xfs: reorder the minlen and prod calculations in xfs_bmap_rtalloc

xfs_bmap_rtalloc is a bit of a mess in terms of calculating the locally
need variables.  Reorder them a bit so that related code is located
next to each other - the raminlen calculation moves up next to where
the maximum len is calculated, and all the prod calculation is move
into a single place and rearranged so that the real prod calculation
only happens when it actually is needed.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

Author: Christoph Hellwig

fs/xfs/xfs_rtalloc.c

@@ -1375,7 +1375,6 @@ xfs_bmap_rtalloc(
 
 	align = xfs_get_extsz_hint(ap->ip);
 retry:
-	prod = xfs_extlen_to_rtxlen(mp, align);
 	error = xfs_bmap_extsize_align(mp, &ap->got, &ap->prev,
 					align, 1, ap->eof, 0,
 					ap->conv, &ap->offset, &ap->length);
@@ -1393,13 +1392,6 @@ xfs_bmap_rtalloc(
 	if (ap->offset != orig_offset)
 		minlen += orig_offset - ap->offset;
 
-	/*
-	 * If the offset & length are not perfectly aligned
-	 * then kill prod, it will just get us in trouble.
-	 */
-	div_u64_rem(ap->offset, align, &mod);
-	if (mod || ap->length % align)
-		prod = 1;
 	/*
 	 * Set ralen to be the actual requested length in rtextents.
 	 *
@@ -1410,6 +1402,7 @@ xfs_bmap_rtalloc(
 	 * adjust the starting point to match it.
 	 */
 	ralen = xfs_extlen_to_rtxlen(mp, min(ap->length, XFS_MAX_BMBT_EXTLEN));
+	raminlen = max_t(xfs_rtxlen_t, 1, xfs_extlen_to_rtxlen(mp, minlen));
 
 	/*
 	 * Lock out modifications to both the RT bitmap and summary inodes
@@ -1438,7 +1431,16 @@ xfs_bmap_rtalloc(
 		start = 0;
 	}
 
-	raminlen = max_t(xfs_rtxlen_t, 1, xfs_extlen_to_rtxlen(mp, minlen));
+	/*
+	 * Only bother calculating a real prod factor if offset & length are
+	 * perfectly aligned, otherwise it will just get us in trouble.
+	 */
+	div_u64_rem(ap->offset, align, &mod);
+	if (mod || ap->length % align)
+		prod = 1;
+	else
+		prod = xfs_extlen_to_rtxlen(mp, align);
+
 	error = xfs_rtallocate_extent(ap->tp, start, raminlen, ralen, &ralen,
 			ap->wasdel, prod, &rtx);
 	if (error == -ENOSPC) {