On Fri, May 27, 2022 at 06:06:08PM -0700, Jaegeuk Kim wrote:
> On 05/27, Eric Biggers wrote:
> > [+Cc linux-block for FUA, and linux-xfs for iomap]
> >
> > On Fri, May 27, 2022 at 01:59:55PM -0700, Jaegeuk Kim wrote:
> > > Some UFS storage gives slower performance on FUA than write+cache_flush.
> > > Let's give a way to manage it.
> > >
> > > Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
> >
> > Should the driver even be saying that it has FUA support in this case? If the
> > driver didn't claim FUA support, that would also solve this problem.
>
> I think there's still some benefit to use FUA such as small chunk writes
> for checkpoint.
>
> >
> > > ---
> > > Documentation/ABI/testing/sysfs-fs-f2fs | 7 +++++++
> > > fs/f2fs/data.c | 2 ++
> > > fs/f2fs/f2fs.h | 1 +
> > > fs/f2fs/sysfs.c | 2 ++
> > > 4 files changed, 12 insertions(+)
> > >
> > > diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
> > > index 9b583dd0298b..cd96b09d7182 100644
> > > --- a/Documentation/ABI/testing/sysfs-fs-f2fs
> > > +++ b/Documentation/ABI/testing/sysfs-fs-f2fs
> > > @@ -434,6 +434,7 @@ Date: April 2020
> > > Contact: "Daeho Jeong" <daehojeong@xxxxxxxxxx>
> > > Description: Give a way to change iostat_period time. 3secs by default.
> > > The new iostat trace gives stats gap given the period.
> > > +
> > > What: /sys/fs/f2fs/<disk>/max_io_bytes
> > > Date: December 2020
> > > Contact: "Jaegeuk Kim" <jaegeuk@xxxxxxxxxx>
> > > @@ -442,6 +443,12 @@ Description: This gives a control to limit the bio size in f2fs.
> > > whereas, if it has a certain bytes value, f2fs won't submit a
> > > bio larger than that size.
> > >
> > > +What: /sys/fs/f2fs/<disk>/no_fua_dio
> > > +Date: May 2022
> > > +Contact: "Jaegeuk Kim" <jaegeuk@xxxxxxxxxx>
> > > +Description: This gives a signal to iomap, which should not use FUA for
> > > + direct IOs. Default: 0.
> >
> > iomap is an implementation detail, so it shouldn't be mentioned in UAPI
> > documentation. UAPI documentation should describe user-visible behavior only.
>
> Ok.
>
> >
> > > +
> > > What: /sys/fs/f2fs/<disk>/stat/sb_status
> > > Date: December 2020
> > > Contact: "Chao Yu" <yuchao0@xxxxxxxxxx>
> > > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> > > index f5f2b7233982..23486486eab2 100644
> > > --- a/fs/f2fs/data.c
> > > +++ b/fs/f2fs/data.c
> > > @@ -4153,6 +4153,8 @@ static int f2fs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> > > if ((inode->i_state & I_DIRTY_DATASYNC) ||
> > > offset + length > i_size_read(inode))
> > > iomap->flags |= IOMAP_F_DIRTY;
> > > + if (F2FS_I_SB(inode)->no_fua_dio)
> > > + iomap->flags |= IOMAP_F_DIRTY;
> >
> > This is overloading the IOMAP_F_DIRTY flag to mean something other than dirty.
> > Perhaps this flag needs to be renamed, or a new flag should be added?
>
> I'm not sure it's acceptable to add another flag for f2fs only.
I think Al and willy have been throwing around patches to tell
iomap_dio_rw or someone that the caller will handle cache flushes and
that it shouldn't initiate them on its own; would that help here?
--D
> >
> > > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> > > index e10838879538..c2400ea0080b 100644
> > > --- a/fs/f2fs/f2fs.h
> > > +++ b/fs/f2fs/f2fs.h
> > > @@ -1671,6 +1671,7 @@ struct f2fs_sb_info {
> > > int dir_level; /* directory level */
> > > int readdir_ra; /* readahead inode in readdir */
> > > u64 max_io_bytes; /* max io bytes to merge IOs */
> > > + int no_fua_dio; /* avoid FUA in DIO */
> >
> > Make this a bool?
>
> Done.
>
> >
> > > diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
> > > index 4c50aedd5144..24d628ca92cc 100644
> > > --- a/fs/f2fs/sysfs.c
> > > +++ b/fs/f2fs/sysfs.c
> > > @@ -771,6 +771,7 @@ F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, iostat_period_ms, iostat_period_ms);
> > > #endif
> > > F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, readdir_ra, readdir_ra);
> > > F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, max_io_bytes, max_io_bytes);
> > > +F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, no_fua_dio, no_fua_dio);
> > > F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, gc_pin_file_thresh, gc_pin_file_threshold);
> > > F2FS_RW_ATTR(F2FS_SBI, f2fs_super_block, extension_list, extension_list);
> > > #ifdef CONFIG_F2FS_FAULT_INJECTION
> > > @@ -890,6 +891,7 @@ static struct attribute *f2fs_attrs[] = {
> > > #endif
> > > ATTR_LIST(readdir_ra),
> > > ATTR_LIST(max_io_bytes),
> > > + ATTR_LIST(no_fua_dio),
> >
> > Where is it validated that only valid values (0 or 1) can be written to this
> > file?
>
> Added.
>
> >
> > - Eric
