linux.git/drivers/md/dm-cache-metadata.c, branch v4.5

Merge tag 'dm-4.4-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

2015-11-05T05:19:53+00:00

Pull device mapper updates from Mike Snitzer:
 "Smaller set of DM changes for this merge.  I've based these changes on
  Jens' for-4.4/reservations branch because the associated DM changes
  required it.

   - Revert a dm-multipath change that caused a regression for
     unprivledged users (e.g. kvm guests) that issued ioctls when a
     multipath device had no available paths.

   - Include Christoph's refactoring of DM's ioctl handling and add
     support for passing through persistent reservations with DM
     multipath.

   - All other changes are very simple cleanups"

* tag 'dm-4.4-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
  dm switch: simplify conditional in alloc_region_table()
  dm delay: document that offsets are specified in sectors
  dm delay: capitalize the start of an delay_ctr() error message
  dm delay: Use DM_MAPIO macros instead of open-coded equivalents
  dm linear: remove redundant target name from error messages
  dm persistent data: eliminate unnecessary return values
  dm: eliminate unused "bioset" process for each bio-based DM device
  dm: convert ffs to __ffs
  dm: drop NULL test before kmem_cache_destroy() and mempool_destroy()
  dm: add support for passing through persistent reservations
  dm: refactor ioctl handling
  Revert "dm mpath: fix stalls when handling invalid ioctls"
  dm: initialize non-blk-mq queue data before queue is used

dm persistent data: eliminate unnecessary return values

2015-10-31T23:06:02+00:00

dm_bm_unlock and dm_tm_unlock return an integer value but the returned
value is always 0.  The calling code sometimes checks the return value
and sometimes doesn't.

Eliminate these unnecessary return values and also the checks for them.

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

dm cache: the CLEAN_SHUTDOWN flag was not being set

2015-10-23T18:02:56+00:00

If the CLEAN_SHUTDOWN flag is not set when a cache is loaded then all cache
blocks are marked as dirty and a full writeback occurs.

__commit_transaction() is responsible for setting/clearing
CLEAN_SHUTDOWN (based the flags_mutator that is passed in).

Fix this issue, of the cache's on-disk flags being wrong, by making sure
__commit_transaction() does not reset the flags after the mutator has
altered the flags in preparation for them being serialized to disk.

before:

sb_flags = mutator(le32_to_cpu(disk_super->flags));
disk_super->flags = cpu_to_le32(sb_flags);
disk_super->flags = cpu_to_le32(cmd->flags);

after:

disk_super->flags = cpu_to_le32(cmd->flags);
sb_flags = mutator(le32_to_cpu(disk_super->flags));
disk_super->flags = cpu_to_le32(sb_flags);

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

dm cache: add fail io mode and needs_check flag

2015-06-11T21:13:00+00:00

If a cache metadata operation fails (e.g. transaction commit) the
cache's metadata device will abort the current transaction, set a new
needs_check flag, and the cache will transition to "read-only" mode.  If
aborting the transaction or setting the needs_check flag fails the cache
will transition to "fail-io" mode.

Once needs_check is set the cache device will not be allowed to
activate.  Activation requires write access to metadata.  Future work is
needed to add proper support for running the cache in read-only mode.

Once in fail-io mode the cache will report a status of "Fail".

Also, add commit() wrapper that will disallow commits if in read_only or
fail mode.

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

dm cache: fix missing ERR_PTR returns and handling

2015-01-28T14:59:20+00:00

Commit 9b1cc9f251 ("dm cache: share cache-metadata object across
inactive and active DM tables") mistakenly ignored the use of ERR_PTR
returns.  Restore missing IS_ERR checks and ERR_PTR returns where
appropriate.

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

dm cache: share cache-metadata object across inactive and active DM tables

2015-01-23T15:57:15+00:00

If a DM table is reloaded with an inactive table when the device is not
suspended (normal procedure for LVM2), then there will be two dm-bufio
objects that can diverge.  This can lead to a situation where the
inactive table uses bufio to read metadata at the same time the active
table writes metadata -- resulting in the inactive table having stale
metadata buffers once it is promoted to the active table slot.

Fix this by using reference counting and a global list of cache metadata
objects to ensure there is only one metadata object per metadata device.

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

dm cache: revert "remove remainder of distinct discard block size"

2014-11-10T20:25:30+00:00

This reverts commit 64ab346a360a4b15c28fb8531918d4a01f4eabd9 because we
actually do want to allow the discard blocksize to be larger than the
cache blocksize.  Further dm-cache discard changes will make this
possible.

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

dm cache metadata: use dm-space-map-metadata.h defined size limits

2014-08-01T16:30:33+00:00

Commit 7d48935e cleaned up the persistent-data's space-map-metadata
limits by elevating them to dm-space-map-metadata.h.  Update
dm-cache-metadata to use these same limits.

The calculation for DM_CACHE_METADATA_MAX_SECTORS didn't account for the
sizeof the disk_bitmap_header.  So the supported maximum metadata size
is a bit smaller (reduced from 33423360 to 33292800 sectors).

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

dm cache metadata: do not allow the data block size to change

2014-07-15T18:07:50+00:00

The block size for the dm-cache's data device must remained fixed for
the life of the cache.  Disallow any attempt to change the cache's data
block size.

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

dm cache: fix a lock-inversion

2014-04-04T18:53:05+00:00

When suspending a cache the policy is walked and the individual policy
hints written to the metadata via sync_metadata().  This led to this
lock order:

      policy->lock
        cache_metadata->root_lock

When loading the cache target the policy is populated while the metadata
lock is held:

      cache_metadata->root_lock
         policy->lock

Fix this potential lock-inversion (ABBA) deadlock in sync_metadata() by
ensuring the cache_metadata root_lock is held whilst all the hints are
written, rather than being repeatedly locked while policy->lock is held
(as was the case with each callout that policy_walk_mappings() made to
the old save_hint() method).

Found by turning on the CONFIG_PROVE_LOCKING ("Lock debugging: prove
locking correctness") build option.  However, it is not clear how the
LOCKDEP reported paths can lead to a deadlock since the two paths,
suspending a target and loading a target, never occur at the same time.
But that doesn't mean the same lock-inversion couldn't have occurred
elsewhere.

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