Re: [PATCH RFC v11 12/19] dm: add finalize hook to target_type

Paul Moore
2023-10-24T03:52:34Z

On Oct 4, 2023 Fan Wu <wufan@linux.microsoft.com> wrote:
>
> This patch adds a target finalize hook.
>
> The hook is triggered just before activating an inactive table of a
> mapped device. If it returns an error the __bind get cancelled.
>
> The dm-verity target will use this hook to attach the dm-verity's
> roothash metadata to the block_device struct of the mapped device.
>
> Signed-off-by: Fan Wu <wufan@linux.microsoft.com>
> ---
> v1-v10:
> + Not present
> ---
> drivers/md/dm.c | 12 ++++++++++++
> include/linux/device-mapper.h | 7 +++++++
> 2 files changed, 19 insertions(+)

We need an ACK and confirmation from Alasdair and/or Mike that this
is the right approach.

> diff --git a/drivers/md/dm.c b/drivers/md/dm.c
> index 64a1f306c96c..3be9cc35306d 100644
> --- a/drivers/md/dm.c
> +++ b/drivers/md/dm.c
> @@ -2239,6 +2239,18 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
> goto out;
> }
>
> + for (unsigned int i = 0; i < t->num_targets; i++) {
> + struct dm_target *ti = dm_table_get_target(t, i);
> +
> + if (ti->type->finalize) {
> + ret = ti->type->finalize(ti);
> + if (ret) {
> + old_map = ERR_PTR(ret);
> + goto out;
> + }
> + }
> + }
> +
> old_map = rcu_dereference_protected(md->map, lockdep_is_held(&md->suspend_lock));
> rcu_assign_pointer(md->map, (void *)t);
> md->immutable_target_type = dm_table_get_immutable_target_type(t);
> diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
> index 69d0435c7ebb..4040e84a8ec7 100644
> --- a/include/linux/device-mapper.h
> +++ b/include/linux/device-mapper.h
> @@ -160,6 +160,12 @@ typedef int (*dm_dax_zero_page_range_fn)(struct dm_target *ti, pgoff_t pgoff,
> */
> typedef size_t (*dm_dax_recovery_write_fn)(struct dm_target *ti, pgoff_t pgoff,
> void *addr, size_t bytes, struct iov_iter *i);
> +/*
> + * Returns:
> + * < 0 : error
> + * = 0 : success
> + */
> +typedef int (*dm_finalize_fn) (struct dm_target *target);
>
> void dm_error(const char *message);
>
> @@ -209,6 +215,7 @@ struct target_type {
> dm_dax_direct_access_fn direct_access;
> dm_dax_zero_page_range_fn dax_zero_page_range;
> dm_dax_recovery_write_fn dax_recovery_write;
> + dm_finalize_fn finalize;
>
> /* For internal device-mapper use. */
> struct list_head list;
> --
> 2.25.1

--
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