_allocated_bytes in dm-mod is
read-only.  This parameter informs the user about memory
consumption.  It is not supposed to be changed by the user.

However, despite being read-only, this parameter can be set on
modprobe or insmod command line:
modprobe dm-mod stats_current_allocated_bytes=12345

The kernel doesn't expect that this variable can be non-zero at module
initialization and if the user sets it, it results in warning.

This patch initializes the variable in the module init routine, so
that user-supplied value is ignored.

Signed-off-by: Mikulas Patocka 
Signed-off-by: Mike Snitzer 
Cc: stable@vger.kernel.org # 3.12+

dm bufio: initialize read-only module parameters

2013-12-11T00:13:20+00:00

Some module parameters in dm-bufio are read-only. These parameters
inform the user about memory consumption. They are not supposed to be
changed by the user.

However, despite being read-only, these parameters can be set on
modprobe or insmod command line, for example:
modprobe dm-bufio current_allocated_bytes=12345

The kernel doesn't expect that these variables can be non-zero at module
initialization and if the user sets them, it results in BUG.

This patch initializes the variables in the module init routine, so that
user-supplied values are ignored.

Signed-off-by: Mikulas Patocka 
Signed-off-by: Mike Snitzer 
Cc: stable@vger.kernel.org # 3.2+

dm cache: actually resize cache

2013-12-10T21:35:15+00:00

Commit f494a9c6b1b6dd9a9f21bbb75d9210d478eeb498 ("dm cache: cache
shrinking support") broke cache resizing support.

dm_cache_resize() is called with cache->cache_size before it gets
updated to new_size, so it is a no-op.  But the dm-cache superblock is
updated with the new_size even though the backing dm-array is not
resized.  Fix this by passing the new_size to dm_cache_resize().

Signed-off-by: Vincent Pelletier 
Acked-by: Joe Thornber 
Signed-off-by: Mike Snitzer

dm cache policy mq: fix promotions to occur as expected

2013-12-10T21:35:14+00:00

Micro benchmarks that repeatedly issued IO to a single block were
failing to cause a promotion from the origin device to the cache.  Fix
this by not updating the stats during map() if -EWOULDBLOCK will be
returned.

The mq policy will only update stats, consider migration, etc, once per
tick period (a unit of time established between dm-cache core and the
policies).

When the IO thread calls the policy's map method, if it would like to
migrate the associated block it returns -EWOULDBLOCK, the IO then gets
handed over to a worker thread which handles the migration.  The worker
thread calls map again, to check the migration is still needed (avoids a
race among other things).  *BUT*, before this fix, if we were still in
the same tick period the stats were already updated by the previous map
call -- so the migration would no longer be requested.

Signed-off-by: Joe Thornber 
Signed-off-by: Mike Snitzer

dm thin: allow pool in read-only mode to transition to read-write mode

2013-12-10T21:35:13+00:00

A thin-pool may be in read-only mode because the pool's data or metadata
space was exhausted.  To allow for recovery, by adding more space to the
pool, we must allow a pool to transition from PM_READ_ONLY to PM_WRITE
mode.  Otherwise, running out of space will render the pool permanently
read-only.

Signed-off-by: Joe Thornber 
Signed-off-by: Mike Snitzer 
Cc: stable@vger.kernel.org

dm thin: re-establish read-only state when switching to fail mode

2013-12-10T21:35:12+00:00

If the thin-pool transitioned to fail mode and the thin-pool's table
were reloaded for some reason: the new table's default pool mode would
be read-write, though it will transition to fail mode during resume.

When the pool mode transitions directly from PM_WRITE to PM_FAIL we need
to re-establish the intermediate read-only state in both the metadata
and persistent-data block manager (as is usually done with the normal
pool mode transition sequence: PM_WRITE -> PM_READ_ONLY -> PM_FAIL).

Signed-off-by: Joe Thornber 
Signed-off-by: Mike Snitzer 
Cc: stable@vger.kernel.org

dm thin: always fallback the pool mode if commit fails

2013-12-10T21:35:12+00:00

Rename commit_or_fallback() to commit().  Now all previous calls to
commit() will trigger the pool mode to fallback if the commit fails.

Also, check the error returned from commit() in alloc_data_block().

Signed-off-by: Joe Thornber 
Signed-off-by: Mike Snitzer 
Cc: stable@vger.kernel.org