tree 1460d2be1b168728b995fb2d6814ceba4cb7a8f2
parent 0a2bd55c194ae8322638aceb4cc276cbf8b2f8b9
author Mikulas Patocka <mpatocka@redhat.com> 1586962898 -0400
committer Mike Snitzer <snitzer@redhat.com> 1587067453 -0400

dm writecache: fix data corruption when reloading the target

The dm-writecache reads metadata in the target constructor. However, when
we reload the target, there could be another active instance running on
the same device. This is the sequence of operations when doing a reload:

1. construct new target
2. suspend old target
3. resume new target
4. destroy old target

Metadata that were written by the old target between steps 1 and 2 would
not be visible by the new target.

Fix the data corruption by loading the metadata in the resume handler.

Also, validate block_size is at least as large as both the devices'
logical block size and only read 1 block from the metadata during
target constructor -- no need to read entirety of metadata now that it
is done during resume.

Fixes: 48debafe4f2f ("dm: add writecache target")
Cc: stable@vger.kernel.org # v4.18+
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>