aoe: defer rexmit timer downdev work to workqueue

When aoe's rexmit_timer() notices that an aoe target fails to respond to
commands for more than aoe_deadsecs, it calls aoedev_downdev() which
cleans the outstanding aoe and block queues. This can involve sleeping,
such as in blk_mq_freeze_queue(), which should not occur in irq context.

This patch defers that aoedev_downdev() call to the aoe device's
workqueue.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=212665
Signed-off-by: Justin Sanders <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Tested-By: Valentin Kleibel <[e-mail]>
Signed-off-by: Jens Axboe <[e-mail]>

drivers/block/aoe/aoe.h

···
 	DEVFL_NEWSIZE = (1<<6),	/* need to update dev size in block layer */
 	DEVFL_FREEING = (1<<7),	/* set when device is being cleaned up */
 	DEVFL_FREED = (1<<8),	/* device has been cleaned up */
+	DEVFL_DEAD = (1<<9),	/* device has timed out of aoe_deadsecs */
 };
 
 enum {

drivers/block/aoe/aoecmd.c

···
 
 	utgts = count_targets(d, NULL);
 
-	if (d->flags & DEVFL_TKILL) {
+	if (d->flags & (DEVFL_TKILL | DEVFL_DEAD)) {
 		spin_unlock_irqrestore(&d->lock, flags);
 		return;
 	}
···
 			 * to clean up.
 			 */
 			list_splice(&flist, &d->factive[0]);
-			aoedev_downdev(d);
+			d->flags |= DEVFL_DEAD;
+			queue_work(aoe_wq, &d->work);
 			goto out;
 		}
 
···
 aoecmd_sleepwork(struct work_struct *work)
 {
 	struct aoedev *d = container_of(work, struct aoedev, work);
+
+	if (d->flags & DEVFL_DEAD)
+		aoedev_downdev(d);
 
 	if (d->flags & DEVFL_GDALLOC)
 		aoeblk_gdalloc(d);

drivers/block/aoe/aoedev.c

···
 	struct list_head *head, *pos, *nx;
 	struct request *rq, *rqnext;
 	int i;
+	unsigned long flags;
 
-	d->flags &= ~DEVFL_UP;
+	spin_lock_irqsave(&d->lock, flags);
+	d->flags &= ~(DEVFL_UP | DEVFL_DEAD);
+	spin_unlock_irqrestore(&d->lock, flags);
 
 	/* clean out active and to-be-retransmitted buffers */
 	for (i = 0; i < NFACTIVE; i++) {