dm thin metadata: try to avoid ever aborting transactions
[ Upstream commit 3ab91828166895600efd9cdc3a0eb32001f7204a ]
Committing a transaction can consume some metadata of it's own, we now
reserve a small amount of metadata to cover this. Free metadata
reported by the kernel will not include this reserve.
If any of the reserve has been used after a commit we enter a new
internal state PM_OUT_OF_METADATA_SPACE. This is reported as
PM_READ_ONLY, so no userland changes are needed. If the metadata
device is resized the pool will move back to PM_WRITE.
These changes mean we never need to abort and rollback a transaction due
to running out of metadata space. This is particularly important
because there have been a handful of reports of data corruption against
DM thin-provisioning that can all be attributed to the thin-pool having
ran out of metadata space.
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2 files changed