[PATCH AUTOSEL 5.4 15/27] btrfs: do not BUG_ON() on failure to migrate space when replacing extents

Sasha Levin
2022-06-28T02:31:08Z

From: Filipe Manana <fdmanana@suse.com>

[ Upstream commit 650c9caba32a0167a018cca0fab32a2965d23513 ]

At btrfs_replace_file_extents(), if we fail to migrate reserved metadata
space from the transaction block reserve into the local block reserve,
we trigger a BUG_ON(). This is because it should not be possible to have
a failure here, as we reserved more space when we started the transaction
than the space we want to migrate. However having a BUG_ON() is way too
drastic, we can perfectly handle the failure and return the error to the
caller. So just do that instead, and add a WARN_ON() to make it easier
to notice the failure if it ever happens (which is particularly useful
for fstests, and the warning will trigger a failure of a test case).

Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/btrfs/file.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 1279359ed172..db29bd901eef 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -2583,7 +2583,8 @@ int btrfs_punch_hole_range(struct inode *inode, struct btrfs_path *path,

ret = btrfs_block_rsv_migrate(&fs_info->trans_block_rsv, rsv,
min_size, false);
- BUG_ON(ret);
+ if (WARN_ON(ret))
+ goto out_trans;
trans->block_rsv = rsv;

cur_offset = start;
@@ -2654,7 +2655,8 @@ int btrfs_punch_hole_range(struct inode *inode, struct btrfs_path *path,

ret = btrfs_block_rsv_migrate(&fs_info->trans_block_rsv,
rsv, min_size, false);
- BUG_ON(ret); /* shouldn't happen */
+ if (WARN_ON(ret))
+ break;
trans->block_rsv = rsv;

if (!clone_info) {
--
2.35.1