linux-kernel - RE:(2) (2) [f2fs-dev] [PATCH] Revert "f2fs: use flush command instead of FUA for zoned device"

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Message-ID: <20240620072218epcms2p11597e482b28804dd5f66b9d42a21b22f@epcms2p1>
Date: Thu, 20 Jun 2024 16:22:18 +0900
From: Daejun Park <daejun7.park@...sung.com>
To: Chao Yu <chao@...nel.org>, "jaegeuk@...nel.org" <jaegeuk@...nel.org>,
	Wenjie Cheng <cwjhust@...il.com>
CC: "qwjhust@...il.com" <qwjhust@...il.com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "linux-f2fs-devel@...ts.sourceforge.net"
	<linux-f2fs-devel@...ts.sourceforge.net>, Daejun Park
	<daejun7.park@...sung.com>
Subject: RE:(2) (2) [f2fs-dev] [PATCH] Revert
 "f2fs: use flush command instead of FUA for zoned device"

>On 2024/6/20 13:56, Daejun Park wrote:
>> Hi Chao,
>>
>>> Jaegeuk,
>>>
>>> Quoted commit message from commit c550e25bca66 ("f2fs: use flush command
>>> instead of FUA for zoned device")
>>> "
>>> The block layer for zoned disk can reorder the FUA'ed IOs. Let's use flush
>>> command to keep the write order.
>>> "
>>>
>>> It seems mq-deadline use fifo queue and make queue depth of zone device
>>> as 1 to IO order, so why FUA'ed write node IOs can be reordered by block
>>> layer?
>>
>> While other writes are aligned by the mq-deadline, write with FUA is not passed
>> to the scheduler but handled at the block layer.
>
>Hi Daejun,
>
>IIUC, do you mean write w/ FUA may be handled directly in below path?
>
>- blk_mq_submit_bio
>  - op_is_flush && blk_insert_flush

Hi Chao,

Yes, I think the path caused an unaligned write when the zone lock was
being applied by mq-deadline.

>
>Thanks,
>
>>
>> Thanks,
>> Daejun
>>
>>>
>>> Thanks,
>>>
>>> On 2024/6/14 8:48, Wenjie Cheng wrote:
>>>> This reverts commit c550e25bca660ed2554cbb48d32b82d0bb98e4b1.
>>>>
>>>> Commit c550e25bca660ed2554cbb48d32b82d0bb98e4b1 ("f2fs: use flush
>>>> command instead of FUA for zoned device") used additional flush
>>>> command to keep write order.
>>>>
>>>> Since Commit dd291d77cc90eb6a86e9860ba8e6e38eebd57d12 ("block:
>>>> Introduce zone write plugging") has enabled the block layer to
>>>> handle this order issue, there is no need to use flush command.
>>>>
>>>> Signed-off-by: Wenjie Cheng <cwjhust@...il.com>
>>>> ---
>>>>    fs/f2fs/file.c 3 +--
>>>>    fs/f2fs/node.c 2 +-
>>>>    2 files changed, 2 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>>>> index eae2e7908072..f08e6208e183 100644
>>>> --- a/fs/f2fs/file.c
>>>> +++ b/fs/f2fs/file.c
>>>> @@ -372,8 +372,7 @@ static int f2fs_do_sync_file(struct file *file, loff_t start, loff_t end,
>>>>             f2fs_remove_ino_entry(sbi, ino, APPEND_INO);
>>>>             clear_inode_flag(inode, FI_APPEND_WRITE);
>>>>    flush_out:
>>>> -        if ((!atomic && F2FS_OPTION(sbi).fsync_mode != FSYNC_MODE_NOBARRIER)
>>>> -            (atomic && !test_opt(sbi, NOBARRIER) && f2fs_sb_has_blkzoned(sbi)))
>>>> +        if (!atomic && F2FS_OPTION(sbi).fsync_mode != FSYNC_MODE_NOBARRIER)
>>>>                     ret = f2fs_issue_flush(sbi, inode->i_ino);
>>>>             if (!ret) {
>>>>                     f2fs_remove_ino_entry(sbi, ino, UPDATE_INO);
>>>> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
>>>> index 144f9f966690..c45d341dcf6e 100644
>>>> --- a/fs/f2fs/node.c
>>>> +++ b/fs/f2fs/node.c
>>>> @@ -1631,7 +1631,7 @@ static int __write_node_page(struct page *page, bool atomic, bool *submitted,
>>>>                     goto redirty_out;
>>>>             }
>>>> 
>>>> -        if (atomic && !test_opt(sbi, NOBARRIER) && !f2fs_sb_has_blkzoned(sbi))
>>>> +        if (atomic && !test_opt(sbi, NOBARRIER))
>>>>                     fio.op_flags = REQ_PREFLUSH REQ_FUA;
>>>> 
>>>>             /* should add to global list before clearing PAGECACHE status */