Re: [PATCH v2 1/2] fs: add FS_XFLAG_VERITY for fs-verity files

["Darrick J. Wong" <djwong@kernel.org>]

On Mon, Jan 19, 2026 at 05:56:42PM +0100, Andrey Albershteyn wrote:
> fs-verity introduced inode flag for inodes with enabled fs-verity on
> them. This patch adds FS_XFLAG_VERITY file attribute which can be
> retrieved with FS_IOC_FSGETXATTR ioctl() and file_getattr() syscall.
> 
> This flag is read-only and can not be set with corresponding set ioctl()
> and file_setattr(). The FS_IOC_SETFLAGS requires file to be opened for
> writing which is not allowed for verity files. The FS_IOC_FSSETXATTR and
> file_setattr() clears this flag from the user input.
> 
> As this is now common flag for both flag interfaces (flags/xflags) add
> it to overlapping flags list to exclude it from overwrite.
> 
> Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>

Technically this uapi change should be cc'd to linux-api, but adding
a flag definition is fairly minor so:

Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

--D

> ---
>  Documentation/filesystems/fsverity.rst | 16 ++++++++++++++++
>  fs/file_attr.c                         |  4 ++++
>  include/linux/fileattr.h               |  6 +++---
>  include/uapi/linux/fs.h                |  1 +
>  4 files changed, 24 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/filesystems/fsverity.rst b/Documentation/filesystems/fsverity.rst
> index 412cf11e3298..22b49b295d1f 100644
> --- a/Documentation/filesystems/fsverity.rst
> +++ b/Documentation/filesystems/fsverity.rst
> @@ -341,6 +341,22 @@ the file has fs-verity enabled.  This can perform better than
>  FS_IOC_GETFLAGS and FS_IOC_MEASURE_VERITY because it doesn't require
>  opening the file, and opening verity files can be expensive.
>  
> +FS_IOC_FSGETXATTR
> +-----------------
> +
> +Since Linux v7.0, the FS_IOC_FSGETXATTR ioctl sets FS_XFLAG_VERITY (0x00020000)
> +in the returned flags when the file has verity enabled. Note that this attribute
> +cannot be set with FS_IOC_FSSETXATTR as enabling verity requires input
> +parameters. See FS_IOC_ENABLE_VERITY.
> +
> +file_getattr
> +------------
> +
> +Since Linux v7.0, the file_getattr() syscall sets FS_XFLAG_VERITY (0x00020000)
> +in the returned flags when the file has verity enabled. Note that this attribute
> +cannot be set with file_setattr() as enabling verity requires input parameters.
> +See FS_IOC_ENABLE_VERITY.
> +
>  .. _accessing_verity_files:
>  
>  Accessing verity files
> diff --git a/fs/file_attr.c b/fs/file_attr.c
> index 13cdb31a3e94..f44c873af92b 100644
> --- a/fs/file_attr.c
> +++ b/fs/file_attr.c
> @@ -37,6 +37,8 @@ void fileattr_fill_xflags(struct file_kattr *fa, u32 xflags)
>  		fa->flags |= FS_DAX_FL;
>  	if (fa->fsx_xflags & FS_XFLAG_PROJINHERIT)
>  		fa->flags |= FS_PROJINHERIT_FL;
> +	if (fa->fsx_xflags & FS_XFLAG_VERITY)
> +		fa->flags |= FS_VERITY_FL;
>  }
>  EXPORT_SYMBOL(fileattr_fill_xflags);
>  
> @@ -67,6 +69,8 @@ void fileattr_fill_flags(struct file_kattr *fa, u32 flags)
>  		fa->fsx_xflags |= FS_XFLAG_DAX;
>  	if (fa->flags & FS_PROJINHERIT_FL)
>  		fa->fsx_xflags |= FS_XFLAG_PROJINHERIT;
> +	if (fa->flags & FS_VERITY_FL)
> +		fa->fsx_xflags |= FS_XFLAG_VERITY;
>  }
>  EXPORT_SYMBOL(fileattr_fill_flags);
>  
> diff --git a/include/linux/fileattr.h b/include/linux/fileattr.h
> index f89dcfad3f8f..3780904a63a6 100644
> --- a/include/linux/fileattr.h
> +++ b/include/linux/fileattr.h
> @@ -7,16 +7,16 @@
>  #define FS_COMMON_FL \
>  	(FS_SYNC_FL | FS_IMMUTABLE_FL | FS_APPEND_FL | \
>  	 FS_NODUMP_FL |	FS_NOATIME_FL | FS_DAX_FL | \
> -	 FS_PROJINHERIT_FL)
> +	 FS_PROJINHERIT_FL | FS_VERITY_FL)
>  
>  #define FS_XFLAG_COMMON \
>  	(FS_XFLAG_SYNC | FS_XFLAG_IMMUTABLE | FS_XFLAG_APPEND | \
>  	 FS_XFLAG_NODUMP | FS_XFLAG_NOATIME | FS_XFLAG_DAX | \
> -	 FS_XFLAG_PROJINHERIT)
> +	 FS_XFLAG_PROJINHERIT | FS_XFLAG_VERITY)
>  
>  /* Read-only inode flags */
>  #define FS_XFLAG_RDONLY_MASK \
> -	(FS_XFLAG_PREALLOC | FS_XFLAG_HASATTR)
> +	(FS_XFLAG_PREALLOC | FS_XFLAG_HASATTR | FS_XFLAG_VERITY)
>  
>  /* Flags to indicate valid value of fsx_ fields */
>  #define FS_XFLAG_VALUES_MASK \
> diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
> index 66ca526cf786..70b2b661f42c 100644
> --- a/include/uapi/linux/fs.h
> +++ b/include/uapi/linux/fs.h
> @@ -253,6 +253,7 @@ struct file_attr {
>  #define FS_XFLAG_FILESTREAM	0x00004000	/* use filestream allocator */
>  #define FS_XFLAG_DAX		0x00008000	/* use DAX for IO */
>  #define FS_XFLAG_COWEXTSIZE	0x00010000	/* CoW extent size allocator hint */
> +#define FS_XFLAG_VERITY		0x00020000	/* fs-verity enabled */
>  #define FS_XFLAG_HASATTR	0x80000000	/* no DIFLAG for this	*/
>  
>  /* the read-only stuff doesn't really belong here, but any other place is
> -- 
> 2.52.0
> 
>