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linux/arch/um/drivers/ubd_kern.c
Jeff Dike 09ace81c1d [PATCH] uml: add host AIO support to block driver 
This adds AIO support to the ubd driver.

The driver breaks a struct request into IO requests to the host, based on the
hardware segments in the request and on any COW blocks covered by the request.

The ubd IO thread is gone, since there is now an equivalent thread in the AIO
module.

There is provision for multiple outstanding requests now.  Requests aren't
retired until all pieces of it have been completed.  The AIO requests have a
shared count, which is decremented as IO operations come in until it reaches
0.  This can be possibly moved to the request struct - haven't looked at this
yet.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-05 00:06:23 -07:00

1336 lines
32 KiB
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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/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/atomic.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 "irq_kern.h"
#include "ubd_user.h"
#include "os.h"
#include "mem.h"
#include "mem_kern.h"
#include "cow.h"
#include "aio.h"
enum ubd_req { UBD_READ, UBD_WRITE };
struct io_thread_req {
enum aio_type op;
int fds[2];
unsigned long offsets[2];
unsigned long long offset;
unsigned long length;
char *buffer;
int sectorsize;
int bitmap_offset;
long bitmap_start;
long bitmap_end;
int error;
};
extern int open_ubd_file(char *file, struct openflags *openflags,
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);
extern void do_io(struct io_thread_req *req, struct request *r,
unsigned long *bitmap);
static inline int ubd_test_bit(__u64 bit, void *data)
{
unsigned char *buffer = data;
__u64 n;
int bits, off;
bits = sizeof(buffer[0]) * 8;
n = bit / bits;
off = bit % bits;
return((buffer[n] & (1 << off)) != 0);
}
static inline void ubd_set_bit(__u64 bit, void *data)
{
unsigned char *buffer = data;
__u64 n;
int bits, off;
bits = sizeof(buffer[0]) * 8;
n = bit / bits;
off = bit % bits;
buffer[n] |= (1 << off);
}
/*End stuff from ubd_user.h*/
#define DRIVER_NAME "uml-blkdev"
static DEFINE_SPINLOCK(ubd_io_lock);
static DEFINE_SPINLOCK(ubd_lock);
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 = MAJOR_NR;
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 {
/* This is the backing file, actually */
char *file;
int fd;
unsigned long *bitmap;
unsigned long bitmap_len;
int bitmap_offset;
int data_offset;
};
#define MAX_SG 64
struct ubd {
char *file;
int count;
int fd;
__u64 size;
struct openflags boot_openflags;
struct openflags openflags;
int no_cow;
struct cow cow;
struct platform_device pdev;
struct scatterlist sg[MAX_SG];
};
#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, \
.cow = DEFAULT_COW, \
}
struct ubd ubd_dev[MAX_DEV] = { [ 0 ... MAX_DEV - 1 ] = DEFAULT_UBD };
static int ubd0_init(void)
{
struct ubd *dev = &ubd_dev[0];
if(dev->file == NULL)
dev->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", 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;
}
else if (('a' <= *str) && (*str <= 'h')) {
n = *str - 'a';
str++;
*ptr = str;
}
return(n);
}
static int ubd_setup_common(char *str, int *index_out)
{
struct ubd *dev;
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)){
printk(KERN_ERR
"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;
}
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);
dev = &ubd_dev[n];
if(dev->file != NULL){
printk(KERN_ERR "ubd_setup : device already configured\n");
goto out;
}
if (index_out)
*index_out = n;
for (i = 0; i < 4; i++) {
switch (*str) {
case 'r':
flags.w = 0;
break;
case 's':
flags.s = 1;
break;
case 'd':
dev->no_cow = 1;
break;
case '=':
str++;
goto break_loop;
default:
printk(KERN_ERR "ubd_setup : Expected '=' or flag letter (r,s or d)\n");
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){
if(dev->no_cow)
printk(KERN_ERR "Can't specify both 'd' and a "
"cow file\n");
else {
*backing_file = '\0';
backing_file++;
}
}
dev->file = str;
dev->cow.file = backing_file;
dev->boot_openflags = flags;
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"
" 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"
" 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);
static int in_ubd;
/* Changed by ubd_handler, which is serialized because interrupts only
* happen on CPU 0.
*/
int intr_count = 0;
static void ubd_end_request(struct request *req, int bytes, int uptodate)
{
if (!end_that_request_first(req, uptodate, bytes >> 9)) {
add_disk_randomness(req->rq_disk);
end_that_request_last(req);
}
}
/* call ubd_finish if you need to serialize */
static void __ubd_finish(struct request *req, int bytes)
{
if(bytes < 0){
ubd_end_request(req, 0, 0);
return;
}
ubd_end_request(req, bytes, 1);
}
static inline void ubd_finish(struct request *req, int bytes)
{
spin_lock(&ubd_io_lock);
__ubd_finish(req, bytes);
spin_unlock(&ubd_io_lock);
}
struct bitmap_io {
atomic_t count;
struct aio_context aio;
};
struct ubd_aio {
struct aio_context aio;
struct request *req;
int len;
struct bitmap_io *bitmap;
void *bitmap_buf;
};
static int ubd_reply_fd = -1;
static irqreturn_t ubd_intr(int irq, void *dev, struct pt_regs *unused)
{
struct aio_thread_reply reply;
struct ubd_aio *aio;
struct request *req;
int err, n, fd = (int) (long) dev;
while(1){
err = os_read_file(fd, &reply, sizeof(reply));
if(err == -EAGAIN)
break;
if(err < 0){
printk("ubd_aio_handler - read returned err %d\n",
-err);
break;
}
aio = container_of(reply.data, struct ubd_aio, aio);
n = reply.err;
if(n == 0){
req = aio->req;
req->nr_sectors -= aio->len >> 9;
if((aio->bitmap != NULL) &&
(atomic_dec_and_test(&aio->bitmap->count))){
aio->aio = aio->bitmap->aio;
aio->len = 0;
kfree(aio->bitmap);
aio->bitmap = NULL;
submit_aio(&aio->aio);
}
else {
if((req->nr_sectors == 0) &&
(aio->bitmap == NULL)){
int len = req->hard_nr_sectors << 9;
ubd_finish(req, len);
}
if(aio->bitmap_buf != NULL)
kfree(aio->bitmap_buf);
kfree(aio);
}
}
else if(n < 0){
ubd_finish(aio->req, n);
if(aio->bitmap != NULL)
kfree(aio->bitmap);
if(aio->bitmap_buf != NULL)
kfree(aio->bitmap_buf);
kfree(aio);
}
}
reactivate_fd(fd, UBD_IRQ);
do_ubd_request(ubd_queue);
return(IRQ_HANDLED);
}
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;
char **back_ptr;
int err, create_cow, *create_ptr;
dev->openflags = dev->boot_openflags;
create_cow = 0;
create_ptr = (dev->cow.file != NULL) ? &create_cow : NULL;
back_ptr = dev->no_cow ? NULL : &dev->cow.file;
dev->fd = open_ubd_file(dev->file, &dev->openflags, back_ptr,
&dev->cow.bitmap_offset, &dev->cow.bitmap_len,
&dev->cow.data_offset, create_ptr);
if((dev->fd == -ENOENT) && create_cow){
dev->fd = create_cow_file(dev->file, dev->cow.file,
dev->openflags, 1 << 9, PAGE_SIZE,
&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){
printk("Failed to open '%s', errno = %d\n", dev->file,
-dev->fd);
return(dev->fd);
}
if(dev->cow.file != NULL){
err = -ENOMEM;
dev->cow.bitmap = (void *) vmalloc(dev->cow.bitmap_len);
if(dev->cow.bitmap == NULL){
printk(KERN_ERR "Failed to vmalloc COW bitmap\n");
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 < 0)
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:
os_close_file(dev->fd);
return(err);
}
static int ubd_new_disk(int major, u64 size, int unit,
struct gendisk **disk_out)
{
struct gendisk *disk;
char from[sizeof("ubd/nnnnn\0")], to[sizeof("discnnnnn/disc\0")];
int err;
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);
if(major == MAJOR_NR){
sprintf(disk->disk_name, "ubd%c", 'a' + unit);
sprintf(disk->devfs_name, "ubd/disc%d", unit);
sprintf(from, "ubd/%d", unit);
sprintf(to, "disc%d/disc", unit);
err = devfs_mk_symlink(from, to);
if(err)
printk("ubd_new_disk failed to make link from %s to "
"%s, error = %d\n", from, to, err);
}
else {
sprintf(disk->disk_name, "ubd_fake%d", unit);
sprintf(disk->devfs_name, "ubd_fake/disc%d", unit);
}
/* sysfs register (not for ide fake devices) */
if (major == MAJOR_NR) {
ubd_dev[unit].pdev.id = unit;
ubd_dev[unit].pdev.name = DRIVER_NAME;
platform_device_register(&ubd_dev[unit].pdev);
disk->driverfs_dev = &ubd_dev[unit].pdev.dev;
}
disk->private_data = &ubd_dev[unit];
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)
{
struct ubd *dev = &ubd_dev[n];
int err;
err = -ENODEV;
if(dev->file == NULL)
goto out;
if (ubd_open_dev(dev))
goto out;
err = ubd_file_size(dev, &dev->size);
if(err < 0)
goto out_close;
dev->size = ROUND_BLOCK(dev->size);
err = ubd_new_disk(MAJOR_NR, dev->size, n, &ubd_gendisk[n]);
if(err)
goto out_close;
if(fake_major != MAJOR_NR)
ubd_new_disk(fake_major, dev->size, n,
&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);
err = 0;
out_close:
ubd_close(dev);
out:
return err;
}
static int ubd_config(char *str)
{
int n, err;
str = uml_strdup(str);
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)
ubd_dev[n].file = NULL;
spin_unlock(&ubd_lock);
return(err);
}
static int ubd_get_config(char *name, char *str, int size, char **error_out)
{
struct ubd *dev;
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);
}
dev = &ubd_dev[n];
spin_lock(&ubd_lock);
if(dev->file == NULL){
CONFIG_CHUNK(str, size, len, "", 1);
goto out;
}
CONFIG_CHUNK(str, size, len, dev->file, 0);
if(dev->cow.file != NULL){
CONFIG_CHUNK(str, size, len, ",", 0);
CONFIG_CHUNK(str, size, len, dev->cow.file, 1);
}
else CONFIG_CHUNK(str, size, len, "", 1);
out:
spin_unlock(&ubd_lock);
return(len);
}
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)
{
struct ubd *dev;
int err = -ENODEV;
spin_lock(&ubd_lock);
if(ubd_gendisk[n] == NULL)
goto out;
dev = &ubd_dev[n];
if(dev->file == NULL)
goto out;
/* you cannot remove a open disk */
err = -EBUSY;
if(dev->count > 0)
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;
}
platform_device_unregister(&dev->pdev);
*dev = ((struct ubd) DEFAULT_UBD);
err = 0;
out:
spin_unlock(&ubd_lock);
return err;
}
static struct mc_device ubd_mc = {
.name = "ubd",
.config = ubd_config,
.get_config = ubd_get_config,
.id = ubd_id,
.remove = ubd_remove,
};
static int ubd_mc_init(void)
{
mconsole_register_dev(&ubd_mc);
return 0;
}
__initcall(ubd_mc_init);
static struct device_driver ubd_driver = {
.name = DRIVER_NAME,
.bus = &platform_bus_type,
};
int ubd_init(void)
{
int i;
ubd_reply_fd = init_aio_irq(UBD_IRQ, "ubd", ubd_intr);
if(ubd_reply_fd < 0)
printk("Setting up ubd AIO failed, err = %d\n", ubd_reply_fd);
devfs_mk_dir("ubd");
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;
}
blk_queue_max_hw_segments(ubd_queue, MAX_SG);
if (fake_major != MAJOR_NR) {
char name[sizeof("ubd_nnn\0")];
snprintf(name, sizeof(name), "ubd_%d", fake_major);
devfs_mk_dir(name);
if (register_blkdev(fake_major, "ubd"))
return -1;
}
driver_register(&ubd_driver);
for (i = 0; i < MAX_DEV; i++)
ubd_add(i);
return 0;
}
late_initcall(ubd_init);
static int ubd_open(struct inode *inode, struct file *filp)
{
struct gendisk *disk = inode->i_bdev->bd_disk;
struct ubd *dev = disk->private_data;
int err = 0;
if(dev->count == 0){
err = ubd_open_dev(dev);
if(err){
printk(KERN_ERR "%s: Can't open \"%s\": errno = %d\n",
disk->disk_name, dev->file, -err);
goto out;
}
}
dev->count++;
set_disk_ro(disk, !dev->openflags.w);
/* This should no more be needed. And it didn't work anyway to exclude
* read-write remounting of filesystems.*/
/*if((filp->f_mode & FMODE_WRITE) && !dev->openflags.w){
if(--dev->count == 0) ubd_close(dev);
err = -EROFS;
}*/
out:
return(err);
}
static int ubd_release(struct inode * inode, struct file * file)
{
struct gendisk *disk = inode->i_bdev->bd_disk;
struct ubd *dev = disk->private_data;
if(--dev->count == 0)
ubd_close(dev);
return(0);
}
static void cowify_bitmap(struct io_thread_req *req, unsigned long *bitmap)
{
__u64 sector = req->offset / req->sectorsize;
int i;
for(i = 0; i < req->length / req->sectorsize; i++){
if(ubd_test_bit(sector + i, bitmap))
continue;
if(req->bitmap_start == -1)
req->bitmap_start = sector + i;
req->bitmap_end = sector + i + 1;
ubd_set_bit(sector + i, bitmap);
}
}
/* Called with ubd_io_lock held */
static int prepare_request(struct request *req, struct io_thread_req *io_req,
unsigned long long offset, int page_offset,
int len, struct page *page)
{
struct gendisk *disk = req->rq_disk;
struct ubd *dev = disk->private_data;
/* This should be impossible now */
if((rq_data_dir(req) == WRITE) && !dev->openflags.w){
printk("Write attempted on readonly ubd device %s\n",
disk->disk_name);
ubd_end_request(req, 0, 0);
return(1);
}
io_req->fds[0] = (dev->cow.file != NULL) ? dev->cow.fd : dev->fd;
io_req->fds[1] = dev->fd;
io_req->offset = offset;
io_req->length = len;
io_req->error = 0;
io_req->op = (rq_data_dir(req) == READ) ? AIO_READ : AIO_WRITE;
io_req->offsets[0] = 0;
io_req->offsets[1] = dev->cow.data_offset;
io_req->buffer = page_address(page) + page_offset;
io_req->sectorsize = 1 << 9;
io_req->bitmap_offset = dev->cow.bitmap_offset;
io_req->bitmap_start = -1;
io_req->bitmap_end = -1;
if((dev->cow.file != NULL) && (io_req->op == UBD_WRITE))
cowify_bitmap(io_req, dev->cow.bitmap);
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;
__u64 sector;
int err;
if(in_ubd)
return;
in_ubd = 1;
while((req = elv_next_request(q)) != NULL){
struct gendisk *disk = req->rq_disk;
struct ubd *dev = disk->private_data;
int n, i;
blkdev_dequeue_request(req);
sector = req->sector;
n = blk_rq_map_sg(q, req, dev->sg);
for(i = 0; i < n; i++){
struct scatterlist *sg = &dev->sg[i];
err = prepare_request(req, &io_req, sector << 9,
sg->offset, sg->length,
sg->page);
if(err)
continue;
sector += sg->length >> 9;
do_io(&io_req, req, dev->cow.bitmap);
}
}
in_ubd = 0;
}
static int ubd_ioctl(struct inode * inode, struct file * file,
unsigned int cmd, unsigned long arg)
{
struct hd_geometry __user *loc = (struct hd_geometry __user *) arg;
struct ubd *dev = inode->i_bdev->bd_disk->private_data;
struct hd_driveid ubd_id = {
.cyls = 0,
.heads = 128,
.sectors = 32,
};
switch (cmd) {
struct hd_geometry g;
struct cdrom_volctrl volume;
case HDIO_GETGEO:
if(!loc) return(-EINVAL);
g.heads = 128;
g.sectors = 32;
g.cylinders = dev->size / (128 * 32 * 512);
g.start = get_start_sect(inode->i_bdev);
return(copy_to_user(loc, &g, sizeof(g)) ? -EFAULT : 0);
case HDIO_GET_IDENTITY:
ubd_id.cyls = dev->size / (128 * 32 * 512);
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);
}
static int same_backing_files(char *from_cmdline, char *from_cow, char *cow)
{
struct uml_stat buf1, buf2;
int err;
if(from_cmdline == NULL) return(1);
if(!strcmp(from_cmdline, from_cow)) return(1);
err = os_stat_file(from_cmdline, &buf1);
if(err < 0){
printk("Couldn't stat '%s', err = %d\n", from_cmdline, -err);
return(1);
}
err = os_stat_file(from_cow, &buf2);
if(err < 0){
printk("Couldn't stat '%s', err = %d\n", from_cow, -err);
return(1);
}
if((buf1.ust_dev == buf2.ust_dev) && (buf1.ust_ino == buf2.ust_ino))
return(1);
printk("Backing file mismatch - \"%s\" requested,\n"
"\"%s\" specified in COW header of \"%s\"\n",
from_cmdline, from_cow, cow);
return(0);
}
static int backing_file_mismatch(char *file, __u64 size, time_t mtime)
{
unsigned long modtime;
long long actual;
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);
}
int open_ubd_file(char *file, struct openflags *openflags,
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;
int fd, err, sectorsize, same, mode = 0644;
fd = os_open_file(file, *openflags, mode);
if(fd < 0){
if((fd == -ENOENT) && (create_cow_out != NULL))
*create_cow_out = 1;
if(!openflags->w ||
((fd != -EROFS) && (fd != -EACCES))) return(fd);
openflags->w = 0;
fd = os_open_file(file, *openflags, mode);
if(fd < 0)
return(fd);
}
err = os_lock_file(fd, openflags->w);
if(err < 0){
printk("Failed to lock '%s', err = %d\n", file, -err);
goto out_close;
}
if(backing_file_out == NULL) return(fd);
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;
}
if(err) return(fd);
if(backing_file_out == NULL) return(fd);
same = same_backing_files(*backing_file_out, backing_file, file);
if(!same && !backing_file_mismatch(*backing_file_out, size, mtime)){
printk("Switching backing file to '%s'\n", *backing_file_out);
err = write_cow_header(file, fd, *backing_file_out,
sectorsize, align, &size);
if(err){
printk("Switch failed, errno = %d\n", -err);
return(err);
}
}
else {
*backing_file_out = backing_file;
err = backing_file_mismatch(*backing_file_out, size, mtime);
if(err) goto out_close;
}
cow_sizes(version, size, sectorsize, align, *bitmap_offset_out,
bitmap_len_out, data_offset_out);
return(fd);
out_close:
os_close_file(fd);
return(err);
}
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;
fd = open_ubd_file(cow_file, &flags, NULL, NULL, NULL, NULL, NULL);
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);
}
void do_io(struct io_thread_req *req, struct request *r, unsigned long *bitmap)
{
struct ubd_aio *aio;
struct bitmap_io *bitmap_io = NULL;
char *buf;
void *bitmap_buf = NULL;
unsigned long len, sector;
int nsectors, start, end, bit, err;
__u64 off;
if(req->bitmap_start != -1){
/* Round up to the nearest word */
int round = sizeof(unsigned long);
len = (req->bitmap_end - req->bitmap_start +
round * 8 - 1) / (round * 8);
len *= round;
off = req->bitmap_start / (8 * round);
off *= round;
bitmap_io = kmalloc(sizeof(*bitmap_io), GFP_KERNEL);
if(bitmap_io == NULL){
printk("Failed to kmalloc bitmap IO\n");
req->error = 1;
return;
}
bitmap_buf = kmalloc(len, GFP_KERNEL);
if(bitmap_buf == NULL){
printk("do_io : kmalloc of bitmap chunk "
"failed\n");
kfree(bitmap_io);
req->error = 1;
return;
}
memcpy(bitmap_buf, &bitmap[off / sizeof(bitmap[0])], len);
*bitmap_io = ((struct bitmap_io)
{ .count = ATOMIC_INIT(0),
.aio = INIT_AIO(AIO_WRITE, req->fds[1],
bitmap_buf, len,
req->bitmap_offset + off,
ubd_reply_fd) } );
}
nsectors = req->length / req->sectorsize;
start = 0;
end = nsectors;
bit = 0;
do {
if(bitmap != NULL){
sector = req->offset / req->sectorsize;
bit = ubd_test_bit(sector + start, bitmap);
end = start;
while((end < nsectors) &&
(ubd_test_bit(sector + end, bitmap) == bit))
end++;
}
off = req->offsets[bit] + req->offset +
start * req->sectorsize;
len = (end - start) * req->sectorsize;
buf = &req->buffer[start * req->sectorsize];
aio = kmalloc(sizeof(*aio), GFP_KERNEL);
if(aio == NULL){
req->error = 1;
return;
}
*aio = ((struct ubd_aio)
{ .aio = INIT_AIO(req->op, req->fds[bit], buf,
len, off, ubd_reply_fd),
.len = len,
.req = r,
.bitmap = bitmap_io,
.bitmap_buf = bitmap_buf });
if(aio->bitmap != NULL)
atomic_inc(&aio->bitmap->count);
err = submit_aio(&aio->aio);
if(err){
printk("do_io - submit_aio failed, "
"err = %d\n", err);
req->error = 1;
return;
}
start = end;
} while(start < nsectors);
}
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