Initial import

1 files changed, 896 insertions, 0 deletions

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
new file mode 100644
index 000000000..39e5f7fae
--- /dev/null
+++ b/drivers/block/nbd.c
@@ -0,0 +1,896 @@
+/*
+ * Network block device - make block devices work over TCP
+ *
+ * Note that you can not swap over this thing, yet. Seems to work but
+ * deadlocks sometimes - you can not swap over TCP in general.
+ * 
+ * Copyright 1997-2000, 2008 Pavel Machek <pavel@ucw.cz>
+ * Parts copyright 2001 Steven Whitehouse <steve@chygwyn.com>
+ *
+ * This file is released under GPLv2 or later.
+ *
+ * (part of code stolen from loop.c)
+ */
+
+#include <linux/major.h>
+
+#include <linux/blkdev.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/fs.h>
+#include <linux/bio.h>
+#include <linux/stat.h>
+#include <linux/errno.h>
+#include <linux/file.h>
+#include <linux/ioctl.h>
+#include <linux/mutex.h>
+#include <linux/compiler.h>
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <net/sock.h>
+#include <linux/net.h>
+#include <linux/kthread.h>
+#include <linux/types.h>
+
+#include <asm/uaccess.h>
+#include <asm/types.h>
+
+#include <linux/nbd.h>
+
+struct nbd_device {
+	int flags;
+	int harderror;		/* Code of hard error			*/
+	struct socket * sock;	/* If == NULL, device is not ready, yet	*/
+	int magic;
+
+	spinlock_t queue_lock;
+	struct list_head queue_head;	/* Requests waiting result */
+	struct request *active_req;
+	wait_queue_head_t active_wq;
+	struct list_head waiting_queue;	/* Requests to be sent */
+	wait_queue_head_t waiting_wq;
+
+	struct mutex tx_lock;
+	struct gendisk *disk;
+	int blksize;
+	loff_t bytesize;
+	pid_t pid; /* pid of nbd-client, if attached */
+	int xmit_timeout;
+	int disconnect; /* a disconnect has been requested by user */
+};
+
+#define NBD_MAGIC 0x68797548
+
+static unsigned int nbds_max = 16;
+static struct nbd_device *nbd_dev;
+static int max_part;
+
+/*
+ * Use just one lock (or at most 1 per NIC). Two arguments for this:
+ * 1. Each NIC is essentially a synchronization point for all servers
+ *    accessed through that NIC so there's no need to have more locks
+ *    than NICs anyway.
+ * 2. More locks lead to more "Dirty cache line bouncing" which will slow
+ *    down each lock to the point where they're actually slower than just
+ *    a single lock.
+ * Thanks go to Jens Axboe and Al Viro for their LKML emails explaining this!
+ */
+static DEFINE_SPINLOCK(nbd_lock);
+
+static inline struct device *nbd_to_dev(struct nbd_device *nbd)
+{
+	return disk_to_dev(nbd->disk);
+}
+
+static const char *nbdcmd_to_ascii(int cmd)
+{
+	switch (cmd) {
+	case  NBD_CMD_READ: return "read";
+	case NBD_CMD_WRITE: return "write";
+	case  NBD_CMD_DISC: return "disconnect";
+	case NBD_CMD_FLUSH: return "flush";
+	case  NBD_CMD_TRIM: return "trim/discard";
+	}
+	return "invalid";
+}
+
+static void nbd_end_request(struct nbd_device *nbd, struct request *req)
+{
+	int error = req->errors ? -EIO : 0;
+	struct request_queue *q = req->q;
+	unsigned long flags;
+
+	dev_dbg(nbd_to_dev(nbd), "request %p: %s\n", req,
+		error ? "failed" : "done");
+
+	spin_lock_irqsave(q->queue_lock, flags);
+	__blk_end_request_all(req, error);
+	spin_unlock_irqrestore(q->queue_lock, flags);
+}
+
+/*
+ * Forcibly shutdown the socket causing all listeners to error
+ */
+static void sock_shutdown(struct nbd_device *nbd, int lock)
+{
+	if (lock)
+		mutex_lock(&nbd->tx_lock);
+	if (nbd->sock) {
+		dev_warn(disk_to_dev(nbd->disk), "shutting down socket\n");
+		kernel_sock_shutdown(nbd->sock, SHUT_RDWR);
+		nbd->sock = NULL;
+	}
+	if (lock)
+		mutex_unlock(&nbd->tx_lock);
+}
+
+static void nbd_xmit_timeout(unsigned long arg)
+{
+	struct task_struct *task = (struct task_struct *)arg;
+
+	printk(KERN_WARNING "nbd: killing hung xmit (%s, pid: %d)\n",
+		task->comm, task->pid);
+	force_sig(SIGKILL, task);
+}
+
+/*
+ *  Send or receive packet.
+ */
+static int sock_xmit(struct nbd_device *nbd, int send, void *buf, int size,
+		int msg_flags)
+{
+	struct socket *sock = nbd->sock;
+	int result;
+	struct msghdr msg;
+	struct kvec iov;
+	sigset_t blocked, oldset;
+	unsigned long pflags = current->flags;
+
+	if (unlikely(!sock)) {
+		dev_err(disk_to_dev(nbd->disk),
+			"Attempted %s on closed socket in sock_xmit\n",
+			(send ? "send" : "recv"));
+		return -EINVAL;
+	}
+
+	/* Allow interception of SIGKILL only
+	 * Don't allow other signals to interrupt the transmission */
+	siginitsetinv(&blocked, sigmask(SIGKILL));
+	sigprocmask(SIG_SETMASK, &blocked, &oldset);
+
+	current->flags |= PF_MEMALLOC;
+	do {
+		sock->sk->sk_allocation = GFP_NOIO | __GFP_MEMALLOC;
+		iov.iov_base = buf;
+		iov.iov_len = size;
+		msg.msg_name = NULL;
+		msg.msg_namelen = 0;
+		msg.msg_control = NULL;
+		msg.msg_controllen = 0;
+		msg.msg_flags = msg_flags | MSG_NOSIGNAL;
+
+		if (send) {
+			struct timer_list ti;
+
+			if (nbd->xmit_timeout) {
+				init_timer(&ti);
+				ti.function = nbd_xmit_timeout;
+				ti.data = (unsigned long)current;
+				ti.expires = jiffies + nbd->xmit_timeout;
+				add_timer(&ti);
+			}
+			result = kernel_sendmsg(sock, &msg, &iov, 1, size);
+			if (nbd->xmit_timeout)
+				del_timer_sync(&ti);
+		} else
+			result = kernel_recvmsg(sock, &msg, &iov, 1, size,
+						msg.msg_flags);
+
+		if (signal_pending(current)) {
+			siginfo_t 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));
+			result = -EINTR;
+			sock_shutdown(nbd, !send);
+			break;
+		}
+
+		if (result <= 0) {
+			if (result == 0)
+				result = -EPIPE; /* short read */
+			break;
+		}
+		size -= result;
+		buf += result;
+	} while (size > 0);
+
+	sigprocmask(SIG_SETMASK, &oldset, NULL);
+	tsk_restore_flags(current, pflags, PF_MEMALLOC);
+
+	return result;
+}
+
+static inline int sock_send_bvec(struct nbd_device *nbd, struct bio_vec *bvec,
+		int flags)
+{
+	int result;
+	void *kaddr = kmap(bvec->bv_page);
+	result = sock_xmit(nbd, 1, kaddr + bvec->bv_offset,
+			   bvec->bv_len, flags);
+	kunmap(bvec->bv_page);
+	return result;
+}
+
+/* always call with the tx_lock held */
+static int nbd_send_req(struct nbd_device *nbd, struct request *req)
+{
+	int result, flags;
+	struct nbd_request request;
+	unsigned long size = blk_rq_bytes(req);
+
+	memset(&request, 0, sizeof(request));
+	request.magic = htonl(NBD_REQUEST_MAGIC);
+	request.type = htonl(nbd_cmd(req));
+
+	if (nbd_cmd(req) != NBD_CMD_FLUSH && nbd_cmd(req) != NBD_CMD_DISC) {
+		request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9);
+		request.len = htonl(size);
+	}
+	memcpy(request.handle, &req, sizeof(req));
+
+	dev_dbg(nbd_to_dev(nbd), "request %p: sending control (%s@%llu,%uB)\n",
+		req, nbdcmd_to_ascii(nbd_cmd(req)),
+		(unsigned long long)blk_rq_pos(req) << 9, blk_rq_bytes(req));
+	result = sock_xmit(nbd, 1, &request, sizeof(request),
+			(nbd_cmd(req) == NBD_CMD_WRITE) ? MSG_MORE : 0);
+	if (result <= 0) {
+		dev_err(disk_to_dev(nbd->disk),
+			"Send control failed (result %d)\n", result);
+		return -EIO;
+	}
+
+	if (nbd_cmd(req) == NBD_CMD_WRITE) {
+		struct req_iterator iter;
+		struct bio_vec bvec;
+		/*
+		 * we are really probing at internals to determine
+		 * whether to set MSG_MORE or not...
+		 */
+		rq_for_each_segment(bvec, req, iter) {
+			flags = 0;
+			if (!rq_iter_last(bvec, iter))
+				flags = MSG_MORE;
+			dev_dbg(nbd_to_dev(nbd), "request %p: sending %d bytes data\n",
+				req, bvec.bv_len);
+			result = sock_send_bvec(nbd, &bvec, flags);
+			if (result <= 0) {
+				dev_err(disk_to_dev(nbd->disk),
+					"Send data failed (result %d)\n",
+					result);
+				return -EIO;
+			}
+		}
+	}
+	return 0;
+}
+
+static struct request *nbd_find_request(struct nbd_device *nbd,
+					struct request *xreq)
+{
+	struct request *req, *tmp;
+	int err;
+
+	err = wait_event_interruptible(nbd->active_wq, nbd->active_req != xreq);
+	if (unlikely(err))
+		return ERR_PTR(err);
+
+	spin_lock(&nbd->queue_lock);
+	list_for_each_entry_safe(req, tmp, &nbd->queue_head, queuelist) {
+		if (req != xreq)
+			continue;
+		list_del_init(&req->queuelist);
+		spin_unlock(&nbd->queue_lock);
+		return req;
+	}
+	spin_unlock(&nbd->queue_lock);
+
+	return ERR_PTR(-ENOENT);
+}
+
+static inline int sock_recv_bvec(struct nbd_device *nbd, struct bio_vec *bvec)
+{
+	int result;
+	void *kaddr = kmap(bvec->bv_page);
+	result = sock_xmit(nbd, 0, kaddr + bvec->bv_offset, bvec->bv_len,
+			MSG_WAITALL);
+	kunmap(bvec->bv_page);
+	return result;
+}
+
+/* NULL returned = something went wrong, inform userspace */
+static struct request *nbd_read_stat(struct nbd_device *nbd)
+{
+	int result;
+	struct nbd_reply reply;
+	struct request *req;
+
+	reply.magic = 0;
+	result = sock_xmit(nbd, 0, &reply, sizeof(reply), MSG_WAITALL);
+	if (result <= 0) {
+		dev_err(disk_to_dev(nbd->disk),
+			"Receive control failed (result %d)\n", result);
+		goto harderror;
+	}
+
+	if (ntohl(reply.magic) != NBD_REPLY_MAGIC) {
+		dev_err(disk_to_dev(nbd->disk), "Wrong magic (0x%lx)\n",
+				(unsigned long)ntohl(reply.magic));
+		result = -EPROTO;
+		goto harderror;
+	}
+
+	req = nbd_find_request(nbd, *(struct request **)reply.handle);
+	if (IS_ERR(req)) {
+		result = PTR_ERR(req);
+		if (result != -ENOENT)
+			goto harderror;
+
+		dev_err(disk_to_dev(nbd->disk), "Unexpected reply (%p)\n",
+			reply.handle);
+		result = -EBADR;
+		goto harderror;
+	}
+
+	if (ntohl(reply.error)) {
+		dev_err(disk_to_dev(nbd->disk), "Other side returned error (%d)\n",
+			ntohl(reply.error));
+		req->errors++;
+		return req;
+	}
+
+	dev_dbg(nbd_to_dev(nbd), "request %p: got reply\n", req);
+	if (nbd_cmd(req) == NBD_CMD_READ) {
+		struct req_iterator iter;
+		struct bio_vec bvec;
+
+		rq_for_each_segment(bvec, req, iter) {
+			result = sock_recv_bvec(nbd, &bvec);
+			if (result <= 0) {
+				dev_err(disk_to_dev(nbd->disk), "Receive data failed (result %d)\n",
+					result);
+				req->errors++;
+				return req;
+			}
+			dev_dbg(nbd_to_dev(nbd), "request %p: got %d bytes data\n",
+				req, bvec.bv_len);
+		}
+	}
+	return req;
+harderror:
+	nbd->harderror = result;
+	return NULL;
+}
+
+static ssize_t pid_show(struct device *dev,
+			struct device_attribute *attr, char *buf)
+{
+	struct gendisk *disk = dev_to_disk(dev);
+
+	return sprintf(buf, "%ld\n",
+		(long) ((struct nbd_device *)disk->private_data)->pid);
+}
+
+static struct device_attribute pid_attr = {
+	.attr = { .name = "pid", .mode = S_IRUGO},
+	.show = pid_show,
+};
+
+static int nbd_do_it(struct nbd_device *nbd)
+{
+	struct request *req;
+	int ret;
+
+	BUG_ON(nbd->magic != NBD_MAGIC);
+
+	sk_set_memalloc(nbd->sock->sk);
+	nbd->pid = task_pid_nr(current);
+	ret = device_create_file(disk_to_dev(nbd->disk), &pid_attr);
+	if (ret) {
+		dev_err(disk_to_dev(nbd->disk), "device_create_file failed!\n");
+		nbd->pid = 0;
+		return ret;
+	}
+
+	while ((req = nbd_read_stat(nbd)) != NULL)
+		nbd_end_request(nbd, req);
+
+	device_remove_file(disk_to_dev(nbd->disk), &pid_attr);
+	nbd->pid = 0;
+	return 0;
+}
+
+static void nbd_clear_que(struct nbd_device *nbd)
+{
+	struct request *req;
+
+	BUG_ON(nbd->magic != NBD_MAGIC);
+
+	/*
+	 * Because we have set nbd->sock to NULL under the tx_lock, all
+	 * modifications to the list must have completed by now.  For
+	 * the same reason, the active_req must be NULL.
+	 *
+	 * As a consequence, we don't need to take the spin lock while
+	 * purging the list here.
+	 */
+	BUG_ON(nbd->sock);
+	BUG_ON(nbd->active_req);
+
+	while (!list_empty(&nbd->queue_head)) {
+		req = list_entry(nbd->queue_head.next, struct request,
+				 queuelist);
+		list_del_init(&req->queuelist);
+		req->errors++;
+		nbd_end_request(nbd, req);
+	}
+
+	while (!list_empty(&nbd->waiting_queue)) {
+		req = list_entry(nbd->waiting_queue.next, struct request,
+				 queuelist);
+		list_del_init(&req->queuelist);
+		req->errors++;
+		nbd_end_request(nbd, req);
+	}
+}
+
+
+static void nbd_handle_req(struct nbd_device *nbd, struct request *req)
+{
+	if (req->cmd_type != REQ_TYPE_FS)
+		goto error_out;
+
+	nbd_cmd(req) = NBD_CMD_READ;
+	if (rq_data_dir(req) == WRITE) {
+		if ((req->cmd_flags & REQ_DISCARD)) {
+			WARN_ON(!(nbd->flags & NBD_FLAG_SEND_TRIM));
+			nbd_cmd(req) = NBD_CMD_TRIM;
+		} else
+			nbd_cmd(req) = NBD_CMD_WRITE;
+		if (nbd->flags & NBD_FLAG_READ_ONLY) {
+			dev_err(disk_to_dev(nbd->disk),
+				"Write on read-only\n");
+			goto error_out;
+		}
+	}
+
+	if (req->cmd_flags & REQ_FLUSH) {
+		BUG_ON(unlikely(blk_rq_sectors(req)));
+		nbd_cmd(req) = NBD_CMD_FLUSH;
+	}
+
+	req->errors = 0;
+
+	mutex_lock(&nbd->tx_lock);
+	if (unlikely(!nbd->sock)) {
+		mutex_unlock(&nbd->tx_lock);
+		dev_err(disk_to_dev(nbd->disk),
+			"Attempted send on closed socket\n");
+		goto error_out;
+	}
+
+	nbd->active_req = req;
+
+	if (nbd_send_req(nbd, req) != 0) {
+		dev_err(disk_to_dev(nbd->disk), "Request send failed\n");
+		req->errors++;
+		nbd_end_request(nbd, req);
+	} else {
+		spin_lock(&nbd->queue_lock);
+		list_add_tail(&req->queuelist, &nbd->queue_head);
+		spin_unlock(&nbd->queue_lock);
+	}
+
+	nbd->active_req = NULL;
+	mutex_unlock(&nbd->tx_lock);
+	wake_up_all(&nbd->active_wq);
+
+	return;
+
+error_out:
+	req->errors++;
+	nbd_end_request(nbd, req);
+}
+
+static int nbd_thread(void *data)
+{
+	struct nbd_device *nbd = data;
+	struct request *req;
+
+	set_user_nice(current, MIN_NICE);
+	while (!kthread_should_stop() || !list_empty(&nbd->waiting_queue)) {
+		/* wait for something to do */
+		wait_event_interruptible(nbd->waiting_wq,
+					 kthread_should_stop() ||
+					 !list_empty(&nbd->waiting_queue));
+
+		/* extract request */
+		if (list_empty(&nbd->waiting_queue))
+			continue;
+
+		spin_lock_irq(&nbd->queue_lock);
+		req = list_entry(nbd->waiting_queue.next, struct request,
+				 queuelist);
+		list_del_init(&req->queuelist);
+		spin_unlock_irq(&nbd->queue_lock);
+
+		/* handle request */
+		nbd_handle_req(nbd, req);
+	}
+	return 0;
+}
+
+/*
+ * We always wait for result of write, for now. It would be nice to make it optional
+ * in future
+ * if ((rq_data_dir(req) == WRITE) && (nbd->flags & NBD_WRITE_NOCHK))
+ *   { printk( "Warning: Ignoring result!\n"); nbd_end_request( req ); }
+ */
+
+static void do_nbd_request(struct request_queue *q)
+		__releases(q->queue_lock) __acquires(q->queue_lock)
+{
+	struct request *req;
+	
+	while ((req = blk_fetch_request(q)) != NULL) {
+		struct nbd_device *nbd;
+
+		spin_unlock_irq(q->queue_lock);
+
+		nbd = req->rq_disk->private_data;
+
+		BUG_ON(nbd->magic != NBD_MAGIC);
+
+		dev_dbg(nbd_to_dev(nbd), "request %p: dequeued (flags=%x)\n",
+			req, req->cmd_type);
+
+		if (unlikely(!nbd->sock)) {
+			dev_err(disk_to_dev(nbd->disk),
+				"Attempted send on closed socket\n");
+			req->errors++;
+			nbd_end_request(nbd, req);
+			spin_lock_irq(q->queue_lock);
+			continue;
+		}
+
+		spin_lock_irq(&nbd->queue_lock);
+		list_add_tail(&req->queuelist, &nbd->waiting_queue);
+		spin_unlock_irq(&nbd->queue_lock);
+
+		wake_up(&nbd->waiting_wq);
+
+		spin_lock_irq(q->queue_lock);
+	}
+}
+
+/* Must be called with tx_lock held */
+
+static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
+		       unsigned int cmd, unsigned long arg)
+{
+	switch (cmd) {
+	case NBD_DISCONNECT: {
+		struct request sreq;
+
+		dev_info(disk_to_dev(nbd->disk), "NBD_DISCONNECT\n");
+		if (!nbd->sock)
+			return -EINVAL;
+
+		mutex_unlock(&nbd->tx_lock);
+		fsync_bdev(bdev);
+		mutex_lock(&nbd->tx_lock);
+		blk_rq_init(NULL, &sreq);
+		sreq.cmd_type = REQ_TYPE_SPECIAL;
+		nbd_cmd(&sreq) = NBD_CMD_DISC;
+
+		/* Check again after getting mutex back.  */
+		if (!nbd->sock)
+			return -EINVAL;
+
+		nbd->disconnect = 1;
+
+		nbd_send_req(nbd, &sreq);
+		return 0;
+	}
+ 
+	case NBD_CLEAR_SOCK: {
+		struct socket *sock = nbd->sock;
+		nbd->sock = NULL;
+		nbd_clear_que(nbd);
+		BUG_ON(!list_empty(&nbd->queue_head));
+		BUG_ON(!list_empty(&nbd->waiting_queue));
+		kill_bdev(bdev);
+		if (sock)
+			sockfd_put(sock);
+		return 0;
+	}
+
+	case NBD_SET_SOCK: {
+		struct socket *sock;
+		int err;
+		if (nbd->sock)
+			return -EBUSY;
+		sock = sockfd_lookup(arg, &err);
+		if (sock) {
+			nbd->sock = sock;
+			if (max_part > 0)
+				bdev->bd_invalidated = 1;
+			nbd->disconnect = 0; /* we're connected now */
+			return 0;
+		}
+		return -EINVAL;
+	}
+
+	case NBD_SET_BLKSIZE:
+		nbd->blksize = arg;
+		nbd->bytesize &= ~(nbd->blksize-1);
+		bdev->bd_inode->i_size = nbd->bytesize;
+		set_blocksize(bdev, nbd->blksize);
+		set_capacity(nbd->disk, nbd->bytesize >> 9);
+		return 0;
+
+	case NBD_SET_SIZE:
+		nbd->bytesize = arg & ~(nbd->blksize-1);
+		bdev->bd_inode->i_size = nbd->bytesize;
+		set_blocksize(bdev, nbd->blksize);
+		set_capacity(nbd->disk, nbd->bytesize >> 9);
+		return 0;
+
+	case NBD_SET_TIMEOUT:
+		nbd->xmit_timeout = arg * HZ;
+		return 0;
+
+	case NBD_SET_FLAGS:
+		nbd->flags = arg;
+		return 0;
+
+	case NBD_SET_SIZE_BLOCKS:
+		nbd->bytesize = ((u64) arg) * nbd->blksize;
+		bdev->bd_inode->i_size = nbd->bytesize;
+		set_blocksize(bdev, nbd->blksize);
+		set_capacity(nbd->disk, nbd->bytesize >> 9);
+		return 0;
+
+	case NBD_DO_IT: {
+		struct task_struct *thread;
+		struct socket *sock;
+		int error;
+
+		if (nbd->pid)
+			return -EBUSY;
+		if (!nbd->sock)
+			return -EINVAL;
+
+		mutex_unlock(&nbd->tx_lock);
+
+		if (nbd->flags & NBD_FLAG_READ_ONLY)
+			set_device_ro(bdev, true);
+		if (nbd->flags & NBD_FLAG_SEND_TRIM)
+			queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
+				nbd->disk->queue);
+		if (nbd->flags & NBD_FLAG_SEND_FLUSH)
+			blk_queue_flush(nbd->disk->queue, REQ_FLUSH);
+		else
+			blk_queue_flush(nbd->disk->queue, 0);
+
+		thread = kthread_run(nbd_thread, nbd, "%s",
+				     nbd->disk->disk_name);
+		if (IS_ERR(thread)) {
+			mutex_lock(&nbd->tx_lock);
+			return PTR_ERR(thread);
+		}
+
+		error = nbd_do_it(nbd);
+		kthread_stop(thread);
+
+		mutex_lock(&nbd->tx_lock);
+		if (error)
+			return error;
+		sock_shutdown(nbd, 0);
+		sock = nbd->sock;
+		nbd->sock = NULL;
+		nbd_clear_que(nbd);
+		dev_warn(disk_to_dev(nbd->disk), "queue cleared\n");
+		kill_bdev(bdev);
+		queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, nbd->disk->queue);
+		set_device_ro(bdev, false);
+		if (sock)
+			sockfd_put(sock);
+		nbd->flags = 0;
+		nbd->bytesize = 0;
+		bdev->bd_inode->i_size = 0;
+		set_capacity(nbd->disk, 0);
+		if (max_part > 0)
+			ioctl_by_bdev(bdev, BLKRRPART, 0);
+		if (nbd->disconnect) /* user requested, ignore socket errors */
+			return 0;
+		return nbd->harderror;
+	}
+
+	case NBD_CLEAR_QUE:
+		/*
+		 * This is for compatibility only.  The queue is always cleared
+		 * by NBD_DO_IT or NBD_CLEAR_SOCK.
+		 */
+		return 0;
+
+	case NBD_PRINT_DEBUG:
+		dev_info(disk_to_dev(nbd->disk),
+			"next = %p, prev = %p, head = %p\n",
+			nbd->queue_head.next, nbd->queue_head.prev,
+			&nbd->queue_head);
+		return 0;
+	}
+	return -ENOTTY;
+}
+
+static int nbd_ioctl(struct block_device *bdev, fmode_t mode,
+		     unsigned int cmd, unsigned long arg)
+{
+	struct nbd_device *nbd = bdev->bd_disk->private_data;
+	int error;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	BUG_ON(nbd->magic != NBD_MAGIC);
+
+	mutex_lock(&nbd->tx_lock);
+	error = __nbd_ioctl(bdev, nbd, cmd, arg);
+	mutex_unlock(&nbd->tx_lock);
+
+	return error;
+}
+
+static const struct block_device_operations nbd_fops =
+{
+	.owner =	THIS_MODULE,
+	.ioctl =	nbd_ioctl,
+};
+
+/*
+ * And here should be modules and kernel interface 
+ *  (Just smiley confuses emacs :-)
+ */
+
+static int __init nbd_init(void)
+{
+	int err = -ENOMEM;
+	int i;
+	int part_shift;
+
+	BUILD_BUG_ON(sizeof(struct nbd_request) != 28);
+
+	if (max_part < 0) {
+		printk(KERN_ERR "nbd: max_part must be >= 0\n");
+		return -EINVAL;
+	}
+
+	part_shift = 0;
+	if (max_part > 0) {
+		part_shift = fls(max_part);
+
+		/*
+		 * Adjust max_part according to part_shift as it is exported
+		 * to user space so that user can know the max number of
+		 * partition kernel should be able to manage.
+		 *
+		 * Note that -1 is required because partition 0 is reserved
+		 * for the whole disk.
+		 */
+		max_part = (1UL << part_shift) - 1;
+	}
+
+	if ((1UL << part_shift) > DISK_MAX_PARTS)
+		return -EINVAL;
+
+	if (nbds_max > 1UL << (MINORBITS - part_shift))
+		return -EINVAL;
+
+	nbd_dev = kcalloc(nbds_max, sizeof(*nbd_dev), GFP_KERNEL);
+	if (!nbd_dev)
+		return -ENOMEM;
+
+	for (i = 0; i < nbds_max; i++) {
+		struct gendisk *disk = alloc_disk(1 << part_shift);
+		if (!disk)
+			goto out;
+		nbd_dev[i].disk = disk;
+		/*
+		 * The new linux 2.5 block layer implementation requires
+		 * every gendisk to have its very own request_queue struct.
+		 * These structs are big so we dynamically allocate them.
+		 */
+		disk->queue = blk_init_queue(do_nbd_request, &nbd_lock);
+		if (!disk->queue) {
+			put_disk(disk);
+			goto out;
+		}
+		/*
+		 * Tell the block layer that we are not a rotational device
+		 */
+		queue_flag_set_unlocked(QUEUE_FLAG_NONROT, disk->queue);
+		queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, disk->queue);
+		disk->queue->limits.discard_granularity = 512;
+		disk->queue->limits.max_discard_sectors = UINT_MAX;
+		disk->queue->limits.discard_zeroes_data = 0;
+		blk_queue_max_hw_sectors(disk->queue, 65536);
+		disk->queue->limits.max_sectors = 256;
+	}
+
+	if (register_blkdev(NBD_MAJOR, "nbd")) {
+		err = -EIO;
+		goto out;
+	}
+
+	printk(KERN_INFO "nbd: registered device at major %d\n", NBD_MAJOR);
+
+	for (i = 0; i < nbds_max; i++) {
+		struct gendisk *disk = nbd_dev[i].disk;
+		nbd_dev[i].magic = NBD_MAGIC;
+		INIT_LIST_HEAD(&nbd_dev[i].waiting_queue);
+		spin_lock_init(&nbd_dev[i].queue_lock);
+		INIT_LIST_HEAD(&nbd_dev[i].queue_head);
+		mutex_init(&nbd_dev[i].tx_lock);
+		init_waitqueue_head(&nbd_dev[i].active_wq);
+		init_waitqueue_head(&nbd_dev[i].waiting_wq);
+		nbd_dev[i].blksize = 1024;
+		nbd_dev[i].bytesize = 0;
+		disk->major = NBD_MAJOR;
+		disk->first_minor = i << part_shift;
+		disk->fops = &nbd_fops;
+		disk->private_data = &nbd_dev[i];
+		sprintf(disk->disk_name, "nbd%d", i);
+		set_capacity(disk, 0);
+		add_disk(disk);
+	}
+
+	return 0;
+out:
+	while (i--) {
+		blk_cleanup_queue(nbd_dev[i].disk->queue);
+		put_disk(nbd_dev[i].disk);
+	}
+	kfree(nbd_dev);
+	return err;
+}
+
+static void __exit nbd_cleanup(void)
+{
+	int i;
+	for (i = 0; i < nbds_max; i++) {
+		struct gendisk *disk = nbd_dev[i].disk;
+		nbd_dev[i].magic = 0;
+		if (disk) {
+			del_gendisk(disk);
+			blk_cleanup_queue(disk->queue);
+			put_disk(disk);
+		}
+	}
+	unregister_blkdev(NBD_MAJOR, "nbd");
+	kfree(nbd_dev);
+	printk(KERN_INFO "nbd: unregistered device at major %d\n", NBD_MAJOR);
+}
+
+module_init(nbd_init);
+module_exit(nbd_cleanup);
+
+MODULE_DESCRIPTION("Network Block Device");
+MODULE_LICENSE("GPL");
+
+module_param(nbds_max, int, 0444);
+MODULE_PARM_DESC(nbds_max, "number of network block devices to initialize (default: 16)");
+module_param(max_part, int, 0444);
+MODULE_PARM_DESC(max_part, "number of partitions per device (default: 0)");