Commit 0d200aefd4ac51787b6b80de1bb7ce93bccd59f6
Committed by
Alasdair G Kergon
Alasdair G Kergon
1 parent
6887a4131d
Exists in
master
and in
20 other branches
dm thin: commit metadata before creating metadata snapshot
Userland sometimes sees a corrupt metadata block if metadata is changing
rapidly when a metadata snapshot is reserved for userland, To make the
problem go away, commit before we take the metadata snapshot (which is a
sensible thing to do anyway).
The checksums mean userland spots this corruption immediately so there's
no risk of acting on incorrect data. No corruption exists from the
kernel's point of view, and thin_check passes after pool shutdown.
I believe this is to do with shared blocks at the first level of the
{device, mapping} btree. Prior to the metadata-snap support no sharing
at this level was possible, so this patch is only required after commit
cc8394d86f045b86ff303d3c9e4ce47d97148951 ("dm thin: provide userspace
access to pool metadata").
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Showing 1 changed file with 7 additions and 0 deletions Side-by-side Diff
drivers/md/dm-thin.c
| ... | ... | @@ -2292,6 +2292,13 @@ |
| 2292 | 2292 | if (r) |
| 2293 | 2293 | return r; |
| 2294 | 2294 | |
| 2295 | + r = dm_pool_commit_metadata(pool->pmd); | |
| 2296 | + if (r) { | |
| 2297 | + DMERR("%s: dm_pool_commit_metadata() failed, error = %d", | |
| 2298 | + __func__, r); | |
| 2299 | + return r; | |
| 2300 | + } | |
| 2301 | + | |
| 2295 | 2302 | r = dm_pool_reserve_metadata_snap(pool->pmd); |
| 2296 | 2303 | if (r) |
| 2297 | 2304 | DMWARN("reserve_metadata_snap message failed."); |