@@ -11850,6 +11850,30 @@ static int check_tree_block_ref(struct btrfs_root *root,
if (!ret)
found_ref = 1;
}
+ /*
+ * Finally check SHARED BLOCK REF, any found will be good
+ * Here we're not doing comprehensive extent backref checking,
+ * only need to ensure there is some extent referring to this
+ * tree block.
+ */
+ if (!found_ref) {
+ btrfs_release_path(&path);
+ key.objectid = bytenr;
+ key.type = BTRFS_SHARED_BLOCK_REF_KEY;
+ key.offset = (u64)-1;
+
+ ret = btrfs_search_slot(NULL, extent_root, &key, &path, 0, 0);
+ if (ret < 0) {
+ err |= BACKREF_MISSING;
+ goto out;
+ }
+ ret = btrfs_previous_extent_item(extent_root, &path, bytenr);
+ if (ret) {
+ err |= BACKREF_MISSING;
+ goto out;
+ }
+ found_ref = 1;
+ }
if (!found_ref)
err |= BACKREF_MISSING;
out:
[BUG] For image with shared block ref only metadata item like: ------ item 66 key (21573632 METADATA_ITEM 0) itemoff 3971 itemsize 24 refs 66 gen 9 flags TREE_BLOCK|FULL_BACKREF tree block skinny level 0 item 0 key (21573632 SHARED_BLOCK_REF 21676032) itemoff 3995 itemsize 0 shared block backref item 1 key (21573632 SHARED_BLOCK_REF 21921792) itemoff 3995 itemsize 0 shared block backref item 2 key (21573632 SHARED_BLOCK_REF 21995520) itemoff 3995 itemsize 0 shared block backref item 3 key (21573632 SHARED_BLOCK_REF 22077440) itemoff 3995 itemsize 0 shared block backref ... ------ Lowmem mode check will report false alerts like: ------ ERROR: extent[21573632 4096] backref lost (owner: 256, level: 0) ------ [CAUSE] In fact, the false alerts is not even from extent tree verfication, but a fs tree helper which is designed to make sure there is some tree block referring to the fs tree block. The idea is to find inlined tree backref then keyed TREE_BLOCK_REF_KEY. However it missed SHARED_BLOCK_REF_KEY, and caused such false alert. [FIX] Add SHARED_BLOCK_REF_KEY to make the warning shut up. Signed-off-by: Qu Wenruo <wqu@suse.com> --- cmds-check.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+)