drivers/block/aoe/aoeblk.c: ratelimit a warning printk

As described in https://bugzilla.kernel.org/show_bug.cgi?id=19922

: I had an AoE device go down overnight, and while a server was trying to
: write to it, it was also writing this message to its logs:
:
: 209                 printk(KERN_INFO "aoe: device %ld.%d is not up\n",
: 210                         d->aoemajor, d->aoeminor);
:
: The message appeared many times per second, and over several hours
: produced about 7.5 gigabytes of log files, filling up all free space on
: the root filesystem.

Cc: "Ed L. Cashin" <ecashin@coraid.com>
Suggested-by: Roman Mamedov <roman@rm.pp.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

drivers/block/aoe/aoeblk.c

@@ -4,12 +4,14 @@
  * block device routines
  */
 
+#include <linux/kernel.h>
 #include <linux/hdreg.h>
 #include <linux/blkdev.h>
 #include <linux/backing-dev.h>
 #include <linux/fs.h>
 #include <linux/ioctl.h>
 #include <linux/slab.h>
+#include <linux/ratelimit.h>
 #include <linux/genhd.h>
 #include <linux/netdevice.h>
 #include <linux/mutex.h>
@@ -207,7 +209,7 @@ aoeblk_make_request(struct request_queue *q, struct bio *bio)
 	spin_lock_irqsave(&d->lock, flags);
 
 	if ((d->flags & DEVFL_UP) == 0) {
-		printk(KERN_INFO "aoe: device %ld.%d is not up\n",
+		pr_info_ratelimited("aoe: device %ld.%d is not up\n",
 			d->aoemajor, d->aoeminor);
 		spin_unlock_irqrestore(&d->lock, flags);
 		mempool_free(buf, d->bufpool);