/*
* 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 timedout;
bool disconnect; /* a disconnect has been requested by user */
struct timer_list timeout_timer;
/* protects initialization and shutdown of the socket */
spinlock_t sock_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 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,
int blocksize, int nr_blocks)
{
int ret;
ret = set_blocksize(bdev, blocksize