mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-28 05:12:49 +00:00
ext4: fix lockdep warning when enabling MMP
[ Upstream commit 949f95ff39
]
When we enable MMP in ext4_multi_mount_protect() during mount or
remount, we end up calling sb_start_write() from write_mmp_block(). This
triggers lockdep warning because freeze protection ranks above s_umount
semaphore we are holding during mount / remount. The problem is harmless
because we are guaranteed the filesystem is not frozen during mount /
remount but still let's fix the warning by not grabbing freeze
protection from ext4_multi_mount_protect().
Cc: stable@kernel.org
Reported-by: syzbot+6b7df7d5506b32467149@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?id=ab7e5b6f400b7778d46f01841422e5718fb81843
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Link: https://lore.kernel.org/r/20230411121019.21940-1-jack@suse.cz
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
parent
c53936d9fb
commit
1de53f2223
1 changed files with 21 additions and 9 deletions
|
@ -39,28 +39,36 @@ static void ext4_mmp_csum_set(struct super_block *sb, struct mmp_struct *mmp)
|
|||
* Write the MMP block using REQ_SYNC to try to get the block on-disk
|
||||
* faster.
|
||||
*/
|
||||
static int write_mmp_block(struct super_block *sb, struct buffer_head *bh)
|
||||
static int write_mmp_block_thawed(struct super_block *sb,
|
||||
struct buffer_head *bh)
|
||||
{
|
||||
struct mmp_struct *mmp = (struct mmp_struct *)(bh->b_data);
|
||||
|
||||
/*
|
||||
* We protect against freezing so that we don't create dirty buffers
|
||||
* on frozen filesystem.
|
||||
*/
|
||||
sb_start_write(sb);
|
||||
ext4_mmp_csum_set(sb, mmp);
|
||||
lock_buffer(bh);
|
||||
bh->b_end_io = end_buffer_write_sync;
|
||||
get_bh(bh);
|
||||
submit_bh(REQ_OP_WRITE, REQ_SYNC | REQ_META | REQ_PRIO, bh);
|
||||
wait_on_buffer(bh);
|
||||
sb_end_write(sb);
|
||||
if (unlikely(!buffer_uptodate(bh)))
|
||||
return -EIO;
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
static int write_mmp_block(struct super_block *sb, struct buffer_head *bh)
|
||||
{
|
||||
int err;
|
||||
|
||||
/*
|
||||
* We protect against freezing so that we don't create dirty buffers
|
||||
* on frozen filesystem.
|
||||
*/
|
||||
sb_start_write(sb);
|
||||
err = write_mmp_block_thawed(sb, bh);
|
||||
sb_end_write(sb);
|
||||
return err;
|
||||
}
|
||||
|
||||
/*
|
||||
* Read the MMP block. It _must_ be read from disk and hence we clear the
|
||||
* uptodate flag on the buffer.
|
||||
|
@ -352,7 +360,11 @@ int ext4_multi_mount_protect(struct super_block *sb,
|
|||
seq = mmp_new_seq();
|
||||
mmp->mmp_seq = cpu_to_le32(seq);
|
||||
|
||||
retval = write_mmp_block(sb, bh);
|
||||
/*
|
||||
* On mount / remount we are protected against fs freezing (by s_umount
|
||||
* semaphore) and grabbing freeze protection upsets lockdep
|
||||
*/
|
||||
retval = write_mmp_block_thawed(sb, bh);
|
||||
if (retval)
|
||||
goto failed;
|
||||
|
||||
|
|
Loading…
Reference in a new issue