btracker_nr_writebacks_queued() has been unused since commit
2e63309507 ("dm cache policy smq: don't do any writebacks unless IDLE")
Remove it.
Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
The commit 4c39529663 adds a warning about duplicate cache names if
CONFIG_DEBUG_VM is selected. These warnings are triggered by the dm-cache
code.
The dm-cache code allocates a slab cache for each device. This commit
changes it to allocate just one slab cache in the module init function.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Fixes: 4c39529663 ("slab: Warn on duplicate cache names when DEBUG_VM=y")
'GPL-2.0-only' is used instead of 'GPL-2.0' because SPDX has
deprecated its use.
Suggested-by: John Wiele <jwiele@redhat.com>
Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Fix drivers/md/dm-cache-background-tracker.c:169:16: warning: symbol
'alloc_work' was not declared. Should it be static?
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
On large systems the cache policy can be over enthusiastic and queue far
too much dirty data to be written back. This consumes memory.
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Currently there is no kmalloc failure check on the allocation of
the background_tracker struct in btracker_create(), and so a NULL return
will lead to a NULL pointer dereference. Add a NULL check.
Detected by CoverityScan, CID#1416587 ("Dereference null return value")
Fixes: b29d4986d ("dm cache: significant rework to leverage dm-bio-prison-v2")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
The cache policy interfaces have been updated to work well with the new
bio-prison v2 interface's ability to queue work immediately (promotion,
demotion, etc) -- overriding benefit being reduced latency on processing
IO through the cache. Previously such work would be left for the DM
cache core to queue on various lists and then process in batches later
-- this caused a serious delay in latency for IO driven by the cache.
The background tracker code was factored out so that all cache policies
can make use of it.
Also, the "cleaner" policy has been removed and is now a variant of the
smq policy that simply disallows migrations.
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
