btrfs: fix btrfs_cont_expand() freeing IS_ERR em
btrfs_cont_expand() tries to free an IS_ERR em as it gets an error from
btrfs_get_extent() and breaks out of its loop.
An instance of -EEXIST was reported in the wild:
https://bugzilla.redhat.com/show_bug.cgi?id=874407
I have no idea if that -EEXIST is surprising, or not. Regardless, this
error handling should be cleaned up to handle other reasonable errors
(ENOMEM, EIO; whatever).
This seemed to be the only buggy freeing of the relatively rare IS_ERR
em so I opted to fix the caller rather than teach free_extent_map() to
use IS_ERR_OR_NULL().
Signed-off-by: Zach Brown <zab@redhat.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index ac98384..3d2c64d 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -3677,6 +3677,7 @@
block_end - cur_offset, 0);
if (IS_ERR(em)) {
err = PTR_ERR(em);
+ em = NULL;
break;
}
last_byte = min(extent_map_end(em), block_end);