summaryrefslogtreecommitdiff
path: root/fs/btrfs
diff options
context:
space:
mode:
authorLiu Bo <bo.li.liu@oracle.com>2018-01-12 18:07:02 -0700
committerDavid Sterba <dsterba@suse.com>2018-01-22 16:08:21 +0100
commit44ac474def527a9c595a88400f4717dacae03b8a (patch)
treebde3b88d6fa242c6667007f3c8a6e7afd705a064 /fs/btrfs
parent0198e5b707cfeb5defbd1b71b1ec6e71580d7db9 (diff)
Btrfs: do not cache rbio pages if using raid6 recover
Since raid6 recover tries all possible combinations of failed stripes, - when raid6 rebuild algorithm is used, i.e. raid6_datap_recov() and raid6_2data_recov(), it may change the in-memory content of failed stripes, if such a raid bio is cached, a later raid write rmw or recover can steal @stripe_pages from it instead of reading from disks, such that it carries the wrong content to do write rmw or recovery and ends up with corruption or recovery failures. - when raid5 rebuild algorithm is used, i.e. xor, raid bio can be cached because the only failed stripe which contains @rbio->bio_pages gets modified, others remain the same so that their in-memory content is consistent with their on-disk content. This adds a check to skip caching rbio if using raid6 recover. Signed-off-by: Liu Bo <bo.li.liu@oracle.com> Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs')
-rw-r--r--fs/btrfs/raid56.c17
1 files changed, 16 insertions, 1 deletions
diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c
index f86ba6a319fe..2f1ff7007280 100644
--- a/fs/btrfs/raid56.c
+++ b/fs/btrfs/raid56.c
@@ -1974,7 +1974,22 @@ cleanup:
cleanup_io:
if (rbio->operation == BTRFS_RBIO_READ_REBUILD) {
- if (err == BLK_STS_OK)
+ /*
+ * - In case of two failures, where rbio->failb != -1:
+ *
+ * Do not cache this rbio since the above read reconstruction
+ * (raid6_datap_recov() or raid6_2data_recov()) may have
+ * changed some content of stripes which are not identical to
+ * on-disk content any more, otherwise, a later write/recover
+ * may steal stripe_pages from this rbio and end up with
+ * corruptions or rebuild failures.
+ *
+ * - In case of single failure, where rbio->failb == -1:
+ *
+ * Cache this rbio iff the above read reconstruction is
+ * excuted without problems.
+ */
+ if (err == BLK_STS_OK && rbio->failb < 0)
cache_rbio_pages(rbio);
else
clear_bit(RBIO_CACHE_READY_BIT, &rbio->flags);