Re: [PATCH v6 4/6] dm,dax: Add dax zero_page_range operation

[Dan Williams <dan.j.williams@intel.com>]

[ Add Mike ]

On Fri, Feb 28, 2020 at 8:35 AM Vivek Goyal <vgoyal@redhat.com> wrote:
>
> This patch adds support for dax zero_page_range operation to dm targets.

Mike,

Sorry, I should have pinged you earlier, but could you take a look at
this patch and ack it if it looks ok to go through the nvdimm tree
with the rest of the series?

>
> Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
> ---
>  drivers/md/dm-linear.c        | 18 ++++++++++++++++++
>  drivers/md/dm-log-writes.c    | 17 +++++++++++++++++
>  drivers/md/dm-stripe.c        | 23 +++++++++++++++++++++++
>  drivers/md/dm.c               | 30 ++++++++++++++++++++++++++++++
>  include/linux/device-mapper.h |  3 +++
>  5 files changed, 91 insertions(+)
>
> diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
> index 8d07fdf63a47..e1db43446327 100644
> --- a/drivers/md/dm-linear.c
> +++ b/drivers/md/dm-linear.c
> @@ -201,10 +201,27 @@ static size_t linear_dax_copy_to_iter(struct dm_target *ti, pgoff_t pgoff,
>         return dax_copy_to_iter(dax_dev, pgoff, addr, bytes, i);
>  }
>
> +static int linear_dax_zero_page_range(struct dm_target *ti, pgoff_t pgoff,
> +                                     size_t nr_pages)
> +{
> +       int ret;
> +       struct linear_c *lc = ti->private;
> +       struct block_device *bdev = lc->dev->bdev;
> +       struct dax_device *dax_dev = lc->dev->dax_dev;
> +       sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
> +
> +       dev_sector = linear_map_sector(ti, sector);
> +       ret = bdev_dax_pgoff(bdev, dev_sector, nr_pages << PAGE_SHIFT, &pgoff);
> +       if (ret)
> +               return ret;
> +       return dax_zero_page_range(dax_dev, pgoff, nr_pages);
> +}
> +
>  #else
>  #define linear_dax_direct_access NULL
>  #define linear_dax_copy_from_iter NULL
>  #define linear_dax_copy_to_iter NULL
> +#define linear_dax_zero_page_range NULL
>  #endif
>
>  static struct target_type linear_target = {
> @@ -226,6 +243,7 @@ static struct target_type linear_target = {
>         .direct_access = linear_dax_direct_access,
>         .dax_copy_from_iter = linear_dax_copy_from_iter,
>         .dax_copy_to_iter = linear_dax_copy_to_iter,
> +       .dax_zero_page_range = linear_dax_zero_page_range,
>  };
>
>  int __init dm_linear_init(void)
> diff --git a/drivers/md/dm-log-writes.c b/drivers/md/dm-log-writes.c
> index 99721c76225d..8ea20b56b4d6 100644
> --- a/drivers/md/dm-log-writes.c
> +++ b/drivers/md/dm-log-writes.c
> @@ -994,10 +994,26 @@ static size_t log_writes_dax_copy_to_iter(struct dm_target *ti,
>         return dax_copy_to_iter(lc->dev->dax_dev, pgoff, addr, bytes, i);
>  }
>
> +static int log_writes_dax_zero_page_range(struct dm_target *ti, pgoff_t pgoff,
> +                                         size_t nr_pages)
> +{
> +       int ret;
> +       struct log_writes_c *lc = ti->private;
> +       sector_t sector = pgoff * PAGE_SECTORS;
> +
> +       ret = bdev_dax_pgoff(lc->dev->bdev, sector, nr_pages << PAGE_SHIFT,
> +                            &pgoff);
> +       if (ret)
> +               return ret;
> +       return dax_zero_page_range(lc->dev->dax_dev, pgoff,
> +                                  nr_pages << PAGE_SHIFT);
> +}
> +
>  #else
>  #define log_writes_dax_direct_access NULL
>  #define log_writes_dax_copy_from_iter NULL
>  #define log_writes_dax_copy_to_iter NULL
> +#define log_writes_dax_zero_page_range NULL
>  #endif
>
>  static struct target_type log_writes_target = {
> @@ -1016,6 +1032,7 @@ static struct target_type log_writes_target = {
>         .direct_access = log_writes_dax_direct_access,
>         .dax_copy_from_iter = log_writes_dax_copy_from_iter,
>         .dax_copy_to_iter = log_writes_dax_copy_to_iter,
> +       .dax_zero_page_range = log_writes_dax_zero_page_range,
>  };
>
>  static int __init dm_log_writes_init(void)
> diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
> index 63bbcc20f49a..fa813c0f993d 100644
> --- a/drivers/md/dm-stripe.c
> +++ b/drivers/md/dm-stripe.c
> @@ -360,10 +360,32 @@ static size_t stripe_dax_copy_to_iter(struct dm_target *ti, pgoff_t pgoff,
>         return dax_copy_to_iter(dax_dev, pgoff, addr, bytes, i);
>  }
>
> +static int stripe_dax_zero_page_range(struct dm_target *ti, pgoff_t pgoff,
> +                                     size_t nr_pages)
> +{
> +       int ret;
> +       sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
> +       struct stripe_c *sc = ti->private;
> +       struct dax_device *dax_dev;
> +       struct block_device *bdev;
> +       uint32_t stripe;
> +
> +       stripe_map_sector(sc, sector, &stripe, &dev_sector);
> +       dev_sector += sc->stripe[stripe].physical_start;
> +       dax_dev = sc->stripe[stripe].dev->dax_dev;
> +       bdev = sc->stripe[stripe].dev->bdev;
> +
> +       ret = bdev_dax_pgoff(bdev, dev_sector, nr_pages << PAGE_SHIFT, &pgoff);
> +       if (ret)
> +               return ret;
> +       return dax_zero_page_range(dax_dev, pgoff, nr_pages);
> +}
> +
>  #else
>  #define stripe_dax_direct_access NULL
>  #define stripe_dax_copy_from_iter NULL
>  #define stripe_dax_copy_to_iter NULL
> +#define stripe_dax_zero_page_range NULL
>  #endif
>
>  /*
> @@ -486,6 +508,7 @@ static struct target_type stripe_target = {
>         .direct_access = stripe_dax_direct_access,
>         .dax_copy_from_iter = stripe_dax_copy_from_iter,
>         .dax_copy_to_iter = stripe_dax_copy_to_iter,
> +       .dax_zero_page_range = stripe_dax_zero_page_range,
>  };
>
>  int __init dm_stripe_init(void)
> diff --git a/drivers/md/dm.c b/drivers/md/dm.c
> index b89f07ee2eff..aa72d9e757c1 100644
> --- a/drivers/md/dm.c
> +++ b/drivers/md/dm.c
> @@ -1198,6 +1198,35 @@ static size_t dm_dax_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff,
>         return ret;
>  }
>
> +static int dm_dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff,
> +                                 size_t nr_pages)
> +{
> +       struct mapped_device *md = dax_get_private(dax_dev);
> +       sector_t sector = pgoff * PAGE_SECTORS;
> +       struct dm_target *ti;
> +       int ret = -EIO;
> +       int srcu_idx;
> +
> +       ti = dm_dax_get_live_target(md, sector, &srcu_idx);
> +
> +       if (!ti)
> +               goto out;
> +       if (WARN_ON(!ti->type->dax_zero_page_range)) {
> +               /*
> +                * ->zero_page_range() is mandatory dax operation. If we are
> +                *  here, something is wrong.
> +                */
> +               dm_put_live_table(md, srcu_idx);
> +               goto out;
> +       }
> +       ret = ti->type->dax_zero_page_range(ti, pgoff, nr_pages);
> +
> + out:
> +       dm_put_live_table(md, srcu_idx);
> +
> +       return ret;
> +}
> +
>  /*
>   * A target may call dm_accept_partial_bio only from the map routine.  It is
>   * allowed for all bio types except REQ_PREFLUSH, REQ_OP_ZONE_RESET,
> @@ -3199,6 +3228,7 @@ static const struct dax_operations dm_dax_ops = {
>         .dax_supported = dm_dax_supported,
>         .copy_from_iter = dm_dax_copy_from_iter,
>         .copy_to_iter = dm_dax_copy_to_iter,
> +       .zero_page_range = dm_dax_zero_page_range,
>  };
>
>  /*
> diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
> index 475668c69dbc..af48d9da3916 100644
> --- a/include/linux/device-mapper.h
> +++ b/include/linux/device-mapper.h
> @@ -141,6 +141,8 @@ typedef long (*dm_dax_direct_access_fn) (struct dm_target *ti, pgoff_t pgoff,
>                 long nr_pages, void **kaddr, pfn_t *pfn);
>  typedef size_t (*dm_dax_copy_iter_fn)(struct dm_target *ti, pgoff_t pgoff,
>                 void *addr, size_t bytes, struct iov_iter *i);
> +typedef int (*dm_dax_zero_page_range_fn)(struct dm_target *ti, pgoff_t pgoff,
> +               size_t nr_pages);
>  #define PAGE_SECTORS (PAGE_SIZE / 512)
>
>  void dm_error(const char *message);
> @@ -195,6 +197,7 @@ struct target_type {
>         dm_dax_direct_access_fn direct_access;
>         dm_dax_copy_iter_fn dax_copy_from_iter;
>         dm_dax_copy_iter_fn dax_copy_to_iter;
> +       dm_dax_zero_page_range_fn dax_zero_page_range;
>
>         /* For internal device-mapper use. */
>         struct list_head list;
> --
> 2.20.1
>
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