[RFC PATCH v13 12/20] dm verity: set DM_TARGET_SINGLETON feature flag

[Mike Snitzer]

On Wed, Feb 28 2024 at  7:54P -0500,
Fan Wu <wufan at linux.microsoft.com> wrote:

> The device-mapper has a flag to mark targets as singleton, which is a
> required flag for immutable targets. Without this flag, multiple
> dm-verity targets can be added to a mapped device, which has no
> practical use cases. Also from dm_table_get_immutable_target(),
> it documented that "Immutable target is implicitly a singleton".
> 
> This patch adds the missing flag, restricting only one
> dm-verity target per mapped device.
> 
> Signed-off-by: Fan Wu <wufan at linux.microsoft.com>

FYI, I have picked this one up and staged it in dm-6.9 and linux-next:
https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=dm-6.9&id=9356fcfe0ac4a8545f9fc32f2e404524e1115ee6

Mike