On Thu, 2010-06-17 at 16:53 +0800, Tao Ma wrote:
> Hi Dave,
> On 06/14/2010 08:29 PM, Dave Chinner wrote:
> > I just had a thought - if you want to avoid holes being reported to
> > fiemap, then add a BMV_IF_NO_HOLES flag to xfs_getbmap() and skip
> > holes in the mappin gloop when this flag is set. That will make
> > fiemap fill in the full number of extents without hacking the
> > extent count...
> Here is the updated one. I have used BVM_IF_NO_HOLES in xfs_getbmap
> to skip increasing index 'cur_ext'. It is a bit ugly, see my commit
> log. I guess maybe we can add another flag in xfs_bmapi so that it
> don't even give us the holes?
Dave said he would commit this but it hasn't been done
yet, so there's still time to comment!
. . .
> diff --git a/fs/xfs/xfs_bmap.c b/fs/xfs/xfs_bmap.c
> index 99587de..d49107d 100644
> --- a/fs/xfs/xfs_bmap.c
> +++ b/fs/xfs/xfs_bmap.c
> @@ -5744,12 +5744,24 @@ xfs_getbmap(
> map[i].br_startblock))
> goto out_free_map;
>
> - nexleft--;
> bmv->bmv_offset =
> out[cur_ext].bmv_offset +
> out[cur_ext].bmv_length;
> bmv->bmv_length =
> max_t(__int64_t, 0, bmvend - bmv->bmv_offset);
> +
> + /*
> + * In case we don't want to return the hole,
> + * don't increase cur_ext so that we can reuse
> + * it in the next loop.
> + */
> + if ((iflags & BMV_IF_NO_HOLES) &&
> + out[cur_ext].bmv_block == -1LL) {
I personally would prefer this to use:
if ((iflags & BMV_IF_NO_HOLES) &&
map[i].br_startblock == HOLESTARTBLOCK) {
I think this is more obvious that this "extent" represents
a hole (as opposed to bmv_block == -1, which is how
xfs_getbmapx_fix_eof_hole() encodes this).
Otherwise looks good.
Reviewed-by: Alex Elder <aelder@xxxxxxx>
> + memset(&out[cur_ext], 0, sizeof(out[cur_ext]));
> + continue;
> + }
> +
> + nexleft--;
> bmv->bmv_entries++;
> cur_ext++;
> }
> diff --git a/fs/xfs/xfs_fs.h b/fs/xfs/xfs_fs.h
> index 7cf7220..87c2e9d 100644
> --- a/fs/xfs/xfs_fs.h
> +++ b/fs/xfs/xfs_fs.h
> @@ -114,8 +114,10 @@ struct getbmapx {
> #define BMV_IF_NO_DMAPI_READ 0x2 /* Do not generate DMAPI read event */
> #define BMV_IF_PREALLOC 0x4 /* rtn status BMV_OF_PREALLOC if req */
> #define BMV_IF_DELALLOC 0x8 /* rtn status BMV_OF_DELALLOC if req */
> +#define BMV_IF_NO_HOLES 0x10 /* Do not return holes */
> #define BMV_IF_VALID \
> - (BMV_IF_ATTRFORK|BMV_IF_NO_DMAPI_READ|BMV_IF_PREALLOC|BMV_IF_DELALLOC)
> + (BMV_IF_ATTRFORK|BMV_IF_NO_DMAPI_READ|BMV_IF_PREALLOC| \
> + BMV_IF_DELALLOC|BMV_IF_NO_HOLES)
>
> /* bmv_oflags values - returned for each non-header segment */
> #define BMV_OF_PREALLOC 0x1 /* segment = unwritten pre-allocation */
_______________________________________________
xfs mailing list
xfs@xxxxxxxxxxx
http://oss.sgi.com/mailman/listinfo/xfs
