xfs: reinstate RT support in xfs_bmapi_reserve_delalloc

Allocate data blocks for RT inodes using xfs_dec_frextents.  While at
it optimize the data device case by doing only a single xfs_dec_fdblocks
call for the extent itself and the indirect blocks.
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>

fs/xfs/libxfs/xfs_bmap.c

@@ -4069,6 +4069,7 @@ xfs_bmapi_reserve_delalloc(
 	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
 	xfs_extlen_t		alen;
 	xfs_extlen_t		indlen;
+	uint64_t		fdblocks;
 	int			error;
 	xfs_fileoff_t		aoff = off;
 
@@ -4111,14 +4112,18 @@ xfs_bmapi_reserve_delalloc(
 	indlen = (xfs_extlen_t)xfs_bmap_worst_indlen(ip, alen);
 	ASSERT(indlen > 0);
 
-	error = xfs_dec_fdblocks(mp, alen, false);
-	if (error)
-		goto out_unreserve_quota;
+	fdblocks = indlen;
+	if (XFS_IS_REALTIME_INODE(ip)) {
+		error = xfs_dec_frextents(mp, xfs_rtb_to_rtx(mp, alen));
+		if (error)
+			goto out_unreserve_quota;
+	} else {
+		fdblocks += alen;
+	}
 
-	error = xfs_dec_fdblocks(mp, indlen, false);
+	error = xfs_dec_fdblocks(mp, fdblocks, false);
 	if (error)
-		goto out_unreserve_blocks;
-
+		goto out_unreserve_frextents;
 
 	ip->i_delayed_blks += alen;
 	xfs_mod_delalloc(ip->i_mount, alen + indlen);
@@ -4142,8 +4147,9 @@ xfs_bmapi_reserve_delalloc(
 
 	return 0;
 
-out_unreserve_blocks:
-	xfs_add_fdblocks(mp, alen);
+out_unreserve_frextents:
+	if (XFS_IS_REALTIME_INODE(ip))
+		xfs_add_frextents(mp, xfs_rtb_to_rtx(mp, alen));
 out_unreserve_quota:
 	if (XFS_IS_QUOTA_ON(mp))
 		xfs_quota_unreserve_blkres(ip, alen);