nbd.patch

--- linux-2.6.32/drivers/block/nbd.c	2012-09-16 12:52:38.123641274 +0200
+++ linux-2.6.32-humbuq/drivers/block/nbd.c	2012-09-16 05:05:16.318784654 +0200
@@ -194,10 +194,12 @@
 
 		if (signal_pending(current)) {
 			siginfo_t info;
+			int gotsig = dequeue_signal_lock(current, &current->blocked, &info);
 			printk(KERN_WARNING "nbd (pid %d: %s) got signal %d\n",
 				task_pid_nr(current), current->comm,
-				dequeue_signal_lock(current, &current->blocked, &info));
+				gotsig);
 			result = -EINTR;
+			if (gotsig) lo->flags &= ~NBD_FLAG_RESUME;
 			sock_shutdown(lo, !send);
 			break;
 		}
@@ -445,7 +447,7 @@
 }
 
 
-static void nbd_handle_req(struct nbd_device *lo, struct request *req)
+static int nbd_handle_req(struct nbd_device *lo, struct request *req)
 {
 	if (req->cmd_type != REQ_TYPE_FS)
 		goto error_out;
@@ -453,7 +455,7 @@
 	nbd_cmd(req) = NBD_CMD_READ;
 	if (rq_data_dir(req) == WRITE) {
 		nbd_cmd(req) = NBD_CMD_WRITE;
-		if (lo->flags & NBD_READ_ONLY) {
+		if (lo->flags & NBD_FLAG_READ_ONLY) {
 			printk(KERN_ERR "%s: Write on read-only\n",
 					lo->disk->disk_name);
 			goto error_out;
@@ -463,7 +465,7 @@
 	req->errors = 0;
 
 	mutex_lock(&lo->tx_lock);
-	if (unlikely(!lo->sock)) {
+	if (unlikely((!lo->sock) && ((lo->flags & NBD_FLAG_RESUME) == 0))) {
 		mutex_unlock(&lo->tx_lock);
 		printk(KERN_ERR "%s: Attempted send on closed socket\n",
 		       lo->disk->disk_name);
@@ -475,8 +477,16 @@
 	if (nbd_send_req(lo, req) != 0) {
 		printk(KERN_ERR "%s: Request send failed\n",
 				lo->disk->disk_name);
-		req->errors++;
-		nbd_end_request(req);
+		if (lo->flags & NBD_FLAG_RESUME) {
+			spin_lock_irq(&lo->queue_lock);
+			list_add(&req->queuelist, &lo->waiting_queue);
+			spin_unlock_irq(&lo->queue_lock);
+			mutex_unlock(&lo->tx_lock);
+			return 1;
+		} else {
+			req->errors++;
+			nbd_end_request(req);
+		}
 	} else {
 		spin_lock(&lo->queue_lock);
 		list_add(&req->queuelist, &lo->queue_head);
@@ -487,11 +497,11 @@
 	mutex_unlock(&lo->tx_lock);
 	wake_up_all(&lo->active_wq);
 
-	return;
-
+	return 0;
 error_out:
 	req->errors++;
 	nbd_end_request(req);
+	return 1;
 }
 
 static int nbd_thread(void *data)
@@ -517,7 +527,8 @@
 		spin_unlock_irq(&lo->queue_lock);
 
 		/* handle request */
-		nbd_handle_req(lo, req);
+		if (nbd_handle_req(lo, req))
+			return 0;
 	}
 	return 0;
 }
@@ -545,7 +556,7 @@
 
 		BUG_ON(lo->magic != LO_MAGIC);
 
-		if (unlikely(!lo->sock)) {
+		if (unlikely((!lo->sock) && ((lo->flags & NBD_FLAG_RESUME) == 0))) {
 			printk(KERN_ERR "%s: Attempted send on closed socket\n",
 				lo->disk->disk_name);
 			req->errors++;
@@ -558,7 +569,8 @@
 		list_add_tail(&req->queuelist, &lo->waiting_queue);
 		spin_unlock_irq(&lo->queue_lock);
 
-		wake_up(&lo->waiting_wq);
+		if (lo->sock)
+			wake_up(&lo->waiting_wq);
 
 		spin_lock_irq(q->queue_lock);
 	}
@@ -638,6 +650,10 @@
 		lo->xmit_timeout = arg * HZ;
 		return 0;
 
+	case NBD_SET_FLAGS:
+		lo->flags = arg;
+		return 0;
+
 	case NBD_SET_SIZE_BLOCKS:
 		lo->bytesize = ((u64) arg) * lo->blksize;
 		bdev->bd_inode->i_size = lo->bytesize;
@@ -672,15 +688,28 @@
 		sock_shutdown(lo, 0);
 		file = lo->file;
 		lo->file = NULL;
-		nbd_clear_que(lo);
-		printk(KERN_WARNING "%s: queue cleared\n", lo->disk->disk_name);
+		if ((lo->flags & NBD_FLAG_RESUME) == 0) {
+			nbd_clear_que(lo);
+			printk(KERN_WARNING "%s: queue cleared and device reset.\n", lo->disk->disk_name);
+			lo->bytesize = 0;
+			bdev->bd_inode->i_size = 0;
+			set_capacity(lo->disk, 0);
+			if (max_part > 0)
+				ioctl_by_bdev(bdev, BLKRRPART, 0);
+		} else {
+			struct request *req, *tmp;
+			int moved = 0;
+			spin_lock(&lo->queue_lock);
+			list_for_each_entry_safe(req, tmp, &lo->queue_head, queuelist) {
+				list_del_init(&req->queuelist);
+				list_add(&req->queuelist, &lo->waiting_queue);
+				moved++;
+			}
+			spin_unlock(&lo->queue_lock);
+			printk(KERN_WARNING "%s: retrying %d requests\n", lo->disk->disk_name, moved);
+		}
 		if (file)
 			fput(file);
-		lo->bytesize = 0;
-		bdev->bd_inode->i_size = 0;
-		set_capacity(lo->disk, 0);
-		if (max_part > 0)
-			ioctl_by_bdev(bdev, BLKRRPART, 0);
 		return lo->harderror;
 	}
 
--- linux-2.6.32/include/linux/nbd.h	2009-12-03 04:51:21.000000000 +0100
+++ linux-2.6.32-humbuq/include/linux/nbd.h	2012-09-16 12:53:03.576536821 +0200
@@ -27,6 +27,7 @@
 #define NBD_SET_SIZE_BLOCKS	_IO( 0xab, 7 )
 #define NBD_DISCONNECT  _IO( 0xab, 8 )
 #define NBD_SET_TIMEOUT _IO( 0xab, 9 )
+#define NBD_SET_FLAGS 	_IO( 0xab, 10 )
 
 enum {
 	NBD_CMD_READ = 0,
@@ -43,8 +44,15 @@
 #include <linux/mutex.h>
 
 /* values for flags field */
-#define NBD_READ_ONLY 0x0001
-#define NBD_WRITE_NOCHK 0x0002
+#define NBD_FLAG_HAS_FLAGS	(1 << 0)	/* Flags are there */
+#define NBD_FLAG_READ_ONLY	(1 << 1)	/* Device is read-only */
+#define NBD_FLAG_SEND_FLUSH	(1 << 2)	/* Send FLUSH */
+#define NBD_FLAG_SEND_FUA	(1 << 3)	/* Send FUA (Force Unit Access) */
+#define NBD_FLAG_ROTATIONAL	(1 << 4)	/* Use elevator algorithm - rotational media */
+#define NBD_FLAG_SEND_TRIM	(1 << 5)	/* Send TRIM (discard) */
+#define NBD_FLAG_RESUME 	(1 << 6) 	/* Resume connection */
+
+
 
 struct request;