[PATCH 02/20] btrfs: handle invalid range and start in merge_extent_mapping()

David Sterba
2024-01-24T21:18:17Z

Turn a BUG_ON to a properly handled error and update the error message
in the caller. It is expected that @em_in and @start passed to
btrfs_add_extent_mapping() overlap. Besides tests, the only caller
btrfs_get_extent() makes sure this is true.

Signed-off-by: David Sterba <dsterba@suse.com>
---
fs/btrfs/extent_map.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index f170e7122e74..ac5e366d57b2 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -539,7 +539,8 @@ static noinline int merge_extent_mapping(struct extent_map_tree *em_tree,
u64 end;
u64 start_diff;

- BUG_ON(map_start < em->start || map_start >= extent_map_end(em));
+ if (map_start < em->start || map_start >= extent_map_end(em))
+ return -EINVAL;

if (existing->start > map_start) {
next = existing;
@@ -634,9 +635,9 @@ int btrfs_add_extent_mapping(struct btrfs_fs_info *fs_info,
free_extent_map(em);
*em_in = NULL;
WARN_ONCE(ret,
-"unexpected error %d: merge existing(start %llu len %llu) with em(start %llu len %llu)\n",
- ret, existing->start, existing->len,
- orig_start, orig_len);
+"extent map merge error existing [%llu, %llu) with em [%llu, %llu) start %llu\n",
+ existing->start, existing->len,
+ orig_start, orig_len, start);
}
free_extent_map(existing);
}
--
2.42.1