ubd_kern.c 31.7 KB
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/*
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 * Copyright (C) 2000 Jeff Dike (jdike@karaya.com)
 * Licensed under the GPL
 */

/* 2001-09-28...2002-04-17
 * Partition stuff by James_McMechan@hotmail.com
 * 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
 * 2003-01-29 more tinkering for 2.5.59-1
 * This should now address the sysfs problems and has
 * the symlink for devfs to allow for booting with
 * the common /dev/ubd/discX/... names rather than
 * only /dev/ubdN/discN this version also has lots of
 * clean ups preparing for ubd-many.
 * James McMechan
 */

#define MAJOR_NR UBD_MAJOR
#define UBD_SHIFT 4

#include "linux/module.h"
#include "linux/blkdev.h"
#include "linux/hdreg.h"
#include "linux/init.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"
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#include "linux/platform_device.h"
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#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 "irq_kern.h"
#include "ubd_user.h"
#include "os.h"
#include "mem.h"
#include "mem_kern.h"
#include "cow.h"

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enum ubd_req { UBD_READ, UBD_WRITE };
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struct io_thread_req {
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	enum ubd_req op;
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	int fds[2];
	unsigned long offsets[2];
	unsigned long long offset;
	unsigned long length;
	char *buffer;
	int sectorsize;
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	unsigned long sector_mask;
	unsigned long long cow_offset;
	unsigned long bitmap_words[2];
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	int error;
};

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extern int open_ubd_file(char *file, struct openflags *openflags, int shared,
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			 char **backing_file_out, int *bitmap_offset_out,
			 unsigned long *bitmap_len_out, int *data_offset_out,
			 int *create_cow_out);
extern int create_cow_file(char *cow_file, char *backing_file,
			   struct openflags flags, int sectorsize,
			   int alignment, int *bitmap_offset_out,
			   unsigned long *bitmap_len_out,
			   int *data_offset_out);
extern int read_cow_bitmap(int fd, void *buf, int offset, int len);
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extern void do_io(struct io_thread_req *req);
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static inline int ubd_test_bit(__u64 bit, unsigned char *data)
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{
	__u64 n;
	int bits, off;

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	bits = sizeof(data[0]) * 8;
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	n = bit / bits;
	off = bit % bits;
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	return((data[n] & (1 << off)) != 0);
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}

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static inline void ubd_set_bit(__u64 bit, unsigned char *data)
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{
	__u64 n;
	int bits, off;

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	bits = sizeof(data[0]) * 8;
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	n = bit / bits;
	off = bit % bits;
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	data[n] |= (1 << off);
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}
/*End stuff from ubd_user.h*/

#define DRIVER_NAME "uml-blkdev"

static DEFINE_SPINLOCK(ubd_io_lock);
static DEFINE_SPINLOCK(ubd_lock);

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static void (*do_ubd)(void);

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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);
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static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo);
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#define MAX_DEV (16)
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static struct block_device_operations ubd_blops = {
        .owner		= THIS_MODULE,
        .open		= ubd_open,
        .release	= ubd_release,
        .ioctl		= ubd_ioctl,
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	.getgeo		= ubd_getgeo,
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};

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

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

static struct gendisk *ubd_gendisk[MAX_DEV];
static struct gendisk *fake_gendisk[MAX_DEV];
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#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 {
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	/* backing file name */
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	char *file;
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	/* backing file fd */
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	int fd;
	unsigned long *bitmap;
	unsigned long bitmap_len;
	int bitmap_offset;
        int data_offset;
};

struct ubd {
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	/* name (and fd, below) of the file opened for writing, either the
	 * backing or the cow file. */
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	char *file;
	int count;
	int fd;
	__u64 size;
	struct openflags boot_openflags;
	struct openflags openflags;
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	int shared;
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	int no_cow;
	struct cow cow;
	struct platform_device pdev;
};

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

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

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struct ubd ubd_devs[MAX_DEV] = { [ 0 ... MAX_DEV - 1 ] = DEFAULT_UBD };
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static int ubd0_init(void)
{
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	struct ubd *ubd_dev = &ubd_devs[0];
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	if(ubd_dev->file == NULL)
		ubd_dev->file = "root_fs";
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	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", NULL);
	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 parse_unit(char **ptr)
{
	char *str = *ptr, *end;
	int n = -1;

	if(isdigit(*str)) {
		n = simple_strtoul(str, &end, 0);
		if(end == str)
			return(-1);
		*ptr = end;
	}
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	else if (('a' <= *str) && (*str <= 'z')) {
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		n = *str - 'a';
		str++;
		*ptr = str;
	}
	return(n);
}

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

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

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

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

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

	n = parse_unit(&str);
	if(n < 0){
		printk(KERN_ERR "ubd_setup : couldn't parse unit number "
		       "'%s'\n", str);
		return(1);
	}
	if(n >= MAX_DEV){
		printk(KERN_ERR "ubd_setup : index %d out of range "
		       "(%d devices, from 0 to %d)\n", n, MAX_DEV, MAX_DEV - 1);
		return(1);
	}

	err = 1;
	spin_lock(&ubd_lock);

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	ubd_dev = &ubd_devs[n];
	if(ubd_dev->file != NULL){
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		printk(KERN_ERR "ubd_setup : device already configured\n");
		goto out;
	}

	if (index_out)
		*index_out = n;

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	for (i = 0; i < sizeof("rscd="); i++) {
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		switch (*str) {
		case 'r':
			flags.w = 0;
			break;
		case 's':
			flags.s = 1;
			break;
		case 'd':
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			ubd_dev->no_cow = 1;
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			break;
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		case 'c':
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			ubd_dev->shared = 1;
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			break;
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		case '=':
			str++;
			goto break_loop;
		default:
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			printk(KERN_ERR "ubd_setup : Expected '=' or flag letter (r, s, c, or d)\n");
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			goto out;
		}
		str++;
	}

        if (*str == '=')
		printk(KERN_ERR "ubd_setup : Too many flags specified\n");
        else
		printk(KERN_ERR "ubd_setup : Expected '='\n");
	goto out;

break_loop:
	err = 0;
	backing_file = strchr(str, ',');

	if (!backing_file) {
		backing_file = strchr(str, ':');
	}

	if(backing_file){
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		if(ubd_dev->no_cow)
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			printk(KERN_ERR "Can't specify both 'd' and a "
			       "cow file\n");
		else {
			*backing_file = '\0';
			backing_file++;
		}
	}
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	ubd_dev->file = str;
	ubd_dev->cow.file = backing_file;
	ubd_dev->boot_openflags = flags;
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out:
	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><flags>=<filename>[(:|,)<filename2>]\n"
"    This is used to associate a device with a file in the underlying\n"
"    filesystem. When specifying two filenames, the first one is the\n"
"    COW name and the second is the backing file name. As separator you can\n"
"    use either a ':' or a ',': the first one allows writing things like;\n"
"	ubd0=~/Uml/root_cow:~/Uml/root_backing_file\n"
"    while with a ',' the shell would not expand the 2nd '~'.\n"
"    When using only one filename, UML will detect whether to thread it like\n"
"    a COW file or a backing file. To override this detection, add the 'd'\n"
"    flag:\n"
"	ubd0d=BackingFile\n"
"    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' will cause data to be written to disk on the host immediately.\n\n"
);

static int udb_setup(char *str)
{
	printk("udb%s specified on command line is almost certainly a ubd -> "
	       "udb TYPO\n", str);
	return(1);
}

__setup("udb", udb_setup);
__uml_help(udb_setup,
"udb\n"
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"    This option is here solely to catch ubd -> udb typos, which can be\n"
"    to impossible to catch visually unless you specifically look for\n"
"    them.  The only result of any option starting with 'udb' is an error\n"
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"    in the boot output.\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);
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/* Only changed by ubd_init, which is an initcall. */
int thread_fd = -1;
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/* Changed by ubd_handler, which is serialized because interrupts only
 * happen on CPU 0.
 */
int intr_count = 0;

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/* call ubd_finish if you need to serialize */
static void __ubd_finish(struct request *req, int error)
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{
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	int nsect;

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

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static inline void ubd_finish(struct request *req, int error)
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{
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 	spin_lock(&ubd_io_lock);
	__ubd_finish(req, error);
	spin_unlock(&ubd_io_lock);
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}

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/* Called without ubd_io_lock held */
static void ubd_handler(void)
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{
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	struct io_thread_req req;
	struct request *rq = elv_next_request(ubd_queue);
	int n;

	do_ubd = NULL;
	intr_count++;
	n = os_read_file(thread_fd, &req, sizeof(req));
	if(n != sizeof(req)){
		printk(KERN_ERR "Pid %d - spurious interrupt in ubd_handler, "
		       "err = %d\n", os_getpid(), -n);
		spin_lock(&ubd_io_lock);
		end_request(rq, 0);
		spin_unlock(&ubd_io_lock);
		return;
	}
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	ubd_finish(rq, req.error);
	reactivate_fd(thread_fd, UBD_IRQ);	
	do_ubd_request(ubd_queue);
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}

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static irqreturn_t ubd_intr(int irq, void *dev)
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{
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	ubd_handler();
	return(IRQ_HANDLED);
}
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/* Only changed by ubd_init, which is an initcall. */
static int io_pid = -1;
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void kill_io_thread(void)
{
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	if(io_pid != -1)
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		os_kill_process(io_pid, 1);
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}
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__uml_exitcall(kill_io_thread);

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

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

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

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

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static int ubd_open_dev(struct ubd *ubd_dev)
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{
	struct openflags flags;
	char **back_ptr;
	int err, create_cow, *create_ptr;

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	ubd_dev->openflags = ubd_dev->boot_openflags;
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	create_cow = 0;
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	create_ptr = (ubd_dev->cow.file != NULL) ? &create_cow : NULL;
	back_ptr = ubd_dev->no_cow ? NULL : &ubd_dev->cow.file;
	ubd_dev->fd = open_ubd_file(ubd_dev->file, &ubd_dev->openflags, ubd_dev->shared,
				back_ptr, &ubd_dev->cow.bitmap_offset,
				&ubd_dev->cow.bitmap_len, &ubd_dev->cow.data_offset,
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				create_ptr);
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	if((ubd_dev->fd == -ENOENT) && create_cow){
		ubd_dev->fd = create_cow_file(ubd_dev->file, ubd_dev->cow.file,
					  ubd_dev->openflags, 1 << 9, PAGE_SIZE,
					  &ubd_dev->cow.bitmap_offset,
					  &ubd_dev->cow.bitmap_len,
					  &ubd_dev->cow.data_offset);
		if(ubd_dev->fd >= 0){
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			printk(KERN_INFO "Creating \"%s\" as COW file for "
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			       "\"%s\"\n", ubd_dev->file, ubd_dev->cow.file);
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		}
	}

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	if(ubd_dev->fd < 0){
		printk("Failed to open '%s', errno = %d\n", ubd_dev->file,
		       -ubd_dev->fd);
		return(ubd_dev->fd);
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	}

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	if(ubd_dev->cow.file != NULL){
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		err = -ENOMEM;
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		ubd_dev->cow.bitmap = (void *) vmalloc(ubd_dev->cow.bitmap_len);
		if(ubd_dev->cow.bitmap == NULL){
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			printk(KERN_ERR "Failed to vmalloc COW bitmap\n");
			goto error;
		}
		flush_tlb_kernel_vm();

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		err = read_cow_bitmap(ubd_dev->fd, ubd_dev->cow.bitmap,
				      ubd_dev->cow.bitmap_offset,
				      ubd_dev->cow.bitmap_len);
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		if(err < 0)
			goto error;

614
		flags = ubd_dev->openflags;
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		flags.w = 0;
616
		err = open_ubd_file(ubd_dev->cow.file, &flags, ubd_dev->shared, NULL,
617
				    NULL, NULL, NULL, NULL);
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		if(err < 0) goto error;
619
		ubd_dev->cow.fd = err;
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	}
	return(0);
 error:
623
	os_close_file(ubd_dev->fd);
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	return(err);
}

static int ubd_new_disk(int major, u64 size, int unit,
			struct gendisk **disk_out)
			
{
	struct gendisk *disk;

	disk = alloc_disk(1 << UBD_SHIFT);
	if(disk == NULL)
		return(-ENOMEM);

	disk->major = major;
	disk->first_minor = unit << UBD_SHIFT;
	disk->fops = &ubd_blops;
	set_capacity(disk, size / 512);
641
	if(major == MAJOR_NR)
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		sprintf(disk->disk_name, "ubd%c", 'a' + unit);
643
	else
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		sprintf(disk->disk_name, "ubd_fake%d", unit);

	/* sysfs register (not for ide fake devices) */
	if (major == MAJOR_NR) {
648 649 650 651
		ubd_devs[unit].pdev.id   = unit;
		ubd_devs[unit].pdev.name = DRIVER_NAME;
		platform_device_register(&ubd_devs[unit].pdev);
		disk->driverfs_dev = &ubd_devs[unit].pdev.dev;
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	}

654
	disk->private_data = &ubd_devs[unit];
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	disk->queue = ubd_queue;
	add_disk(disk);

	*disk_out = disk;
	return 0;
}

#define ROUND_BLOCK(n) ((n + ((1 << 9) - 1)) & (-1 << 9))

static int ubd_add(int n)
{
666
	struct ubd *ubd_dev = &ubd_devs[n];
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	int err;

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	err = -ENODEV;
670
	if(ubd_dev->file == NULL)
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		goto out;
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673
	err = ubd_file_size(ubd_dev, &ubd_dev->size);
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	if(err < 0)
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		goto out;
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677
	ubd_dev->size = ROUND_BLOCK(ubd_dev->size);
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679
	err = ubd_new_disk(MAJOR_NR, ubd_dev->size, n, &ubd_gendisk[n]);
680
	if(err)
681
		goto out;
682

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	if(fake_major != MAJOR_NR)
684
		ubd_new_disk(fake_major, ubd_dev->size, n,
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			     &fake_gendisk[n]);

	/* perhaps this should also be under the "if (fake_major)" above */
	/* using the fake_disk->disk_name and also the fakehd_set name */
	if (fake_ide)
		make_ide_entries(ubd_gendisk[n]->disk_name);

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	err = 0;
out:
	return err;
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}

static int ubd_config(char *str)
{
	int n, err;

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	str = kstrdup(str, GFP_KERNEL);
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	if(str == NULL){
		printk(KERN_ERR "ubd_config failed to strdup string\n");
		return(1);
	}
	err = ubd_setup_common(str, &n);
	if(err){
		kfree(str);
		return(-1);
	}
	if(n == -1) return(0);

 	spin_lock(&ubd_lock);
	err = ubd_add(n);
	if(err)
716
		ubd_devs[n].file = NULL;
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 	spin_unlock(&ubd_lock);

	return(err);
}

static int ubd_get_config(char *name, char *str, int size, char **error_out)
{
724
	struct ubd *ubd_dev;
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	int n, len = 0;

	n = parse_unit(&name);
	if((n >= MAX_DEV) || (n < 0)){
		*error_out = "ubd_get_config : device number out of range";
		return(-1);
	}

733
	ubd_dev = &ubd_devs[n];
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	spin_lock(&ubd_lock);

736
	if(ubd_dev->file == NULL){
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		CONFIG_CHUNK(str, size, len, "", 1);
		goto out;
	}

741
	CONFIG_CHUNK(str, size, len, ubd_dev->file, 0);
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743
	if(ubd_dev->cow.file != NULL){
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		CONFIG_CHUNK(str, size, len, ",", 0);
745
		CONFIG_CHUNK(str, size, len, ubd_dev->cow.file, 1);
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	}
	else CONFIG_CHUNK(str, size, len, "", 1);

 out:
	spin_unlock(&ubd_lock);
	return(len);
}

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static int ubd_id(char **str, int *start_out, int *end_out)
{
        int n;

	n = parse_unit(str);
        *start_out = 0;
        *end_out = MAX_DEV - 1;
        return n;
}

static int ubd_remove(int n)
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{
766
	struct ubd *ubd_dev;
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	int err = -ENODEV;
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	spin_lock(&ubd_lock);
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	if(ubd_gendisk[n] == NULL)
		goto out;
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774
	ubd_dev = &ubd_devs[n];
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776
	if(ubd_dev->file == NULL)
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		goto out;
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	/* you cannot remove a open disk */
	err = -EBUSY;
781
	if(ubd_dev->count > 0)
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		goto out;

	del_gendisk(ubd_gendisk[n]);
	put_disk(ubd_gendisk[n]);
	ubd_gendisk[n] = NULL;

	if(fake_gendisk[n] != NULL){
		del_gendisk(fake_gendisk[n]);
		put_disk(fake_gendisk[n]);
		fake_gendisk[n] = NULL;
	}

794 795
	platform_device_unregister(&ubd_dev->pdev);
	*ubd_dev = ((struct ubd) DEFAULT_UBD);
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	err = 0;
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out:
	spin_unlock(&ubd_lock);
	return err;
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}

static struct mc_device ubd_mc = {
	.name		= "ubd",
	.config		= ubd_config,
 	.get_config	= ubd_get_config,
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	.id		= ubd_id,
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	.remove		= ubd_remove,
};

static int ubd_mc_init(void)
{
	mconsole_register_dev(&ubd_mc);
	return 0;
}

__initcall(ubd_mc_init);

818 819 820 821
static struct platform_driver ubd_driver = {
	.driver = {
		.name  = DRIVER_NAME,
	},
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};

int ubd_init(void)
{
        int i;

	if (register_blkdev(MAJOR_NR, "ubd"))
		return -1;

	ubd_queue = blk_init_queue(do_ubd_request, &ubd_io_lock);
	if (!ubd_queue) {
		unregister_blkdev(MAJOR_NR, "ubd");
		return -1;
	}
		
	if (fake_major != MAJOR_NR) {
		char name[sizeof("ubd_nnn\0")];

		snprintf(name, sizeof(name), "ubd_%d", fake_major);
		if (register_blkdev(fake_major, "ubd"))
			return -1;
	}
844
	platform_driver_register(&ubd_driver);
845
	for (i = 0; i < MAX_DEV; i++)
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		ubd_add(i);
	return 0;
}

late_initcall(ubd_init);

852 853 854 855 856 857 858 859 860 861 862
int ubd_driver_init(void){
	unsigned long stack;
	int err;

	/* Set by CONFIG_BLK_DEV_UBD_SYNC or ubd=sync.*/
	if(global_openflags.s){
		printk(KERN_INFO "ubd: Synchronous mode\n");
		/* Letting ubd=sync be like using ubd#s= instead of ubd#= is
		 * enough. So use anyway the io thread. */
	}
	stack = alloc_stack(0, 0);
863
	io_pid = start_io_thread(stack + PAGE_SIZE - sizeof(void *),
864 865
				 &thread_fd);
	if(io_pid < 0){
866
		printk(KERN_ERR
867 868 869 870 871
		       "ubd : Failed to start I/O thread (errno = %d) - "
		       "falling back to synchronous I/O\n", -io_pid);
		io_pid = -1;
		return(0);
	}
872
	err = um_request_irq(UBD_IRQ, thread_fd, IRQ_READ, ubd_intr,
873
			     IRQF_DISABLED, "ubd", ubd_devs);
874 875
	if(err != 0)
		printk(KERN_ERR "um_request_irq failed - errno = %d\n", -err);
876
	return 0;
877 878 879 880
}

device_initcall(ubd_driver_init);

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static int ubd_open(struct inode *inode, struct file *filp)
{
	struct gendisk *disk = inode->i_bdev->bd_disk;
884
	struct ubd *ubd_dev = disk->private_data;
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	int err = 0;

887 888
	if(ubd_dev->count == 0){
		err = ubd_open_dev(ubd_dev);
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		if(err){
			printk(KERN_ERR "%s: Can't open \"%s\": errno = %d\n",
891
			       disk->disk_name, ubd_dev->file, -err);
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			goto out;
		}
	}
895 896
	ubd_dev->count++;
	set_disk_ro(disk, !ubd_dev->openflags.w);
897 898 899

	/* This should no more be needed. And it didn't work anyway to exclude
	 * read-write remounting of filesystems.*/
900 901
	/*if((filp->f_mode & FMODE_WRITE) && !ubd_dev->openflags.w){
	        if(--ubd_dev->count == 0) ubd_close(ubd_dev);
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	        err = -EROFS;
903
	}*/
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 out:
	return(err);
}

static int ubd_release(struct inode * inode, struct file * file)
{
	struct gendisk *disk = inode->i_bdev->bd_disk;
911
	struct ubd *ubd_dev = disk->private_data;
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913 914
	if(--ubd_dev->count == 0)
		ubd_close(ubd_dev);
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	return(0);
}

918 919 920 921
static void cowify_bitmap(__u64 io_offset, int length, unsigned long *cow_mask,
			  __u64 *cow_offset, unsigned long *bitmap,
			  __u64 bitmap_offset, unsigned long *bitmap_words,
			  __u64 bitmap_len)
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{
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	__u64 sector = io_offset >> 9;
	int i, update_bitmap = 0;

	for(i = 0; i < length >> 9; i++){
		if(cow_mask != NULL)
			ubd_set_bit(i, (unsigned char *) cow_mask);
		if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
			continue;
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932 933 934 935 936 937
		update_bitmap = 1;
		ubd_set_bit(sector + i, (unsigned char *) bitmap);
	}

	if(!update_bitmap)
		return;
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939
	*cow_offset = sector / (sizeof(unsigned long) * 8);
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	/* This takes care of the case where we're exactly at the end of the
	 * device, and *cow_offset + 1 is off the end.  So, just back it up
	 * by one word.  Thanks to Lynn Kerby for the fix and James McMechan
	 * for the original diagnosis.
	 */
	if(*cow_offset == ((bitmap_len + sizeof(unsigned long) - 1) /
			   sizeof(unsigned long) - 1))
		(*cow_offset)--;

	bitmap_words[0] = bitmap[*cow_offset];
	bitmap_words[1] = bitmap[*cow_offset + 1];

	*cow_offset *= sizeof(unsigned long);
	*cow_offset += bitmap_offset;
}

static void cowify_req(struct io_thread_req *req, unsigned long *bitmap,
		       __u64 bitmap_offset, __u64 bitmap_len)
{
	__u64 sector = req->offset >> 9;
	int i;

	if(req->length > (sizeof(req->sector_mask) * 8) << 9)
		panic("Operation too long");

	if(req->op == UBD_READ) {
		for(i = 0; i < req->length >> 9; i++){
			if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
969
				ubd_set_bit(i, (unsigned char *)
970 971 972 973 974 975
					    &req->sector_mask);
                }
	}
	else cowify_bitmap(req->offset, req->length, &req->sector_mask,
			   &req->cow_offset, bitmap, bitmap_offset,
			   req->bitmap_words, bitmap_len);
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}

/* Called with ubd_io_lock held */
979
static int prepare_request(struct request *req, struct io_thread_req *io_req)
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{
	struct gendisk *disk = req->rq_disk;
982
	struct ubd *ubd_dev = disk->private_data;
983 984 985
	__u64 offset;
	int len;

986
	/* This should be impossible now */
987
	if((rq_data_dir(req) == WRITE) && !ubd_dev->openflags.w){
988
		printk("Write attempted on readonly ubd device %s\n",
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		       disk->disk_name);
990
		end_request(req, 0);
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		return(1);
	}

994 995 996
	offset = ((__u64) req->sector) << 9;
	len = req->current_nr_sectors << 9;

997 998
	io_req->fds[0] = (ubd_dev->cow.file != NULL) ? ubd_dev->cow.fd : ubd_dev->fd;
	io_req->fds[1] = ubd_dev->fd;
999
	io_req->cow_offset = -1;
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	io_req->offset = offset;
	io_req->length = len;
	io_req->error = 0;
1003 1004 1005
	io_req->sector_mask = 0;

	io_req->op = (rq_data_dir(req) == READ) ? UBD_READ : UBD_WRITE;
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	io_req->offsets[0] = 0;
1007
	io_req->offsets[1] = ubd_dev->cow.data_offset;
1008
	io_req->buffer = req->buffer;
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	io_req->sectorsize = 1 << 9;

1011 1012 1013
	if(ubd_dev->cow.file != NULL)
		cowify_req(io_req, ubd_dev->cow.bitmap, ubd_dev->cow.bitmap_offset,
			   ubd_dev->cow.bitmap_len);
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	return(0);
}

/* Called with ubd_io_lock held */
static void do_ubd_request(request_queue_t *q)
{
	struct io_thread_req io_req;
	struct request *req;
1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044
	int err, n;

	if(thread_fd == -1){
		while((req = elv_next_request(q)) != NULL){
			err = prepare_request(req, &io_req);
			if(!err){
				do_io(&io_req);
				__ubd_finish(req, io_req.error);
			}
		}
	}
	else {
		if(do_ubd || (req = elv_next_request(q)) == NULL)
			return;
		err = prepare_request(req, &io_req);
		if(!err){
			do_ubd = ubd_handler;
			n = os_write_file(thread_fd, (char *) &io_req,
					 sizeof(io_req));
			if(n != sizeof(io_req))
				printk("write to io thread failed, "
				       "errno = %d\n", -n);
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		}
	}
}

1049 1050
static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
{
1051
	struct ubd *ubd_dev = bdev->bd_disk->private_data;
1052 1053 1054

	geo->heads = 128;
	geo->sectors = 32;
1055
	geo->cylinders = ubd_dev->size / (128 * 32 * 512);
1056 1057 1058
	return 0;
}

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static int ubd_ioctl(struct inode * inode, struct file * file,
		     unsigned int cmd, unsigned long arg)
{
1062
	struct ubd *ubd_dev = inode->i_bdev->bd_disk->private_data;
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	struct hd_driveid ubd_id = {
		.cyls		= 0,
		.heads		= 128,
		.sectors	= 32,
	};

	switch (cmd) {
		struct cdrom_volctrl volume;
	case HDIO_GET_IDENTITY:
1072
		ubd_id.cyls = ubd_dev->size / (128 * 32 * 512);
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		if(copy_to_user((char __user *) arg, (char *) &ubd_id,
				 sizeof(ubd_id)))
			return(-EFAULT);
		return(0);
		
	case CDROMVOLREAD:
		if(copy_from_user(&volume, (char __user *) arg, sizeof(volume)))
			return(-EFAULT);
		volume.channel0 = 255;
		volume.channel1 = 255;
		volume.channel2 = 255;
		volume.channel3 = 255;
		if(copy_to_user((char __user *) arg, &volume, sizeof(volume)))
			return(-EFAULT);
		return(0);
	}
	return(-EINVAL);
}

1092
static int path_requires_switch(char *from_cmdline, char *from_cow, char *cow)
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{
	struct uml_stat buf1, buf2;
	int err;

1097 1098 1099 1100
	if(from_cmdline == NULL)
		return 0;
	if(!strcmp(from_cmdline, from_cow))
		return 0;
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	err = os_stat_file(from_cmdline, &buf1);
	if(err < 0){
		printk("Couldn't stat '%s', err = %d\n", from_cmdline, -err);
1105
		return 0;
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	}
	err = os_stat_file(from_cow, &buf2);
	if(err < 0){
		printk("Couldn't stat '%s', err = %d\n", from_cow, -err);
1110
		return 1;
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	}
	if((buf1.ust_dev == buf2.ust_dev) && (buf1.ust_ino == buf2.ust_ino))
1113
		return 0;
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	printk("Backing file mismatch - \"%s\" requested,\n"
	       "\"%s\" specified in COW header of \"%s\"\n",
	       from_cmdline, from_cow, cow);
1118
	return 1;
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}

static int backing_file_mismatch(char *file, __u64 size, time_t mtime)
{
	unsigned long modtime;
1124
	unsigned long long actual;
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	int err;

	err = os_file_modtime(file, &modtime);
	if(err < 0){
		printk("Failed to get modification time of backing file "
		       "\"%s\", err = %d\n", file, -err);
		return(err);
	}

	err = os_file_size(file, &actual);
	if(err < 0){
		printk("Failed to get size of backing file \"%s\", "
		       "err = %d\n", file, -err);
		return(err);
	}

  	if(actual != size){
		/*__u64 can be a long on AMD64 and with %lu GCC complains; so
		 * the typecast.*/
		printk("Size mismatch (%llu vs %llu) of COW header vs backing "
		       "file\n", (unsigned long long) size, actual);
		return(-EINVAL);
	}
	if(modtime != mtime){
		printk("mtime mismatch (%ld vs %ld) of COW header vs backing "
		       "file\n", mtime, modtime);
		return(-EINVAL);
	}
	return(0);
}

int read_cow_bitmap(int fd, void *buf, int offset, int len)
{
	int err;

	err = os_seek_file(fd, offset);
	if(err < 0)
		return(err);

	err = os_read_file(fd, buf, len);
	if(err < 0)
		return(err);

	return(0);
}

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int open_ubd_file(char *file, struct openflags *openflags, int shared,
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		  char **backing_file_out, int *bitmap_offset_out,
		  unsigned long *bitmap_len_out, int *data_offset_out,
		  int *create_cow_out)
{
	time_t mtime;
	unsigned long long size;
	__u32 version, align;
	char *backing_file;
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	int fd, err, sectorsize, asked_switch, mode = 0644;
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	fd = os_open_file(file, *openflags, mode);
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	if (fd < 0) {
		if ((fd == -ENOENT) && (create_cow_out != NULL))
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			*create_cow_out = 1;
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                if (!openflags->w ||
                   ((fd != -EROFS) && (fd != -EACCES)))
			return fd;
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		openflags->w = 0;
		fd = os_open_file(file, *openflags, mode);
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		if (fd < 0)
			return fd;
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        }

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	if(shared)
		printk("Not locking \"%s\" on the host\n", file);
	else {
		err = os_lock_file(fd, openflags->w);
		if(err < 0){
			printk("Failed to lock '%s', err = %d\n", file, -err);
			goto out_close;
		}
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	}

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	/* Successful return case! */
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	if(backing_file_out == NULL)
		return(fd);
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	err = read_cow_header(file_reader, &fd, &version, &backing_file, &mtime,
			      &size, &sectorsize, &align, bitmap_offset_out);
	if(err && (*backing_file_out != NULL)){
		printk("Failed to read COW header from COW file \"%s\", "
		       "errno = %d\n", file, -err);
		goto out_close;
	}
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	if(err)
		return(fd);
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	asked_switch = path_requires_switch(*backing_file_out, backing_file, file);
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	/* Allow switching only if no mismatch. */
	if (asked_switch && !backing_file_mismatch(*backing_file_out, size, mtime)) {
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		printk("Switching backing file to '%s'\n", *backing_file_out);
		err = write_cow_header(file, fd, *backing_file_out,
				       sectorsize, align, &size);
1226
		if (err) {
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			printk("Switch failed, errno = %d\n", -err);
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			goto out_close;
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		}
1230
	} else {
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		*backing_file_out = backing_file;
		err = backing_file_mismatch(*backing_file_out, size, mtime);
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		if (err)
			goto out_close;
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	}

	cow_sizes(version, size, sectorsize, align, *bitmap_offset_out,
		  bitmap_len_out, data_offset_out);

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        return fd;
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 out_close:
	os_close_file(fd);
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	return err;
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}

int create_cow_file(char *cow_file, char *backing_file, struct openflags flags,
		    int sectorsize, int alignment, int *bitmap_offset_out,
		    unsigned long *bitmap_len_out, int *data_offset_out)
{
	int err, fd;

	flags.c = 1;
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	fd = open_ubd_file(cow_file, &flags, 0, NULL, NULL, NULL, NULL, NULL);
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	if(fd < 0){
		err = fd;
		printk("Open of COW file '%s' failed, errno = %d\n", cow_file,
		       -err);
		goto out;
	}

	err = init_cow_file(fd, cow_file, backing_file, sectorsize, alignment,
			    bitmap_offset_out, bitmap_len_out,
			    data_offset_out);
	if(!err)
		return(fd);
	os_close_file(fd);
 out:
	return(err);
}

1271
static int update_bitmap(struct io_thread_req *req)
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{
1273
	int n;
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	if(req->cow_offset == -1)
		return(0);
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	n = os_seek_file(req->fds[1], req->cow_offset);
	if(n < 0){
		printk("do_io - bitmap lseek failed : err = %d\n", -n);
		return(1);
	}
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	n = os_write_file(req->fds[1], &req->bitmap_words,
		          sizeof(req->bitmap_words));
	if(n != sizeof(req->bitmap_words)){
		printk("do_io - bitmap update failed, err = %d fd = %d\n", -n,
		       req->fds[1]);
		return(1);
	}
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1292 1293
	return(0);
}
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void do_io(struct io_thread_req *req)
{
	char *buf;
	unsigned long len;
	int n, nsectors, start, end, bit;
	int err;
	__u64 off;

	nsectors = req->length / req->sectorsize;
	start = 0;
	do {
		bit = ubd_test_bit(start, (unsigned char *) &req->sector_mask);
		end = start;
		while((end < nsectors) &&
		      (ubd_test_bit(end, (unsigned char *)
				    &req->sector_mask) == bit))
			end++;

		off = req->offset + req->offsets[bit] +
			start * req->sectorsize;
		len = (end - start) * req->sectorsize;
		buf = &req->buffer[start * req->sectorsize];

		err = os_seek_file(req->fds[bit], off);
		if(err < 0){
			printk("do_io - lseek failed : err = %d\n", -err);
			req->error = 1;
			return;
		}
		if(req->op == UBD_READ){
			n = 0;
			do {
				buf = &buf[n];
				len -= n;
				n = os_read_file(req->fds[bit], buf, len);
				if (n < 0) {
					printk("do_io - read failed, err = %d "
					       "fd = %d\n", -n, req->fds[bit]);
					req->error = 1;
					return;
				}
			} while((n < len) && (n != 0));
			if (n < len) memset(&buf[n], 0, len - n);
		} else {
			n = os_write_file(req->fds[bit], buf, len);
			if(n != len){
				printk("do_io - write failed err = %d "
				       "fd = %d\n", -n, req->fds[bit]);
				req->error = 1;
				return;
			}
		}

		start = end;
	} while(start < nsectors);
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1351
	req->error = update_bitmap(req);
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}
1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387

/* Changed in start_io_thread, which is serialized by being called only
 * from ubd_init, which is an initcall.
 */
int kernel_fd = -1;

/* Only changed by the io thread */
int io_count = 0;

int io_thread(void *arg)
{
	struct io_thread_req req;
	int n;

	ignore_sigwinch_sig();
	while(1){
		n = os_read_file(kernel_fd, &req, sizeof(req));
		if(n != sizeof(req)){
			if(n < 0)
				printk("io_thread - read failed, fd = %d, "
				       "err = %d\n", kernel_fd, -n);
			else {
				printk("io_thread - short read, fd = %d, "
				       "length = %d\n", kernel_fd, n);
			}
			continue;
		}
		io_count++;
		do_io(&req);
		n = os_write_file(kernel_fd, &req, sizeof(req));
		if(n != sizeof(req))
			printk("io_thread - write failed, fd = %d, err = %d\n",
			       kernel_fd, -n);
	}

1388 1389
	return 0;
}