xfs: split xfs_mod_freecounter

xfs_mod_freecounter has two entirely separate code paths for adding or
subtracting from the free counters.  Only the subtract case looks at the
rsvd flag and can return an error.

Split xfs_mod_freecounter into separate helpers for subtracting or
adding the freecounter, and remove all the impossible to reach error
handling for the addition case.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 22d4462..0311a98 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -1985,10 +1985,11 @@ xfs_bmap_add_extent_delay_real(
 	}
 
 	/* adjust for changes in reserved delayed indirect blocks */
-	if (da_new != da_old) {
-		ASSERT(state == 0 || da_new < da_old);
-		error = xfs_mod_fdblocks(mp, (int64_t)(da_old - da_new),
-				false);
+	if (da_new < da_old) {
+		xfs_add_fdblocks(mp, da_old - da_new);
+	} else if (da_new > da_old) {
+		ASSERT(state == 0);
+		error = xfs_dec_fdblocks(mp, da_new - da_old, false);
 	}
 
 	xfs_bmap_check_leaf_extents(bma->cur, bma->ip, whichfork);
@@ -2690,8 +2691,8 @@ xfs_bmap_add_extent_hole_delay(
 	}
 	if (oldlen != newlen) {
 		ASSERT(oldlen > newlen);
-		xfs_mod_fdblocks(ip->i_mount, (int64_t)(oldlen - newlen),
-				 false);
+		xfs_add_fdblocks(ip->i_mount, oldlen - newlen);
+
 		/*
 		 * Nothing to do for disk quota accounting here.
 		 */
@@ -4110,11 +4111,11 @@ xfs_bmapi_reserve_delalloc(
 	indlen = (xfs_extlen_t)xfs_bmap_worst_indlen(ip, alen);
 	ASSERT(indlen > 0);
 
-	error = xfs_mod_fdblocks(mp, -((int64_t)alen), false);
+	error = xfs_dec_fdblocks(mp, alen, false);
 	if (error)
 		goto out_unreserve_quota;
 
-	error = xfs_mod_fdblocks(mp, -((int64_t)indlen), false);
+	error = xfs_dec_fdblocks(mp, indlen, false);
 	if (error)
 		goto out_unreserve_blocks;
 
@@ -4142,7 +4143,7 @@ xfs_bmapi_reserve_delalloc(
 	return 0;
 
 out_unreserve_blocks:
-	xfs_mod_fdblocks(mp, alen, false);
+	xfs_add_fdblocks(mp, alen);
 out_unreserve_quota:
 	if (XFS_IS_QUOTA_ON(mp))
 		xfs_quota_unreserve_blkres(ip, alen);
@@ -4928,7 +4929,7 @@ xfs_bmap_del_extent_delay(
 	ASSERT(got_endoff >= del_endoff);
 
 	if (isrt)
-		xfs_mod_frextents(mp, xfs_rtb_to_rtx(mp, del->br_blockcount));
+		xfs_add_frextents(mp, xfs_rtb_to_rtx(mp, del->br_blockcount));
 
 	/*
 	 * Update the inode delalloc counter now and wait to update the
@@ -5015,7 +5016,7 @@ xfs_bmap_del_extent_delay(
 	if (!isrt)
 		da_diff += del->br_blockcount;
 	if (da_diff) {
-		xfs_mod_fdblocks(mp, da_diff, false);
+		xfs_add_fdblocks(mp, da_diff);
 		xfs_mod_delalloc(mp, -da_diff);
 	}
 	return error;