This is a note to let you know that I've just added the patch titled
dm space map metadata: fix bug in resizing of thin metadata
to the 3.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
dm-space-map-metadata-fix-bug-in-resizing-of-thin-metadata.patch
and it can be found in the queue-3.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From fca028438fb903852beaf7c3fe1cd326651af57d Mon Sep 17 00:00:00 2001
From: Joe Thornber <ejt@xxxxxxxxxx>
Date: Tue, 21 Jan 2014 11:07:32 +0000
Subject: dm space map metadata: fix bug in resizing of thin metadata
From: Joe Thornber <ejt@xxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/md/persistent-data/dm-space-map-metadata.c | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)
--- 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_
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:
/*
Patches currently in stable-queue which might be from ejt@xxxxxxxxxx are
queue-3.12/dm-thin-fix-discard-support-to-a-previously-shared-block.patch
queue-3.12/dm-space-map-metadata-fix-extending-the-space-map.patch
queue-3.12/dm-space-map-common-make-sure-new-space-is-used-during-extend.patch
queue-3.12/dm-thin-initialize-dm_thin_new_mapping-returned-by-get_next_mapping.patch
queue-3.12/dm-space-map-metadata-fix-bug-in-resizing-of-thin-metadata.patch
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