/* * 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 <asm/uaccess.h> #include <asm/system.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 DEFINE_MUTEX(nbd_mutex); static unsigned int debugflags; #endif /* NDEBUG */ 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); #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 error = req->errors ? -EIO : 0; struct request_queue *q = req->q; unsigned long flags; dprintk(DBG_BLKDEV, "%s: request %p: %s\n", req->rq_disk->disk_name, req, error ? "failed" : "done"); spin_lock_irqsave(q->queue_lock, flags); __blk_end_request_all(req, error); spin_unlock_irqrestore(q->queue_lock, flags); } static void sock_shutdown(struct nbd_device *lo, int lock) { /* 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 */ if (lock) mutex_lock(&lo->tx_lock); if (lo->sock) { printk(KERN_WARNING "%s: shutting down socket\n", lo->disk->disk_name); kernel_sock_shutdown(lo->sock, SHUT_RDWR); lo->sock = NULL; } if (lock) mutex_unlock(&lo->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 *lo, int send, void *buf, int size, int msg_flags) { struct socket *sock = lo->sock; int result; struct msghdr msg; struct kvec iov; sigset_t blocked, oldset; if (unlikely(!sock)) { printk(KERN_ERR "%s: Attempted %s on closed socket in sock_xmit\n", lo->disk->disk_name, (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); 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_flags = msg_flags | MSG_NOSIGNAL; if (send) { struct timer_list ti; if (lo->xmit_timeout) { init_timer(&ti); ti.function = nbd_xmit_timeout; ti.data = (unsigned long)current; ti.expires = jiffies + lo->xmit_timeout; add_timer(&ti); } result = kernel_sendmsg(sock, &msg, &iov, 1, size); if (lo->xmit_timeout) del_timer_sync(&ti); } else result = kernel_recvmsg(sock, &msg, &iov, 1, size, 0); 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(lo, !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); return result; } static inline int sock_send_bvec(struct nbd_device *lo, struct bio_vec *bvec, int flags) { int result; void *kaddr = kmap(bvec->bv_page); result = sock_xmit(lo, 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 *lo, struct request *req) { int result, flags; struct nbd_request request; unsigned long size = blk_rq_bytes(req); request.magic = htonl(NBD_REQUEST_MAGIC); request.type = htonl(nbd_cmd(req)); request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9); request.len = htonl(size); memcpy(request.handle, &req, sizeof(req)); dprintk(DBG_TX, "%s: request %p: sending control (%s@%llu,%uB)\n", lo->disk->disk_name, req, nbdcmd_to_ascii(nbd_cmd(req)), (unsigned long long)blk_rq_pos(req) << 9, blk_rq_bytes(req)); result = sock_xmit(lo, 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 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(req, iter)) 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(lo, bvec, flags); if (result <= 0) { printk(KERN_ERR "%s: Send data failed (result %d)\n", lo->disk->disk_name, result); goto error_out; } } } return 0; error_out: return -EIO; } static struct request *nbd_find_request(struct nbd_device *lo, struct request *xreq) { struct request *req, *tmp; int err; err = wait_event_interruptible(lo->active_wq, lo->active_req != xreq); if (unlikely(err)) goto out; spin_lock(&lo->queue_lock); list_for_each_entry_safe(req, tmp, &lo->queue_head, queuelist) { if (req != xreq) continue; list_del_init(&req->queuelist); spin_unlock(&lo->queue_lock); return req; } spin_unlock(&lo->queue_lock); err = -ENOENT; out: return ERR_PTR(err); } static inline int sock_recv_bvec(struct nbd_device *lo, struct bio_vec *bvec) { int result; void *kaddr = kmap(bvec->bv_page); result = sock_xmit(lo, 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; reply.magic = 0; result = sock_xmit(lo, 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; } 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; } req = nbd_find_request(lo, *(struct request **)reply.handle); if (IS_ERR(req)) { result = PTR_ERR(req); if (result != -ENOENT) goto harderror; printk(KERN_ERR "%s: Unexpected reply (%p)\n", lo->disk->disk_name, reply.handle); result = -EBADR; 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) { struct req_iterator iter; struct bio_vec *bvec; rq_for_each_segment(bvec, req, iter) { result = sock_recv_bvec(lo, bvec); if (result <= 0) { printk(KERN_ERR "%s: Receive data failed (result %d)\n", lo->disk->disk_name, result); req->errors++; return req; } 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 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 *lo) { struct request *req; int ret; BUG_ON(lo->magic != LO_MAGIC); lo->pid = current->pid; ret = sysfs_create_file(&disk_to_dev(lo->disk)->kobj, &pid_attr.attr); if (ret) { printk(KERN_ERR "nbd: sysfs_create_file failed!"); lo->pid = 0; return ret; } while ((req = nbd_read_stat(lo)) != NULL) nbd_end_request(req); sysfs_remove_file(&disk_to_dev(lo->disk)->kobj, &pid_attr.attr); lo->pid = 0; return 0; } static void nbd_clear_que(struct nbd_device *lo) { struct request *req; BUG_ON(lo->magic != LO_MAGIC); /* * Because we have set lo->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(lo->sock); BUG_ON(lo->active_req); while (!list_empty(&lo->queue_head)) { req = list_entry(lo->queue_head.next, struct request, queuelist); list_del_init(&req->queuelist); req->errors++; nbd_end_request(req); } } static void nbd_handle_req(struct nbd_device *lo, 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) { 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; mutex_lock(&lo->tx_lock); if (unlikely(!lo->sock)) { mutex_unlock(&lo->tx_lock); printk(KERN_ERR "%s: Attempted send on closed socket\n", lo->disk->disk_name); goto error_out; } lo->active_req = req; if (nbd_send_req(lo, req) != 0) { printk(KERN_ERR "%s: Request send failed\n", lo->disk->disk_name); req->errors++; nbd_end_request(req); } else { spin_lock(&lo->queue_lock); list_add(&req->queuelist, &lo->queue_head); spin_unlock(&lo->queue_lock); } lo->active_req = NULL; mutex_unlock(&lo->tx_lock); wake_up_all(&lo->active_wq); return; error_out: req->errors++; nbd_end_request(req); } static int nbd_thread(void *data) { struct nbd_device *lo = data; struct request *req; set_user_nice(current, -20); while (!kthread_should_stop() || !list_empty(&lo->waiting_queue)) { /* wait for something to do */ wait_event_interruptible(lo->waiting_wq, kthread_should_stop() || !list_empty(&lo->waiting_queue)); /* extract request */ if (list_empty(&lo->waiting_queue)) continue; spin_lock_irq(&lo->queue_lock); req = list_entry(lo->waiting_queue.next, struct request, queuelist); list_del_init(&req->queuelist); spin_unlock_irq(&lo->queue_lock); /* handle request */ nbd_handle_req(lo, 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) && (lo->flags & NBD_WRITE_NOCHK)) * { printk( "Warning: Ignoring result!\n"); nbd_end_request( req ); } */ static void do_nbd_request(struct request_queue *q) { struct request *req; while ((req = blk_fetch_request(q)) != NULL) { struct nbd_device *lo; spin_unlock_irq(q->queue_lock); dprintk(DBG_BLKDEV, "%s: request %p: dequeued (flags=%x)\n", req->rq_disk->disk_name, req, req->cmd_type); lo = req->rq_disk->private_data; BUG_ON(lo->magic != LO_MAGIC); if (unlikely(!lo->sock)) { printk(KERN_ERR "%s: Attempted send on closed socket\n", lo->disk->disk_name); req->errors++; nbd_end_request(req); spin_lock_irq(q->queue_lock); continue; } spin_lock_irq(&lo->queue_lock); list_add_tail(&req->queuelist, &lo->waiting_queue); spin_unlock_irq(&lo->queue_lock); wake_up(&lo->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 *lo, unsigned int cmd, unsigned long arg) { switch (cmd) { case NBD_DISCONNECT: { struct request sreq; printk(KERN_INFO "%s: NBD_DISCONNECT\n", lo->disk->disk_name); blk_rq_init(NULL, &sreq); sreq.cmd_type = REQ_TYPE_SPECIAL; nbd_cmd(&sreq) = NBD_CMD_DISC; if (!lo->sock) return -EINVAL; nbd_send_req(lo, &sreq); return 0; } case NBD_CLEAR_SOCK: { struct file *file; lo->sock = NULL; file = lo->file; lo->file = NULL; nbd_clear_que(lo); BUG_ON(!list_empty(&lo->queue_head)); if (file) fput(file); return 0; } case NBD_SET_SOCK: { struct file *file; if (lo->file) return -EBUSY; file = fget(arg); if (file) { struct inode *inode = file->f_path.dentry->d_inode; if (S_ISSOCK(inode->i_mode)) { lo->file = file; lo->sock = SOCKET_I(inode); if (max_part > 0) bdev->bd_invalidated = 1; return 0; } else { fput(file); } } return -EINVAL; } case NBD_SET_BLKSIZE: lo->blksize = arg; lo->bytesize &= ~(lo->blksize-1); bdev->bd_inode->i_size = lo->bytesize; set_blocksize(bdev, lo->blksize); set_capacity(lo->disk, lo->bytesize >> 9); return 0; case NBD_SET_SIZE: lo->bytesize = arg & ~(lo->blksize-1); bdev->bd_inode->i_size = lo->bytesize; set_blocksize(bdev, lo->blksize); set_capacity(lo->disk, lo->bytesize >> 9); return 0; case NBD_SET_TIMEOUT: lo->xmit_timeout = arg * HZ; return 0; case NBD_SET_SIZE_BLOCKS: lo->bytesize = ((u64) arg) * lo->blksize; bdev->bd_inode->i_size = lo->bytesize; set_blocksize(bdev, lo->blksize); set_capacity(lo->disk, lo->bytesize >> 9); return 0; case NBD_DO_IT: { struct task_struct *thread; struct file *file; int error; if (lo->pid) return -EBUSY; if (!lo->file) return -EINVAL; mutex_unlock(&lo->tx_lock); thread = kthread_create(nbd_thread, lo, lo->disk->disk_name); if (IS_ERR(thread)) { mutex_lock(&lo->tx_lock); return PTR_ERR(thread); } wake_up_process(thread); error = nbd_do_it(lo); kthread_stop(thread); mutex_lock(&lo->tx_lock); if (error) return error; sock_shutdown(lo, 0); file = lo->file; lo->file = NULL; nbd_clear_que(lo); printk(KERN_WARNING "%s: queue cleared\n", lo->disk->disk_name); if (file) fput(file); lo->bytesize = 0; bdev->bd_inode->i_size = 0; set_capacity(lo->disk, 0); if (max_part > 0) ioctl_by_bdev(bdev, BLKRRPART, 0); return lo->harderror; } case NBD_CLEAR_QUE: /* * This is for compatibility only. The queue is always cleared * by NBD_DO_IT or NBD_CLEAR_SOCK. */ BUG_ON(!lo->sock && !list_empty(&lo->queue_head)); return 0; case NBD_PRINT_DEBUG: printk(KERN_INFO "%s: next = %p, prev = %p, head = %p\n", bdev->bd_disk->disk_name, lo->queue_head.next, lo->queue_head.prev, &lo->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 *lo = bdev->bd_disk->private_data; int error; 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); mutex_lock(&nbd_mutex); mutex_lock(&lo->tx_lock); error = __nbd_ioctl(bdev, lo, cmd, arg); mutex_unlock(&lo->tx_lock); mutex_unlock(&nbd_mutex); 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_CRIT "nbd: max_part must be >= 0\n"); return -EINVAL; } nbd_dev = kcalloc(nbds_max, sizeof(*nbd_dev), GFP_KERNEL); if (!nbd_dev) return -ENOMEM; part_shift = 0; if (max_part > 0) part_shift = fls(max_part); 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); } 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); for (i = 0; i < nbds_max; i++) { struct gendisk *disk = nbd_dev[i].disk; nbd_dev[i].file = NULL; nbd_dev[i].magic = LO_MAGIC; nbd_dev[i].flags = 0; 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)"); #ifndef NDEBUG module_param(debugflags, int, 0644); MODULE_PARM_DESC(debugflags, "flags for controlling debug output"); #endif