linux-stable.git/drivers/md/dm-snap-persistent.c, branch v4.3.2

dm snapshot persistent: fix missing cleanup in persistent_ctr error path

2015-10-13T16:20:54+00:00

If an unsupported option is given then the early return from
persistent_ctr() leaked memory allocated for the 'pstore' and never
destroyed the 'metadata_wq'.

Fixes: b0d3cc011e53 ("dm snapshot: add new persistent store option to support overflow")
Signed-off-by: Sudip Mukherjee 
Signed-off-by: Mike Snitzer

dm snapshot: add new persistent store option to support overflow

2015-10-09T20:57:03+00:00

Commit 76c44f6d80 introduced the possibly for "Overflow" to be reported
by the snapshot device's status.  Older userspace (e.g. lvm2) does not
handle the "Overflow" status response.

Fix this incompatibility by requiring newer userspace code, that can
cope with "Overflow", request the persistent store with overflow support
by using "PO" (Persistent with Overflow) for the snapshot store type.

Reported-by: Zdenek Kabelac 
Fixes: 76c44f6d80 ("dm snapshot: don't invalidate on-disk image on snapshot write overflow")
Reviewed-by: Mikulas Patocka 
Signed-off-by: Mike Snitzer

dm: remove unlikely() before IS_ERR()

2015-08-12T15:32:21+00:00

IS_ERR() already contains an 'unlikely' compiler flag so there is no
need to do that again from IS_ERR() callers.

Signed-off-by: Viresh Kumar 
Signed-off-by: Mike Snitzer

dm snapshot: remove unnecessary NULL checks before vfree() calls

2015-02-09T18:06:49+00:00

The vfree() function performs input parameter validation.
Thus the NULL pointer test around vfree() calls is not needed.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring 
Signed-off-by: Mike Snitzer

dm snapshot: fix metadata corruption

2014-03-03T22:58:13+00:00

Commit 55494bf2947dccdf2 ("dm snapshot: use dm-bufio") broke snapshots.
Before that 3.14-rc1 commit, loading a snapshot's list of exceptions
involved reading exception areas one by one into ps->area and inserting
those exceptions into the hash table.  Commit 55494bf2947dccdf2 changed
it so that dm-bufio with prefetch is used to load exceptions in batchs.
Exceptions are loaded correctly, but ps->area is left uninitialized.
When a new exception is allocated, it is stored in this uninitialized
ps->area which will be written to the disk.  This causes metadata
corruption.

Fix this corruption by copying the last area that was read via dm-bufio
into ps->area.

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

dm snapshot: use dm-bufio prefetch

2014-01-15T04:23:03+00:00

This patch modifies dm-snapshot so that it prefetches the buffers when
loading the exceptions.

The number of buffers read ahead is specified in the DM_PREFETCH_CHUNKS
macro.  The current value for DM_PREFETCH_CHUNKS (12) was found to
provide the best performance on a single 15k SCSI spindle.  In the
future we may modify this default or make it configurable.

Also, introduce the function dm_bufio_set_minimum_buffers to setup
bufio's number of internal buffers before freeing happens.  dm-bufio may
hold more buffers if enough memory is available.  There is no guarantee
that the specified number of buffers will be available - if you need a
guarantee, use the argument reserved_buffers for
dm_bufio_client_create.

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

dm snapshot: use dm-bufio

2014-01-15T04:23:02+00:00

Use dm-bufio for initial loading of the exceptions.
Introduce a new function dm_bufio_forget that frees the given buffer.

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

dm snapshot: prepare for switch to using dm-bufio

2014-01-14T18:38:32+00:00

Change the functions get_exception, read_exception and insert_exceptions
so that ps->area is passed as an argument.

This patch doesn't change any functionality, but it refactors the code
to allow for a cleaner switch over to using dm-bufio.

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

dm snapshot: call destroy_work_on_stack() to pair with INIT_WORK_ONSTACK()

2014-01-07T15:31:34+00:00

In case CONFIG_DEBUG_OBJECTS_WORK is defined, it is needed to
call destroy_work_on_stack() which frees the debug object to pair
with INIT_WORK_ONSTACK().

Signed-off-by: Liu, Chuansheng 
Signed-off-by: Mike Snitzer

dm snapshot: fix data corruption

2013-10-16T02:17:47+00:00

This patch fixes a particular type of data corruption that has been
encountered when loading a snapshot's metadata from disk.

When we allocate a new chunk in persistent_prepare, we increment
ps->next_free and we make sure that it doesn't point to a metadata area
by further incrementing it if necessary.

When we load metadata from disk on device activation, ps->next_free is
positioned after the last used data chunk. However, if this last used
data chunk is followed by a metadata area, ps->next_free is positioned
erroneously to the metadata area. A newly-allocated chunk is placed at
the same location as the metadata area, resulting in data or metadata
corruption.

This patch changes the code so that ps->next_free skips the metadata
area when metadata are loaded in function read_exceptions.

The patch also moves a piece of code from persistent_prepare_exception
to a separate function skip_metadata to avoid code duplication.

CVE-2013-4299

Signed-off-by: Mikulas Patocka 
Cc: stable@vger.kernel.org
Cc: Mike Snitzer 
Signed-off-by: Alasdair G Kergon