aoe: don't call set_capacity from irq context

Updating the block device size from irq context can lead to torn
writes of the 64-bit value, and prevents us from using normal
process context locking primitives to serialize access to the 64-bit
nr_sectors value.  Defer the set_capacity to the already existing
workqueue handler, where it can be merged with the update of the
block device size by using set_capacity_and_notify.  As an extra
bonus this also adds proper uevent notifications for the resize.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/aoe/aoecmd.c

@@ -890,19 +890,13 @@ void
 aoecmd_sleepwork(struct work_struct *work)
 {
 	struct aoedev *d = container_of(work, struct aoedev, work);
-	struct block_device *bd;
-	u64 ssize;
 
 	if (d->flags & DEVFL_GDALLOC)
 		aoeblk_gdalloc(d);
 
 	if (d->flags & DEVFL_NEWSIZE) {
-		ssize = get_capacity(d->gd);
-		bd = bdget_disk(d->gd, 0);
-		if (bd) {
-			bd_set_nr_sectors(bd, ssize);
-			bdput(bd);
-		}
+		set_capacity_and_notify(d->gd, d->ssize);
+
 		spin_lock_irq(&d->lock);
 		d->flags |= DEVFL_UP;
 		d->flags &= ~DEVFL_NEWSIZE;
@@ -971,10 +965,9 @@ ataid_complete(struct aoedev *d, struct aoetgt *t, unsigned char *id)
 	d->geo.start = 0;
 	if (d->flags & (DEVFL_GDALLOC|DEVFL_NEWSIZE))
 		return;
-	if (d->gd != NULL) {
-		set_capacity(d->gd, ssize);
+	if (d->gd != NULL)
 		d->flags |= DEVFL_NEWSIZE;
-	} else
+	else
 		d->flags |= DEVFL_GDALLOC;
 	schedule_work(&d->work);
 }