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linux/arch/um/drivers/ubd_kern.c
Jeff Dike f28169d200 [PATCH] uml: return hotplug errors to host 
I noticed that errors happening while hotplugging devices from the host were
never returned back to the mconsole client.  In some cases, success was
returned instead of even an information-free error.

This patch cleans that up by having the low-level configuration code pass back
an error string along with an error code.  At the top level, which knows
whether it is early boot time or responding to an mconsole request, the string
is printk'd or returned to the mconsole client.

There are also whitespace and trivial code cleanups in the surrounding code.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-11 10:51:21 -08:00

1433 lines
33 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/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"
#include "linux/platform_device.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"
enum ubd_req { UBD_READ, UBD_WRITE };
struct io_thread_req {
enum ubd_req op;
int fds[2];
unsigned long offsets[2];
unsigned long long offset;
unsigned long length;
char *buffer;
int sectorsize;
unsigned long sector_mask;
unsigned long long cow_offset;
unsigned long bitmap_words[2];
int error;
};
extern int open_ubd_file(char *file, struct openflags *openflags, int shared,
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);
static inline int ubd_test_bit(__u64 bit, unsigned char *data)
{
__u64 n;
int bits, off;
bits = sizeof(data[0]) * 8;
n = bit / bits;
off = bit % bits;
return((data[n] & (1 << off)) != 0);
}
static inline void ubd_set_bit(__u64 bit, unsigned char *data)
{
__u64 n;
int bits, off;
bits = sizeof(data[0]) * 8;
n = bit / bits;
off = bit % bits;
data[n] |= (1 << off);
}
/*End stuff from ubd_user.h*/
#define DRIVER_NAME "uml-blkdev"
/* Can be taken in interrupt context, and is passed to the block layer to lock
* the request queue. Kernel side code knows that. */
static DEFINE_SPINLOCK(ubd_io_lock);
static DEFINE_MUTEX(ubd_lock);
/* XXX - this made sense in 2.4 days, now it's only used as a boolean, and
* probably it doesn't make sense even for that. */
static int do_ubd;
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);
static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo);
#define MAX_DEV (16)
static struct block_device_operations ubd_blops = {
.owner = THIS_MODULE,
.open = ubd_open,
.release = ubd_release,
.ioctl = ubd_ioctl,
.getgeo = ubd_getgeo,
};
/* 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 {
/* backing file name */
char *file;
/* backing file fd */
int fd;
unsigned long *bitmap;
unsigned long bitmap_len;
int bitmap_offset;
int data_offset;
};
struct ubd {
/* name (and fd, below) of the file opened for writing, either the
* backing or the cow file. */
char *file;
int count;
int fd;
__u64 size;
struct openflags boot_openflags;
struct openflags openflags;
unsigned shared:1;
unsigned no_cow:1;
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, \
.shared = 0, \
.cow = DEFAULT_COW, \
}
struct ubd ubd_devs[MAX_DEV] = { [ 0 ... MAX_DEV - 1 ] = DEFAULT_UBD };
/* 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 <= 'z')) {
n = *str - 'a';
str++;
*ptr = str;
}
return(n);
}
/* If *index_out == -1 at exit, the passed option was a general one;
* otherwise, the str pointer is used (and owned) inside ubd_devs array, so it
* should not be freed on exit.
*/
static int ubd_setup_common(char *str, int *index_out, char **error_out)
{
struct ubd *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)){
*error_out = "Didn't parse major number";
return -EINVAL;
}
err = -EINVAL;
mutex_lock(&ubd_lock);
if(fake_major != MAJOR_NR){
*error_out = "Can't assign a fake major twice";
goto out1;
}
fake_major = major;
printk(KERN_INFO "Setting extra ubd major number to %d\n",
major);
err = 0;
out1:
mutex_unlock(&ubd_lock);
return err;
}
n = parse_unit(&str);
if(n < 0){
*error_out = "Couldn't parse device number";
return -EINVAL;
}
if(n >= MAX_DEV){
*error_out = "Device number out of range";
return 1;
}
err = -EBUSY;
mutex_lock(&ubd_lock);
ubd_dev = &ubd_devs[n];
if(ubd_dev->file != NULL){
*error_out = "Device is already configured";
goto out;
}
if (index_out)
*index_out = n;
err = -EINVAL;
for (i = 0; i < sizeof("rscd="); i++) {
switch (*str) {
case 'r':
flags.w = 0;
break;
case 's':
flags.s = 1;
break;
case 'd':
ubd_dev->no_cow = 1;
break;
case 'c':
ubd_dev->shared = 1;
break;
case '=':
str++;
goto break_loop;
default:
*error_out = "Expected '=' or flag letter "
"(r, s, c, or d)";
goto out;
}
str++;
}
if (*str == '=')
*error_out = "Too many flags specified";
else
*error_out = "Missing '='";
goto out;
break_loop:
backing_file = strchr(str, ',');
if (backing_file == NULL)
backing_file = strchr(str, ':');
if(backing_file != NULL){
if(ubd_dev->no_cow){
*error_out = "Can't specify both 'd' and a cow file";
goto out;
}
else {
*backing_file = '\0';
backing_file++;
}
}
err = 0;
ubd_dev->file = str;
ubd_dev->cow.file = backing_file;
ubd_dev->boot_openflags = flags;
out:
mutex_unlock(&ubd_lock);
return err;
}
static int ubd_setup(char *str)
{
char *error;
int err;
err = ubd_setup_common(str, NULL, &error);
if(err)
printk(KERN_ERR "Failed to initialize device with \"%s\" : "
"%s\n", str, error);
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 treat 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);
/* 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.
* XXX: currently unused.
*/
static int intr_count = 0;
/* call ubd_finish if you need to serialize */
static void __ubd_finish(struct request *req, int error)
{
int nsect;
if(error){
end_request(req, 0);
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;
end_request(req, 1);
}
/* Callable only from interrupt context - otherwise you need to do
* spin_lock_irq()/spin_lock_irqsave() */
static inline void ubd_finish(struct request *req, int error)
{
spin_lock(&ubd_io_lock);
__ubd_finish(req, error);
spin_unlock(&ubd_io_lock);
}
/* XXX - move this inside ubd_intr. */
/* Called without ubd_io_lock held, and only in interrupt context. */
static void ubd_handler(void)
{
struct io_thread_req req;
struct request *rq = elv_next_request(ubd_queue);
int n;
do_ubd = 0;
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;
}
ubd_finish(rq, req.error);
reactivate_fd(thread_fd, UBD_IRQ);
spin_lock(&ubd_io_lock);
do_ubd_request(ubd_queue);
spin_unlock(&ubd_io_lock);
}
static irqreturn_t ubd_intr(int irq, void *dev)
{
ubd_handler();
return(IRQ_HANDLED);
}
/* 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 inline int ubd_file_size(struct ubd *ubd_dev, __u64 *size_out)
{
char *file;
file = ubd_dev->cow.file ? ubd_dev->cow.file : ubd_dev->file;
return(os_file_size(file, size_out));
}
static void ubd_close_dev(struct ubd *ubd_dev)
{
os_close_file(ubd_dev->fd);
if(ubd_dev->cow.file == NULL)
return;
os_close_file(ubd_dev->cow.fd);
vfree(ubd_dev->cow.bitmap);
ubd_dev->cow.bitmap = NULL;
}
static int ubd_open_dev(struct ubd *ubd_dev)
{
struct openflags flags;
char **back_ptr;
int err, create_cow, *create_ptr;
int fd;
ubd_dev->openflags = ubd_dev->boot_openflags;
create_cow = 0;
create_ptr = (ubd_dev->cow.file != NULL) ? &create_cow : NULL;
back_ptr = ubd_dev->no_cow ? NULL : &ubd_dev->cow.file;
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,
create_ptr);
if((fd == -ENOENT) && create_cow){
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(fd >= 0){
printk(KERN_INFO "Creating \"%s\" as COW file for "
"\"%s\"\n", ubd_dev->file, ubd_dev->cow.file);
}
}
if(fd < 0){
printk("Failed to open '%s', errno = %d\n", ubd_dev->file,
-fd);
return fd;
}
ubd_dev->fd = fd;
if(ubd_dev->cow.file != NULL){
err = -ENOMEM;
ubd_dev->cow.bitmap = (void *) vmalloc(ubd_dev->cow.bitmap_len);
if(ubd_dev->cow.bitmap == NULL){
printk(KERN_ERR "Failed to vmalloc COW bitmap\n");
goto error;
}
flush_tlb_kernel_vm();
err = read_cow_bitmap(ubd_dev->fd, ubd_dev->cow.bitmap,
ubd_dev->cow.bitmap_offset,
ubd_dev->cow.bitmap_len);
if(err < 0)
goto error;
flags = ubd_dev->openflags;
flags.w = 0;
err = open_ubd_file(ubd_dev->cow.file, &flags, ubd_dev->shared, NULL,
NULL, NULL, NULL, NULL);
if(err < 0) goto error;
ubd_dev->cow.fd = err;
}
return(0);
error:
os_close_file(ubd_dev->fd);
return(err);
}
static int ubd_disk_register(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);
if(major == MAJOR_NR)
sprintf(disk->disk_name, "ubd%c", 'a' + unit);
else
sprintf(disk->disk_name, "ubd_fake%d", unit);
/* sysfs register (not for ide fake devices) */
if (major == MAJOR_NR) {
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;
}
disk->private_data = &ubd_devs[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, char **error_out)
{
struct ubd *ubd_dev = &ubd_devs[n];
int err = 0;
if(ubd_dev->file == NULL)
goto out;
err = ubd_file_size(ubd_dev, &ubd_dev->size);
if(err < 0){
*error_out = "Couldn't determine size of device's file";
goto out;
}
ubd_dev->size = ROUND_BLOCK(ubd_dev->size);
err = ubd_disk_register(MAJOR_NR, ubd_dev->size, n, &ubd_gendisk[n]);
if(err)
goto out;
if(fake_major != MAJOR_NR)
ubd_disk_register(fake_major, ubd_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:
return err;
}
static int ubd_config(char *str, char **error_out)
{
int n, ret;
/* This string is possibly broken up and stored, so it's only
* freed if ubd_setup_common fails, or if only general options
* were set.
*/
str = kstrdup(str, GFP_KERNEL);
if (str == NULL) {
*error_out = "Failed to allocate memory";
return -ENOMEM;
}
ret = ubd_setup_common(str, &n, error_out);
if (ret)
goto err_free;
if (n == -1) {
ret = 0;
goto err_free;
}
mutex_lock(&ubd_lock);
ret = ubd_add(n, error_out);
if (ret)
ubd_devs[n].file = NULL;
mutex_unlock(&ubd_lock);
out:
return ret;
err_free:
kfree(str);
goto out;
}
static int ubd_get_config(char *name, char *str, int size, char **error_out)
{
struct ubd *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);
}
ubd_dev = &ubd_devs[n];
mutex_lock(&ubd_lock);
if(ubd_dev->file == NULL){
CONFIG_CHUNK(str, size, len, "", 1);
goto out;
}
CONFIG_CHUNK(str, size, len, ubd_dev->file, 0);
if(ubd_dev->cow.file != NULL){
CONFIG_CHUNK(str, size, len, ",", 0);
CONFIG_CHUNK(str, size, len, ubd_dev->cow.file, 1);
}
else CONFIG_CHUNK(str, size, len, "", 1);
out:
mutex_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, char **error_out)
{
struct ubd *ubd_dev;
int err = -ENODEV;
mutex_lock(&ubd_lock);
if(ubd_gendisk[n] == NULL)
goto out;
ubd_dev = &ubd_devs[n];
if(ubd_dev->file == NULL)
goto out;
/* you cannot remove a open disk */
err = -EBUSY;
if(ubd_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(&ubd_dev->pdev);
*ubd_dev = ((struct ubd) DEFAULT_UBD);
err = 0;
out:
mutex_unlock(&ubd_lock);
return err;
}
/* All these are called by mconsole in process context and without
* ubd-specific locks.
*/
static struct mc_device ubd_mc = {
.name = "ubd",
.config = ubd_config,
.get_config = ubd_get_config,
.id = ubd_id,
.remove = ubd_remove,
};
static int __init ubd_mc_init(void)
{
mconsole_register_dev(&ubd_mc);
return 0;
}
__initcall(ubd_mc_init);
static int __init ubd0_init(void)
{
struct ubd *ubd_dev = &ubd_devs[0];
if(ubd_dev->file == NULL)
ubd_dev->file = "root_fs";
return(0);
}
__initcall(ubd0_init);
static struct platform_driver ubd_driver = {
.driver = {
.name = DRIVER_NAME,
},
};
static int __init ubd_init(void)
{
char *error;
int i, err;
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;
}
platform_driver_register(&ubd_driver);
for (i = 0; i < MAX_DEV; i++){
err = ubd_add(i, &error);
if(err)
printk(KERN_ERR "Failed to initialize ubd device %d :"
"%s\n", i, error);
}
return 0;
}
late_initcall(ubd_init);
static int __init 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);
io_pid = start_io_thread(stack + PAGE_SIZE - sizeof(void *),
&thread_fd);
if(io_pid < 0){
printk(KERN_ERR
"ubd : Failed to start I/O thread (errno = %d) - "
"falling back to synchronous I/O\n", -io_pid);
io_pid = -1;
return(0);
}
err = um_request_irq(UBD_IRQ, thread_fd, IRQ_READ, ubd_intr,
IRQF_DISABLED, "ubd", ubd_devs);
if(err != 0)
printk(KERN_ERR "um_request_irq failed - errno = %d\n", -err);
return 0;
}
device_initcall(ubd_driver_init);
static int ubd_open(struct inode *inode, struct file *filp)
{
struct gendisk *disk = inode->i_bdev->bd_disk;
struct ubd *ubd_dev = disk->private_data;
int err = 0;
if(ubd_dev->count == 0){
err = ubd_open_dev(ubd_dev);
if(err){
printk(KERN_ERR "%s: Can't open \"%s\": errno = %d\n",
disk->disk_name, ubd_dev->file, -err);
goto out;
}
}
ubd_dev->count++;
set_disk_ro(disk, !ubd_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) && !ubd_dev->openflags.w){
if(--ubd_dev->count == 0) ubd_close_dev(ubd_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 *ubd_dev = disk->private_data;
if(--ubd_dev->count == 0)
ubd_close_dev(ubd_dev);
return(0);
}
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)
{
__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;
update_bitmap = 1;
ubd_set_bit(sector + i, (unsigned char *) bitmap);
}
if(!update_bitmap)
return;
*cow_offset = sector / (sizeof(unsigned long) * 8);
/* 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))
ubd_set_bit(i, (unsigned char *)
&req->sector_mask);
}
}
else cowify_bitmap(req->offset, req->length, &req->sector_mask,
&req->cow_offset, bitmap, bitmap_offset,
req->bitmap_words, bitmap_len);
}
/* Called with ubd_io_lock held */
static int prepare_request(struct request *req, struct io_thread_req *io_req)
{
struct gendisk *disk = req->rq_disk;
struct ubd *ubd_dev = disk->private_data;
__u64 offset;
int len;
/* This should be impossible now */
if((rq_data_dir(req) == WRITE) && !ubd_dev->openflags.w){
printk("Write attempted on readonly ubd device %s\n",
disk->disk_name);
end_request(req, 0);
return(1);
}
offset = ((__u64) req->sector) << 9;
len = req->current_nr_sectors << 9;
io_req->fds[0] = (ubd_dev->cow.file != NULL) ? ubd_dev->cow.fd : ubd_dev->fd;
io_req->fds[1] = ubd_dev->fd;
io_req->cow_offset = -1;
io_req->offset = offset;
io_req->length = len;
io_req->error = 0;
io_req->sector_mask = 0;
io_req->op = (rq_data_dir(req) == READ) ? UBD_READ : UBD_WRITE;
io_req->offsets[0] = 0;
io_req->offsets[1] = ubd_dev->cow.data_offset;
io_req->buffer = req->buffer;
io_req->sectorsize = 1 << 9;
if(ubd_dev->cow.file != NULL)
cowify_req(io_req, ubd_dev->cow.bitmap, ubd_dev->cow.bitmap_offset,
ubd_dev->cow.bitmap_len);
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;
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 = 1;
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);
}
}
}
static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
{
struct ubd *ubd_dev = bdev->bd_disk->private_data;
geo->heads = 128;
geo->sectors = 32;
geo->cylinders = ubd_dev->size / (128 * 32 * 512);
return 0;
}
static int ubd_ioctl(struct inode * inode, struct file * file,
unsigned int cmd, unsigned long arg)
{
struct ubd *ubd_dev = inode->i_bdev->bd_disk->private_data;
struct hd_driveid ubd_id = {
.cyls = 0,
.heads = 128,
.sectors = 32,
};
switch (cmd) {
struct cdrom_volctrl volume;
case HDIO_GET_IDENTITY:
ubd_id.cyls = ubd_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 path_requires_switch(char *from_cmdline, char *from_cow, char *cow)
{
struct uml_stat buf1, buf2;
int err;
if(from_cmdline == NULL)
return 0;
if(!strcmp(from_cmdline, from_cow))
return 0;
err = os_stat_file(from_cmdline, &buf1);
if(err < 0){
printk("Couldn't stat '%s', err = %d\n", from_cmdline, -err);
return 0;
}
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 0;
printk("Backing file mismatch - \"%s\" requested,\n"
"\"%s\" specified in COW header of \"%s\"\n",
from_cmdline, from_cow, cow);
return 1;
}
static int backing_file_mismatch(char *file, __u64 size, time_t mtime)
{
unsigned long modtime;
unsigned 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, int shared,
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, asked_switch, 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;
}
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;
}
}
/* Successful return case! */
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);
asked_switch = path_requires_switch(*backing_file_out, backing_file, file);
/* Allow switching only if no mismatch. */
if (asked_switch && !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);
goto out_close;
}
} 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, 0, 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);
}
static int update_bitmap(struct io_thread_req *req)
{
int n;
if(req->cow_offset == -1)
return(0);
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);
}
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);
}
return(0);
}
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);
req->error = update_bitmap(req);
}
/* 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. XXX: currently unused. */
static 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);
}
return 0;
}
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