[PATCH 5/9] aoe: support larger I/O requests via aoe_maxsectors module param

[Ed Cashin <ecashin@coraid.com>]

The GPFS filesystem is an example of an aoe user that requires the
aoe driver to support I/O request sizes larger than the default.
Most users will not need large I/O request sizes, because they would
need to be split up into multiple AoE commands anyway.

Signed-off-by: Ed Cashin <ecashin@coraid.com>
---
 drivers/block/aoe/aoeblk.c |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/drivers/block/aoe/aoeblk.c b/drivers/block/aoe/aoeblk.c
index 00dfc50..d5aa3b8 100644
--- a/drivers/block/aoe/aoeblk.c
+++ b/drivers/block/aoe/aoeblk.c
@@ -16,11 +16,18 @@
 #include <linux/netdevice.h>
 #include <linux/mutex.h>
 #include <linux/export.h>
+#include <linux/moduleparam.h>
 #include "aoe.h"
 
 static DEFINE_MUTEX(aoeblk_mutex);
 static struct kmem_cache *buf_pool_cache;
 
+/* GPFS needs a larger value than the default. */
+static int aoe_maxsectors;
+module_param(aoe_maxsectors, int, 0644);
+MODULE_PARM_DESC(aoe_maxsectors,
+	"When nonzero, set the maximum number of sectors per I/O request");
+
 static ssize_t aoedisk_show_state(struct device *dev,
 				  struct device_attribute *attr, char *page)
 {
@@ -248,6 +255,8 @@ aoeblk_gdalloc(void *vp)
 	d->blkq = gd->queue = q;
 	q->queuedata = d;
 	d->gd = gd;
+	if (aoe_maxsectors)
+		blk_queue_max_hw_sectors(q, aoe_maxsectors);
 	gd->major = AOE_MAJOR;
 	gd->first_minor = d->sysminor;
 	gd->fops = &aoe_bdops;
-- 
1.7.1