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.
>
> > 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
