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authorJoe Thornber <ejt@redhat.com>2014-01-21 11:07:32 +0000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-02-13 13:48:01 -0800
commit88972eec55f81c2500ee2923023850faa13edb67 (patch)
tree1ca3d2d03d19ce9c804936302a656bb145c41f80
parentf15396a3699d02f863e80623e0771d3f95f08974 (diff)
downloadlinaro-lsk-88972eec55f81c2500ee2923023850faa13edb67.tar.gz
dm space map metadata: fix bug in resizing of thin metadata
commit fca028438fb903852beaf7c3fe1cd326651af57d upstream. This bug was introduced in commit 7e664b3dec431e ("dm space map metadata: fix extending the space map"). When extending a dm-thin metadata volume we: - Switch the space map into a simple bootstrap mode, which allocates all space linearly from the newly added space. - Add new bitmap entries for the new space - Increment the reference counts for those newly allocated bitmap entries - Commit changes to disk - Switch back out of bootstrap mode. But, the disk commit may allocate space itself, if so this fact will be lost when switching out of bootstrap mode. The bug exhibited itself as an error when the bitmap_root, with an erroneous ref count of 0, was subsequently decremented as part of a later disk commit. This would cause the disk commit to fail, and thinp to enter read_only mode. The metadata was not damaged (thin_check passed). The fix is to put the increments + commit into a loop, running until the commit has not allocated extra space. In practise this loop only runs twice. With this fix the following device mapper testsuite test passes: dmtest run --suite thin-provisioning -n thin_remove_works_after_resize Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/md/persistent-data/dm-space-map-metadata.c18
1 files changed, 14 insertions, 4 deletions
diff --git a/drivers/md/persistent-data/dm-space-map-metadata.c b/drivers/md/persistent-data/dm-space-map-metadata.c
index f04d92f313c..afb419e514b 100644
--- a/drivers/md/persistent-data/dm-space-map-metadata.c
+++ b/drivers/md/persistent-data/dm-space-map-metadata.c
@@ -617,13 +617,23 @@ static int sm_metadata_extend(struct dm_space_map *sm, dm_block_t extra_blocks)
if (r)
goto out;
- for (i = old_len; !r && i < smm->begin; i++) {
- r = sm_ll_inc(&smm->ll, i, &ev);
+ /*
+ * We repeatedly increment then commit until the commit doesn't
+ * allocate any new blocks.
+ */
+ do {
+ for (i = old_len; !r && i < smm->begin; i++) {
+ r = sm_ll_inc(&smm->ll, i, &ev);
+ if (r)
+ goto out;
+ }
+ old_len = smm->begin;
+
+ r = sm_ll_commit(&smm->ll);
if (r)
goto out;
- }
- r = sm_metadata_commit(sm);
+ } while (old_len != smm->begin);
out:
/*