--- /dev/null
+/*
+ * 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, ¤t->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)");
Code Review / kvmfornfv.git / blobdiff