[PATCH 4/6] btrfs: replace ASSERT with proper error handling in stripe lookup fallback

[robbieko <robbieko@synology.com>]

After falling back to the previous item in btrfs_delete_raid_extent(),
the code uses ASSERT(found_start <= start) to verify the found extent
actually precedes our target range. If the B-tree state is unexpected
(e.g. no overlapping extent exists), this triggers a kernel BUG/panic
in debug builds, or silently continues with wrong data otherwise.

Replace the ASSERT with a proper bounds check that returns -ENOENT if
the found extent does not actually overlap with the start position.

Signed-off-by: robbieko <robbieko@synology.com>
---
 fs/btrfs/raid-stripe-tree.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/raid-stripe-tree.c b/fs/btrfs/raid-stripe-tree.c
index 2f41cec637d4..5909ad35a1b0 100644
--- a/fs/btrfs/raid-stripe-tree.c
+++ b/fs/btrfs/raid-stripe-tree.c
@@ -154,7 +154,10 @@ int btrfs_delete_raid_extent(struct btrfs_trans_handle *trans, u64 start, u64 le
 			btrfs_item_key_to_cpu(leaf, &key, slot);
 			found_start = key.objectid;
 			found_end = found_start + key.offset;
-			ASSERT(found_start <= start);
+			if (found_start > start || found_end <= start) {
+				ret = -ENOENT;
+				break;
+			}
 		}
 
 		if (key.type != BTRFS_RAID_STRIPE_KEY)
-- 
2.43.0


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