aoe: support larger I/O requests via aoe_maxsectors module param

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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/block/aoe/aoeblk.c b/drivers/block/aoe/aoeblk.c
index 00dfc5008ad4bddd8a8efa036eb1bbbc8cc8ec23..d5aa3b8c9f33b999184cce1044e06a2e88244595 100644 (file)
--- 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;