/*
* 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 <linux/blk-mq.h>
#include <linux/uaccess.h>
#include <asm/types.h>
#include <linux/nbd.h>
struct nbd_sock {
struct socket *sock;
struct mutex tx_lock;
};
#define NBD_TIMEDOUT 0
#define NBD_DISCONNECT_REQUESTED 1
#define NBD_DISCONNECTED 2
#define NBD_RUNNING 3
struct nbd_device {
u32 flags;
unsigned long runtime_flags;
struct nbd_sock **socks;
int magic;
struct blk_mq_tag_set tag_set;
struct mutex config_lock;
struct gendisk *disk;
int num_connections;
atomic_t recv_threads;
wait_queue_head_t recv_wq;
loff_t blksize;
loff_t bytesize;
struct task_struct *task_recv;
struct task_struct *task_setup;
#if IS_ENABLED(CONFIG_DEBUG_FS)
struct dentry *dbg_dir;
#endif
};
struct nbd_cmd {
struct nbd_device *nbd;
struct completion send_complete;
};
#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;
static inline struct device *nbd_to_dev(struct nbd_device *nbd)
{
return disk_to_dev(nbd->disk);
}
static bool nbd_is_connected(struct nbd_device *nbd)
{
return !!nbd->task_recv;
}
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 int nbd_size_clear(struct nbd_device *nbd, struct block_device *bdev)
{
bdev->bd_inode->i_size = 0;
set_capacity(nbd->disk, 0);
kobject_uevent(&nbd_to_dev(nbd)->kobj, KOBJ_CHANGE);
return 0;
}
static void nbd_size_update(struct nbd_device *nbd, struct block_device *bdev)
{
if (!nbd_is_connected(nbd))
return;
bdev->bd_inode->i_size = nbd->bytesize;
set_capacity(nbd->disk, nbd->bytesize >> 9);
kobject_uevent(&nbd_to_dev(nbd)->kobj, KOBJ_CHANGE);
}
static int nbd_size_set(struct nbd_device *nbd, struct block_device *bdev,
loff_t blocksize, loff_t nr_blocks)
{
int ret;
ret = set_blocksize(bdev, blocksize);
if (ret)
return ret;
nbd->blksize = blocksize;
nbd->bytesize = blocksize * nr_blocks;
nbd_size_update(nbd, bdev);
return 0;
}
static void nbd_end_request(struct nbd_cmd *cmd)
{
struct nbd_device *nbd = cmd->nbd;
struct request *req = blk_mq_rq_from_pdu(cmd);
int error = req->errors ? -EIO : 0;
dev_dbg(nbd_to_dev(nbd), "request %p: %s\n", cmd,
error ? "failed" : "done");
blk_mq_complete_request(req, error);
}
/*
* Forcibly shutdown the socket causing all listeners to error
*/
static void sock_shutdown(struct nbd_device *nbd)
{
int i;
if (nbd->num_connections == 0)
return;
if (test_and_set_bit(NBD_DISCONNECTED, &nbd->runtime_flags))
return;
for (i = 0; i < nbd->num_connections; i++) {
struct nbd_sock *nsock = nbd->socks[i];
mutex_lock(&nsock->tx_lock);
kernel_sock_shutdown(nsock->sock, SHUT_RDWR);
mutex_unlock(&nsock->tx_lock);
}
dev_warn(disk_to_dev(nbd->disk), "shutting down sockets\n");
}
static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req,
bool reserved)
{
struct nbd_cmd *cmd = blk_mq_rq_to_pdu(req);
struct nbd_device *nbd = cmd->nbd;
dev_err(nbd_to_dev(nbd), "Connection timed out, shutting down connection\n");
set_bit(NBD_TIMEDOUT, &nbd->runtime_flags);
req->errors++;
/*
* If our disconnect packet times out then we're already holding the
* config_lock and could deadlock here, so just set an error and return,
* we'll handle shutting everything down later.
*/
if (req->cmd_type == REQ_TYPE_DRV_PRIV)
return BLK_EH_HANDLED;
mutex_lock(&nbd->config_lock);
sock_shutdown(nbd);
mutex_unlock(&nbd->config_lock);
return BLK_EH_HANDLED;
}
/*
* Send or receive packet.
*/
static int sock_xmit(struct nbd_device *nbd, int index, int send, void *buf,
int size, int msg_flags)
{
struct socket *sock = nbd->socks[index]->sock;
int result;
struct msghdr msg;
struct kvec iov;
unsigned long pflags = current->flags;
if (unlikely(!sock)) {
dev_err_ratelimited(disk_to_dev(nbd->disk),
"Attempted %s on closed socket in sock_xmit\n",
(send ? "send" : "recv"));
return -EINVAL;
}
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);
tsk_restore_flags(current, pflags, PF_MEMALLOC);
return result;
}
static inline int sock_send_bvec(struct nbd_device *nbd, int index,
struct bio_vec *bvec, int flags)
{
int result;
void *kaddr = kmap(bvec->bv_page);
result = sock_xmit(nbd, index, 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_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
{
struct request *req = blk_mq_rq_from_pdu(cmd);
int result, flags;
struct nbd_request request;
unsigned long size = blk_rq_bytes(req);
struct bio *bio;
u32 type;
u32 tag = blk_mq_unique_tag(req);
if (req_op(req) == REQ_OP_DISCARD)
type = NBD_CMD_TRIM;
else if (req_op(req) == REQ_OP_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) {
request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9);
request.len = htonl(size);
}
memcpy(request.handle, &tag, sizeof(tag));
dev_dbg(nbd_to_dev(nbd), "request %p: sending control (%s@%llu,%uB)\n",
cmd, nbdcmd_to_ascii(type),
(unsigned long long)blk_rq_pos(req) << 9, blk_rq_bytes(req));
result = sock_xmit(nbd, index, 1, &request, sizeof(request),
(type == NBD_CMD_WRITE) ? MSG_MORE : 0);
if (result <= 0) {
dev_err_ratelimited(disk_to_dev(nbd->disk),
"Send control failed (result %d)\n", result);
return -EIO;
}
if (type != NBD_CMD_WRITE)
return 0;
flags = 0;
bio = req->bio;
while (bio) {
struct bio *next = bio->bi_next;
struct bvec_iter iter;
struct bio_vec bvec;
bio_for_each_segment(bvec, bio, iter) {
bool is_last = !next && bio_iter_last(bvec, iter);
if (is_last)
flags = MSG_MORE;
dev_dbg(nbd_to_dev(nbd), "req
