[13/14] btrfs: handle unexpected parent block offset in btrfs_alloc_tree_block()

Commit Message

David Sterba Feb. 8, 2024, 9 a.m. UTC

Change a BUG_ON to a proper error handling, here it checks that a root
other than reloc tree does not see a non-zero offset. This is set by
btrfs_force_cow_block() and is a special case so the check makes sure
it's not accidentally set by other callers.

Signed-off-by: David Sterba <[e-mail]>
---
 fs/btrfs/extent-tree.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

Patch

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 0d72d0f7cefc..3708f886d21a 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -5187,8 +5187,16 @@  struct extent_buffer *btrfs_alloc_tree_block(struct btrfs_trans_handle *trans,
 			parent = ins.objectid;
 		flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
 		owning_root = reloc_src_root;
-	} else
-		BUG_ON(parent > 0);
+	} else {
+		if (unlikely(parent > 0)) {
+			/*
+			 * Other roots than reloc tree don't expect start
+			 * offset of a parent block.
+			 */
+			ret = -EUCLEAN;
+			goto out_free_reserved;
+		}
+	}
 
 	if (root_objectid != BTRFS_TREE_LOG_OBJECTID) {
 		extent_op = btrfs_alloc_delayed_extent_op();