linux/drivers/block/nbd.c
Markus Pargmann dcc909d90c nbd: Add locking for tasks
The timeout handling introduced in
	7e2893a16d (nbd: Fix timeout detection)
introduces a race condition which may lead to killing of tasks that are
not in nbd context anymore. This was not observed or reproducable yet.

This patch adds locking to critical use of task_recv and task_send to
avoid killing tasks that already left the NBD thread functions. This
lock is only acquired if a timeout occures or the nbd device
starts/stops.

Reported-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Reviewed-by: Ben Hutchings <ben@decadent.org.uk>
Fixes: 7e2893a16d ("nbd: Fix timeout detection")
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-10-08 14:21:24 -06:00

1137 lines
27 KiB
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, 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 <linux/debugfs.h>
#include <asm/uaccess.h>
#include <asm/types.h>
#include <linux/nbd.h>
struct nbd_device {
u32 flags;
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;
int xmit_timeout;
bool disconnect; /* a disconnect has been requested by user */
struct timer_list timeout_timer;
spinlock_t tasks_lock;
struct task_struct *task_recv;
struct task_struct *task_send;
#if IS_ENABLED(CONFIG_DEBUG_FS)
struct dentry *dbg_dir;
#endif
};
#if IS_ENABLED(CONFIG_DEBUG_FS)
static struct dentry *nbd_dbg_dir;
#endif
#define nbd_name(nbd) ((nbd)->disk->disk_name)
#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)
{
if (!nbd->sock)
return;
dev_warn(disk_to_dev(nbd->disk), "shutting down socket\n");
kernel_sock_shutdown(nbd->sock, SHUT_RDWR);
nbd->sock = NULL;
del_timer_sync(&nbd->timeout_timer);
}
static void nbd_xmit_timeout(unsigned long arg)
{
struct nbd_device *nbd = (struct nbd_device *)arg;
unsigned long flags;
if (list_empty(&nbd->queue_head))
return;
nbd->disconnect = true;
spin_lock_irqsave(&nbd->tasks_lock, flags);
if (nbd->task_recv)
force_sig(SIGKILL, nbd->task_recv);
if (nbd->task_send)
force_sig(SIGKILL, nbd->task_send);
spin_unlock_irqrestore(&nbd->tasks_lock, flags);
dev_err(nbd_to_dev(nbd), "Connection timed out, killed receiver and sender, shutting down connection\n");
}
/*
* 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)
result = kernel_sendmsg(sock, &msg, &iov, 1, size);
else
result = kernel_recvmsg(sock, &msg, &iov, 1, size,
msg.msg_flags);
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);
if (!send && nbd->xmit_timeout)
mod_timer(&nbd->timeout_timer, jiffies + nbd->xmit_timeout);
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);
u32 type;
if (req->cmd_type == REQ_TYPE_DRV_PRIV)
type = NBD_CMD_DISC;
else if (req->cmd_flags & REQ_DISCARD)
type = NBD_CMD_TRIM;
else if (req->cmd_flags & REQ_FLUSH)
type = NBD_CMD_FLUSH;
else if (rq_data_dir(req) == WRITE)
type = NBD_CMD_WRITE;
else
type = NBD_CMD_READ;
memset(&request, 0, sizeof(request));
request.magic = htonl(NBD_REQUEST_MAGIC);
request.type = htonl(type);
if (type != NBD_CMD_FLUSH && type != 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(type),
(unsigned long long)blk_rq_pos(req) << 9, blk_rq_bytes(req));
result = sock_xmit(nbd, 1, &request, sizeof(request),
(type == 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 (type == 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);
return ERR_PTR(result);
}
if (ntohl(reply.magic) != NBD_REPLY_MAGIC) {
dev_err(disk_to_dev(nbd->disk), "Wrong magic (0x%lx)\n",
(unsigned long)ntohl(reply.magic));
return ERR_PTR(-EPROTO);
}
req = nbd_find_request(nbd, *(struct request **)reply.handle);
if (IS_ERR(req)) {
result = PTR_ERR(req);
if (result != -ENOENT)
return ERR_PTR(result);
dev_err(disk_to_dev(nbd->disk), "Unexpected reply (%p)\n",
reply.handle);
return ERR_PTR(-EBADR);
}
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 (rq_data_dir(req) != WRITE) {
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;
}
static ssize_t pid_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct gendisk *disk = dev_to_disk(dev);
struct nbd_device *nbd = (struct nbd_device *)disk->private_data;
return sprintf(buf, "%d\n", task_pid_nr(nbd->task_recv));
}
static struct device_attribute pid_attr = {
.attr = { .name = "pid", .mode = S_IRUGO},
.show = pid_show,
};
static int nbd_thread_recv(struct nbd_device *nbd)
{
struct request *req;
int ret;
unsigned long flags;
BUG_ON(nbd->magic != NBD_MAGIC);
sk_set_memalloc(nbd->sock->sk);
spin_lock_irqsave(&nbd->tasks_lock, flags);
nbd->task_recv = current;
spin_unlock_irqrestore(&nbd->tasks_lock, flags);
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");
spin_lock_irqsave(&nbd->tasks_lock, flags);
nbd->task_recv = NULL;
spin_unlock_irqrestore(&nbd->tasks_lock, flags);
return ret;
}
while (1) {
req = nbd_read_stat(nbd);
if (IS_ERR(req)) {
ret = PTR_ERR(req);
break;
}
nbd_end_request(nbd, req);
}
device_remove_file(disk_to_dev(nbd->disk), &pid_attr);
spin_lock_irqsave(&nbd->tasks_lock, flags);
nbd->task_recv = NULL;
spin_unlock_irqrestore(&nbd->tasks_lock, flags);
if (signal_pending(current)) {
siginfo_t info;
ret = dequeue_signal_lock(current, &current->blocked, &info);
dev_warn(nbd_to_dev(nbd), "pid %d, %s, got signal %d\n",
task_pid_nr(current), current->comm, ret);
mutex_lock(&nbd->tx_lock);
sock_shutdown(nbd);
mutex_unlock(&nbd->tx_lock);
ret = -ETIMEDOUT;
}
return ret;
}
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);
}
dev_dbg(disk_to_dev(nbd->disk), "queue cleared\n");
}
static void nbd_handle_req(struct nbd_device *nbd, struct request *req)
{
if (req->cmd_type != REQ_TYPE_FS)
goto error_out;
if (rq_data_dir(req) == WRITE &&
(nbd->flags & NBD_FLAG_READ_ONLY)) {
dev_err(disk_to_dev(nbd->disk),
"Write on read-only\n");
goto error_out;
}
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->xmit_timeout && list_empty_careful(&nbd->queue_head))
mod_timer(&nbd->timeout_timer, jiffies + nbd->xmit_timeout);
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_send(void *data)
{
struct nbd_device *nbd = data;
struct request *req;
unsigned long flags;
spin_lock_irqsave(&nbd->tasks_lock, flags);
nbd->task_send = current;
spin_unlock_irqrestore(&nbd->tasks_lock, flags);
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));
if (signal_pending(current)) {
siginfo_t info;
int ret;
ret = dequeue_signal_lock(current, &current->blocked,
&info);
dev_warn(nbd_to_dev(nbd), "pid %d, %s, got signal %d\n",
task_pid_nr(current), current->comm, ret);
mutex_lock(&nbd->tx_lock);
sock_shutdown(nbd);
mutex_unlock(&nbd->tx_lock);
break;
}
/* 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);
}
spin_lock_irqsave(&nbd->tasks_lock, flags);
nbd->task_send = NULL;
spin_unlock_irqrestore(&nbd->tasks_lock, flags);
/* Clear maybe pending signals */
if (signal_pending(current)) {
siginfo_t info;
dequeue_signal_lock(current, &current->blocked, &info);
}
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 nbd_request_handler(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);
}
}
static int nbd_dev_dbg_init(struct nbd_device *nbd);
static void nbd_dev_dbg_close(struct nbd_device *nbd);
/* 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_DRV_PRIV;
/* Check again after getting mutex back. */
if (!nbd->sock)
return -EINVAL;
nbd->disconnect = true;
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 = false; /* 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;
if (arg)
mod_timer(&nbd->timeout_timer,
jiffies + nbd->xmit_timeout);
else
del_timer_sync(&nbd->timeout_timer);
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->task_recv)
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_send, nbd, "%s",
nbd_name(nbd));
if (IS_ERR(thread)) {
mutex_lock(&nbd->tx_lock);
return PTR_ERR(thread);
}
nbd_dev_dbg_init(nbd);
error = nbd_thread_recv(nbd);
nbd_dev_dbg_close(nbd);
kthread_stop(thread);
mutex_lock(&nbd->tx_lock);
sock_shutdown(nbd);
sock = nbd->sock;
nbd->sock = NULL;
nbd_clear_que(nbd);
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)
blkdev_reread_part(bdev);
if (nbd->disconnect) /* user requested, ignore socket errors */
return 0;
return error;
}
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,
};
#if IS_ENABLED(CONFIG_DEBUG_FS)
static int nbd_dbg_tasks_show(struct seq_file *s, void *unused)
{
struct nbd_device *nbd = s->private;
if (nbd->task_recv)
seq_printf(s, "recv: %d\n", task_pid_nr(nbd->task_recv));
if (nbd->task_send)
seq_printf(s, "send: %d\n", task_pid_nr(nbd->task_send));
return 0;
}
static int nbd_dbg_tasks_open(struct inode *inode, struct file *file)
{
return single_open(file, nbd_dbg_tasks_show, inode->i_private);
}
static const struct file_operations nbd_dbg_tasks_ops = {
.open = nbd_dbg_tasks_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
static int nbd_dbg_flags_show(struct seq_file *s, void *unused)
{
struct nbd_device *nbd = s->private;
u32 flags = nbd->flags;
seq_printf(s, "Hex: 0x%08x\n\n", flags);
seq_puts(s, "Known flags:\n");
if (flags & NBD_FLAG_HAS_FLAGS)
seq_puts(s, "NBD_FLAG_HAS_FLAGS\n");
if (flags & NBD_FLAG_READ_ONLY)
seq_puts(s, "NBD_FLAG_READ_ONLY\n");
if (flags & NBD_FLAG_SEND_FLUSH)
seq_puts(s, "NBD_FLAG_SEND_FLUSH\n");
if (flags & NBD_FLAG_SEND_TRIM)
seq_puts(s, "NBD_FLAG_SEND_TRIM\n");
return 0;
}
static int nbd_dbg_flags_open(struct inode *inode, struct file *file)
{
return single_open(file, nbd_dbg_flags_show, inode->i_private);
}
static const struct file_operations nbd_dbg_flags_ops = {
.open = nbd_dbg_flags_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
static int nbd_dev_dbg_init(struct nbd_device *nbd)
{
struct dentry *dir;
struct dentry *f;
dir = debugfs_create_dir(nbd_name(nbd), nbd_dbg_dir);
if (IS_ERR_OR_NULL(dir)) {
dev_err(nbd_to_dev(nbd), "Failed to create debugfs dir for '%s' (%ld)\n",
nbd_name(nbd), PTR_ERR(dir));
return PTR_ERR(dir);
}
nbd->dbg_dir = dir;
f = debugfs_create_file("tasks", 0444, dir, nbd, &nbd_dbg_tasks_ops);
if (IS_ERR_OR_NULL(f)) {
dev_err(nbd_to_dev(nbd), "Failed to create debugfs file 'tasks', %ld\n",
PTR_ERR(f));
return PTR_ERR(f);
}
f = debugfs_create_u64("size_bytes", 0444, dir, &nbd->bytesize);
if (IS_ERR_OR_NULL(f)) {
dev_err(nbd_to_dev(nbd), "Failed to create debugfs file 'size_bytes', %ld\n",
PTR_ERR(f));
return PTR_ERR(f);
}
f = debugfs_create_u32("timeout", 0444, dir, &nbd->xmit_timeout);
if (IS_ERR_OR_NULL(f)) {
dev_err(nbd_to_dev(nbd), "Failed to create debugfs file 'timeout', %ld\n",
PTR_ERR(f));
return PTR_ERR(f);
}
f = debugfs_create_u32("blocksize", 0444, dir, &nbd->blksize);
if (IS_ERR_OR_NULL(f)) {
dev_err(nbd_to_dev(nbd), "Failed to create debugfs file 'blocksize', %ld\n",
PTR_ERR(f));
return PTR_ERR(f);
}
f = debugfs_create_file("flags", 0444, dir, &nbd, &nbd_dbg_flags_ops);
if (IS_ERR_OR_NULL(f)) {
dev_err(nbd_to_dev(nbd), "Failed to create debugfs file 'flags', %ld\n",
PTR_ERR(f));
return PTR_ERR(f);
}
return 0;
}
static void nbd_dev_dbg_close(struct nbd_device *nbd)
{
debugfs_remove_recursive(nbd->dbg_dir);
}
static int nbd_dbg_init(void)
{
struct dentry *dbg_dir;
dbg_dir = debugfs_create_dir("nbd", NULL);
if (IS_ERR(dbg_dir))
return PTR_ERR(dbg_dir);
nbd_dbg_dir = dbg_dir;
return 0;
}
static void nbd_dbg_close(void)
{
debugfs_remove_recursive(nbd_dbg_dir);
}
#else /* IS_ENABLED(CONFIG_DEBUG_FS) */
static int nbd_dev_dbg_init(struct nbd_device *nbd)
{
return 0;
}
static void nbd_dev_dbg_close(struct nbd_device *nbd)
{
}
static int nbd_dbg_init(void)
{
return 0;
}
static void nbd_dbg_close(void)
{
}
#endif
/*
* 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(nbd_request_handler, &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;
blk_queue_max_discard_sectors(disk->queue, 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);
nbd_dbg_init();
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);
spin_lock_init(&nbd_dev[i].tasks_lock);
INIT_LIST_HEAD(&nbd_dev[i].queue_head);
mutex_init(&nbd_dev[i].tx_lock);
init_timer(&nbd_dev[i].timeout_timer);
nbd_dev[i].timeout_timer.function = nbd_xmit_timeout;
nbd_dev[i].timeout_timer.data = (unsigned long)&nbd_dev[i];
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;
nbd_dbg_close();
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)");