Re: [PATCH RFC 1/8] block: Introduce provisioning primitives

[Sarthak Kukreti <sarthakkukreti@chromium.org>]

On Fri, Sep 23, 2022 at 8:15 AM Mike Snitzer <snitzer@redhat.com> wrote:
>
> On Thu, Sep 15 2022 at 12:48P -0400,
> Sarthak Kukreti <sarthakkukreti@chromium.org> wrote:
>
> > From: Sarthak Kukreti <sarthakkukreti@chromium.org>
> >
> > Introduce block request REQ_OP_PROVISION. The intent of this request
> > is to request underlying storage to preallocate disk space for the given
> > block range. Block device that support this capability will export
> > a provision limit within their request queues.
> >
> > Signed-off-by: Sarthak Kukreti <sarthakkukreti@chromium.org>
> > ---
> >  block/blk-core.c          |  5 ++++
> >  block/blk-lib.c           | 55 +++++++++++++++++++++++++++++++++++++++
> >  block/blk-merge.c         | 17 ++++++++++++
> >  block/blk-settings.c      | 19 ++++++++++++++
> >  block/blk-sysfs.c         |  8 ++++++
> >  block/bounce.c            |  1 +
> >  include/linux/bio.h       |  6 +++--
> >  include/linux/blk_types.h |  5 +++-
> >  include/linux/blkdev.h    | 16 ++++++++++++
> >  9 files changed, 129 insertions(+), 3 deletions(-)
> >
> > diff --git a/block/blk-settings.c b/block/blk-settings.c
> > index 8bb9eef5310e..be79ad68b330 100644
> > --- a/block/blk-settings.c
> > +++ b/block/blk-settings.c
> > @@ -57,6 +57,7 @@ void blk_set_default_limits(struct queue_limits *lim)
> >       lim->misaligned = 0;
> >       lim->zoned = BLK_ZONED_NONE;
> >       lim->zone_write_granularity = 0;
> > +     lim->max_provision_sectors = 0;
> >  }
> >  EXPORT_SYMBOL(blk_set_default_limits);
> >
> > @@ -81,6 +82,7 @@ void blk_set_stacking_limits(struct queue_limits *lim)
> >       lim->max_dev_sectors = UINT_MAX;
> >       lim->max_write_zeroes_sectors = UINT_MAX;
> >       lim->max_zone_append_sectors = UINT_MAX;
> > +     lim->max_provision_sectors = UINT_MAX;
> >  }
> >  EXPORT_SYMBOL(blk_set_stacking_limits);
> >
>
> Please work through the blk_stack_limits() implementation too (simple
> min_not_zero?).
>
(Sorry, I might have misunderstood what you meant) Doesn't the chunk
at L572 handle this:


@@ -572,6 +588,9 @@ int blk_stack_limits(struct queue_limits *t,
struct queue_limits *b,
        t->max_segment_size = min_not_zero(t->max_segment_size,
                                           b->max_segment_size);

+       t->max_provision_sectors = min_not_zero(t->max_provision_sectors,
+                                               b->max_provision_sectors);
+
        t->misaligned |= b->misaligned;