On Thu, 7 Dec 2023, Eric Biggers wrote:
> On Wed, Dec 06, 2023 at 07:39:35PM +0800, Hongyu Jin wrote:
> > From: Hongyu Jin <[email protected]>
> >
> > when read FEC and hash from disk, I/O priority are inconsistent
> > with data block and blocked by other I/O with low I/O priority.
> >
> > Add dm_bufio_prefetch_by_ioprio() and dm_bufio_read_by_ioprio(),
> > can pecific I/O priority for some I/O.
> > Make I/O for FEC and hash has same I/O priority with data I/O.
Hi Hongyu,
+1 for the feature, thank you for cleaning up ioprio in device mapper!
A few years ago we proposed a similar prior patch in dm-crypt; however, it
was never committed, and I did not have the time to shepherd it through.
Maybe this has since been addressed in some other way, or perhaps your
work solves what we were doing with dm-crypt; either way, here is the
link to that thread incase it is relevant to your work:
https://www.mail-archive.com/[email protected]/msg03828.html
I look forward to seeing all (or at least the most common) device mapper
targets cleanly support ioprio.
Cheers,
--
Eric Wheeler
> > Co-developed-by: Yibin Ding <[email protected]>
> > Signed-off-by: Yibin Ding <[email protected]>
> > Signed-off-by: Hongyu Jin <[email protected]>
> >
> > ---
> > Changes in v2:
> > - Add ioprio field in struct dm_io_region
> > - Initial struct dm_io_region::ioprio to IOPRIO_DEFAULT
> > - Add two interface
> > ---
> > drivers/md/dm-bufio.c | 50 ++++++++++++++++++++++-----------
> > drivers/md/dm-integrity.c | 5 ++++
> > drivers/md/dm-io.c | 1 +
> > drivers/md/dm-log.c | 1 +
> > drivers/md/dm-raid1.c | 2 ++
> > drivers/md/dm-snap-persistent.c | 2 ++
> > drivers/md/dm-verity-fec.c | 3 +-
> > drivers/md/dm-verity-target.c | 10 +++++--
> > drivers/md/dm-writecache.c | 4 +++
> > include/linux/dm-bufio.h | 6 ++++
> > include/linux/dm-io.h | 2 ++
> > 11 files changed, 66 insertions(+), 20 deletions(-)
>
> Changing so many things in one patch should be avoided if possible. Is there
> a
> way to split this patch up? Maybe first add ioprio support to dm-io, then add
> ioprio support to dm-bufio, then make dm-verity set the correct ioprio?
>
> > void *dm_bufio_read(struct dm_bufio_client *c, sector_t block,
> > struct dm_buffer **bp)
> > +{
> > + return dm_bufio_read_by_ioprio(c, block, bp, IOPRIO_DEFAULT);
> > +}
> > +EXPORT_SYMBOL_GPL(dm_bufio_read);
> > +
> > +void *dm_bufio_read_by_ioprio(struct dm_bufio_client *c, sector_t block,
> > + struct dm_buffer **bp, unsigned short ioprio)
> > {
> > if (WARN_ON_ONCE(dm_bufio_in_request()))
> > return ERR_PTR(-EINVAL);
> >
> > - return new_read(c, block, NF_READ, bp);
> > + return new_read(c, block, NF_READ, bp, ioprio);
> > }
> > -EXPORT_SYMBOL_GPL(dm_bufio_read);
> > +EXPORT_SYMBOL_GPL(dm_bufio_read_by_ioprio);
> >
> > void *dm_bufio_new(struct dm_bufio_client *c, sector_t block,
> > struct dm_buffer **bp)
> > @@ -1909,12 +1918,19 @@ void *dm_bufio_new(struct dm_bufio_client *c,
> > sector_t block,
> > if (WARN_ON_ONCE(dm_bufio_in_request()))
> > return ERR_PTR(-EINVAL);
> >
> > - return new_read(c, block, NF_FRESH, bp);
> > + return new_read(c, block, NF_FRESH, bp, IOPRIO_DEFAULT);
> > }
> > EXPORT_SYMBOL_GPL(dm_bufio_new);
> >
> > void dm_bufio_prefetch(struct dm_bufio_client *c,
> > sector_t block, unsigned int n_blocks)
> > +{
> > + return dm_bufio_prefetch_by_ioprio(c, block, n_blocks, IOPRIO_DEFAULT);
> > +}
> > +EXPORT_SYMBOL_GPL(dm_bufio_prefetch);
> > +
> > +void dm_bufio_prefetch_by_ioprio(struct dm_bufio_client *c,
> > + sector_t block, unsigned int n_blocks, unsigned short
> > ioprio)
>
> I think it would be cleaner to just add the ioprio parameter to
> dm_bufio_read()
> and dm_bufio_prefetch(), instead of adding new functions.
>
> > diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c
> > index 26adcfea0302..5945ac1dfdff 100644
> > --- a/drivers/md/dm-verity-target.c
> > +++ b/drivers/md/dm-verity-target.c
> > @@ -51,6 +51,7 @@ static DEFINE_STATIC_KEY_FALSE(use_tasklet_enabled);
> > struct dm_verity_prefetch_work {
> > struct work_struct work;
> > struct dm_verity *v;
> > + struct dm_verity_io *io;
> > sector_t block;
> > unsigned int n_blocks;
> > };
>
> Isn't it possible for 'io' to complete and be freed while the prefetch work is
> still running?
>
> - Eric
>
>
