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

[Chao Yu]

On 2024/6/20 15:56, Daejun Park wrote:
> > On 2024/6/20 15:22, Daejun Park wrote:
> > > > 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.
> >
> > But, blk_insert_flush() may return false due to policy should be
> > REQ_FSEQ_DATA or REQ_FSEQ_DATA REQ_FSEQ_POSTFLUSH, then
> > blk_mq_insert_request() after blk_insert_flush() will be called?
>
> I was just discussing the handling of FUAs in commit c550e25bca66,
> which is not an issue in the current code as FUAs are handled correctly.

Yup, I think it needs to be reverted. :)

Thanks,

> Thanks,
>
>
> > Thanks,
> >
> > > > 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@xxxxxxxxx>
> > > > > > > ---
> > > > > > >        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 */