nilfs2: determine empty node blocks as corrupted

Due to the nature of b-trees, nilfs2 itself and admin tools such as
mkfs.nilfs2 will never create an intermediate b-tree node block with 0
child nodes, nor will they delete (key, pointer)-entries that would result
in such a state.  However, it is possible that a b-tree node block is
corrupted on the backing device and is read with 0 child nodes.

Because operation is not guaranteed if the number of child nodes is 0 for
intermediate node blocks other than the root node, modify
nilfs_btree_node_broken(), which performs sanity checks when reading a
b-tree node block, so that such cases will be judged as metadata
corruption.

Link: https://lkml.kernel.org/r/20240904081401.16682-3-konishi.ryusuke@gmail.com
Fixes: 17c76b0104 ("nilfs2: B-tree based block mapping")
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: Lizhi Xu <lizhi.xu@windriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Ryusuke Konishi 2024-09-04 17:13:08 +09:00 committed by Andrew Morton
parent 9403001ad6
commit 111b812d36

View File

@ -350,7 +350,7 @@ static int nilfs_btree_node_broken(const struct nilfs_btree_node *node,
if (unlikely(level < NILFS_BTREE_LEVEL_NODE_MIN ||
level >= NILFS_BTREE_LEVEL_MAX ||
(flags & NILFS_BTREE_NODE_ROOT) ||
nchildren < 0 ||
nchildren <= 0 ||
nchildren > NILFS_BTREE_NODE_NCHILDREN_MAX(size))) {
nilfs_crit(inode->i_sb,
"bad btree node (ino=%lu, blocknr=%llu): level = %d, flags = 0x%x, nchildren = %d",