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 <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org # 3.9+
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 <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org # 3.12+
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 <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org # 3.12+
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 <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org # 3.2+
Commit f494a9c6b1 ("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 <plr.vincent@gmail.com>
Acked-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
The cache target's invalidate_cblocks message allows cache block
(cblock) ranges to be expressed with: <cblock start>-<cblock end>
The range's <cblock end> value is "one past the end", so the range
includes <cblock start> through <cblock end>-1.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Joe Thornber <ejt@redhat.com>
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 <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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 <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
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 <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
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 <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
Switch the thin pool to read-only mode in alloc_data_block() if
dm_pool_alloc_data_block() fails because the pool's metadata space is
exhausted.
Differentiate between data and metadata space in messages about no
free space available.
This issue was noticed with the device-mapper-test-suite using:
dmtest run --suite thin-provisioning -n /exhausting_metadata_space_causes_fail_mode/
The quantity of errors logged in this case must be reduced.
before patch:
device-mapper: thin: 253:4: reached low water mark for metadata device: sending event.
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: space map common: dm_tm_shadow_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: space map common: dm_tm_shadow_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: space map common: dm_tm_shadow_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: space map common: dm_tm_shadow_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: space map common: dm_tm_shadow_block() failed
<snip ... these repeat for a _very_ long while ... >
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: 253:4: commit failed: error = -28
device-mapper: thin: 253:4: switching pool to read-only mode
after patch:
device-mapper: thin: 253:4: reached low water mark for metadata device: sending event.
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: 253:4: no free metadata space available.
device-mapper: thin: 253:4: switching pool to read-only mode
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Joe Thornber <ejt@redhat.com>
Cc: stable@vger.kernel.org
Switch the thin pool to read-only mode when dm_thin_insert_block() fails
since there is little reason to expect the cause of the failure to be
resolved without further action by user space.
This issue was noticed with the device-mapper-test-suite using:
dmtest run --suite thin-provisioning -n /exhausting_metadata_space_causes_fail_mode/
The quantity of errors logged in this case must be reduced.
before patch:
device-mapper: thin: dm_thin_insert_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: dm_thin_insert_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: dm_thin_insert_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: dm_thin_insert_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: dm_thin_insert_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: dm_thin_insert_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: dm_thin_insert_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: dm_thin_insert_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: dm_thin_insert_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: dm_thin_insert_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: space map metadata: unable to allocate new metadata block
<snip ... these repeat for a long while ... >
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: space map common: dm_tm_shadow_block() failed
device-mapper: thin: 253:4: no free metadata space available.
device-mapper: thin: 253:4: switching pool to read-only mode
after patch:
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: 253:4: dm_thin_insert_block() failed: error = -28
device-mapper: thin: 253:4: switching pool to read-only mode
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
The dm_round_up function may overflow to zero. In this case,
dm_table_create() must fail rather than go on to allocate an empty array
with alloc_targets().
This fixes a possible memory corruption that could be caused by passing
too large a number in "param->target_count".
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
There is a possible leak of snapshot space in case of crash.
The reason for space leaking is that chunks in the snapshot device are
allocated sequentially, but they are finished (and stored in the metadata)
out of order, depending on the order in which copying finished.
For example, supposed that the metadata contains the following records
SUPERBLOCK
METADATA (blocks 0 ... 250)
DATA 0
DATA 1
DATA 2
...
DATA 250
Now suppose that you allocate 10 new data blocks 251-260. Suppose that
copying of these blocks finish out of order (block 260 finished first
and the block 251 finished last). Now, the snapshot device looks like
this:
SUPERBLOCK
METADATA (blocks 0 ... 250, 260, 259, 258, 257, 256)
DATA 0
DATA 1
DATA 2
...
DATA 250
DATA 251
DATA 252
DATA 253
DATA 254
DATA 255
METADATA (blocks 255, 254, 253, 252, 251)
DATA 256
DATA 257
DATA 258
DATA 259
DATA 260
Now, if the machine crashes after writing the first metadata block but
before writing the second metadata block, the space for areas DATA 250-255
is leaked, it contains no valid data and it will never be used in the
future.
This patch makes dm-snapshot complete exceptions in the same order they
were allocated, thus fixing this bug.
Note: when backporting this patch to the stable kernel, change the version
field in the following way:
* if version in the stable kernel is {1, 11, 1}, change it to {1, 12, 0}
* if version in the stable kernel is {1, 10, 0} or {1, 10, 1}, change it
to {1, 10, 2}
Userspace reads the version to determine if the bug was fixed, so the
version change is needed.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
The dm-delay target uses a shared workqueue for multiple instances. This
can cause deadlock if two or more dm-delay targets are stacked on the top
of each other.
This patch changes dm-delay to use a per-instance workqueue.
Cc: stable@vger.kernel.org # 2.6.22+
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Document passthrough mode, cache shrinking, and cache invalidation.
Also, use strcasecmp() and hlist_unhashed().
Reported-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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 [<cblock>|<cblock begin>-<cblock end>]*
E.g.
dmsetup message my_cache 0 invalidate_cblocks 2345 3456-4567 5678-6789
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Implement policy_remove_cblock() and add remove_cblock method to the mq
policy. These methods will be used by the following cache block
invalidation patch which adds the 'invalidate_cblocks' message to the
cache core.
Also, update some comments in dm-cache-policy.h
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Rather than storing the cblock in each cache entry, we allocate all
entries in an array and infer the cblock from the entry position.
Saves 4 bytes of memory per cache block. In addition, this gives us an
easy way of looking up cache entries by cblock.
We no longer need to keep an explicit bitset to track which cblocks
have been allocated. And no searching is needed to find free cblocks.
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Need to check the version to verify on-disk metadata is supported.
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
"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 <ejt@redhat.com>
Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Morgan Mears <Morgan.Mears@netapp.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Allow a cache to shrink if the blocks being removed from the cache are
not dirty.
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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 <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Previously these promotions only got priority if there were unused cache
blocks. Now we give them priority if there are any clean blocks in the
cache.
The fio_soak_test in the device-mapper-test-suite now gives uniform
performance across subvolumes (~16 seconds).
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Joe Thornber
Mikulas Patocka
Vincent Pelletier
Mike Snitzer