Re: [GIT PULL 11/14 for v6.17] vfs integrity

[Hugh Dickins <hughd@google.com>]

On Fri, 25 Jul 2025, Christian Brauner wrote:

> Hey Linus,
> 
> /* Summary */
> This adds the new FS_IOC_GETLBMD_CAP ioctl() to query metadata and
> protection info (PI) capabilities. This ioctl returns information about
> the files integrity profile. This is useful for userspace applications
> to understand a files end-to-end data protection support and configure
> the I/O accordingly.
> 
> For now this interface is only supported by block devices. However the
> design and placement of this ioctl in generic FS ioctl space allows us
> to extend it to work over files as well. This maybe useful when
> filesystems start supporting PI-aware layouts.
> 
> A new structure struct logical_block_metadata_cap is introduced, which
> contains the following fields:
> 
> - lbmd_flags:
>   bitmask of logical block metadata capability flags
> 
> - lbmd_interval:
>   the amount of data described by each unit of logical block metadata
> 
> - lbmd_size:
>   size in bytes of the logical block metadata associated with each
>   interval
> 
> - lbmd_opaque_size:
>   size in bytes of the opaque block tag associated with each interval
> 
> - lbmd_opaque_offset:
>   offset in bytes of the opaque block tag within the logical block
>   metadata
> 
> - lbmd_pi_size:
>   size in bytes of the T10 PI tuple associated with each interval
> 
> - lbmd_pi_offset:
>   offset in bytes of T10 PI tuple within the logical block metadata
> 
> - lbmd_pi_guard_tag_type:
>   T10 PI guard tag type
>     
> - lbmd_pi_app_tag_size:
>    size in bytes of the T10 PI application tag
> 
> - lbmd_pi_ref_tag_size:
>    size in bytes of the T10 PI reference tag
> 
> - lbmd_pi_storage_tag_size:
>   size in bytes of the T10 PI storage tag
> 
> The internal logic to fetch the capability is encapsulated in a helper
> function blk_get_meta_cap(), which uses the blk_integrity profile
> associated with the device. The ioctl returns -EOPNOTSUPP, if
> CONFIG_BLK_DEV_INTEGRITY is not enabled.
> 
> /* Testing */
> 
> gcc (Debian 14.2.0-19) 14.2.0
> Debian clang version 19.1.7 (3)
> 
> No build failures or warnings were observed.
> 
> /* Conflicts */
> 
> Merge conflicts with mainline
> =============================
> 
> No known conflicts.
> 
> Merge conflicts with other trees
> ================================
> 
> No known conflicts.
> 
> The following changes since commit 19272b37aa4f83ca52bdf9c16d5d81bdd1354494:
> 
>   Linux 6.16-rc1 (2025-06-08 13:44:43 -0700)
> 
> are available in the Git repository at:
> 
>   git@gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs tags/vfs-6.17-rc1.integrity
> 
> for you to fetch changes up to bc5b0c8febccbeabfefc9b59083b223ec7c7b53a:
> 
>   block: fix lbmd_guard_tag_type assignment in FS_IOC_GETLBMD_CAP (2025-07-23 14:55:51 +0200)
> 
> Please consider pulling these changes from the signed vfs-6.17-rc1.integrity tag.
> 
> Thanks!
> Christian
> 
> ----------------------------------------------------------------
> vfs-6.17-rc1.integrity
> 
> ----------------------------------------------------------------
> Anuj Gupta (5):
>       block: rename tuple_size field in blk_integrity to metadata_size
>       block: introduce pi_tuple_size field in blk_integrity
>       nvme: set pi_offset only when checksum type is not BLK_INTEGRITY_CSUM_NONE
>       fs: add ioctl to query metadata and protection info capabilities
>       block: fix lbmd_guard_tag_type assignment in FS_IOC_GETLBMD_CAP
> 
> Arnd Bergmann (1):
>       block: fix FS_IOC_GETLBMD_CAP parsing in blkdev_common_ioctl()
> 
> Christian Brauner (1):
>       Merge patch series "add ioctl to query metadata and protection info capabilities"
> 
>  block/bio-integrity-auto.c        |  4 +--
>  block/blk-integrity.c             | 70 ++++++++++++++++++++++++++++++++++++++-
>  block/blk-settings.c              | 44 ++++++++++++++++++++++--
>  block/ioctl.c                     |  6 ++++
>  block/t10-pi.c                    | 16 ++++-----
>  drivers/md/dm-crypt.c             |  4 +--
>  drivers/md/dm-integrity.c         | 12 +++----
>  drivers/nvdimm/btt.c              |  2 +-
>  drivers/nvme/host/core.c          |  7 ++--
>  drivers/nvme/target/io-cmd-bdev.c |  2 +-
>  drivers/scsi/sd_dif.c             |  3 +-
>  include/linux/blk-integrity.h     | 11 ++++--
>  include/linux/blkdev.h            |  3 +-
>  include/uapi/linux/fs.h           | 59 +++++++++++++++++++++++++++++++++
>  14 files changed, 213 insertions(+), 30 deletions(-)

It would be great if Klara's patch at
https://lore.kernel.org/lkml/20250725164334.9606-1-klarasmodin@gmail.com/
could follow just after this pull: I had been bisecting -next to find out
why "losetup /dev/loop0 tmpfsfile" was failing, and that patch fixes it -
and presumably other odd failures for anyone without BLK_DEV_INTEGRITY=y.

Thanks,
Hugh