[dm-devel] [RFC PATCH v3 1/2] block: add simple copy support

[Selva Jove]

On Fri, Dec 11, 2020 at 9:56 PM Johannes Thumshirn
<Johannes.Thumshirn at wdc.com> wrote:
>
> On 11/12/2020 15:57, SelvaKumar S wrote:
> [...]
> > +int blk_copy_emulate(struct block_device *bdev, struct blk_copy_payload *payload,
> > +             gfp_t gfp_mask)
> > +{
> > +     struct request_queue *q = bdev_get_queue(bdev);
> > +     struct bio *bio;
> > +     void *buf = NULL;
> > +     int i, nr_srcs, max_range_len, ret, cur_dest, cur_size;
> > +
> > +     nr_srcs = payload->copy_range;
> > +     max_range_len = q->limits.max_copy_range_sectors << SECTOR_SHIFT;
> > +     cur_dest = payload->dest;
> > +     buf = kvmalloc(max_range_len, GFP_ATOMIC);
>
> Why GFP_ATOMIC and not the passed in gfp_mask? Especially as this is a kvmalloc()
> which has the potential to grow quite big.
>
> > +int __blkdev_issue_copy(struct block_device *bdev, sector_t dest,
> > +             sector_t nr_srcs, struct range_entry *rlist, gfp_t gfp_mask,
> > +             int flags, struct bio **biop)
> > +{
>
> [...]
>
> > +     total_size = struct_size(payload, range, nr_srcs);
> > +     payload = kmalloc(total_size, GFP_ATOMIC | __GFP_NOWARN);
>
> Same here.
>
>
> > diff --git a/block/ioctl.c b/block/ioctl.c
> > index 6b785181344f..a4a507d85e56 100644
> > --- a/block/ioctl.c
> > +++ b/block/ioctl.c
> > @@ -142,6 +142,47 @@ static int blk_ioctl_discard(struct block_device *bdev, fmode_t mode,
> >                                   GFP_KERNEL, flags);
> >  }
> >
> > +static int blk_ioctl_copy(struct block_device *bdev, fmode_t mode,
> > +             unsigned long arg, unsigned long flags)
> > +{
>
> [...]
>
> > +
> > +     rlist = kmalloc_array(crange.nr_range, sizeof(*rlist),
> > +                     GFP_ATOMIC | __GFP_NOWARN);
>
> And here. I think this one can even be GFP_KERNEL.
>
>
>

Thanks. Will fix this.