[ Upstream commit 6a5e3de9c2 ]
lockdep reported a potential deadlock:
a) TCMU device removal context:
- call del_gendisk() to get q->q_usage_counter
- call start_flush_work() to get work_completion of wb->dwork
b) f2fs writeback context:
- in wb_workfn(), which holds work_completion of wb->dwork
- call f2fs_balance_fs() to get sbi->gc_lock
c) f2fs vfs_write context:
- call f2fs_gc() to get sbi->gc_lock
- call f2fs_write_checkpoint() to get sbi->cp_global_sem
d) f2fs mount context:
- call recover_fsync_data() to get sbi->cp_global_sem
- call f2fs_check_and_fix_write_pointer() to call blkdev_report_zones()
that goes down to blk_mq_alloc_request and get q->q_usage_counter
Original callstack is in Closes tag.
However, I think this is a false alarm due to before mount returns
successfully (context d), we can not access file therein via vfs_write
(context c).
Let's introduce per-sb cp_global_sem_key, and assign the key for
cp_global_sem, so that lockdep can recognize cp_global_sem from
different super block correctly.
A lot of work are done by Shin'ichiro Kawasaki, thanks a lot for
the work.
Fixes: c426d99127 ("f2fs: Check write pointer consistency of open zones")
Cc: stable@kernel.org
Reported-and-tested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Closes: https://lore.kernel.org/linux-f2fs-devel/20260218125237.3340441-1-shinichiro.kawasaki@wdc.com
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
[ adapted to plain `struct rw_semaphore` (no `f2fs_rwsem` wrapper) and moved success-path `lockdep_unregister_key` from `kill_f2fs_super` to `f2fs_put_super` where sbi is actually freed ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
8ae13862d8