xfs: introduce the xfs_iext_cursor abstraction

Add a new xfs_iext_cursor structure to hide the direct extent map
index manipulations. In addition to the existing lookup/get/insert/
remove and update routines new primitives to get the first and last
extent cursor, as well as moving up and down by one extent are
provided.  Also new are convenience to increment/decrement the
cursor and retreive the new extent, as well as to peek into the
previous/next extent without updating the cursor and last but not
least a macro to iterate over all extents in a fork.

[darrick: rename for_each_iext to for_each_xfs_iext]

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
This commit is contained in:
Christoph Hellwig 2017-11-03 10:34:43 -07:00 committed by Darrick J. Wong
parent 906abed501
commit b2b1712a64
13 changed files with 407 additions and 337 deletions

View file

@ -266,7 +266,7 @@ xfs_dir2_leaf_readbuf(
xfs_dablk_t next_ra;
xfs_dablk_t map_off;
xfs_dablk_t last_da;
xfs_extnum_t idx;
struct xfs_iext_cursor icur;
int ra_want;
int error = 0;
@ -283,7 +283,7 @@ xfs_dir2_leaf_readbuf(
*/
last_da = xfs_dir2_byte_to_da(geo, XFS_DIR2_LEAF_OFFSET);
map_off = xfs_dir2_db_to_da(geo, xfs_dir2_byte_to_db(geo, *cur_off));
if (!xfs_iext_lookup_extent(dp, ifp, map_off, &idx, &map))
if (!xfs_iext_lookup_extent(dp, ifp, map_off, &icur, &map))
goto out;
if (map.br_startoff >= last_da)
goto out;
@ -311,7 +311,7 @@ xfs_dir2_leaf_readbuf(
if (next_ra >= last_da)
goto out_no_ra;
if (map.br_blockcount < geo->fsbcount &&
!xfs_iext_get_extent(ifp, ++idx, &map))
!xfs_iext_next_extent(ifp, &icur, &map))
goto out_no_ra;
if (map.br_startoff >= last_da)
goto out_no_ra;
@ -334,7 +334,7 @@ xfs_dir2_leaf_readbuf(
ra_want -= geo->fsbcount;
next_ra += geo->fsbcount;
}
if (!xfs_iext_get_extent(ifp, ++idx, &map)) {
if (!xfs_iext_next_extent(ifp, &icur, &map)) {
*ra_blk = last_da;
break;
}