Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 731 insertions, 0 deletions

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
new file mode 100644
index 000000000000..efdf04450bf7
--- /dev/null
+++ b/drivers/block/nbd.c
@@ -0,0 +1,731 @@
+/*
+ * 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 Pavel Machek <pavel@ucw.cz>
+ * Parts copyright 2001 Steven Whitehouse <steve@chygwyn.com>
+ *
+ * (part of code stolen from loop.c)
+ *
+ * 97-3-25 compiled 0-th version, not yet tested it 
+ *   (it did not work, BTW) (later that day) HEY! it works!
+ *   (bit later) hmm, not that much... 2:00am next day:
+ *   yes, it works, but it gives something like 50kB/sec
+ * 97-4-01 complete rewrite to make it possible for many requests at 
+ *   once to be processed
+ * 97-4-11 Making protocol independent of endianity etc.
+ * 97-9-13 Cosmetic changes
+ * 98-5-13 Attempt to make 64-bit-clean on 64-bit machines
+ * 99-1-11 Attempt to make 64-bit-clean on 32-bit machines <ankry@mif.pg.gda.pl>
+ * 01-2-27 Fix to store proper blockcount for kernel (calculated using
+ *   BLOCK_SIZE_BITS, not device blocksize) <aga@permonline.ru>
+ * 01-3-11 Make nbd work with new Linux block layer code. It now supports
+ *   plugging like all the other block devices. Also added in MSG_MORE to
+ *   reduce number of partial TCP segments sent. <steve@chygwyn.com>
+ * 01-12-6 Fix deadlock condition by making queue locks independent of
+ *   the transmit lock. <steve@chygwyn.com>
+ * 02-10-11 Allow hung xmit to be aborted via SIGKILL & various fixes.
+ *   <Paul.Clements@SteelEye.com> <James.Bottomley@SteelEye.com>
+ * 03-06-22 Make nbd work with new linux 2.5 block layer design. This fixes
+ *   memory corruption from module removal and possible memory corruption
+ *   from sending/receiving disk data. <ldl@aros.net>
+ * 03-06-23 Cosmetic changes. <ldl@aros.net>
+ * 03-06-23 Enhance diagnostics support. <ldl@aros.net>
+ * 03-06-24 Remove unneeded blksize_bits field from nbd_device struct.
+ *   <ldl@aros.net>
+ * 03-06-24 Cleanup PARANOIA usage & code. <ldl@aros.net>
+ * 04-02-19 Remove PARANOIA, plus various cleanups (Paul Clements)
+ * possible FIXME: make set_sock / set_blksize / set_size / do_it one syscall
+ * why not: would need access_ok and friends, would share yet another
+ *          structure with userland
+ */
+
+#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 <net/sock.h>
+
+#include <linux/devfs_fs_kernel.h>
+
+#include <asm/uaccess.h>
+#include <asm/types.h>
+
+#include <linux/nbd.h>
+
+#define LO_MAGIC 0x68797548
+
+#ifdef NDEBUG
+#define dprintk(flags, fmt...)
+#else /* NDEBUG */
+#define dprintk(flags, fmt...) do { \
+	if (debugflags & (flags)) printk(KERN_DEBUG fmt); \
+} while (0)
+#define DBG_IOCTL       0x0004
+#define DBG_INIT        0x0010
+#define DBG_EXIT        0x0020
+#define DBG_BLKDEV      0x0100
+#define DBG_RX          0x0200
+#define DBG_TX          0x0400
+static unsigned int debugflags;
+#endif /* NDEBUG */
+
+static struct nbd_device nbd_dev[MAX_NBD];
+
+/*
+ * 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);
+
+#ifndef NDEBUG
+static const char *ioctl_cmd_to_ascii(int cmd)
+{
+	switch (cmd) {
+	case NBD_SET_SOCK: return "set-sock";
+	case NBD_SET_BLKSIZE: return "set-blksize";
+	case NBD_SET_SIZE: return "set-size";
+	case NBD_DO_IT: return "do-it";
+	case NBD_CLEAR_SOCK: return "clear-sock";
+	case NBD_CLEAR_QUE: return "clear-que";
+	case NBD_PRINT_DEBUG: return "print-debug";
+	case NBD_SET_SIZE_BLOCKS: return "set-size-blocks";
+	case NBD_DISCONNECT: return "disconnect";
+	case BLKROSET: return "set-read-only";
+	case BLKFLSBUF: return "flush-buffer-cache";
+	}
+	return "unknown";
+}
+
+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";
+	}
+	return "invalid";
+}
+#endif /* NDEBUG */
+
+static void nbd_end_request(struct request *req)
+{
+	int uptodate = (req->errors == 0) ? 1 : 0;
+	request_queue_t *q = req->q;
+	unsigned long flags;
+
+	dprintk(DBG_BLKDEV, "%s: request %p: %s\n", req->rq_disk->disk_name,
+			req, uptodate? "done": "failed");
+
+	spin_lock_irqsave(q->queue_lock, flags);
+	if (!end_that_request_first(req, uptodate, req->nr_sectors)) {
+		end_that_request_last(req);
+	}
+	spin_unlock_irqrestore(q->queue_lock, flags);
+}
+
+/*
+ *  Send or receive packet.
+ */
+static int sock_xmit(struct socket *sock, int send, void *buf, int size,
+		int msg_flags)
+{
+	int result;
+	struct msghdr msg;
+	struct kvec iov;
+	unsigned long flags;
+	sigset_t oldset;
+
+	/* Allow interception of SIGKILL only
+	 * Don't allow other signals to interrupt the transmission */
+	spin_lock_irqsave(&current->sighand->siglock, flags);
+	oldset = current->blocked;
+	sigfillset(&current->blocked);
+	sigdelsetmask(&current->blocked, sigmask(SIGKILL));
+	recalc_sigpending();
+	spin_unlock_irqrestore(&current->sighand->siglock, flags);
+
+	do {
+		sock->sk->sk_allocation = GFP_NOIO;
+		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_namelen = 0;
+		msg.msg_flags = msg_flags | MSG_NOSIGNAL;
+
+		if (send)
+			result = kernel_sendmsg(sock, &msg, &iov, 1, size);
+		else
+			result = kernel_recvmsg(sock, &msg, &iov, 1, size, 0);
+
+		if (signal_pending(current)) {
+			siginfo_t info;
+			spin_lock_irqsave(&current->sighand->siglock, flags);
+			printk(KERN_WARNING "nbd (pid %d: %s) got signal %d\n",
+				current->pid, current->comm, 
+				dequeue_signal(current, &current->blocked, &info));
+			spin_unlock_irqrestore(&current->sighand->siglock, flags);
+			result = -EINTR;
+			break;
+		}
+
+		if (result <= 0) {
+			if (result == 0)
+				result = -EPIPE; /* short read */
+			break;
+		}
+		size -= result;
+		buf += result;
+	} while (size > 0);
+
+	spin_lock_irqsave(&current->sighand->siglock, flags);
+	current->blocked = oldset;
+	recalc_sigpending();
+	spin_unlock_irqrestore(&current->sighand->siglock, flags);
+
+	return result;
+}
+
+static inline int sock_send_bvec(struct socket *sock, struct bio_vec *bvec,
+		int flags)
+{
+	int result;
+	void *kaddr = kmap(bvec->bv_page);
+	result = sock_xmit(sock, 1, kaddr + bvec->bv_offset, bvec->bv_len,
+			flags);
+	kunmap(bvec->bv_page);
+	return result;
+}
+
+static int nbd_send_req(struct nbd_device *lo, struct request *req)
+{
+	int result, i, flags;
+	struct nbd_request request;
+	unsigned long size = req->nr_sectors << 9;
+	struct socket *sock = lo->sock;
+
+	request.magic = htonl(NBD_REQUEST_MAGIC);
+	request.type = htonl(nbd_cmd(req));
+	request.from = cpu_to_be64((u64) req->sector << 9);
+	request.len = htonl(size);
+	memcpy(request.handle, &req, sizeof(req));
+
+	down(&lo->tx_lock);
+
+	if (!sock || !lo->sock) {
+		printk(KERN_ERR "%s: Attempted send on closed socket\n",
+				lo->disk->disk_name);
+		goto error_out;
+	}
+
+	dprintk(DBG_TX, "%s: request %p: sending control (%s@%llu,%luB)\n",
+			lo->disk->disk_name, req,
+			nbdcmd_to_ascii(nbd_cmd(req)),
+			(unsigned long long)req->sector << 9,
+			req->nr_sectors << 9);
+	result = sock_xmit(sock, 1, &request, sizeof(request),
+			(nbd_cmd(req) == NBD_CMD_WRITE)? MSG_MORE: 0);
+	if (result <= 0) {
+		printk(KERN_ERR "%s: Send control failed (result %d)\n",
+				lo->disk->disk_name, result);
+		goto error_out;
+	}
+
+	if (nbd_cmd(req) == NBD_CMD_WRITE) {
+		struct bio *bio;
+		/*
+		 * we are really probing at internals to determine
+		 * whether to set MSG_MORE or not...
+		 */
+		rq_for_each_bio(bio, req) {
+			struct bio_vec *bvec;
+			bio_for_each_segment(bvec, bio, i) {
+				flags = 0;
+				if ((i < (bio->bi_vcnt - 1)) || bio->bi_next)
+					flags = MSG_MORE;
+				dprintk(DBG_TX, "%s: request %p: sending %d bytes data\n",
+						lo->disk->disk_name, req,
+						bvec->bv_len);
+				result = sock_send_bvec(sock, bvec, flags);
+				if (result <= 0) {
+					printk(KERN_ERR "%s: Send data failed (result %d)\n",
+							lo->disk->disk_name,
+							result);
+					goto error_out;
+				}
+			}
+		}
+	}
+	up(&lo->tx_lock);
+	return 0;
+
+error_out:
+	up(&lo->tx_lock);
+	return 1;
+}
+
+static struct request *nbd_find_request(struct nbd_device *lo, char *handle)
+{
+	struct request *req;
+	struct list_head *tmp;
+	struct request *xreq;
+
+	memcpy(&xreq, handle, sizeof(xreq));
+
+	spin_lock(&lo->queue_lock);
+	list_for_each(tmp, &lo->queue_head) {
+		req = list_entry(tmp, struct request, queuelist);
+		if (req != xreq)
+			continue;
+		list_del_init(&req->queuelist);
+		spin_unlock(&lo->queue_lock);
+		return req;
+	}
+	spin_unlock(&lo->queue_lock);
+	return NULL;
+}
+
+static inline int sock_recv_bvec(struct socket *sock, struct bio_vec *bvec)
+{
+	int result;
+	void *kaddr = kmap(bvec->bv_page);
+	result = sock_xmit(sock, 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 *lo)
+{
+	int result;
+	struct nbd_reply reply;
+	struct request *req;
+	struct socket *sock = lo->sock;
+
+	reply.magic = 0;
+	result = sock_xmit(sock, 0, &reply, sizeof(reply), MSG_WAITALL);
+	if (result <= 0) {
+		printk(KERN_ERR "%s: Receive control failed (result %d)\n",
+				lo->disk->disk_name, result);
+		goto harderror;
+	}
+	req = nbd_find_request(lo, reply.handle);
+	if (req == NULL) {
+		printk(KERN_ERR "%s: Unexpected reply (%p)\n",
+				lo->disk->disk_name, reply.handle);
+		result = -EBADR;
+		goto harderror;
+	}
+
+	if (ntohl(reply.magic) != NBD_REPLY_MAGIC) {
+		printk(KERN_ERR "%s: Wrong magic (0x%lx)\n",
+				lo->disk->disk_name,
+				(unsigned long)ntohl(reply.magic));
+		result = -EPROTO;
+		goto harderror;
+	}
+	if (ntohl(reply.error)) {
+		printk(KERN_ERR "%s: Other side returned error (%d)\n",
+				lo->disk->disk_name, ntohl(reply.error));
+		req->errors++;
+		return req;
+	}
+
+	dprintk(DBG_RX, "%s: request %p: got reply\n",
+			lo->disk->disk_name, req);
+	if (nbd_cmd(req) == NBD_CMD_READ) {
+		int i;
+		struct bio *bio;
+		rq_for_each_bio(bio, req) {
+			struct bio_vec *bvec;
+			bio_for_each_segment(bvec, bio, i) {
+				result = sock_recv_bvec(sock, bvec);
+				if (result <= 0) {
+					printk(KERN_ERR "%s: Receive data failed (result %d)\n",
+							lo->disk->disk_name,
+							result);
+					goto harderror;
+				}
+				dprintk(DBG_RX, "%s: request %p: got %d bytes data\n",
+					lo->disk->disk_name, req, bvec->bv_len);
+			}
+		}
+	}
+	return req;
+harderror:
+	lo->harderror = result;
+	return NULL;
+}
+
+static void nbd_do_it(struct nbd_device *lo)
+{
+	struct request *req;
+
+	BUG_ON(lo->magic != LO_MAGIC);
+
+	while ((req = nbd_read_stat(lo)) != NULL)
+		nbd_end_request(req);
+	return;
+}
+
+static void nbd_clear_que(struct nbd_device *lo)
+{
+	struct request *req;
+
+	BUG_ON(lo->magic != LO_MAGIC);
+
+	do {
+		req = NULL;
+		spin_lock(&lo->queue_lock);
+		if (!list_empty(&lo->queue_head)) {
+			req = list_entry(lo->queue_head.next, struct request, queuelist);
+			list_del_init(&req->queuelist);
+		}
+		spin_unlock(&lo->queue_lock);
+		if (req) {
+			req->errors++;
+			nbd_end_request(req);
+		}
+	} while (req);
+}
+
+/*
+ * We always wait for result of write, for now. It would be nice to make it optional
+ * in future
+ * if ((req->cmd == WRITE) && (lo->flags & NBD_WRITE_NOCHK)) 
+ *   { printk( "Warning: Ignoring result!\n"); nbd_end_request( req ); }
+ */
+
+static void do_nbd_request(request_queue_t * q)
+{
+	struct request *req;
+	
+	while ((req = elv_next_request(q)) != NULL) {
+		struct nbd_device *lo;
+
+		blkdev_dequeue_request(req);
+		dprintk(DBG_BLKDEV, "%s: request %p: dequeued (flags=%lx)\n",
+				req->rq_disk->disk_name, req, req->flags);
+
+		if (!(req->flags & REQ_CMD))
+			goto error_out;
+
+		lo = req->rq_disk->private_data;
+
+		BUG_ON(lo->magic != LO_MAGIC);
+
+		if (!lo->file) {
+			printk(KERN_ERR "%s: Request when not-ready\n",
+					lo->disk->disk_name);
+			goto error_out;
+		}
+		nbd_cmd(req) = NBD_CMD_READ;
+		if (rq_data_dir(req) == WRITE) {
+			nbd_cmd(req) = NBD_CMD_WRITE;
+			if (lo->flags & NBD_READ_ONLY) {
+				printk(KERN_ERR "%s: Write on read-only\n",
+						lo->disk->disk_name);
+				goto error_out;
+			}
+		}
+
+		req->errors = 0;
+		spin_unlock_irq(q->queue_lock);
+
+		spin_lock(&lo->queue_lock);
+
+		if (!lo->file) {
+			spin_unlock(&lo->queue_lock);
+			printk(KERN_ERR "%s: failed between accept and semaphore, file lost\n",
+					lo->disk->disk_name);
+			req->errors++;
+			nbd_end_request(req);
+			spin_lock_irq(q->queue_lock);
+			continue;
+		}
+
+		list_add(&req->queuelist, &lo->queue_head);
+		spin_unlock(&lo->queue_lock);
+
+		if (nbd_send_req(lo, req) != 0) {
+			printk(KERN_ERR "%s: Request send failed\n",
+					lo->disk->disk_name);
+			if (nbd_find_request(lo, (char *)&req) != NULL) {
+				/* we still own req */
+				req->errors++;
+				nbd_end_request(req);
+			} else /* we're racing with nbd_clear_que */
+				printk(KERN_DEBUG "nbd: can't find req\n");
+		}
+
+		spin_lock_irq(q->queue_lock);
+		continue;
+
+error_out:
+		req->errors++;
+		spin_unlock(q->queue_lock);
+		nbd_end_request(req);
+		spin_lock(q->queue_lock);
+	}
+	return;
+}
+
+static int nbd_ioctl(struct inode *inode, struct file *file,
+		     unsigned int cmd, unsigned long arg)
+{
+	struct nbd_device *lo = inode->i_bdev->bd_disk->private_data;
+	int error;
+	struct request sreq ;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	BUG_ON(lo->magic != LO_MAGIC);
+
+	/* Anyone capable of this syscall can do *real bad* things */
+	dprintk(DBG_IOCTL, "%s: nbd_ioctl cmd=%s(0x%x) arg=%lu\n",
+			lo->disk->disk_name, ioctl_cmd_to_ascii(cmd), cmd, arg);
+
+	switch (cmd) {
+	case NBD_DISCONNECT:
+	        printk(KERN_INFO "%s: NBD_DISCONNECT\n", lo->disk->disk_name);
+		sreq.flags = REQ_SPECIAL;
+		nbd_cmd(&sreq) = NBD_CMD_DISC;
+		/*
+		 * Set these to sane values in case server implementation
+		 * fails to check the request type first and also to keep
+		 * debugging output cleaner.
+		 */
+		sreq.sector = 0;
+		sreq.nr_sectors = 0;
+                if (!lo->sock)
+			return -EINVAL;
+                nbd_send_req(lo, &sreq);
+                return 0;
+ 
+	case NBD_CLEAR_SOCK:
+		error = 0;
+		down(&lo->tx_lock);
+		lo->sock = NULL;
+		up(&lo->tx_lock);
+		spin_lock(&lo->queue_lock);
+		file = lo->file;
+		lo->file = NULL;
+		spin_unlock(&lo->queue_lock);
+		nbd_clear_que(lo);
+		spin_lock(&lo->queue_lock);
+		if (!list_empty(&lo->queue_head)) {
+			printk(KERN_ERR "nbd: disconnect: some requests are in progress -> please try again.\n");
+			error = -EBUSY;
+		}
+		spin_unlock(&lo->queue_lock);
+		if (file)
+			fput(file);
+		return error;
+	case NBD_SET_SOCK:
+		if (lo->file)
+			return -EBUSY;
+		error = -EINVAL;
+		file = fget(arg);
+		if (file) {
+			inode = file->f_dentry->d_inode;
+			if (S_ISSOCK(inode->i_mode)) {
+				lo->file = file;
+				lo->sock = SOCKET_I(inode);
+				error = 0;
+			} else {
+				fput(file);
+			}
+		}
+		return error;
+	case NBD_SET_BLKSIZE:
+		lo->blksize = arg;
+		lo->bytesize &= ~(lo->blksize-1);
+		inode->i_bdev->bd_inode->i_size = lo->bytesize;
+		set_blocksize(inode->i_bdev, lo->blksize);
+		set_capacity(lo->disk, lo->bytesize >> 9);
+		return 0;
+	case NBD_SET_SIZE:
+		lo->bytesize = arg & ~(lo->blksize-1);
+		inode->i_bdev->bd_inode->i_size = lo->bytesize;
+		set_blocksize(inode->i_bdev, lo->blksize);
+		set_capacity(lo->disk, lo->bytesize >> 9);
+		return 0;
+	case NBD_SET_SIZE_BLOCKS:
+		lo->bytesize = ((u64) arg) * lo->blksize;
+		inode->i_bdev->bd_inode->i_size = lo->bytesize;
+		set_blocksize(inode->i_bdev, lo->blksize);
+		set_capacity(lo->disk, lo->bytesize >> 9);
+		return 0;
+	case NBD_DO_IT:
+		if (!lo->file)
+			return -EINVAL;
+		nbd_do_it(lo);
+		/* on return tidy up in case we have a signal */
+		/* Forcibly shutdown the socket causing all listeners
+		 * to error
+		 *
+		 * FIXME: This code is duplicated from sys_shutdown, but
+		 * there should be a more generic interface rather than
+		 * calling socket ops directly here */
+		down(&lo->tx_lock);
+		if (lo->sock) {
+			printk(KERN_WARNING "%s: shutting down socket\n",
+				lo->disk->disk_name);
+			lo->sock->ops->shutdown(lo->sock,
+				SEND_SHUTDOWN|RCV_SHUTDOWN);
+			lo->sock = NULL;
+		}
+		up(&lo->tx_lock);
+		spin_lock(&lo->queue_lock);
+		file = lo->file;
+		lo->file = NULL;
+		spin_unlock(&lo->queue_lock);
+		nbd_clear_que(lo);
+		printk(KERN_WARNING "%s: queue cleared\n", lo->disk->disk_name);
+		if (file)
+			fput(file);
+		return lo->harderror;
+	case NBD_CLEAR_QUE:
+		down(&lo->tx_lock);
+		if (lo->sock) {
+			up(&lo->tx_lock);
+			return 0; /* probably should be error, but that would
+				   * break "nbd-client -d", so just return 0 */
+		}
+		up(&lo->tx_lock);
+		nbd_clear_que(lo);
+		return 0;
+	case NBD_PRINT_DEBUG:
+		printk(KERN_INFO "%s: next = %p, prev = %p, head = %p\n",
+			inode->i_bdev->bd_disk->disk_name,
+			lo->queue_head.next, lo->queue_head.prev,
+			&lo->queue_head);
+		return 0;
+	}
+	return -EINVAL;
+}
+
+static 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;
+
+	if (sizeof(struct nbd_request) != 28) {
+		printk(KERN_CRIT "nbd: sizeof nbd_request needs to be 28 in order to work!\n" );
+		return -EIO;
+	}
+
+	for (i = 0; i < MAX_NBD; i++) {
+		struct gendisk *disk = alloc_disk(1);
+		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;
+		}
+	}
+
+	if (register_blkdev(NBD_MAJOR, "nbd")) {
+		err = -EIO;
+		goto out;
+	}
+
+	printk(KERN_INFO "nbd: registered device at major %d\n", NBD_MAJOR);
+	dprintk(DBG_INIT, "nbd: debugflags=0x%x\n", debugflags);
+
+	devfs_mk_dir("nbd");
+	for (i = 0; i < MAX_NBD; i++) {
+		struct gendisk *disk = nbd_dev[i].disk;
+		nbd_dev[i].file = NULL;
+		nbd_dev[i].magic = LO_MAGIC;
+		nbd_dev[i].flags = 0;
+		spin_lock_init(&nbd_dev[i].queue_lock);
+		INIT_LIST_HEAD(&nbd_dev[i].queue_head);
+		init_MUTEX(&nbd_dev[i].tx_lock);
+		nbd_dev[i].blksize = 1024;
+		nbd_dev[i].bytesize = 0x7ffffc00ULL << 10; /* 2TB */
+		disk->major = NBD_MAJOR;
+		disk->first_minor = i;
+		disk->fops = &nbd_fops;
+		disk->private_data = &nbd_dev[i];
+		disk->flags |= GENHD_FL_SUPPRESS_PARTITION_INFO;
+		sprintf(disk->disk_name, "nbd%d", i);
+		sprintf(disk->devfs_name, "nbd/%d", i);
+		set_capacity(disk, 0x7ffffc00ULL << 1); /* 2 TB */
+		add_disk(disk);
+	}
+
+	return 0;
+out:
+	while (i--) {
+		blk_cleanup_queue(nbd_dev[i].disk->queue);
+		put_disk(nbd_dev[i].disk);
+	}
+	return err;
+}
+
+static void __exit nbd_cleanup(void)
+{
+	int i;
+	for (i = 0; i < MAX_NBD; i++) {
+		struct gendisk *disk = nbd_dev[i].disk;
+		if (disk) {
+			del_gendisk(disk);
+			blk_cleanup_queue(disk->queue);
+			put_disk(disk);
+		}
+	}
+	devfs_remove("nbd");
+	unregister_blkdev(NBD_MAJOR, "nbd");
+	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");
+
+#ifndef NDEBUG
+module_param(debugflags, int, 0644);
+MODULE_PARM_DESC(debugflags, "flags for controlling debug output");
+#endif