linux-kernel - Re: [PATCH v2 1/2] f2fs: Apply bio flags to direct I/O

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Message-ID: <CALBjLoDVk976imbZ8-G97jD0aHE2yzL5y-covCmp7V-97aEg6g@mail.gmail.com>
Date: Mon, 30 Jun 2025 16:02:20 -0700
From: Daniel Lee <chullee@...gle.com>
To: Chao Yu <chao@...nel.org>
Cc: Jaegeuk Kim <jaegeuk@...nel.org>, linux-f2fs-devel@...ts.sourceforge.net, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] f2fs: Apply bio flags to direct I/O

On Mon, Jun 16, 2025 at 5:41 AM Chao Yu <chao@...nel.org> wrote:
>
> On 6/15/25 22:42, Daniel Lee wrote:
> > Bio flags like REQ_PRIO, REQ_META, and REQ_FUA, determined by
> > f2fs_io_flags(), were not being applied to direct I/O (DIO) writes.
> > This meant that DIO writes would not respect filesystem-level hints
> > (for REQ_META/FUA) or inode-level hints (like F2FS_IOPRIO_WRITE).
> >
> > This patch refactors f2fs_io_flags() to use a direct inode pointer
> > instead of deriving it from a page. The function is then called from
> > the DIO write path, ensuring that bio flags are handled consistently
> > for both buffered and DIO writes.
> >
> > Signed-off-by: Daniel Lee <chullee@...gle.com>
> > ---
> >  fs/f2fs/data.c | 10 +++++-----
> >  fs/f2fs/f2fs.h |  1 +
> >  fs/f2fs/file.c | 11 +++++++++++
> >  3 files changed, 17 insertions(+), 5 deletions(-)
> >
> > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> > index 31e892842625..71dde494b892 100644
> > --- a/fs/f2fs/data.c
> > +++ b/fs/f2fs/data.c
> > @@ -416,10 +416,9 @@ int f2fs_target_device_index(struct f2fs_sb_info *sbi, block_t blkaddr)
> >       return 0;
> >  }
> >
> > -static blk_opf_t f2fs_io_flags(struct f2fs_io_info *fio)
> > +blk_opf_t f2fs_io_flags(struct f2fs_io_info *fio, struct inode *inode)
> >  {
> >       unsigned int temp_mask = GENMASK(NR_TEMP_TYPE - 1, 0);
> > -     struct folio *fio_folio = page_folio(fio->page);
> >       unsigned int fua_flag, meta_flag, io_flag;
> >       blk_opf_t op_flags = 0;
> >
> > @@ -446,8 +445,8 @@ static blk_opf_t f2fs_io_flags(struct f2fs_io_info *fio)
> >       if (BIT(fio->temp) & fua_flag)
> >               op_flags |= REQ_FUA;
> >
> > -     if (fio->type == DATA &&
> > -         F2FS_I(fio_folio->mapping->host)->ioprio_hint == F2FS_IOPRIO_WRITE)
> > +     if (inode && fio->type == DATA &&
> > +         F2FS_I(inode)->ioprio_hint == F2FS_IOPRIO_WRITE)
> >               op_flags |= REQ_PRIO;
> >
> >       return op_flags;
> > @@ -459,10 +458,11 @@ static struct bio *__bio_alloc(struct f2fs_io_info *fio, int npages)
> >       struct block_device *bdev;
> >       sector_t sector;
> >       struct bio *bio;
> > +     struct inode *inode = fio->page ? fio->page->mapping->host : NULL;
>
> fio->page will always be true now? We can pass fio->page->mapping->host to f2fs_io_flags()
> directly?
>
> Thanks,

Thanks for the insight. Since fio->page is always non-null here, I'll
remove the unnecessary code.

>
> >
> >       bdev = f2fs_target_device(sbi, fio->new_blkaddr, &sector);
> >       bio = bio_alloc_bioset(bdev, npages,
> > -                             fio->op | fio->op_flags | f2fs_io_flags(fio),
> > +                             fio->op | fio->op_flags | f2fs_io_flags(fio, inode),
> >                               GFP_NOIO, &f2fs_bioset);
> >       bio->bi_iter.bi_sector = sector;
> >       if (is_read_io(fio->op)) {
> > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> > index 9333a22b9a01..3e02687c1b58 100644
> > --- a/fs/f2fs/f2fs.h
> > +++ b/fs/f2fs/f2fs.h
> > @@ -3972,6 +3972,7 @@ void f2fs_submit_page_write(struct f2fs_io_info *fio);
> >  struct block_device *f2fs_target_device(struct f2fs_sb_info *sbi,
> >               block_t blk_addr, sector_t *sector);
> >  int f2fs_target_device_index(struct f2fs_sb_info *sbi, block_t blkaddr);
> > +blk_opf_t f2fs_io_flags(struct f2fs_io_info *fio, struct inode *inode);
> >  void f2fs_set_data_blkaddr(struct dnode_of_data *dn, block_t blkaddr);
> >  void f2fs_update_data_blkaddr(struct dnode_of_data *dn, block_t blkaddr);
> >  int f2fs_reserve_new_blocks(struct dnode_of_data *dn, blkcnt_t count);
> > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > index 696131e655ed..3eb40d7bf602 100644
> > --- a/fs/f2fs/file.c
> > +++ b/fs/f2fs/file.c
> > @@ -5015,6 +5015,17 @@ static void f2fs_dio_write_submit_io(const struct iomap_iter *iter,
> >       enum log_type type = f2fs_rw_hint_to_seg_type(sbi, inode->i_write_hint);
> >       enum temp_type temp = f2fs_get_segment_temp(sbi, type);
> >
> > +     /* if fadvise set to hot, override the temperature */
> > +     struct f2fs_io_info fio = {
> > +             .sbi = sbi,
> > +             .type = DATA,
> > +             .op = REQ_OP_WRITE,
> > +             .temp = file_is_hot(inode) ? HOT : temp,
> > +             .op_flags = bio->bi_opf,
> > +             .page = NULL,
> > +     };
> > +     bio->bi_opf |= f2fs_io_flags(&fio, inode);
> > +
> >       bio->bi_write_hint = f2fs_io_type_to_rw_hint(sbi, DATA, temp);
> >       submit_bio(bio);
> >  }
>