Re: [PATCH v4 0/9] make statx() return DIO alignment information

[Jeff Layton]

On Fri, 2022-07-22 at 00:12 -0700, Eric Biggers wrote:
> This patchset makes the statx() system call return direct I/O (DIO)
> alignment information.  This allows userspace to easily determine
> whether a file supports DIO, and if so with what alignment restrictions.
> 
> Patch 1 adds the basic VFS support for STATX_DIOALIGN.  Patch 2 wires it
> up for all block device files.  The remaining patches wire it up for
> regular files on ext4, f2fs, and xfs.  Support for regular files on
> other filesystems can be added later.
> 
> I've also written a man-pages patch, which I'm sending separately.
> 
> Note, f2fs has one corner case where DIO reads are allowed but not DIO
> writes.  The proposed statx fields can't represent this.  My proposal
> (patch 6) is to just eliminate this case, as it seems much too weird.
> But I'd appreciate any feedback on that part.
> 
> This patchset applies to v5.19-rc7.
> 
> Changed v3 => v4:
>    - Added xfs support.
> 
>    - Moved the helper function for block devices into block/bdev.c.
>    
>    - Adjusted the ext4 patch to not introduce a bug where misaligned DIO
>      starts being allowed on encrypted files when it gets combined with
>      the patch "iomap: add support for dma aligned direct-io" that is
>      queued in the block tree for 5.20.
> 
>    - Made a simplification in fscrypt_dio_supported().
> 
> Changed v2 => v3:
>    - Dropped the stx_offset_align_optimal field, since its purpose
>      wasn't clearly distinguished from the existing stx_blksize.
> 
>    - Renamed STATX_IOALIGN to STATX_DIOALIGN, to reflect the new focus
>      on DIO only.
> 
>    - Similarly, renamed stx_{mem,offset}_align_dio to
>      stx_dio_{mem,offset}_align, to reflect the new focus on DIO only.
> 
>    - Wired up STATX_DIOALIGN on block device files.
> 
> Changed v1 => v2:
>    - No changes.
> 
> Eric Biggers (9):
>   statx: add direct I/O alignment information
>   vfs: support STATX_DIOALIGN on block devices
>   fscrypt: change fscrypt_dio_supported() to prepare for STATX_DIOALIGN
>   ext4: support STATX_DIOALIGN
>   f2fs: move f2fs_force_buffered_io() into file.c
>   f2fs: don't allow DIO reads but not DIO writes
>   f2fs: simplify f2fs_force_buffered_io()
>   f2fs: support STATX_DIOALIGN
>   xfs: support STATX_DIOALIGN
> 
>  block/bdev.c              | 25 ++++++++++++++++++++
>  fs/crypto/inline_crypt.c  | 49 +++++++++++++++++++--------------------
>  fs/ext4/ext4.h            |  1 +
>  fs/ext4/file.c            | 37 ++++++++++++++++++++---------
>  fs/ext4/inode.c           | 36 ++++++++++++++++++++++++++++
>  fs/f2fs/f2fs.h            | 45 -----------------------------------
>  fs/f2fs/file.c            | 45 ++++++++++++++++++++++++++++++++++-
>  fs/stat.c                 | 14 +++++++++++
>  fs/xfs/xfs_iops.c         |  9 +++++++
>  include/linux/blkdev.h    |  4 ++++
>  include/linux/fscrypt.h   |  7 ++----
>  include/linux/stat.h      |  2 ++
>  include/uapi/linux/stat.h |  4 +++-
>  13 files changed, 190 insertions(+), 88 deletions(-)
> 
> base-commit: ff6992735ade75aae3e35d16b17da1008d753d28

Hi Eric,

Can I ask what your plans are with this set? I didn't see it in
linux-next yet, so I wasn't sure when you were looking to get it merged.
I'm working on patches to add a new statx field for the i_version
counter as well and I want to make sure that our work doesn't collide.

Thanks,
-- 
Jeff Layton <jlayton@xxxxxxxxxx>