[PATCH 3/4] btrfs: tree-checker: Refactor root key check into separate function

Qu Wenruo
2019-12-09T10:54:46Z

ROOT_ITEM key check itself is not as simple as single line check, and
will be reused for both ROOT_ITEM and DIR_ITEM/DIR_INDEX location key
check, so refactor such check into check_root_key().

Also since we are here, fix a comment error about ROOT_ITEM offset,
which is transid of snapshot creation, not some "older kernel behavior".

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
fs/btrfs/tree-checker.c | 61 +++++++++++++++++++++++++++++++----------
1 file changed, 46 insertions(+), 15 deletions(-)

diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
index 68dad9ec38dd..9a6743ee874a 100644
--- a/fs/btrfs/tree-checker.c
+++ b/fs/btrfs/tree-checker.c
@@ -413,6 +413,48 @@ static int check_inode_key(struct extent_buffer *leaf, struct btrfs_key *key,
return 0;
}

+static int check_root_key(struct extent_buffer *leaf, struct btrfs_key *key,
+ int slot)
+{
+ struct btrfs_key item_key;
+ bool is_root_item;
+
+ btrfs_item_key_to_cpu(leaf, &item_key, slot);
+ is_root_item = (item_key.type == BTRFS_ROOT_ITEM_KEY);
+
+ /* No such tree id */
+ if (key->objectid == 0) {
+ if (is_root_item)
+ generic_err(leaf, slot, "invalid root id 0");
+ else
+ dir_item_err(leaf, slot,
+ "invalid location key root id 0");
+ return -EUCLEAN;
+ }
+
+ /* DIR_ITEM/INDEX/INODE_REF is not allowed to point to non-fs trees */
+ if (!is_fstree(key->objectid) && !is_root_item) {
+ dir_item_err(leaf, slot,
+ "invalid location key objectid, have %llu expect [%llu, %llu]",
+ key->objectid, BTRFS_FIRST_FREE_OBJECTID,
+ BTRFS_LAST_FREE_OBJECTID);
+ return -EUCLEAN;
+ }
+ /*
+ * ROOT_ITEM with non-zero offset means, this is a snapshot, created at
+ * @offset transid.
+ * Furthermore, for location key in DIR_ITEM, its offset is always -1.
+ *
+ * So here we only check offset for reloc tree whose key->offset must
+ * be a valid tree.
+ */
+ if (key->objectid == BTRFS_TREE_RELOC_OBJECTID && key->offset == 0) {
+ generic_err(leaf, slot, "invalid root id 0 for reloc tree");
+ return -EUCLEAN;
+ }
+ return 0;
+}
+
static int check_dir_item(struct extent_buffer *leaf,
struct btrfs_key *key, struct btrfs_key *prev_key,
int slot)
@@ -925,22 +967,11 @@ static int check_root_item(struct extent_buffer *leaf, struct btrfs_key *key,
struct btrfs_root_item ri;
const u64 valid_root_flags = BTRFS_ROOT_SUBVOL_RDONLY |
BTRFS_ROOT_SUBVOL_DEAD;
+ int ret;

- /* No such tree id */
- if (key->objectid == 0) {
- generic_err(leaf, slot, "invalid root id 0");
- return -EUCLEAN;
- }
-
- /*
- * Some older kernel may create ROOT_ITEM with non-zero offset, so here
- * we only check offset for reloc tree whose key->offset must be a
- * valid tree.
- */
- if (key->objectid == BTRFS_TREE_RELOC_OBJECTID && key->offset == 0) {
- generic_err(leaf, slot, "invalid root id 0 for reloc tree");
- return -EUCLEAN;
- }
+ ret = check_root_key(leaf, key, slot);
+ if (ret < 0)
+ return ret;

if (btrfs_item_size_nr(leaf, slot) != sizeof(ri)) {
generic_err(leaf, slot,
--
2.24.0