nbd: allow block mq to deal with timeouts

Instead of rolling our own timer, just utilize the blk mq req timeout and do the
disconnect if any of our commands timeout.

Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/block/nbd.c

@@ -50,16 +50,13 @@ struct nbd_device {
 	struct socket * sock;	/* If == NULL, device is not ready, yet	*/
 	int magic;
 
-	atomic_t outstanding_cmds;
 	struct blk_mq_tag_set tag_set;
 
 	struct mutex tx_lock;
 	struct gendisk *disk;
 	int blksize;
 	loff_t bytesize;
-	int xmit_timeout;
 
-	struct timer_list timeout_timer;
 	/* protects initialization and shutdown of the socket */
 	spinlock_t sock_lock;
 	struct task_struct *task_recv;
@@ -154,7 +151,6 @@ static void nbd_end_request(struct nbd_cmd *cmd)
 	dev_dbg(nbd_to_dev(nbd), "request %p: %s\n", cmd,
 		error ? "failed" : "done");
 
-	atomic_dec(&nbd->outstanding_cmds);
 	blk_mq_complete_request(req, error);
 }
 
@@ -165,7 +161,7 @@ static void sock_shutdown(struct nbd_device *nbd)
 {
 	struct socket *sock;
 
-	spin_lock_irq(&nbd->sock_lock);
+	spin_lock(&nbd->sock_lock);
 
 	if (!nbd->sock) {
 		spin_unlock_irq(&nbd->sock_lock);
@@ -175,24 +171,20 @@ static void sock_shutdown(struct nbd_device *nbd)
 	sock = nbd->sock;
 	dev_warn(disk_to_dev(nbd->disk), "shutting down socket\n");
 	nbd->sock = NULL;
-	spin_unlock_irq(&nbd->sock_lock);
+	spin_unlock(&nbd->sock_lock);
 
 	kernel_sock_shutdown(sock, SHUT_RDWR);
 	sockfd_put(sock);
-
-	del_timer(&nbd->timeout_timer);
 }
 
-static void nbd_xmit_timeout(unsigned long arg)
+static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req,
+						 bool reserved)
 {
-	struct nbd_device *nbd = (struct nbd_device *)arg;
+	struct nbd_cmd *cmd = blk_mq_rq_to_pdu(req);
+	struct nbd_device *nbd = cmd->nbd;
 	struct socket *sock = NULL;
-	unsigned long flags;
-
-	if (!atomic_read(&nbd->outstanding_cmds))
-		return;
 
-	spin_lock_irqsave(&nbd->sock_lock, flags);
+	spin_lock(&nbd->sock_lock);
 
 	set_bit(NBD_TIMEDOUT, &nbd->runtime_flags);
 
@@ -201,13 +193,15 @@ static void nbd_xmit_timeout(unsigned long arg)
 		get_file(sock->file);
 	}
 
-	spin_unlock_irqrestore(&nbd->sock_lock, flags);
+	spin_unlock(&nbd->sock_lock);
 	if (sock) {
 		kernel_sock_shutdown(sock, SHUT_RDWR);
 		sockfd_put(sock);
 	}
 
+	req->errors++;
 	dev_err(nbd_to_dev(nbd), "Connection timed out, shutting down connection\n");
+	return BLK_EH_HANDLED;
 }
 
 /*
@@ -257,9 +251,6 @@ static int sock_xmit(struct nbd_device *nbd, int send, void *buf, int size,
 
 	tsk_restore_flags(current, pflags, PF_MEMALLOC);
 
-	if (!send && nbd->xmit_timeout)
-		mod_timer(&nbd->timeout_timer, jiffies + nbd->xmit_timeout);
-
 	return result;
 }
 
@@ -512,10 +503,6 @@ static void nbd_handle_cmd(struct nbd_cmd *cmd)
 		goto error_out;
 	}
 
-	if (nbd->xmit_timeout && !atomic_read(&nbd->outstanding_cmds))
-		mod_timer(&nbd->timeout_timer, jiffies + nbd->xmit_timeout);
-
-	atomic_inc(&nbd->outstanding_cmds);
 	if (nbd_send_cmd(nbd, cmd) != 0) {
 		dev_err(disk_to_dev(nbd->disk), "Request send failed\n");
 		req->errors++;
@@ -569,9 +556,8 @@ static void nbd_reset(struct nbd_device *nbd)
 	nbd->bytesize = 0;
 	set_capacity(nbd->disk, 0);
 	nbd->flags = 0;
-	nbd->xmit_timeout = 0;
+	nbd->tag_set.timeout = 0;
 	queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, nbd->disk->queue);
-	del_timer_sync(&nbd->timeout_timer);
 }
 
 static void nbd_bdev_reset(struct block_device *bdev)
@@ -668,13 +654,7 @@ static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
 		return nbd_size_set(nbd, bdev, nbd->blksize, arg);
 
 	case NBD_SET_TIMEOUT:
-		nbd->xmit_timeout = arg * HZ;
-		if (arg)
-			mod_timer(&nbd->timeout_timer,
-				  jiffies + nbd->xmit_timeout);
-		else
-			del_timer_sync(&nbd->timeout_timer);
-
+		nbd->tag_set.timeout = arg * HZ;
 		return 0;
 
 	case NBD_SET_FLAGS:
@@ -836,7 +816,7 @@ static int nbd_dev_dbg_init(struct nbd_device *nbd)
 
 	debugfs_create_file("tasks", 0444, dir, nbd, &nbd_dbg_tasks_ops);
 	debugfs_create_u64("size_bytes", 0444, dir, &nbd->bytesize);
-	debugfs_create_u32("timeout", 0444, dir, &nbd->xmit_timeout);
+	debugfs_create_u32("timeout", 0444, dir, &nbd->tag_set.timeout);
 	debugfs_create_u32("blocksize", 0444, dir, &nbd->blksize);
 	debugfs_create_file("flags", 0444, dir, nbd, &nbd_dbg_flags_ops);
 
@@ -903,6 +883,7 @@ static struct blk_mq_ops nbd_mq_ops = {
 	.queue_rq	= nbd_queue_rq,
 	.map_queue	= blk_mq_map_queue,
 	.init_request	= nbd_init_request,
+	.timeout	= nbd_xmit_timeout,
 };
 
 /*
@@ -1007,10 +988,6 @@ static int __init nbd_init(void)
 		nbd_dev[i].magic = NBD_MAGIC;
 		spin_lock_init(&nbd_dev[i].sock_lock);
 		mutex_init(&nbd_dev[i].tx_lock);
-		init_timer(&nbd_dev[i].timeout_timer);
-		nbd_dev[i].timeout_timer.function = nbd_xmit_timeout;
-		nbd_dev[i].timeout_timer.data = (unsigned long)&nbd_dev[i];
-		atomic_set(&nbd_dev[i].outstanding_cmds, 0);
 		disk->major = NBD_MAJOR;
 		disk->first_minor = i << part_shift;
 		disk->fops = &nbd_fops;