| Message ID | 147216786073.525.16014208838990530622.stgit@birch.djwong.org (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
On Thu, Aug 25, 2016 at 04:31:00PM -0700, Darrick J. Wong wrote: > Introduce XFLAGs for the new XFS reflink inode flag and the CoW extent > size hint, and actually plumb the CoW extent size hint into the fsxattr > structure. Just curious, but why would we even bother to expose the reflink flag to userspace?
On Mon, Sep 05, 2016 at 07:56:22AM -0700, Christoph Hellwig wrote: > On Thu, Aug 25, 2016 at 04:31:00PM -0700, Darrick J. Wong wrote: > > Introduce XFLAGs for the new XFS reflink inode flag and the CoW extent > > size hint, and actually plumb the CoW extent size hint into the fsxattr > > structure. > > Just curious, but why would we even bother to expose the reflink flag > to userspace? So far I've put the reflink flag to use in xfs_scrub to look for obvious signs of brokenness such as extents that overlap or have the shared flag set but the inode flag is off; and to skip various kinds of checks that don't have to happen when blocks don't overlap. I doubt there's much of a use for the flag outside of the XFS utilities. For a while I pondered only exposing the fsxattr flag if the caller had CAP_SYS_ADMIN (the level of priviledge required to run scrub) but decided that I wouldn't change the existing interface like that unless I had a really good reason. --D
On Tue, Sep 06, 2016 at 12:15:15PM -0700, Darrick J. Wong wrote: > So far I've put the reflink flag to use in xfs_scrub to look for > obvious signs of brokenness such as extents that overlap or have the > shared flag set but the inode flag is off; and to skip various kinds > of checks that don't have to happen when blocks don't overlap. > > I doubt there's much of a use for the flag outside of the XFS utilities. > For a while I pondered only exposing the fsxattr flag if the caller had > CAP_SYS_ADMIN (the level of priviledge required to run scrub) but > decided that I wouldn't change the existing interface like that unless > I had a really good reason. I don't think CAP_SYS_ADMIN is nessecarily the right thing, but it's still an XFS implementation detail which I don't think we should pollute a flags API for normal user space applications with.
On Sun, Sep 11, 2016 at 05:58:08AM -0700, Christoph Hellwig wrote: > On Tue, Sep 06, 2016 at 12:15:15PM -0700, Darrick J. Wong wrote: > > So far I've put the reflink flag to use in xfs_scrub to look for > > obvious signs of brokenness such as extents that overlap or have the > > shared flag set but the inode flag is off; and to skip various kinds > > of checks that don't have to happen when blocks don't overlap. > > > > I doubt there's much of a use for the flag outside of the XFS utilities. > > For a while I pondered only exposing the fsxattr flag if the caller had > > CAP_SYS_ADMIN (the level of priviledge required to run scrub) but > > decided that I wouldn't change the existing interface like that unless > > I had a really good reason. > > I don't think CAP_SYS_ADMIN is nessecarily the right thing, but it's > still an XFS implementation detail which I don't think we should > pollute a flags API for normal user space applications with. I can work around it in xfs_scrub, so I'll give back the xflag bit for reflink. --D
diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h index 3b00f7c..fb371a5 100644 --- a/include/uapi/linux/fs.h +++ b/include/uapi/linux/fs.h @@ -157,7 +157,8 @@ struct fsxattr { __u32 fsx_extsize; /* extsize field value (get/set)*/ __u32 fsx_nextents; /* nextents field value (get) */ __u32 fsx_projid; /* project identifier (get/set) */ - unsigned char fsx_pad[12]; + __u32 fsx_cowextsize; /* CoW extsize field value (get/set)*/ + unsigned char fsx_pad[8]; }; /* @@ -178,6 +179,8 @@ struct fsxattr { #define FS_XFLAG_NODEFRAG 0x00002000 /* do not defragment */ #define FS_XFLAG_FILESTREAM 0x00004000 /* use filestream allocator */ #define FS_XFLAG_DAX 0x00008000 /* use DAX for IO */ +#define FS_XFLAG_REFLINK 0x00010000 /* file is reflinked */ +#define FS_XFLAG_COWEXTSIZE 0x00020000 /* CoW extent size allocator hint */ #define FS_XFLAG_HASATTR 0x80000000 /* no DIFLAG for this */ /* the read-only stuff doesn't really belong here, but any other place is
Introduce XFLAGs for the new XFS reflink inode flag and the CoW extent size hint, and actually plumb the CoW extent size hint into the fsxattr structure. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> --- include/uapi/linux/fs.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)