Btrfs: avoid I/O repair BUG() from btree_read_extent_buffer_pages()

From btree_read_extent_buffer_pages(), currently repair_io_failure()
can be called with mirror_num being zero when submit_one_bio() returned
an error before. This used to cause a BUG_ON(!mirror_num) in
repair_io_failure() and indeed this is not a case that needs the I/O
repair code to rewrite disk blocks.
This commit prevents calling repair_io_failure() in this case and thus
avoids the BUG_ON() and malfunction.

Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index dd6676b446f654cb6ce6140a68c5c265432cd4d9..1a4a2a97592670b2d6f747afb240f9ee6722b19a 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -407,7 +407,7 @@ static int btree_read_extent_buffer_pages(struct btrfs_root *root,
                        break;
        }
 
-       if (failed && !ret)
+       if (failed && !ret && failed_mirror)
                repair_eb_io_failure(root, eb, failed_mirror);
 
        return ret;