xfs: optimize xfs_reflink_cancel_cow_blocks

Rewrite xfs_reflink_cancel_cow_blocks so that we only do a search for
the first extent in the extent list and then iterate over the remaining
extents using the extent index, passing the extent we operate on
directly to xfs_bmap_del_extent_delay or xfs_bmap_del_extent_cow instead
of going through xfs_bunmapi and doing yet another extent list lookup.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 09bd5dc..1e9c589 100644 (file)
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -511,53 +511,49 @@ xfs_reflink_cancel_cow_blocks(
        xfs_fileoff_t                   offset_fsb,
        xfs_fileoff_t                   end_fsb)
 {
-       struct xfs_bmbt_irec            irec;
-       xfs_filblks_t                   count_fsb;
+       struct xfs_ifork                *ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
+       struct xfs_bmbt_irec            got, prev, del;
+       xfs_extnum_t                    idx;
        xfs_fsblock_t                   firstfsb;
        struct xfs_defer_ops            dfops;
-       int                             error = 0;
-       int                             nimaps;
+       int                             error = 0, eof = 0;
 
        if (!xfs_is_reflink_inode(ip))
                return 0;
 
-       /* Go find the old extent in the CoW fork. */
-       while (offset_fsb < end_fsb) {
-               nimaps = 1;
-               count_fsb = (xfs_filblks_t)(end_fsb - offset_fsb);
-               error = xfs_bmapi_read(ip, offset_fsb, count_fsb, &irec,
-                               &nimaps, XFS_BMAPI_COWFORK);
-               if (error)
-                       break;
-               ASSERT(nimaps == 1);
+       xfs_bmap_search_extents(ip, offset_fsb, XFS_COW_FORK, &eof, &idx,
+                       &got, &prev);
+       if (eof)
+               return 0;
 
-               trace_xfs_reflink_cancel_cow(ip, &irec);
+       while (got.br_startoff < end_fsb) {
+               del = got;
+               xfs_trim_extent(&del, offset_fsb, end_fsb - offset_fsb);
+               trace_xfs_reflink_cancel_cow(ip, &del);
 
-               if (irec.br_startblock == DELAYSTARTBLOCK) {
-                       /* Remove the mapping from the CoW fork. */
-                       error = xfs_bunmapi_cow(ip, &irec);
+               if (isnullstartblock(del.br_startblock)) {
+                       error = xfs_bmap_del_extent_delay(ip, XFS_COW_FORK,
+                                       &idx, &got, &del);
                        if (error)
                                break;
-               } else if (irec.br_startblock == HOLESTARTBLOCK) {
-                       /* empty */
                } else {
                        xfs_trans_ijoin(*tpp, ip, 0);
                        xfs_defer_init(&dfops, &firstfsb);
 
                        /* Free the CoW orphan record. */
                        error = xfs_refcount_free_cow_extent(ip->i_mount,
-                                       &dfops, irec.br_startblock,
-                                       irec.br_blockcount);
+                                       &dfops, del.br_startblock,
+                                       del.br_blockcount);
                        if (error)
                                break;
 
                        xfs_bmap_add_free(ip->i_mount, &dfops,
-                                       irec.br_startblock, irec.br_blockcount,
+                                       del.br_startblock, del.br_blockcount,
                                        NULL);
 
                        /* Update quota accounting */
                        xfs_trans_mod_dquot_byino(*tpp, ip, XFS_TRANS_DQ_BCOUNT,
-                                       -(long)irec.br_blockcount);
+                                       -(long)del.br_blockcount);
 
                        /* Roll the transaction */
                        error = xfs_defer_finish(tpp, &dfops, ip);
@@ -567,13 +563,12 @@ xfs_reflink_cancel_cow_blocks(
                        }
 
                        /* Remove the mapping from the CoW fork. */
-                       error = xfs_bunmapi_cow(ip, &irec);
-                       if (error)
-                               break;
+                       xfs_bmap_del_extent_cow(ip, &idx, &got, &del);
                }
 
-               /* Roll on... */
-               offset_fsb = irec.br_startoff + irec.br_blockcount;
+               if (++idx >= ifp->if_bytes / sizeof(struct xfs_bmbt_rec))
+                       return 0;
+               xfs_bmbt_get_all(xfs_iext_get_ext(ifp, idx), &got);
        }
 
        return error;