xfs: simplify xfs_bmap_punch_delalloc_range

Instead of using xfs_bmapi_read to find delalloc extents and then punch
them out using xfs_bunmapi, opencode the loop to iterate over the extents
and call xfs_bmap_del_extent_delay directly.  This both simplifies the
code and reduces the number of extent tree lookups required.

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>

diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index c35009a8669953dfee4013615ca62b47237b4d77..c195b9d857af403ffa70d1ed3a76b9fa6927b9fb 100644 (file)
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -685,12 +685,10 @@ out_unlock_iolock:
 }
 
 /*
- * dead simple method of punching delalyed allocation blocks from a range in
- * the inode. Walks a block at a time so will be slow, but is only executed in
- * rare error cases so the overhead is not critical. This will always punch out
- * both the start and end blocks, even if the ranges only partially overlap
- * them, so it is up to the caller to ensure that partial blocks are not
- * passed in.
+ * Dead simple method of punching delalyed allocation blocks from a range in
+ * the inode.  This will always punch out both the start and end blocks, even
+ * if the ranges only partially overlap them, so it is up to the caller to
+ * ensure that partial blocks are not passed in.
  */
 int
 xfs_bmap_punch_delalloc_range(
@@ -698,63 +696,44 @@ xfs_bmap_punch_delalloc_range(
        xfs_fileoff_t           start_fsb,
        xfs_fileoff_t           length)
 {
-       xfs_fileoff_t           remaining = length;
+       struct xfs_ifork        *ifp = &ip->i_df;
+       xfs_fileoff_t           end_fsb = start_fsb + length;
+       struct xfs_bmbt_irec    got, del;
+       struct xfs_iext_cursor  icur;
        int                     error = 0;
 
        ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
 
-       do {
-               int             done;
-               xfs_bmbt_irec_t imap;
-               int             nimaps = 1;
-               xfs_fsblock_t   firstblock;
-               struct xfs_defer_ops dfops;
+       if (!(ifp->if_flags & XFS_IFEXTENTS)) {
+               error = xfs_iread_extents(NULL, ip, XFS_DATA_FORK);
+               if (error)
+                       return error;
+       }
 
-               /*
-                * Map the range first and check that it is a delalloc extent
-                * before trying to unmap the range. Otherwise we will be
-                * trying to remove a real extent (which requires a
-                * transaction) or a hole, which is probably a bad idea...
-                */
-               error = xfs_bmapi_read(ip, start_fsb, 1, &imap, &nimaps,
-                                      XFS_BMAPI_ENTIRE);
+       if (!xfs_iext_lookup_extent_before(ip, ifp, &end_fsb, &icur, &got))
+               return 0;
 
-               if (error) {
-                       /* something screwed, just bail */
-                       if (!XFS_FORCED_SHUTDOWN(ip->i_mount)) {
-                               xfs_alert(ip->i_mount,
-                       "Failed delalloc mapping lookup ino %lld fsb %lld.",
-                                               ip->i_ino, start_fsb);
-                       }
-                       break;
-               }
-               if (!nimaps) {
-                       /* nothing there */
-                       goto next_block;
-               }
-               if (imap.br_startblock != DELAYSTARTBLOCK) {
-                       /* been converted, ignore */
-                       goto next_block;
-               }
-               WARN_ON(imap.br_blockcount == 0);
+       while (got.br_startoff + got.br_blockcount > start_fsb) {
+               del = got;
+               xfs_trim_extent(&del, start_fsb, length);
 
                /*
-                * Note: while we initialise the firstblock/dfops pair, they
-                * should never be used because blocks should never be
-                * allocated or freed for a delalloc extent and hence we need
-                * don't cancel or finish them after the xfs_bunmapi() call.
+                * A delete can push the cursor forward. Step back to the
+                * previous extent on non-delalloc or extents outside the
+                * target range.
                 */
-               xfs_defer_init(&dfops, &firstblock);
-               error = xfs_bunmapi(NULL, ip, start_fsb, 1, 0, 1, &firstblock,
-                                       &dfops, &done);
-               if (error)
-                       break;
+               if (!del.br_blockcount ||
+                   !isnullstartblock(del.br_startblock)) {
+                       if (!xfs_iext_prev_extent(ifp, &icur, &got))
+                               break;
+                       continue;
+               }
 
-               ASSERT(!xfs_defer_has_unfinished_work(&dfops));
-next_block:
-               start_fsb++;
-               remaining--;
-       } while(remaining > 0);
+               error = xfs_bmap_del_extent_delay(ip, XFS_DATA_FORK, &icur,
+                                                 &got, &del);
+               if (error || !xfs_iext_get_extent(ifp, &icur, &got))
+                       break;
+       }
 
        return error;
 }