Re: [PATCH] block: change blk_get_meta_cap() stub return -ENOIOCTLCMD

[Christoph Hellwig]

On Fri, Jul 25, 2025 at 06:43:34PM +0200, Klara Modin wrote:
> When introduced in commit 9eb22f7fedfc ("fs: add ioctl to query metadata
> and protection info capabilities") the stub of blk_get_meta_cap() for
> !BLK_DEV_INTEGRITY always returns -EOPNOTSUPP. The motivation was that
> while the command was unsupported in that configuration it was still
> recognized.
> 
> A later change instead assumed -ENOIOCTLCMD as is required for unknown
> ioctl commands per Documentation/driver-api/ioctl.rst. The result being
> that on !BLK_DEV_INTEGRITY configs, any ioctl which reaches
> blkdev_common_ioctl() will return -EOPNOTSUPP.

FYI, I still think we should not fail the command for
!BLK_DEV_INTEGRITY, but just report no capabilities.