Merge with Linux 2.5.74.

[linux-2.6/linux-mips.git] / drivers / block / nbd.c

/*
 * 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>
 *
 * possible FIXME: make set_sock / set_blksize / set_size / do_it one syscall
 * why not: would need verify_area and friends, would share yet another 
 *          structure with userland
 */

#define PARANOIA
#include <linux/major.h>

#include <linux/blk.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/blkdev.h>
#include <linux/blk.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

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 spinlock_t nbd_lock = SPIN_LOCK_UNLOCKED;

#define DEBUG( s )
/* #define DEBUG( s ) printk( s ) 
 */

static int requests_in;
static int requests_out;

static void nbd_end_request(struct request *req)
{
        int uptodate = (req->errors == 0) ? 1 : 0;
        request_queue_t *q = req->q;
        unsigned long flags;

#ifdef PARANOIA
        requests_out++;
#endif
        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);
}

static int nbd_open(struct inode *inode, struct file *file)
{
        struct nbd_device *lo = inode->i_bdev->bd_disk->private_data;
        lo->refcnt++;
        return 0;
}

/*
 *  Send or receive packet.
 */
static int nbd_xmit(int send, struct socket *sock, char *buf, int size, int msg_flags)
{
        mm_segment_t oldfs;
        int result;
        struct msghdr msg;
        struct iovec iov;
        unsigned long flags;
        sigset_t oldset;

        oldfs = get_fs();
        set_fs(get_ds());
        /* 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_iov = &iov;
                msg.msg_iovlen = 1;
                msg.msg_control = NULL;
                msg.msg_controllen = 0;
                msg.msg_namelen = 0;
                msg.msg_flags = msg_flags | MSG_NOSIGNAL;

                if (send)
                        result = sock_sendmsg(sock, &msg, size);
                else
                        result = sock_recvmsg(sock, &msg, 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) {
#ifdef PARANOIA
                        printk(KERN_ERR "NBD: %s - sock=%ld at buf=%ld, size=%d returned %d.\n",
                               send ? "send" : "receive", (long) sock, (long) buf, size, result);
#endif
                        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);

        set_fs(oldfs);
        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 = nbd_xmit(1, sock, kaddr + bvec->bv_offset, bvec->bv_len,
                        flags);
        kunmap(bvec->bv_page);
        return result;
}

#define FAIL( s ) { printk( KERN_ERR "NBD: " s "(result %d)\n", result ); goto error_out; }

void 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;

        DEBUG("NBD: sending control, ");
        
        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 "NBD: Attempted sendmsg to closed socket\n");
                goto error_out;
        }

        result = nbd_xmit(1, sock, (char *) &request, sizeof(request), nbd_cmd(req) == NBD_CMD_WRITE ? MSG_MORE : 0);
        if (result <= 0)
                FAIL("Sendmsg failed for control.");

        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;
                                DEBUG("data, ");
                                result = sock_send_bvec(sock, bvec, flags);
                                if (result <= 0)
                                        FAIL("Send data failed.");
                        }
                }
        }
        up(&lo->tx_lock);
        return;

      error_out:
        up(&lo->tx_lock);
        req->errors++;
}

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 = nbd_xmit(0, sock, kaddr + bvec->bv_offset, bvec->bv_len,
                        MSG_WAITALL);
        kunmap(bvec->bv_page);
        return result;
}

#define HARDFAIL( s ) { printk( KERN_ERR "NBD: " s "(result %d)\n", result ); lo->harderror = result; return NULL; }
struct request *nbd_read_stat(struct nbd_device *lo)
                /* NULL returned = something went wrong, inform userspace       */ 
{
        int result;
        struct nbd_reply reply;
        struct request *req;
        struct socket *sock = lo->sock;

        DEBUG("reading control, ");
        reply.magic = 0;
        result = nbd_xmit(0, sock, (char *) &reply, sizeof(reply), MSG_WAITALL);
        if (result <= 0)
                HARDFAIL("Recv control failed.");
        req = nbd_find_request(lo, reply.handle);
        if (req == NULL)
                HARDFAIL("Unexpected reply");

        DEBUG("ok, ");
        if (ntohl(reply.magic) != NBD_REPLY_MAGIC)
                HARDFAIL("Not enough magic.");
        if (ntohl(reply.error))
                FAIL("Other side returned error.");

        if (nbd_cmd(req) == NBD_CMD_READ) {
                int i;
                struct bio *bio;
                DEBUG("data, ");
                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)
                                        HARDFAIL("Recv data failed.");
                        }
                }
        }
        DEBUG("done.\n");
        return req;

/* Can we get here? Yes, if other side returns error */
      error_out:
        req->errors++;
        return req;
}

void nbd_do_it(struct nbd_device *lo)
{
        struct request *req;

        while (1) {
                req = nbd_read_stat(lo);

                if (!req) {
                        printk(KERN_ALERT "req should never be null\n" );
                        goto out;
                }
                BUG_ON(lo->magic != LO_MAGIC);
                nbd_end_request(req);
        }
 out:
        return;
}

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 ); }
 */

#undef FAIL
#define FAIL( s ) { printk( KERN_ERR "%s: " s "\n", req->rq_disk->disk_name ); goto error_out; }

static void do_nbd_request(request_queue_t * q)
{
        struct request *req;
        
        while ((req = elv_next_request(q)) != NULL) {
                struct nbd_device *lo;

                if (!(req->flags & REQ_CMD))
                        goto error_out;

                lo = req->rq_disk->private_data;
                if (!lo->file)
                        FAIL("Request when not-ready.");
                nbd_cmd(req) = NBD_CMD_READ;
                if (rq_data_dir(req) == WRITE) {
                        nbd_cmd(req) = NBD_CMD_WRITE;
                        if (lo->flags & NBD_READ_ONLY)
                                FAIL("Write on read-only");
                }
                BUG_ON(lo->magic != LO_MAGIC);
                requests_in++;

                req->errors = 0;
                blkdev_dequeue_request(req);
                spin_unlock_irq(q->queue_lock);

                spin_lock(&lo->queue_lock);

                if (!lo->file) {
                        spin_unlock(&lo->queue_lock);
                        printk(KERN_ERR "nbd: failed between accept and semaphore, file lost\n");
                        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);

                nbd_send_req(lo, req);

                if (req->errors) {
                        printk(KERN_ERR "nbd: nbd_send_req failed\n");
                        spin_lock(&lo->queue_lock);
                        list_del_init(&req->queuelist);
                        spin_unlock(&lo->queue_lock);
                        nbd_end_request(req);
                        spin_lock_irq(q->queue_lock);
                        continue;
                }

                spin_lock_irq(q->queue_lock);
                continue;

              error_out:
                req->errors++;
                blkdev_dequeue_request(req);
                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, temp;
        struct request sreq ;

        /* Anyone capable of this syscall can do *real bad* things */

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;
        switch (cmd) {
        case NBD_DISCONNECT:
                printk(KERN_INFO "NBD_DISCONNECT\n");
                sreq.flags = REQ_SPECIAL;
                nbd_cmd(&sreq) = NBD_CMD_DISC;
                if (!lo->sock)
                        return -EINVAL;
                nbd_send_req(lo, &sreq);
                return 0 ;
 
        case NBD_CLEAR_SOCK:
                nbd_clear_que(lo);
                spin_lock(&lo->queue_lock);
                if (!list_empty(&lo->queue_head)) {
                        spin_unlock(&lo->queue_lock);
                        printk(KERN_ERR "nbd: Some requests are in progress -> can not turn off.\n");
                        return -EBUSY;
                }
                file = lo->file;
                if (!file) {
                        spin_unlock(&lo->queue_lock);
                        return -EINVAL;
                }
                lo->file = NULL;
                lo->sock = NULL;
                spin_unlock(&lo->queue_lock);
                fput(file);
                return 0;
        case NBD_SET_SOCK:
                if (lo->file)
                        return -EBUSY;
                error = -EINVAL;
                file = fget(arg);
                if (file) {
                        inode = file->f_dentry->d_inode;
                        if (inode->i_sock) {
                                lo->file = file;
                                lo->sock = SOCKET_I(inode);
                                error = 0;
                        } else {
                                fput(file);
                        }
                }
                return error;
        case NBD_SET_BLKSIZE:
                if ((arg & (arg-1)) || (arg < 512) || (arg > PAGE_SIZE))
                        return -EINVAL;
                lo->blksize = arg;
                temp = arg >> 9;
                lo->blksize_bits = 9;
                while (temp > 1) {
                        lo->blksize_bits++;
                        temp >>= 1;
                }
                lo->bytesize &= ~(lo->blksize-1); 
                set_capacity(lo->disk, lo->bytesize >> 9);
                return 0;
        case NBD_SET_SIZE:
                lo->bytesize = arg & ~(lo->blksize-1); 
                set_capacity(lo->disk, lo->bytesize >> 9);
                return 0;
        case NBD_SET_SIZE_BLOCKS:
                lo->bytesize = ((u64) arg) << lo->blksize_bits;
                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);
                printk(KERN_WARNING "nbd: shutting down socket\n");
                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 "nbd: queue cleared\n");
                if (file)
                        fput(file);
                return lo->harderror;
        case NBD_CLEAR_QUE:
                nbd_clear_que(lo);
                return 0;
#ifdef PARANOIA
        case NBD_PRINT_DEBUG:
                printk(KERN_INFO "%s: next = %p, prev = %p. Global: in %d, out %d\n",
                       inode->i_bdev->bd_disk->disk_name, lo->queue_head.next,
                       lo->queue_head.prev, requests_in, requests_out);
                return 0;
#endif
        }
        return -EINVAL;
}

static int nbd_release(struct inode *inode, struct file *file)
{
        struct nbd_device *lo = inode->i_bdev->bd_disk->private_data;
        if (lo->refcnt <= 0)
                printk(KERN_ALERT "nbd_release: refcount(%d) <= 0\n", lo->refcnt);
        lo->refcnt--;
        /* N.B. Doesn't lo->file need an fput?? */
        return 0;
}

static struct block_device_operations nbd_fops =
{
        .owner =        THIS_MODULE,
        .open =         nbd_open,
        .release =      nbd_release,
        .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 "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 = kmalloc(sizeof(struct request_queue), GFP_KERNEL);
                if (!disk->queue) {
                        put_disk(disk);
                        goto out;
                }
                blk_init_queue(disk->queue, do_nbd_request, &nbd_lock);
        }

        if (register_blkdev(NBD_MAJOR, "nbd")) {
                err = -EIO;
                goto out;
        }
#ifdef MODULE
        printk("nbd: registered device at major %d\n", NBD_MAJOR);
#endif
        devfs_mk_dir("nbd");
        for (i = 0; i < MAX_NBD; i++) {
                struct gendisk *disk = nbd_dev[i].disk;
                nbd_dev[i].refcnt = 0;
                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].blksize_bits = 10;
                nbd_dev[i].bytesize = ((u64)0x7ffffc00) << 10; /* 2TB */
                disk->major = NBD_MAJOR;
                disk->first_minor = i;
                disk->fops = &nbd_fops;
                disk->private_data = &nbd_dev[i];
                sprintf(disk->disk_name, "nbd%d", i);
                sprintf(disk->devfs_name, "nbd/%d", i);
                set_capacity(disk, 0x3ffffe);
                add_disk(disk);
        }

        return 0;
out:
        while (i--) {
                kfree(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) {
                        if (disk->queue) {
                                blk_cleanup_queue(disk->queue);
                                kfree(disk->queue);
                                disk->queue = NULL;
                        }
                        del_gendisk(disk);
                        put_disk(disk);
                }
        }
        devfs_remove("nbd");
        unregister_blkdev(NBD_MAJOR, "nbd");
#ifdef MODULE
        printk("nbd: unregistered device at major %d\n", NBD_MAJOR);
#endif
}

module_init(nbd_init);
module_exit(nbd_cleanup);

MODULE_DESCRIPTION("Network Block Device");
MODULE_LICENSE("GPL");