[PATCH 5.19 113/717] f2fs: complete checkpoints during remount

Greg Kroah-Hartman
2022-10-22T07:42:29Z

From: Jaegeuk Kim <jaegeuk@kernel.org>

commit 4f99484d27961cb194cebcd917176fa038a5025f upstream.

Otherwise, pending checkpoints can contribute a race condition to give a
quota warning.

- Thread - checkpoint thread
add checkpoints to the list
do_remount()
down_write(&sb->s_umount);
f2fs_remount()
block_operations()
down_read_trylock(&sb->s_umount) = 0
up_write(&sb->s_umount);
f2fs_quota_sync()
dquot_writeback_dquots()
WARN_ON_ONCE(!rwsem_is_locked(&sb->s_umount));

Or,

do_remount()
down_write(&sb->s_umount);
f2fs_remount()
create a ckpt thread
f2fs_enable_checkpoint() adds checkpoints
wait for f2fs_sync_fs()
trigger another pending checkpoint
block_operations()
down_read_trylock(&sb->s_umount) = 0
up_write(&sb->s_umount);
f2fs_quota_sync()
dquot_writeback_dquots()
WARN_ON_ONCE(!rwsem_is_locked(&sb->s_umount));

Cc: stable@vger.kernel.org
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/f2fs/super.c | 6 ++++++
1 file changed, 6 insertions(+)

--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -2146,6 +2146,9 @@ static void f2fs_enable_checkpoint(struc
f2fs_up_write(&sbi->gc_lock);

f2fs_sync_fs(sbi->sb, 1);
+
+ /* Let's ensure there's no pending checkpoint anymore */
+ f2fs_flush_ckpt_thread(sbi);
}

static int f2fs_remount(struct super_block *sb, int *flags, char *data)
@@ -2311,6 +2314,9 @@ static int f2fs_remount(struct super_blo
f2fs_stop_ckpt_thread(sbi);
need_restart_ckpt = true;
} else {
+ /* Flush if the prevous checkpoint, if exists. */
+ f2fs_flush_ckpt_thread(sbi);
+
err = f2fs_start_ckpt_thread(sbi);
if (err) {
f2fs_err(sbi,