From 7f5d565819d4276246ee352378d71d303dc34ca5 Mon Sep 17 00:00:00 2001
From: "Martin K. Petersen" <martin.petersen@oracle.com>
Date: Fri, 31 Jul 2009 11:49:12 -0400
Subject: [PATCH] --- yaml --- r: 156368 b: refs/heads/master c:
 70dd5bf3b99964d52862ad2810c24cc32a553535 h: refs/heads/master v: v3

---
 [refs]                     |  2 +-
 trunk/block/blk-settings.c | 11 +++++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index aa8d90255157..ce7f23d58b19 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 7c958e32649e0c35801762878fb0b6da8c55a515
+refs/heads/master: 70dd5bf3b99964d52862ad2810c24cc32a553535
diff --git a/trunk/block/blk-settings.c b/trunk/block/blk-settings.c
index 1f7197434166..e1327ddfc13b 100644
--- a/trunk/block/blk-settings.c
+++ b/trunk/block/blk-settings.c
@@ -7,6 +7,7 @@
 #include <linux/bio.h>
 #include <linux/blkdev.h>
 #include <linux/bootmem.h>	/* for max_pfn/max_low_pfn */
+#include <linux/gcd.h>
 
 #include "blk.h"
 
@@ -520,6 +521,16 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
 		return -1;
 	}
 
+	/* Find lcm() of optimal I/O size */
+	if (t->io_opt && b->io_opt)
+		t->io_opt = (t->io_opt * b->io_opt) / gcd(t->io_opt, b->io_opt);
+	else if (b->io_opt)
+		t->io_opt = b->io_opt;
+
+	/* Verify that optimal I/O size is a multiple of io_min */
+	if (t->io_min && t->io_opt % t->io_min)
+		return -1;
+
 	return 0;
 }
 EXPORT_SYMBOL(blk_stack_limits);