08 Mar, 2017
1 commit
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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
Signed-off-by: Mike Snitzer
17 Feb, 2017
1 commit
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If "metadata2" is provided as a table argument when creating/loading a
cache target a more compact metadata format, with separate dirty bits,
is used. "metadata2" improves speed of shutting down a cache target.Signed-off-by: Joe Thornber
Signed-off-by: Mike Snitzer
11 Mar, 2016
1 commit
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Otherwise operations may be attempted that will only ever go on to crash
(since the metadata device is either missing or unreliable if 'fail_io'
is set).Signed-off-by: Joe Thornber
Signed-off-by: Mike Snitzer
Cc: stable@vger.kernel.org
12 Jun, 2015
1 commit
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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
11 Nov, 2014
1 commit
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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
02 Aug, 2014
1 commit
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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
05 Apr, 2014
1 commit
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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_lockWhen loading the cache target the policy is populated while the metadata
lock is held:cache_metadata->root_lock
policy->lockFix 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
28 Mar, 2014
1 commit
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Discard block size not being equal to cache block size causes data
corruption by erroneously avoiding migrations in issue_copy() because
the discard state is being cleared for a group of cache blocks when it
should not.Completely remove all code that enabled a distinction between the
cache block size and discard block size.Signed-off-by: Heinz Mauelshagen
Signed-off-by: Mike Snitzer
12 Nov, 2013
1 commit
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"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 invalidatesThis 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
21 Mar, 2013
1 commit
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When reading the dm cache metadata from disk, ignore the policy hints
unless they were generated by the same major version number of the same
policy module.The hints are considered to be private data belonging to the specific
module that generated them and there is no requirement for them to make
sense to different versions of the policy that generated them.
Policy modules are all required to work fine if no previous hints are
supplied (or if existing hints are lost).Signed-off-by: Mike Snitzer
Signed-off-by: Alasdair G Kergon
02 Mar, 2013
1 commit
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Add a target that allows a fast device such as an SSD to be used as a
cache for a slower device such as a disk.A plug-in architecture was chosen so that the decisions about which data
to migrate and when are delegated to interchangeable tunable policy
modules. The first general purpose module we have developed, called
"mq" (multiqueue), follows in the next patch. Other modules are
under development.Signed-off-by: Joe Thornber
Signed-off-by: Heinz Mauelshagen
Signed-off-by: Mike Snitzer
Signed-off-by: Alasdair G Kergon