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