linux-kernel - Re: [f2fs-dev] [PATCH 2/2 v2] f2fs: complete checkpoints during remount

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Message-ID: <791f5692-0814-2bd7-712a-829e1cedb891@kernel.org>
Date:   Tue, 13 Sep 2022 11:11:23 +0800
From:   Chao Yu <chao@...nel.org>
To:     Jaegeuk Kim <jaegeuk@...nel.org>, linux-kernel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH 2/2 v2] f2fs: complete checkpoints during
 remount

On 2022/8/25 4:30, Jaegeuk Kim wrote:
> 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));
> 
> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>

Reviewed-by: Chao Yu <chao@...nel.org>

Thanks,