On 2024/6/6 17:52, Chao Yu wrote:
After commit 261eeb9c1585 ("f2fs: introduce checkpoint_merge mount
option"), checkpoint can be triggered in background thread, it missed
to cover f2fs inner checkpoint operation w/ sb_{start,end}_intwrite(),
fix it.
It needs to use sb_start_intwrite_trylock(), otherwise, it will cause
deadlock as below:
- freeze_super
- sb_wait_write(SB_FREEZE_WRITE)
- sb_wait_write(SB_FREEZE_PAGEFAULT)
- sb_wait_write(SB_FREEZE_FS)
- sync
- iterate_supers
- super_lock_shared
- down_read(&sb->s_umount)
- sync_fs_one_sb
- f2fs_sync_fs
- f2fs_issue_checkpoint
- wait_for_completion
-
issue_checkpoint_thread
-
sb_start_intwrite(sbi->sb);
- thaw_super
- super_lock_excl
- down_write(&sb->s_umount)
Thanks,
Fixes: 261eeb9c1585 ("f2fs: introduce checkpoint_merge mount option")
Cc: Daeho Jeong <daehoje...@google.com>
Signed-off-by: Chao Yu <c...@kernel.org>
---
fs/f2fs/checkpoint.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index 55d444bec5c0..66eaad591b60 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -1828,8 +1828,11 @@ static int issue_checkpoint_thread(void *data)
if (kthread_should_stop())
return 0;
- if (!llist_empty(&cprc->issue_list))
+ if (!llist_empty(&cprc->issue_list)) {
+ sb_start_intwrite(sbi->sb);
__checkpoint_and_complete_reqs(sbi);
+ sb_end_intwrite(sbi->sb);
+ }
wait_event_interruptible(*q,
kthread_should_stop() || !llist_empty(&cprc->issue_list));
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