[PATCH -v2] ext4: fix fencepost error in lazytime optimization
From: Theodore Ts'o <tytso@mit.edu>
Date: 2015-07-05 10:00:56
Also in:
stable
Subsystem:
ext4 file system, filesystems (vfs and infrastructure), the rest · Maintainers:
"Theodore Ts'o", Alexander Viro, Christian Brauner, Linus Torvalds
Commit 8f4d8558391: "ext4: fix lazytime optimization" was not a complete fix. In the case where the inode number is a multiple of 16, and we could still end up updating an inode with dirty timestamps written to the wrong inode on disk. Oops. This can be easily reproduced by using generic/005 with a file system with metadata_csum and lazytime enabled. Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@vger.kernel.org --- fs/ext4/inode.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index e057c6f..4ad73d3 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c@@ -4348,7 +4348,12 @@ static void ext4_update_other_inodes_time(struct super_block *sb, int inode_size = EXT4_INODE_SIZE(sb); oi.orig_ino = orig_ino; - ino = (orig_ino & ~(inodes_per_block - 1)) + 1; + /* + * Calculate the first inode in the inode table block. Inode + * numbers are one-based. That is, the first inode in a block + * (assuming 4k blocks and 256 byte inodes) is (n*16 + 1). + */ + ino = ((orig_ino - 1) & ~(inodes_per_block - 1)) + 1; for (i = 0; i < inodes_per_block; i++, ino++, buf += inode_size) { if (ino == orig_ino) continue;
--
2.3.0