linux-kernel - Re: [f2fs-dev] [PATCH] f2fs: do checkpoint in kill

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Date:   Tue, 10 Jul 2018 14:09:20 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     Jaegeuk Kim <jaegeuk@...nel.org>, Chao Yu <chao@...nel.org>
CC:     <linux-kernel@...r.kernel.org>,
        <linux-f2fs-devel@...ts.sourceforge.net>
Subject: Re: [f2fs-dev] [PATCH] f2fs: do checkpoint in kill_sb

On 2018/7/10 4:36, Jaegeuk Kim wrote:
> On 07/09, Chao Yu wrote:
>> On 2018/7/7 9:20, Jaegeuk Kim wrote:
>>> When unmounting f2fs in force mode, we can get it stuck by io_schedule()
>>
>> force mode means force shutdown?
> 
> Yes.
> 
>>
>>> by some pending IOs in meta_inode.
>>>
>>> io_schedule+0xd/0x30
>>> wait_on_page_bit_common+0xc6/0x130
>>
>> Looks like a deadlock here? Does this mean we forget to submit cached bio in
>> somewhere?
> 
> I'm hitting this randomly, when running all the testcases in xfstests.
> I can't find the missing flow, and only get this during kill_sb.

I guess we need this before returning from ->writepage{,s}:

if (is_sbi_flag_set(sbi, SBI_IS_SHUTDOWN))
	f2fs_submit_merged_write()

How about trying this instead?

Thanks,

> 
>>
>> Thanks,
>>
>>> __filemap_fdatawait_range+0xbd/0x100
>>> filemap_fdatawait_keep_errors+0x15/0x40
>>> sync_inodes_sb+0x1cf/0x240
>>> sync_filesystem+0x52/0x90
>>> generic_shutdown_super+0x1d/0x110
>>> ceph_kill_sb+0x28/0x80 [ceph]
>>> deactivate_locked_super+0x35/0x60
>>> cleanup_mnt+0x36/0x70
>>> task_work_run+0x79/0xa0
>>> exit_to_usermode_loop+0x62/0x70
>>> do_syscall_64+0xdb/0xf0
>>> entry_SYSCALL_64_after_hwframe+0x44/0xa9
>>> 0xffffffffffffffff
>>>
>>> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
>>> ---
>>>  fs/f2fs/super.c | 16 +++++++++++++---
>>>  1 file changed, 13 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
>>> index 3995e926ba3a..1dc6809fac38 100644
>>> --- a/fs/f2fs/super.c
>>> +++ b/fs/f2fs/super.c
>>> @@ -3089,9 +3089,19 @@ static struct dentry *f2fs_mount(struct file_system_type *fs_type, int flags,
>>>  static void kill_f2fs_super(struct super_block *sb)
>>>  {
>>>  	if (sb->s_root) {
>>> -		set_sbi_flag(F2FS_SB(sb), SBI_IS_CLOSE);
>>> -		f2fs_stop_gc_thread(F2FS_SB(sb));
>>> -		f2fs_stop_discard_thread(F2FS_SB(sb));
>>> +		struct f2fs_sb_info *sbi = F2FS_SB(sb);
>>> +
>>> +		set_sbi_flag(sbi, SBI_IS_CLOSE);
>>> +		f2fs_stop_gc_thread(sbi);
>>> +		f2fs_stop_discard_thread(sbi);
>>> +
>>> +		if (is_sbi_flag_set(sbi, SBI_IS_DIRTY) ||
>>> +				!is_set_ckpt_flags(sbi, CP_UMOUNT_FLAG)) {
>>> +			struct cp_control cpc = {
>>> +				.reason = CP_UMOUNT,
>>> +			};
>>> +			f2fs_write_checkpoint(sbi, &cpc);
>>> +		}
>>>  	}
>>>  	kill_block_super(sb);
>>>  }
>>>
> 
> .
>