On Sat, May 06 2023 at  2:29P -0400,
Sarthak Kukreti <sarthakkukr...@chromium.org> wrote:

> dm-thinpool uses the provision request to provision
> blocks for a dm-thin device. dm-thinpool currently does not
> pass through REQ_OP_PROVISION to underlying devices.
> 
> For shared blocks, provision requests will break sharing and copy the
> contents of the entire block. Additionally, if 'skip_block_zeroing'
> is not set, dm-thin will opt to zero out the entire range as a part
> of provisioning.
> 
> Signed-off-by: Sarthak Kukreti <sarthakkukr...@chromium.org>
> ---
>  drivers/md/dm-thin.c | 70 +++++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 66 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
> index 2b13c949bd72..3f94f53ac956 100644
> --- a/drivers/md/dm-thin.c
> +++ b/drivers/md/dm-thin.c
...
> @@ -4114,6 +4171,8 @@ static void pool_io_hints(struct dm_target *ti, struct 
> queue_limits *limits)
>        * The pool uses the same discard limits as the underlying data
>        * device.  DM core has already set this up.
>        */
> +
> +     limits->max_provision_sectors = pool->sectors_per_block;

Just noticed that setting limits->max_provision_sectors needs to move
above pool_io_hints code that sets up discards -- otherwise the early
return from if (!pt->adjusted_pf.discard_enabled) will cause setting
max_provision_sectors to be skipped.

Here is a roll up of the fixes that need to be folded into this patch:

diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 3f94f53ac956..90c8e36cb327 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -4151,6 +4151,8 @@ static void pool_io_hints(struct dm_target *ti, struct 
queue_limits *limits)
                blk_limits_io_opt(limits, pool->sectors_per_block << 
SECTOR_SHIFT);
        }
 
+       limits->max_provision_sectors = pool->sectors_per_block;
+
        /*
         * pt->adjusted_pf is a staging area for the actual features to use.
         * They get transferred to the live pool in bind_control_target()
@@ -4171,8 +4173,6 @@ static void pool_io_hints(struct dm_target *ti, struct 
queue_limits *limits)
         * The pool uses the same discard limits as the underlying data
         * device.  DM core has already set this up.
         */
-
-       limits->max_provision_sectors = pool->sectors_per_block;
 }
 
 static struct target_type pool_target = {
@@ -4349,6 +4349,7 @@ static int thin_ctr(struct dm_target *ti, unsigned int 
argc, char **argv)
 
        ti->num_provision_bios = 1;
        ti->provision_supported = true;
+       ti->max_provision_granularity = true;
 
        mutex_unlock(&dm_thin_pool_table.mutex);
 

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