The patch titled
Subject: nilfs2: handle inconsistent state in nilfs_btnode_create_block()
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
nilfs2-handle-inconsistent-state-in-nilfs_btnode_create_block.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/nilfs2-handle-inconsistent-state-in-nilfs_btnode_create_block.patch
This patch will later appear in the mm-hotfixes-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: handle inconsistent state in nilfs_btnode_create_block()
Date: Thu, 25 Jul 2024 14:20:07 +0900
Syzbot reported that a buffer state inconsistency was detected in
nilfs_btnode_create_block(), triggering a kernel bug.
It is not appropriate to treat this inconsistency as a bug; it can occur
if the argument block address (the buffer index of the newly created
block) is a virtual block number and has been reallocated due to
corruption of the bitmap used to manage its allocation state.
So, modify nilfs_btnode_create_block() and its callers to treat it as a
possible filesystem error, rather than triggering a kernel bug.
Link: https://lkml.kernel.org/r/20240725052007.4562-1-konishi.ryusuke@xxxxxxxxx
Fixes: a60be987d45d ("nilfs2: B-tree node cache")
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx>
Reported-by: syzbot+89cc4f2324ed37988b60@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=89cc4f2324ed37988b60
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/nilfs2/btnode.c | 25 ++++++++++++++++++++-----
fs/nilfs2/btree.c | 4 ++--
2 files changed, 22 insertions(+), 7 deletions(-)
--- a/fs/nilfs2/btnode.c~nilfs2-handle-inconsistent-state-in-nilfs_btnode_create_block
+++ a/fs/nilfs2/btnode.c
@@ -51,12 +51,21 @@ nilfs_btnode_create_block(struct address
bh = nilfs_grab_buffer(inode, btnc, blocknr, BIT(BH_NILFS_Node));
if (unlikely(!bh))
- return NULL;
+ return ERR_PTR(-ENOMEM);
if (unlikely(buffer_mapped(bh) || buffer_uptodate(bh) ||
buffer_dirty(bh))) {
- brelse(bh);
- BUG();
+ /*
+ * The block buffer at the specified new address was already
+ * in use. This can happen if it is a virtual block number
+ * and has been reallocated due to corruption of the bitmap
+ * used to manage its allocation state (if not, the buffer
+ * clearing of an abandoned b-tree node is missing somewhere).
+ */
+ nilfs_error(inode->i_sb,
+ "state inconsistency probably due to duplicate use of b-tree node block address %llu (ino=%lu)",
+ (unsigned long long)blocknr, inode->i_ino);
+ goto failed;
}
memset(bh->b_data, 0, i_blocksize(inode));
bh->b_bdev = inode->i_sb->s_bdev;
@@ -67,6 +76,12 @@ nilfs_btnode_create_block(struct address
folio_unlock(bh->b_folio);
folio_put(bh->b_folio);
return bh;
+
+failed:
+ folio_unlock(bh->b_folio);
+ folio_put(bh->b_folio);
+ brelse(bh);
+ return ERR_PTR(-EIO);
}
int nilfs_btnode_submit_block(struct address_space *btnc, __u64 blocknr,
@@ -217,8 +232,8 @@ retry:
}
nbh = nilfs_btnode_create_block(btnc, newkey);
- if (!nbh)
- return -ENOMEM;
+ if (IS_ERR(nbh))
+ return PTR_ERR(nbh);
BUG_ON(nbh == obh);
ctxt->newbh = nbh;
--- a/fs/nilfs2/btree.c~nilfs2-handle-inconsistent-state-in-nilfs_btnode_create_block
+++ a/fs/nilfs2/btree.c
@@ -63,8 +63,8 @@ static int nilfs_btree_get_new_block(con
struct buffer_head *bh;
bh = nilfs_btnode_create_block(btnc, ptr);
- if (!bh)
- return -ENOMEM;
+ if (IS_ERR(bh))
+ return PTR_ERR(bh);
set_buffer_nilfs_volatile(bh);
*bhp = bh;
_
Patches currently in -mm which might be from konishi.ryusuke@xxxxxxxxx are
nilfs2-handle-inconsistent-state-in-nilfs_btnode_create_block.patch
