linux.git/drivers/md/dm-cache-target.c, branch v3.13

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: resolve small nits and improve Documentation

2013-11-12T18:11:09+00:00

Document passthrough mode, cache shrinking, and cache invalidation.
Also, use strcasecmp() and hlist_unhashed().

Reported-by: Alasdair G Kergon 
Signed-off-by: Mike Snitzer

dm cache: add cache block invalidation support

2013-11-11T16:37:51+00:00

Cache block invalidation is removing an entry from the cache without
writing it back.  Cache blocks can be invalidated via the
'invalidate_cblocks' message, which takes an arbitrary number of cblock
ranges:
   invalidate_cblocks [|-]*

E.g.
   dmsetup message my_cache 0 invalidate_cblocks 2345 3456-4567 5678-6789

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

dm cache: add passthrough mode

2013-11-11T16:37:49+00:00

"Passthrough" is a dm-cache operating mode (like writethrough or
writeback) which is intended to be used when the cache contents are not
known to be coherent with the origin device.  It behaves as follows:

* All reads are served from the origin device (all reads miss the cache)
* All writes are forwarded to the origin device; additionally, write
  hits cause cache block invalidates

This mode decouples cache coherency checks from cache device creation,
largely to avoid having to perform coherency checks while booting.  Boot
scripts can create cache devices in passthrough mode and put them into
service (mount cached filesystems, for example) without having to worry
about coherency.  Coherency that exists is maintained, although the
cache will gradually cool as writes take place.

Later, applications can perform coherency checks, the nature of which
will depend on the type of the underlying storage.  If coherency can be
verified, the cache device can be transitioned to writethrough or
writeback mode while still warm; otherwise, the cache contents can be
discarded prior to transitioning to the desired operating mode.

Signed-off-by: Joe Thornber 
Signed-off-by: Heinz Mauelshagen 
Signed-off-by: Morgan Mears 
Signed-off-by: Mike Snitzer

dm cache: cache shrinking support

2013-11-11T16:37:45+00:00

Allow a cache to shrink if the blocks being removed from the cache are
not dirty.

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

dm cache: promotion optimisation for writes

2013-11-09T23:20:26+00:00

If a write block triggers promotion and covers a whole block we can
avoid a copy.

Introduce dm_{hook,unhook}_bio to simplify saving and restoring bio
fields (bi_private is now used by overwrite).  Switch writethrough
support over to using these helpers too.

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

dm cache: optimize commit_if_needed

2013-11-09T23:20:24+00:00

Check commit_requested flag _before_ calling
dm_cache_changed_this_transaction() superfluously.

Also, be sure to set last_commit_jiffies _after_ dm_cache_commit()
completes.

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

dm cache: log error message if dm_kcopyd_copy() fails

2013-11-09T23:20:19+00:00

A migration failure should be logged (albeit limited).

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

dm cache: use cell_defer() boolean argument consistently

2013-11-09T23:20:19+00:00

Fix a few cell_defer() calls that weren't passing a bool.

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

dm cache: return -EINVAL if the user specifies unknown cache policy

2013-11-09T23:20:18+00:00

Return -EINVAL when the specified cache policy is unknown rather than
returning -ENOMEM.

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