This is a note to let you know that I've just added the patch titled
nilfs2: determine empty node blocks as corrupted
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
nilfs2-determine-empty-node-blocks-as-corrupted.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 9ffde729ae53c9404b09a11000b80e5b9f509ed4
Author: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx>
Date: Wed Sep 4 17:13:08 2024 +0900
nilfs2: determine empty node blocks as corrupted
[ Upstream commit 111b812d3662f3a1b831d19208f83aa711583fe6 ]
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@xxxxxxxxx
Fixes: 17c76b0104e4 ("nilfs2: B-tree based block mapping")
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx>
Cc: Lizhi Xu <lizhi.xu@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/nilfs2/btree.c b/fs/nilfs2/btree.c
index c2aca9cd78644..7cfff27b4b4a5 100644
--- a/fs/nilfs2/btree.c
+++ b/fs/nilfs2/btree.c
@@ -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",
