ubd_kern.c

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/* 
 * Copyright (C) 2000 Jeff Dike ([e-mail])
 * Licensed under the GPL
 */

/* 2001-09-28...2002-04-17
 * Partition stuff by [e-mail]
 * old style ubd by setting UBD_SHIFT to 0
 * 2002-09-27...2002-10-18 massive tinkering for 2.5
 * partitions have changed in 2.5
 */

#define MAJOR_NR UBD_MAJOR
#define UBD_SHIFT 4

#include "linux/config.h"
#include "linux/module.h"
#include "linux/blkdev.h"
#include "linux/hdreg.h"
#include "linux/init.h"
#include "linux/devfs_fs_kernel.h"
#include "linux/cdrom.h"
#include "linux/proc_fs.h"
#include "linux/ctype.h"
#include "linux/capability.h"
#include "linux/mm.h"
#include "linux/vmalloc.h"
#include "linux/blkpg.h"
#include "linux/genhd.h"
#include "linux/spinlock.h"
#include "asm/segment.h"
#include "asm/uaccess.h"
#include "asm/irq.h"
#include "asm/types.h"
#include "asm/tlbflush.h"
#include "user_util.h"
#include "mem_user.h"
#include "kern_util.h"
#include "kern.h"
#include "mconsole_kern.h"
#include "init.h"
#include "irq_user.h"
#include "ubd_user.h"
#include "2_5compat.h"
#include "os.h"

static spinlock_t ubd_io_lock = SPIN_LOCK_UNLOCKED;
static spinlock_t ubd_lock = SPIN_LOCK_UNLOCKED;

static void (*do_ubd)(void);

static int ubd_open(struct inode * inode, struct file * filp);
static int ubd_release(struct inode * inode, struct file * file);
static int ubd_ioctl(struct inode * inode, struct file * file,
		     unsigned int cmd, unsigned long arg);

#define MAX_DEV (8)

static struct block_device_operations ubd_blops = {
        .owner		= THIS_MODULE,
        .open		= ubd_open,
        .release	= ubd_release,
        .ioctl		= ubd_ioctl,
};

/* Protected by the queue_lock */
static request_queue_t *ubd_queue;

/* Protected by ubd_lock */
static int fake_major = 0;

static struct gendisk *ubd_gendisk[MAX_DEV];
static struct gendisk *fake_gendisk[MAX_DEV];
 
#ifdef CONFIG_BLK_DEV_UBD_SYNC
#define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 1, .c = 0, \
					 .cl = 1 })
#else
#define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 0, .c = 0, \
					 .cl = 1 })
#endif

/* Not protected - changed only in ubd_setup_common and then only to
 * to enable O_SYNC.
 */
static struct openflags global_openflags = OPEN_FLAGS;

struct cow {
	char *file;
	int fd;
	unsigned long *bitmap;
	unsigned long bitmap_len;
	int bitmap_offset;
        int data_offset;
};

struct ubd {
	char *file;
	int is_dir;
	int count;
	int fd;
	__u64 size;
	struct openflags boot_openflags;
	struct openflags openflags;
	struct cow cow;
};

#define DEFAULT_COW { \
	.file =			NULL, \
        .fd =			-1, \
        .bitmap =		NULL, \
	.bitmap_offset =	0, \
        .data_offset =		0, \
}

#define DEFAULT_UBD { \
	.file = 		NULL, \
	.is_dir =		0, \
	.count =		0, \
	.fd =			-1, \
	.size =			-1, \
	.boot_openflags =	OPEN_FLAGS, \
	.openflags =		OPEN_FLAGS, \
        .cow =			DEFAULT_COW, \
}

struct ubd ubd_dev[MAX_DEV] = { [ 0 ... MAX_DEV - 1 ] = DEFAULT_UBD };

static int ubd0_init(void)
{
	if(ubd_dev[0].file == NULL)
		ubd_dev[0].file = "root_fs";
	return(0);
}

__initcall(ubd0_init);

/* Only changed by fake_ide_setup which is a setup */
static int fake_ide = 0;
static struct proc_dir_entry *proc_ide_root = NULL;
static struct proc_dir_entry *proc_ide = NULL;

static void make_proc_ide(void)
{
	proc_ide_root = proc_mkdir("ide", 0);
	proc_ide = proc_mkdir("ide0", proc_ide_root);
}

static int proc_ide_read_media(char *page, char **start, off_t off, int count,
			       int *eof, void *data)
{
	int len;

	strcpy(page, "disk\n");
	len = strlen("disk\n");
	len -= off;
	if (len < count){
		*eof = 1;
		if (len <= 0) return 0;
	}
	else len = count;
	*start = page + off;
	return len;
}

static void make_ide_entries(char *dev_name)
{
	struct proc_dir_entry *dir, *ent;
	char name[64];

	if(proc_ide_root == NULL) make_proc_ide();

	dir = proc_mkdir(dev_name, proc_ide);
	if(!dir) return;

	ent = create_proc_entry("media", S_IFREG|S_IRUGO, dir);
	if(!ent) return;
	ent->nlink = 1;
	ent->data = NULL;
	ent->read_proc = proc_ide_read_media;
	ent->write_proc = NULL;
	sprintf(name,"ide0/%s", dev_name);
	proc_symlink(dev_name, proc_ide_root, name);
}

static int fake_ide_setup(char *str)
{
	fake_ide = 1;
	return(1);
}

__setup("fake_ide", fake_ide_setup);

__uml_help(fake_ide_setup,
"fake_ide\n"
"    Create ide0 entries that map onto ubd devices.\n\n"
);

static int ubd_setup_common(char *str, int *index_out)
{
	struct openflags flags = global_openflags;
	char *backing_file;
	int n, err;

	if(index_out) *index_out = -1;
	n = *str++;
	if(n == '='){
		static int fake_major_allowed = 1;
		char *end;
		int major;

		if(!strcmp(str, "sync")){
			global_openflags.s = 1;
			return(0);
		}
		major = simple_strtoul(str, &end, 0);
		if((*end != '\0') || (end == str)){
			printk(KERN_ERR 
			       "ubd_setup : didn't parse major number\n");
			return(1);
		}

		if(!fake_major_allowed){
			printk(KERN_ERR "Can't assign a fake major twice\n");
			return(1);
		}

		err = 1;
 		spin_lock(&ubd_lock);
 		if(!fake_major_allowed){
 			printk(KERN_ERR "Can't assign a fake major twice\n");
 			goto out1;
 		}
 
 		fake_major = major;
		fake_major_allowed = 0;

		printk(KERN_INFO "Setting extra ubd major number to %d\n",
		       major);
 		err = 0;
 	out1:
 		spin_unlock(&ubd_lock);
		return(err);
	}

	if(n < '0'){
		printk(KERN_ERR "ubd_setup : index out of range\n"); }

	if((n >= '0') && (n <= '9')) n -= '0';
	else if((n >= 'a') && (n <= 'z')) n -= 'a';
	else {
		printk(KERN_ERR "ubd_setup : device syntax invalid\n");
		return(1);
	}
	if(n >= MAX_DEV){
		printk(KERN_ERR "ubd_setup : index out of range "
		       "(%d devices)\n", MAX_DEV);	
		return(1);
	}

	err = 1;
	spin_lock(&ubd_lock);

	if(ubd_dev[n].file != NULL){
		printk(KERN_ERR "ubd_setup : device already configured\n");
		goto out2;
	}

	if(index_out) *index_out = n;

	if (*str == 'r'){
		flags.w = 0;
		str++;
	}
	if (*str == 's'){
		flags.s = 1;
		str++;
	}
	if(*str++ != '='){
		printk(KERN_ERR "ubd_setup : Expected '='\n");
		goto out2;
	}

	err = 0;
	backing_file = strchr(str, ',');
	if(backing_file){
		*backing_file = '\0';
		backing_file++;
	}
	ubd_dev[n].file = str;
	if(ubd_is_dir(ubd_dev[n].file))
		ubd_dev[n].is_dir = 1;
	ubd_dev[n].cow.file = backing_file;
	ubd_dev[n].boot_openflags = flags;
 out2:
	spin_unlock(&ubd_lock);
	return(err);
}

static int ubd_setup(char *str)
{
	ubd_setup_common(str, NULL);
	return(1);
}

__setup("ubd", ubd_setup);
__uml_help(ubd_setup,
"ubd<n>=<filename>\n"
"    This is used to associate a device with a file in the underlying\n"
"    filesystem. Usually, there is a filesystem in the file, but \n"
"    that's not required. Swap devices containing swap files can be\n"
"    specified like this. Also, a file which doesn't contain a\n"
"    filesystem can have its contents read in the virtual \n"
"    machine by running dd on the device. n must be in the range\n"
"    0 to 7. Appending an 'r' to the number will cause that device\n"
"    to be mounted read-only. For example ubd1r=./ext_fs. Appending\n"
"    an 's' (has to be _after_ 'r', if there is one) will cause data\n"
"    to be written to disk on the host immediately.\n\n"
);

static int fakehd_set = 0;
static int fakehd(char *str)
{
	printk(KERN_INFO 
	       "fakehd : Changing ubd name to \"hd\".\n");
	fakehd_set = 1;
	return 1;
}

__setup("fakehd", fakehd);
__uml_help(fakehd,
"fakehd\n"
"    Change the ubd device name to \"hd\".\n\n"
);

static void do_ubd_request(request_queue_t * q);

/* Only changed by ubd_init, which is an initcall. */
int thread_fd = -1;

/* Changed by ubd_handler, which is serialized because interrupts only
 * happen on CPU 0.
 */
int intr_count = 0;

static void ubd_finish(struct request *req, int error)
{
	int nsect;

	if(error){
 		spin_lock(&ubd_io_lock);
		end_request(req, 0);
 		spin_unlock(&ubd_io_lock);
		return;
	}
	nsect = req->current_nr_sectors;
	req->sector += nsect;
	req->buffer += nsect << 9;
	req->errors = 0;
	req->nr_sectors -= nsect;
	req->current_nr_sectors = 0;
	spin_lock(&ubd_io_lock);
	end_request(req, 1);
	spin_unlock(&ubd_io_lock);
}

static void ubd_handler(void)
{
	struct io_thread_req req;
	struct request *rq = elv_next_request(ubd_queue);
	int n;

	do_ubd = NULL;
	intr_count++;
	n = read_ubd_fs(thread_fd, &req, sizeof(req));
	if(n != sizeof(req)){
		printk(KERN_ERR "Pid %d - spurious interrupt in ubd_handler, "
		       "errno = %d\n", os_getpid(), -n);
		spin_lock(&ubd_io_lock);
		end_request(rq, 0);
		spin_unlock(&ubd_io_lock);
		return;
	}
        
        if((req.offset != ((__u64) (rq->sector)) << 9) ||
	   (req.length != (rq->current_nr_sectors) << 9))
		panic("I/O op mismatch");
	
	ubd_finish(rq, req.error);
	reactivate_fd(thread_fd, UBD_IRQ);	
	do_ubd_request(ubd_queue);
}

static void ubd_intr(int irq, void *dev, struct pt_regs *unused)
{
	ubd_handler();
}

/* Only changed by ubd_init, which is an initcall. */
static int io_pid = -1;

void kill_io_thread(void)
{
	if(io_pid != -1) 
		os_kill_process(io_pid, 1);
}

__uml_exitcall(kill_io_thread);

static int ubd_file_size(struct ubd *dev, __u64 *size_out)
{
	char *file;

	file = dev->cow.file ? dev->cow.file : dev->file;
	return(os_file_size(file, size_out));
}

static void ubd_close(struct ubd *dev)
{
	os_close_file(dev->fd);
	if(dev->cow.file == NULL)
		return;

	os_close_file(dev->cow.fd);
	vfree(dev->cow.bitmap);
	dev->cow.bitmap = NULL;
}

static int ubd_open_dev(struct ubd *dev)
{
	struct openflags flags;
	int err, n, create_cow, *create_ptr;

	create_cow = 0;
	create_ptr = (dev->cow.file != NULL) ? &create_cow : NULL;
	dev->fd = open_ubd_file(dev->file, &dev->openflags, &dev->cow.file,
				&dev->cow.bitmap_offset, &dev->cow.bitmap_len, 
				&dev->cow.data_offset, create_ptr);

	if((dev->fd == -ENOENT) && create_cow){
		n = dev - ubd_dev;
		dev->fd = create_cow_file(dev->file, dev->cow.file, 
					  dev->openflags, 1 << 9,
					  &dev->cow.bitmap_offset, 
					  &dev->cow.bitmap_len,
					  &dev->cow.data_offset);
		if(dev->fd >= 0){
			printk(KERN_INFO "Creating \"%s\" as COW file for "
			       "\"%s\"\n", dev->file, dev->cow.file);
		}
	}

	if(dev->fd < 0) return(dev->fd);

	if(dev->cow.file != NULL){
		err = -ENOMEM;
		dev->cow.bitmap = (void *) vmalloc(dev->cow.bitmap_len);
		if(dev->cow.bitmap == NULL) goto error;
		flush_tlb_kernel_vm();

		err = read_cow_bitmap(dev->fd, dev->cow.bitmap, 
				      dev->cow.bitmap_offset, 
				      dev->cow.bitmap_len);
		if(err) goto error;

		flags = dev->openflags;
		flags.w = 0;
		err = open_ubd_file(dev->cow.file, &flags, NULL, NULL, NULL, 
				    NULL, NULL);
		if(err < 0) goto error;
		dev->cow.fd = err;
	}
	return(0);
 error: