Re: [PATCH 11/24] xfs: map an inode's offset to an exact physical block

[Dave Chinner <david@fromorbit.com>]

On Wed, Jul 29, 2015 at 03:34:09PM -0700, Darrick J. Wong wrote:
> Teach the bmap routine to know how to map a range of file blocks to a
> specific range of physical blocks, instead of simply allocating fresh
> blocks.  This enables reflink to map a file to blocks that are already
> in use.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
>  fs/xfs/libxfs/xfs_bmap.c |   21 +++++++++++++++++++++
>  fs/xfs/libxfs/xfs_bmap.h |    3 +++
>  2 files changed, 24 insertions(+)
> 
> 
> diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> index dfdd9e6..1297b94 100644
> --- a/fs/xfs/libxfs/xfs_bmap.c
> +++ b/fs/xfs/libxfs/xfs_bmap.c
> @@ -3897,6 +3897,15 @@ STATIC int
>  xfs_bmap_alloc(
>  	struct xfs_bmalloca	*ap)	/* bmap alloc argument struct */
>  {
> +	if (ap->flags & XFS_BMAPI_EXACT) {
> +		trace_xfs_reflink_relink_blocks(ap->ip, *ap->firstblock,
> +				ap->length);
> +		ap->blkno = *ap->firstblock;
> +		ap->ip->i_d.di_nblocks += ap->length;
> +		xfs_trans_log_inode(ap->tp, ap->ip, XFS_ILOG_CORE);
> +		return 0;
> +	}

XFS_BMAPI_EXACT is confusing to me - "exact" already means something
in the xfs_bmapi API w.r.t. the XFS_BMAPI_ENTIRE flag. That is, if
XFS_BMAPI_ENTIRE is not set, we want the map returned to span only
the /exact range requested/. If XFS_BMAPI_ENTIRE is set, we want the
entire extent that overlaps the range requested...

So I think this might be better named to match it's intended
function. e.g. remap, reuse, ref_only, etc.

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs