The patch titled
Subject: nilfs2: determine empty node blocks as corrupted
has been added to the -mm mm-nonmm-unstable branch. Its filename is
nilfs2-determine-empty-node-blocks-as-corrupted.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/nilfs2-determine-empty-node-blocks-as-corrupted.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx>
Subject: nilfs2: determine empty node blocks as corrupted
Date: Wed, 4 Sep 2024 17:13:08 +0900
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>
---
fs/nilfs2/btree.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/nilfs2/btree.c~nilfs2-determine-empty-node-blocks-as-corrupted
+++ a/fs/nilfs2/btree.c
@@ -350,7 +350,7 @@ static int nilfs_btree_node_broken(const
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",
_
Patches currently in -mm which might be from konishi.ryusuke@xxxxxxxxx are
nilfs2-fix-potential-null-ptr-deref-in-nilfs_btree_insert.patch
nilfs2-determine-empty-node-blocks-as-corrupted.patch
nilfs2-fix-potential-oob-read-in-nilfs_btree_check_delete.patch
