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   1 /*
   2  * Copyright (C) 2000 Jeff Dike (jdike@karaya.com)
   3  * Licensed under the GPL
   4  */
   5
   6 /* 2001-09-28...2002-04-17
   7  * Partition stuff by James_McMechan@hotmail.com
   8  * old style ubd by setting UBD_SHIFT to 0
   9  * 2002-09-27...2002-10-18 massive tinkering for 2.5
  10  * partitions have changed in 2.5
  11  * 2003-01-29 more tinkering for 2.5.59-1
  12  * This should now address the sysfs problems and has
  13  * the symlink for devfs to allow for booting with
  14  * the common /dev/ubd/discX/... names rather than
  15  * only /dev/ubdN/discN this version also has lots of
  16  * clean ups preparing for ubd-many.
  17  * James McMechan
  18  */
  19
  20 #define MAJOR_NR UBD_MAJOR
  21 #define UBD_SHIFT 4
  22
  23 #include "linux/module.h"
  24 #include "linux/blkdev.h"
  25 #include "linux/hdreg.h"
  26 #include "linux/init.h"
  27 #include "linux/cdrom.h"
  28 #include "linux/proc_fs.h"
  29 #include "linux/ctype.h"
  30 #include "linux/capability.h"
  31 #include "linux/mm.h"
  32 #include "linux/vmalloc.h"
  33 #include "linux/blkpg.h"
  34 #include "linux/genhd.h"
  35 #include "linux/spinlock.h"
  36 #include "linux/platform_device.h"
  37 #include "asm/segment.h"
  38 #include "asm/uaccess.h"
  39 #include "asm/irq.h"
  40 #include "asm/types.h"
  41 #include "asm/tlbflush.h"
  42 #include "mem_user.h"
  43 #include "kern_util.h"
  44 #include "kern.h"
  45 #include "mconsole_kern.h"
  46 #include "init.h"
  47 #include "irq_user.h"
  48 #include "irq_kern.h"
  49 #include "ubd_user.h"
  50 #include "os.h"
  51 #include "mem.h"
  52 #include "mem_kern.h"
  53 #include "cow.h"
  54
  55 enum ubd_req { UBD_READ, UBD_WRITE };
  56
  57 struct io_thread_req {
  58         struct request *req;
  59         enum ubd_req op;
  60         int fds[2];
  61         unsigned long offsets[2];
  62         unsigned long long offset;
  63         unsigned long length;
  64         char *buffer;
  65         int sectorsize;
  66         unsigned long sector_mask;
  67         unsigned long long cow_offset;
  68         unsigned long bitmap_words[2];
  69         int error;
  70 };
  71
  72 extern int open_ubd_file(char *file, struct openflags *openflags, int shared,
  73                          char **backing_file_out, int *bitmap_offset_out,
  74                          unsigned long *bitmap_len_out, int *data_offset_out,
  75                          int *create_cow_out);
  76 extern int create_cow_file(char *cow_file, char *backing_file,
  77                            struct openflags flags, int sectorsize,
  78                            int alignment, int *bitmap_offset_out,
  79                            unsigned long *bitmap_len_out,
  80                            int *data_offset_out);
  81 extern int read_cow_bitmap(int fd, void *buf, int offset, int len);
  82 extern void do_io(struct io_thread_req *req);
  83
  84 static inline int ubd_test_bit(__u64 bit, unsigned char *data)
  85 {
  86         __u64 n;
  87         int bits, off;
  88
  89         bits = sizeof(data[0]) * 8;
  90         n = bit / bits;
  91         off = bit % bits;
  92         return((data[n] & (1 << off)) != 0);
  93 }
  94
  95 static inline void ubd_set_bit(__u64 bit, unsigned char *data)
  96 {
  97         __u64 n;
  98         int bits, off;
  99
 100         bits = sizeof(data[0]) * 8;
 101         n = bit / bits;
 102         off = bit % bits;
 103         data[n] |= (1 << off);
 104 }
 105 /*End stuff from ubd_user.h*/
 106
 107 #define DRIVER_NAME "uml-blkdev"
 108
 109 static DEFINE_MUTEX(ubd_lock);
 110
 111 static int ubd_open(struct inode * inode, struct file * filp);
 112 static int ubd_release(struct inode * inode, struct file * file);
 113 static int ubd_ioctl(struct inode * inode, struct file * file,
 114                      unsigned int cmd, unsigned long arg);
 115 static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo);
 116
 117 #define MAX_DEV (16)
 118
 119 static struct block_device_operations ubd_blops = {
 120         .owner          = THIS_MODULE,
 121         .open           = ubd_open,
 122         .release        = ubd_release,
 123         .ioctl          = ubd_ioctl,
 124         .getgeo         = ubd_getgeo,
 125 };
 126
 127 /* Protected by ubd_lock */
 128 static int fake_major = MAJOR_NR;
 129 static struct gendisk *ubd_gendisk[MAX_DEV];
 130 static struct gendisk *fake_gendisk[MAX_DEV];
 131
 132 #ifdef CONFIG_BLK_DEV_UBD_SYNC
 133 #define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 1, .c = 0, \
 134                                          .cl = 1 })
 135 #else
 136 #define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 0, .c = 0, \
 137                                          .cl = 1 })
 138 #endif
 139 static struct openflags global_openflags = OPEN_FLAGS;
 140
 141 struct cow {
 142         /* backing file name */
 143         char *file;
 144         /* backing file fd */
 145         int fd;
 146         unsigned long *bitmap;
 147         unsigned long bitmap_len;
 148         int bitmap_offset;
 149         int data_offset;
 150 };
 151
 152 struct ubd {
 153         /* name (and fd, below) of the file opened for writing, either the
 154          * backing or the cow file. */
 155         char *file;
 156         int count;
 157         int fd;
 158         __u64 size;
 159         struct openflags boot_openflags;
 160         struct openflags openflags;
 161         unsigned shared:1;
 162         unsigned no_cow:1;
 163         struct cow cow;
 164         struct platform_device pdev;
 165         struct request_queue *queue;
 166         spinlock_t lock;
 167         int active;
 168 };
 169
 170 #define DEFAULT_COW { \
 171         .file =                 NULL, \
 172         .fd =                   -1, \
 173         .bitmap =               NULL, \
 174         .bitmap_offset =        0, \
 175         .data_offset =          0, \
 176 }
 177
 178 #define DEFAULT_UBD { \
 179         .file =                 NULL, \
 180         .count =                0, \
 181         .fd =                   -1, \
 182         .size =                 -1, \
 183         .boot_openflags =       OPEN_FLAGS, \
 184         .openflags =            OPEN_FLAGS, \
 185         .no_cow =               0, \
 186         .shared =               0, \
 187         .cow =                  DEFAULT_COW, \
 188         .lock =                 SPIN_LOCK_UNLOCKED,     \
 189         .active =               0, \
 190 }
 191
 192 /* Protected by ubd_lock */
 193 struct ubd ubd_devs[MAX_DEV] = { [ 0 ... MAX_DEV - 1 ] = DEFAULT_UBD };
 194
 195 /* Only changed by fake_ide_setup which is a setup */
 196 static int fake_ide = 0;
 197 static struct proc_dir_entry *proc_ide_root = NULL;
 198 static struct proc_dir_entry *proc_ide = NULL;
 199
 200 static void make_proc_ide(void)
 201 {
 202         proc_ide_root = proc_mkdir("ide", NULL);
 203         proc_ide = proc_mkdir("ide0", proc_ide_root);
 204 }
 205
 206 static int proc_ide_read_media(char *page, char **start, off_t off, int count,
 207                                int *eof, void *data)
 208 {
 209         int len;
 210
 211         strcpy(page, "disk\n");
 212         len = strlen("disk\n");
 213         len -= off;
 214         if (len < count){
 215                 *eof = 1;
 216                 if (len <= 0) return 0;
 217         }
 218         else len = count;
 219         *start = page + off;
 220         return len;
 221 }
 222
 223 static void make_ide_entries(char *dev_name)
 224 {
 225         struct proc_dir_entry *dir, *ent;
 226         char name[64];
 227
 228         if(proc_ide_root == NULL) make_proc_ide();
 229
 230         dir = proc_mkdir(dev_name, proc_ide);
 231         if(!dir) return;
 232
 233         ent = create_proc_entry("media", S_IFREG|S_IRUGO, dir);
 234         if(!ent) return;
 235         ent->data = NULL;
 236         ent->read_proc = proc_ide_read_media;
 237         ent->write_proc = NULL;
 238         sprintf(name,"ide0/%s", dev_name);
 239         proc_symlink(dev_name, proc_ide_root, name);
 240 }
 241
 242 static int fake_ide_setup(char *str)
 243 {
 244         fake_ide = 1;
 245         return(1);
 246 }
 247
 248 __setup("fake_ide", fake_ide_setup);
 249
 250 __uml_help(fake_ide_setup,
 251 "fake_ide\n"
 252 "    Create ide0 entries that map onto ubd devices.\n\n"
 253 );
 254
 255 static int parse_unit(char **ptr)
 256 {
 257         char *str = *ptr, *end;
 258         int n = -1;
 259
 260         if(isdigit(*str)) {
 261                 n = simple_strtoul(str, &end, 0);
 262                 if(end == str)
 263                         return(-1);
 264                 *ptr = end;
 265         }
 266         else if (('a' <= *str) && (*str <= 'z')) {
 267                 n = *str - 'a';
 268                 str++;
 269                 *ptr = str;
 270         }
 271         return(n);
 272 }
 273
 274 /* If *index_out == -1 at exit, the passed option was a general one;
 275  * otherwise, the str pointer is used (and owned) inside ubd_devs array, so it
 276  * should not be freed on exit.
 277  */
 278 static int ubd_setup_common(char *str, int *index_out, char **error_out)
 279 {
 280         struct ubd *ubd_dev;
 281         struct openflags flags = global_openflags;
 282         char *backing_file;
 283         int n, err = 0, i;
 284
 285         if(index_out) *index_out = -1;
 286         n = *str;
 287         if(n == '='){
 288                 char *end;
 289                 int major;
 290
 291                 str++;
 292                 if(!strcmp(str, "sync")){
 293                         global_openflags = of_sync(global_openflags);
 294                         goto out1;
 295                 }
 296
 297                 err = -EINVAL;
 298                 major = simple_strtoul(str, &end, 0);
 299                 if((*end != '\0') || (end == str)){
 300                         *error_out = "Didn't parse major number";
 301                         goto out1;
 302                 }
 303
 304                 mutex_lock(&ubd_lock);
 305                 if(fake_major != MAJOR_NR){
 306                         *error_out = "Can't assign a fake major twice";
 307                         goto out1;
 308                 }
 309
 310                 fake_major = major;
 311
 312                 printk(KERN_INFO "Setting extra ubd major number to %d\n",
 313                        major);
 314                 err = 0;
 315         out1:
 316                 mutex_unlock(&ubd_lock);
 317                 return err;
 318         }
 319
 320         n = parse_unit(&str);
 321         if(n < 0){
 322                 *error_out = "Couldn't parse device number";
 323                 return -EINVAL;
 324         }
 325         if(n >= MAX_DEV){
 326                 *error_out = "Device number out of range";
 327                 return 1;
 328         }
 329
 330         err = -EBUSY;
 331         mutex_lock(&ubd_lock);
 332
 333         ubd_dev = &ubd_devs[n];
 334         if(ubd_dev->file != NULL){
 335                 *error_out = "Device is already configured";
 336                 goto out;
 337         }
 338
 339         if (index_out)
 340                 *index_out = n;
 341
 342         err = -EINVAL;
 343         for (i = 0; i < sizeof("rscd="); i++) {
 344                 switch (*str) {
 345                 case 'r':
 346                         flags.w = 0;
 347                         break;
 348                 case 's':
 349                         flags.s = 1;
 350                         break;
 351                 case 'd':
 352                         ubd_dev->no_cow = 1;
 353                         break;
 354                 case 'c':
 355                         ubd_dev->shared = 1;
 356                         break;
 357                 case '=':
 358                         str++;
 359                         goto break_loop;
 360                 default:
 361                         *error_out = "Expected '=' or flag letter "
 362                                 "(r, s, c, or d)";
 363                         goto out;
 364                 }
 365                 str++;
 366         }
 367
 368         if (*str == '=')
 369                 *error_out = "Too many flags specified";
 370         else
 371                 *error_out = "Missing '='";
 372         goto out;
 373
 374 break_loop:
 375         backing_file = strchr(str, ',');
 376
 377         if (backing_file == NULL)
 378                 backing_file = strchr(str, ':');
 379
 380         if(backing_file != NULL){
 381                 if(ubd_dev->no_cow){
 382                         *error_out = "Can't specify both 'd' and a cow file";
 383                         goto out;
 384                 }
 385                 else {
 386                         *backing_file = '\0';
 387                         backing_file++;
 388                 }
 389         }
 390         err = 0;
 391         ubd_dev->file = str;
 392         ubd_dev->cow.file = backing_file;
 393         ubd_dev->boot_openflags = flags;
 394 out:
 395         mutex_unlock(&ubd_lock);
 396         return err;
 397 }
 398
 399 static int ubd_setup(char *str)
 400 {
 401         char *error;
 402         int err;
 403
 404         err = ubd_setup_common(str, NULL, &error);
 405         if(err)
 406                 printk(KERN_ERR "Failed to initialize device with \"%s\" : "
 407                        "%s\n", str, error);
 408         return 1;
 409 }
 410
 411 __setup("ubd", ubd_setup);
 412 __uml_help(ubd_setup,
 413 "ubd<n><flags>=<filename>[(:|,)<filename2>]\n"
 414 "    This is used to associate a device with a file in the underlying\n"
 415 "    filesystem. When specifying two filenames, the first one is the\n"
 416 "    COW name and the second is the backing file name. As separator you can\n"
 417 "    use either a ':' or a ',': the first one allows writing things like;\n"
 418 "       ubd0=~/Uml/root_cow:~/Uml/root_backing_file\n"
 419 "    while with a ',' the shell would not expand the 2nd '~'.\n"
 420 "    When using only one filename, UML will detect whether to treat it like\n"
 421 "    a COW file or a backing file. To override this detection, add the 'd'\n"
 422 "    flag:\n"
 423 "       ubd0d=BackingFile\n"
 424 "    Usually, there is a filesystem in the file, but \n"
 425 "    that's not required. Swap devices containing swap files can be\n"
 426 "    specified like this. Also, a file which doesn't contain a\n"
 427 "    filesystem can have its contents read in the virtual \n"
 428 "    machine by running 'dd' on the device. <n> must be in the range\n"
 429 "    0 to 7. Appending an 'r' to the number will cause that device\n"
 430 "    to be mounted read-only. For example ubd1r=./ext_fs. Appending\n"
 431 "    an 's' will cause data to be written to disk on the host immediately.\n\n"
 432 );
 433
 434 static int udb_setup(char *str)
 435 {
 436         printk("udb%s specified on command line is almost certainly a ubd -> "
 437                "udb TYPO\n", str);
 438         return(1);
 439 }
 440
 441 __setup("udb", udb_setup);
 442 __uml_help(udb_setup,
 443 "udb\n"
 444 "    This option is here solely to catch ubd -> udb typos, which can be\n"
 445 "    to impossible to catch visually unless you specifically look for\n"
 446 "    them.  The only result of any option starting with 'udb' is an error\n"
 447 "    in the boot output.\n\n"
 448 );
 449
 450 static int fakehd_set = 0;
 451 static int fakehd(char *str)
 452 {
 453         printk(KERN_INFO "fakehd : Changing ubd name to \"hd\".\n");
 454         fakehd_set = 1;
 455         return 1;
 456 }
 457
 458 __setup("fakehd", fakehd);
 459 __uml_help(fakehd,
 460 "fakehd\n"
 461 "    Change the ubd device name to \"hd\".\n\n"
 462 );
 463
 464 static void do_ubd_request(request_queue_t * q);
 465
 466 /* Only changed by ubd_init, which is an initcall. */
 467 int thread_fd = -1;
 468
 469 /* call ubd_finish if you need to serialize */
 470 static void __ubd_finish(struct request *req, int error)
 471 {
 472         int nsect;
 473
 474         if(error){
 475                 end_request(req, 0);
 476                 return;
 477         }
 478         nsect = req->current_nr_sectors;
 479         req->sector += nsect;
 480         req->buffer += nsect << 9;
 481         req->errors = 0;
 482         req->nr_sectors -= nsect;
 483         req->current_nr_sectors = 0;
 484         end_request(req, 1);
 485 }
 486
 487 /* Callable only from interrupt context - otherwise you need to do
 488  * spin_lock_irq()/spin_lock_irqsave() */
 489 static inline void ubd_finish(struct request *req, int error)
 490 {
 491         struct ubd *dev = req->rq_disk->private_data;
 492
 493         spin_lock(&dev->lock);
 494         __ubd_finish(req, error);
 495         spin_unlock(&dev->lock);
 496 }
 497
 498 /* XXX - move this inside ubd_intr. */
 499 /* Called without dev->lock held, and only in interrupt context. */
 500 static void ubd_handler(void)
 501 {
 502         struct io_thread_req req;
 503         struct request *rq;
 504         struct ubd *dev;
 505         int n;
 506
 507         n = os_read_file(thread_fd, &req, sizeof(req));
 508         if(n != sizeof(req)){
 509                 printk(KERN_ERR "Pid %d - spurious interrupt in ubd_handler, "
 510                        "err = %d\n", os_getpid(), -n);
 511                 return;
 512         }
 513
 514         rq = req.req;
 515         dev = rq->rq_disk->private_data;
 516         dev->active = 0;
 517
 518         ubd_finish(rq, req.error);
 519         reactivate_fd(thread_fd, UBD_IRQ);
 520         spin_lock(&dev->lock);
 521         do_ubd_request(dev->queue);
 522         spin_unlock(&dev->lock);
 523 }
 524
 525 static irqreturn_t ubd_intr(int irq, void *dev)
 526 {
 527         ubd_handler();
 528         return(IRQ_HANDLED);
 529 }
 530
 531 /* Only changed by ubd_init, which is an initcall. */
 532 static int io_pid = -1;
 533
 534 void kill_io_thread(void)
 535 {
 536         if(io_pid != -1)
 537                 os_kill_process(io_pid, 1);
 538 }
 539
 540 __uml_exitcall(kill_io_thread);
 541
 542 static inline int ubd_file_size(struct ubd *ubd_dev, __u64 *size_out)
 543 {
 544         char *file;
 545
 546         file = ubd_dev->cow.file ? ubd_dev->cow.file : ubd_dev->file;
 547         return(os_file_size(file, size_out));
 548 }
 549
 550 static void ubd_close_dev(struct ubd *ubd_dev)
 551 {
 552         os_close_file(ubd_dev->fd);
 553         if(ubd_dev->cow.file == NULL)
 554                 return;
 555
 556         os_close_file(ubd_dev->cow.fd);
 557         vfree(ubd_dev->cow.bitmap);
 558         ubd_dev->cow.bitmap = NULL;
 559 }
 560
 561 static int ubd_open_dev(struct ubd *ubd_dev)
 562 {
 563         struct openflags flags;
 564         char **back_ptr;
 565         int err, create_cow, *create_ptr;
 566         int fd;
 567
 568         ubd_dev->openflags = ubd_dev->boot_openflags;
 569         create_cow = 0;
 570         create_ptr = (ubd_dev->cow.file != NULL) ? &create_cow : NULL;
 571         back_ptr = ubd_dev->no_cow ? NULL : &ubd_dev->cow.file;
 572
 573         fd = open_ubd_file(ubd_dev->file, &ubd_dev->openflags, ubd_dev->shared,
 574                                 back_ptr, &ubd_dev->cow.bitmap_offset,
 575                                 &ubd_dev->cow.bitmap_len, &ubd_dev->cow.data_offset,
 576                                 create_ptr);
 577
 578         if((fd == -ENOENT) && create_cow){
 579                 fd = create_cow_file(ubd_dev->file, ubd_dev->cow.file,
 580                                           ubd_dev->openflags, 1 << 9, PAGE_SIZE,
 581                                           &ubd_dev->cow.bitmap_offset,
 582                                           &ubd_dev->cow.bitmap_len,
 583                                           &ubd_dev->cow.data_offset);
 584                 if(fd >= 0){
 585                         printk(KERN_INFO "Creating \"%s\" as COW file for "
 586                                "\"%s\"\n", ubd_dev->file, ubd_dev->cow.file);
 587                 }
 588         }
 589
 590         if(fd < 0){
 591                 printk("Failed to open '%s', errno = %d\n", ubd_dev->file,
 592                        -fd);
 593                 return fd;
 594         }
 595         ubd_dev->fd = fd;
 596
 597         if(ubd_dev->cow.file != NULL){
 598                 err = -ENOMEM;
 599                 ubd_dev->cow.bitmap = (void *) vmalloc(ubd_dev->cow.bitmap_len);
 600                 if(ubd_dev->cow.bitmap == NULL){
 601                         printk(KERN_ERR "Failed to vmalloc COW bitmap\n");
 602                         goto error;
 603                 }
 604                 flush_tlb_kernel_vm();
 605
 606                 err = read_cow_bitmap(ubd_dev->fd, ubd_dev->cow.bitmap,
 607                                       ubd_dev->cow.bitmap_offset,
 608                                       ubd_dev->cow.bitmap_len);
 609                 if(err < 0)
 610                         goto error;
 611
 612                 flags = ubd_dev->openflags;
 613                 flags.w = 0;
 614                 err = open_ubd_file(ubd_dev->cow.file, &flags, ubd_dev->shared, NULL,
 615                                     NULL, NULL, NULL, NULL);
 616                 if(err < 0) goto error;
 617                 ubd_dev->cow.fd = err;
 618         }
 619         return(0);
 620  error:
 621         os_close_file(ubd_dev->fd);
 622         return(err);
 623 }
 624
 625 static void ubd_device_release(struct device *dev)
 626 {
 627         struct ubd *ubd_dev = dev->driver_data;
 628
 629         blk_cleanup_queue(ubd_dev->queue);
 630         *ubd_dev = ((struct ubd) DEFAULT_UBD);
 631 }
 632
 633 static int ubd_disk_register(int major, u64 size, int unit,
 634                              struct gendisk **disk_out)
 635 {
 636         struct gendisk *disk;
 637
 638         disk = alloc_disk(1 << UBD_SHIFT);
 639         if(disk == NULL)
 640                 return(-ENOMEM);
 641
 642         disk->major = major;
 643         disk->first_minor = unit << UBD_SHIFT;
 644         disk->fops = &ubd_blops;
 645         set_capacity(disk, size / 512);
 646         if(major == MAJOR_NR)
 647                 sprintf(disk->disk_name, "ubd%c", 'a' + unit);
 648         else
 649                 sprintf(disk->disk_name, "ubd_fake%d", unit);
 650
 651         /* sysfs register (not for ide fake devices) */
 652         if (major == MAJOR_NR) {
 653                 ubd_devs[unit].pdev.id   = unit;
 654                 ubd_devs[unit].pdev.name = DRIVER_NAME;
 655                 ubd_devs[unit].pdev.dev.release = ubd_device_release;
 656                 ubd_devs[unit].pdev.dev.driver_data = &ubd_devs[unit];
 657                 platform_device_register(&ubd_devs[unit].pdev);
 658                 disk->driverfs_dev = &ubd_devs[unit].pdev.dev;
 659         }
 660
 661         disk->private_data = &ubd_devs[unit];
 662         disk->queue = ubd_devs[unit].queue;
 663         add_disk(disk);
 664
 665         *disk_out = disk;
 666         return 0;
 667 }
 668
 669 #define ROUND_BLOCK(n) ((n + ((1 << 9) - 1)) & (-1 << 9))
 670
 671 static int ubd_add(int n, char **error_out)
 672 {
 673         struct ubd *ubd_dev = &ubd_devs[n];
 674         int err = 0;
 675
 676         if(ubd_dev->file == NULL)
 677                 goto out;
 678
 679         err = ubd_file_size(ubd_dev, &ubd_dev->size);
 680         if(err < 0){
 681                 *error_out = "Couldn't determine size of device's file";
 682                 goto out;
 683         }
 684
 685         ubd_dev->size = ROUND_BLOCK(ubd_dev->size);
 686
 687         err = -ENOMEM;
 688         ubd_dev->queue = blk_init_queue(do_ubd_request, &ubd_dev->lock);
 689         if (ubd_dev->queue == NULL) {
 690                 *error_out = "Failed to initialize device queue";
 691                 goto out;
 692         }
 693         ubd_dev->queue->queuedata = ubd_dev;
 694
 695         err = ubd_disk_register(MAJOR_NR, ubd_dev->size, n, &ubd_gendisk[n]);
 696         if(err){
 697                 *error_out = "Failed to register device";
 698                 goto out_cleanup;
 699         }
 700
 701         if(fake_major != MAJOR_NR)
 702                 ubd_disk_register(fake_major, ubd_dev->size, n,
 703                                   &fake_gendisk[n]);
 704
 705         /* perhaps this should also be under the "if (fake_major)" above */
 706         /* using the fake_disk->disk_name and also the fakehd_set name */
 707         if (fake_ide)
 708                 make_ide_entries(ubd_gendisk[n]->disk_name);
 709
 710         err = 0;
 711 out:
 712         return err;
 713
 714 out_cleanup:
 715         blk_cleanup_queue(ubd_dev->queue);
 716         goto out;
 717 }
 718
 719 static int ubd_config(char *str, char **error_out)
 720 {
 721         int n, ret;
 722
 723         /* This string is possibly broken up and stored, so it's only
 724          * freed if ubd_setup_common fails, or if only general options
 725          * were set.
 726          */
 727         str = kstrdup(str, GFP_KERNEL);
 728         if (str == NULL) {
 729                 *error_out = "Failed to allocate memory";
 730                 return -ENOMEM;
 731         }
 732
 733         ret = ubd_setup_common(str, &n, error_out);
 734         if (ret)
 735                 goto err_free;
 736
 737         if (n == -1) {
 738                 ret = 0;
 739                 goto err_free;
 740         }
 741
 742         mutex_lock(&ubd_lock);
 743         ret = ubd_add(n, error_out);
 744         if (ret)
 745                 ubd_devs[n].file = NULL;
 746         mutex_unlock(&ubd_lock);
 747
 748 out:
 749         return ret;
 750
 751 err_free:
 752         kfree(str);
 753         goto out;
 754 }
 755
 756 static int ubd_get_config(char *name, char *str, int size, char **error_out)
 757 {
 758         struct ubd *ubd_dev;
 759         int n, len = 0;
 760
 761         n = parse_unit(&name);
 762         if((n >= MAX_DEV) || (n < 0)){
 763                 *error_out = "ubd_get_config : device number out of range";
 764                 return(-1);
 765         }
 766
 767         ubd_dev = &ubd_devs[n];
 768         mutex_lock(&ubd_lock);
 769
 770         if(ubd_dev->file == NULL){
 771                 CONFIG_CHUNK(str, size, len, "", 1);
 772                 goto out;
 773         }
 774
 775         CONFIG_CHUNK(str, size, len, ubd_dev->file, 0);
 776
 777         if(ubd_dev->cow.file != NULL){
 778                 CONFIG_CHUNK(str, size, len, ",", 0);
 779                 CONFIG_CHUNK(str, size, len, ubd_dev->cow.file, 1);
 780         }
 781         else CONFIG_CHUNK(str, size, len, "", 1);
 782
 783  out:
 784         mutex_unlock(&ubd_lock);
 785         return(len);
 786 }
 787
 788 static int ubd_id(char **str, int *start_out, int *end_out)
 789 {
 790         int n;
 791
 792         n = parse_unit(str);
 793         *start_out = 0;
 794         *end_out = MAX_DEV - 1;
 795         return n;
 796 }
 797
 798 static int ubd_remove(int n, char **error_out)
 799 {
 800         struct gendisk *disk = ubd_gendisk[n];
 801         struct ubd *ubd_dev;
 802         int err = -ENODEV;
 803
 804         mutex_lock(&ubd_lock);
 805
 806         ubd_dev = &ubd_devs[n];
 807
 808         if(ubd_dev->file == NULL)
 809                 goto out;
 810
 811         /* you cannot remove a open disk */
 812         err = -EBUSY;
 813         if(ubd_dev->count > 0)
 814                 goto out;
 815
 816         ubd_gendisk[n] = NULL;
 817         if(disk != NULL){
 818                 del_gendisk(disk);
 819                 put_disk(disk);
 820         }
 821
 822         if(fake_gendisk[n] != NULL){
 823                 del_gendisk(fake_gendisk[n]);
 824                 put_disk(fake_gendisk[n]);
 825                 fake_gendisk[n] = NULL;
 826         }
 827
 828         err = 0;
 829         platform_device_unregister(&ubd_dev->pdev);
 830 out:
 831         mutex_unlock(&ubd_lock);
 832         return err;
 833 }
 834
 835 /* All these are called by mconsole in process context and without
 836  * ubd-specific locks.  The structure itself is const except for .list.
 837  */
 838 static struct mc_device ubd_mc = {
 839         .list           = LIST_HEAD_INIT(ubd_mc.list),
 840         .name           = "ubd",
 841         .config         = ubd_config,
 842         .get_config     = ubd_get_config,
 843         .id             = ubd_id,
 844         .remove         = ubd_remove,
 845 };
 846
 847 static int __init ubd_mc_init(void)
 848 {
 849         mconsole_register_dev(&ubd_mc);
 850         return 0;
 851 }
 852
 853 __initcall(ubd_mc_init);
 854
 855 static int __init ubd0_init(void)
 856 {
 857         struct ubd *ubd_dev = &ubd_devs[0];
 858
 859         mutex_lock(&ubd_lock);
 860         if(ubd_dev->file == NULL)
 861                 ubd_dev->file = "root_fs";
 862         mutex_unlock(&ubd_lock);
 863
 864         return(0);
 865 }
 866
 867 __initcall(ubd0_init);
 868
 869 /* Used in ubd_init, which is an initcall */
 870 static struct platform_driver ubd_driver = {
 871         .driver = {
 872                 .name  = DRIVER_NAME,
 873         },
 874 };
 875
 876 static int __init ubd_init(void)
 877 {
 878         char *error;
 879         int i, err;
 880
 881         if (register_blkdev(MAJOR_NR, "ubd"))
 882                 return -1;
 883
 884         if (fake_major != MAJOR_NR) {
 885                 char name[sizeof("ubd_nnn\0")];
 886
 887                 snprintf(name, sizeof(name), "ubd_%d", fake_major);
 888                 if (register_blkdev(fake_major, "ubd"))
 889                         return -1;
 890         }
 891         platform_driver_register(&ubd_driver);
 892         mutex_lock(&ubd_lock);
 893         for (i = 0; i < MAX_DEV; i++){
 894                 err = ubd_add(i, &error);
 895                 if(err)
 896                         printk(KERN_ERR "Failed to initialize ubd device %d :"
 897                                "%s\n", i, error);
 898         }
 899         mutex_unlock(&ubd_lock);
 900         return 0;
 901 }
 902
 903 late_initcall(ubd_init);
 904
 905 static int __init ubd_driver_init(void){
 906         unsigned long stack;
 907         int err;
 908
 909         /* Set by CONFIG_BLK_DEV_UBD_SYNC or ubd=sync.*/
 910         if(global_openflags.s){
 911                 printk(KERN_INFO "ubd: Synchronous mode\n");
 912                 /* Letting ubd=sync be like using ubd#s= instead of ubd#= is
 913                  * enough. So use anyway the io thread. */
 914         }
 915         stack = alloc_stack(0, 0);
 916         io_pid = start_io_thread(stack + PAGE_SIZE - sizeof(void *),
 917                                  &thread_fd);
 918         if(io_pid < 0){
 919                 printk(KERN_ERR
 920                        "ubd : Failed to start I/O thread (errno = %d) - "
 921                        "falling back to synchronous I/O\n", -io_pid);
 922                 io_pid = -1;
 923                 return(0);
 924         }
 925         err = um_request_irq(UBD_IRQ, thread_fd, IRQ_READ, ubd_intr,
 926                              IRQF_DISABLED, "ubd", ubd_devs);
 927         if(err != 0)
 928                 printk(KERN_ERR "um_request_irq failed - errno = %d\n", -err);
 929         return 0;
 930 }
 931
 932 device_initcall(ubd_driver_init);
 933
 934 static int ubd_open(struct inode *inode, struct file *filp)
 935 {
 936         struct gendisk *disk = inode->i_bdev->bd_disk;
 937         struct ubd *ubd_dev = disk->private_data;
 938         int err = 0;
 939
 940         if(ubd_dev->count == 0){
 941                 err = ubd_open_dev(ubd_dev);
 942                 if(err){
 943                         printk(KERN_ERR "%s: Can't open \"%s\": errno = %d\n",
 944                                disk->disk_name, ubd_dev->file, -err);
 945                         goto out;
 946                 }
 947         }
 948         ubd_dev->count++;
 949         set_disk_ro(disk, !ubd_dev->openflags.w);
 950
 951         /* This should no more be needed. And it didn't work anyway to exclude
 952          * read-write remounting of filesystems.*/
 953         /*if((filp->f_mode & FMODE_WRITE) && !ubd_dev->openflags.w){
 954                 if(--ubd_dev->count == 0) ubd_close_dev(ubd_dev);
 955                 err = -EROFS;
 956         }*/
 957  out:
 958         return(err);
 959 }
 960
 961 static int ubd_release(struct inode * inode, struct file * file)
 962 {
 963         struct gendisk *disk = inode->i_bdev->bd_disk;
 964         struct ubd *ubd_dev = disk->private_data;
 965
 966         if(--ubd_dev->count == 0)
 967                 ubd_close_dev(ubd_dev);
 968         return(0);
 969 }
 970
 971 static void cowify_bitmap(__u64 io_offset, int length, unsigned long *cow_mask,
 972                           __u64 *cow_offset, unsigned long *bitmap,
 973                           __u64 bitmap_offset, unsigned long *bitmap_words,
 974                           __u64 bitmap_len)
 975 {
 976         __u64 sector = io_offset >> 9;
 977         int i, update_bitmap = 0;
 978
 979         for(i = 0; i < length >> 9; i++){
 980                 if(cow_mask != NULL)
 981                         ubd_set_bit(i, (unsigned char *) cow_mask);
 982                 if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
 983                         continue;
 984
 985                 update_bitmap = 1;
 986                 ubd_set_bit(sector + i, (unsigned char *) bitmap);
 987         }
 988
 989         if(!update_bitmap)
 990                 return;
 991
 992         *cow_offset = sector / (sizeof(unsigned long) * 8);
 993
 994         /* This takes care of the case where we're exactly at the end of the
 995          * device, and *cow_offset + 1 is off the end.  So, just back it up
 996          * by one word.  Thanks to Lynn Kerby for the fix and James McMechan
 997          * for the original diagnosis.
 998          */
 999         if(*cow_offset == ((bitmap_len + sizeof(unsigned long) - 1) /
1000                            sizeof(unsigned long) - 1))
1001                 (*cow_offset)--;
1002
1003         bitmap_words[0] = bitmap[*cow_offset];
1004         bitmap_words[1] = bitmap[*cow_offset + 1];
1005
1006         *cow_offset *= sizeof(unsigned long);
1007         *cow_offset += bitmap_offset;
1008 }
1009
1010 static void cowify_req(struct io_thread_req *req, unsigned long *bitmap,
1011                        __u64 bitmap_offset, __u64 bitmap_len)
1012 {
1013         __u64 sector = req->offset >> 9;
1014         int i;
1015
1016         if(req->length > (sizeof(req->sector_mask) * 8) << 9)
1017                 panic("Operation too long");
1018
1019         if(req->op == UBD_READ) {
1020                 for(i = 0; i < req->length >> 9; i++){
1021                         if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
1022                                 ubd_set_bit(i, (unsigned char *)
1023                                             &req->sector_mask);
1024                 }
1025         }
1026         else cowify_bitmap(req->offset, req->length, &req->sector_mask,
1027                            &req->cow_offset, bitmap, bitmap_offset,
1028                            req->bitmap_words, bitmap_len);
1029 }
1030
1031 /* Called with dev->lock held */
1032 static int prepare_request(struct request *req, struct io_thread_req *io_req)
1033 {
1034         struct gendisk *disk = req->rq_disk;
1035         struct ubd *ubd_dev = disk->private_data;
1036         __u64 offset;
1037         int len;
1038
1039         /* This should be impossible now */
1040         if((rq_data_dir(req) == WRITE) && !ubd_dev->openflags.w){
1041                 printk("Write attempted on readonly ubd device %s\n",
1042                        disk->disk_name);
1043                 end_request(req, 0);
1044                 return(1);
1045         }
1046
1047         offset = ((__u64) req->sector) << 9;
1048         len = req->current_nr_sectors << 9;
1049
1050         io_req->req = req;
1051         io_req->fds[0] = (ubd_dev->cow.file != NULL) ? ubd_dev->cow.fd : ubd_dev->fd;
1052         io_req->fds[1] = ubd_dev->fd;
1053         io_req->cow_offset = -1;
1054         io_req->offset = offset;
1055         io_req->length = len;
1056         io_req->error = 0;
1057         io_req->sector_mask = 0;
1058
1059         io_req->op = (rq_data_dir(req) == READ) ? UBD_READ : UBD_WRITE;
1060         io_req->offsets[0] = 0;
1061         io_req->offsets[1] = ubd_dev->cow.data_offset;
1062         io_req->buffer = req->buffer;
1063         io_req->sectorsize = 1 << 9;
1064
1065         if(ubd_dev->cow.file != NULL)
1066                 cowify_req(io_req, ubd_dev->cow.bitmap, ubd_dev->cow.bitmap_offset,
1067                            ubd_dev->cow.bitmap_len);
1068
1069         return(0);
1070 }
1071
1072 /* Called with dev->lock held */
1073 static void do_ubd_request(request_queue_t *q)
1074 {
1075         struct io_thread_req io_req;
1076         struct request *req;
1077         int err, n;
1078
1079         if(thread_fd == -1){
1080                 while((req = elv_next_request(q)) != NULL){
1081                         err = prepare_request(req, &io_req);
1082                         if(!err){
1083                                 do_io(&io_req);
1084                                 __ubd_finish(req, io_req.error);
1085                         }
1086                 }
1087         }
1088         else {
1089                 struct ubd *dev = q->queuedata;
1090                 if(dev->active || (req = elv_next_request(q)) == NULL)
1091                         return;
1092                 err = prepare_request(req, &io_req);
1093                 if(!err){
1094                         dev->active = 1;
1095                         n = os_write_file(thread_fd, (char *) &io_req,
1096                                          sizeof(io_req));
1097                         if(n != sizeof(io_req))
1098                                 printk("write to io thread failed, "
1099                                        "errno = %d\n", -n);
1100                 }
1101         }
1102 }
1103
1104 static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
1105 {
1106         struct ubd *ubd_dev = bdev->bd_disk->private_data;
1107
1108         geo->heads = 128;
1109         geo->sectors = 32;
1110         geo->cylinders = ubd_dev->size / (128 * 32 * 512);
1111         return 0;
1112 }
1113
1114 static int ubd_ioctl(struct inode * inode, struct file * file,
1115                      unsigned int cmd, unsigned long arg)
1116 {
1117         struct ubd *ubd_dev = inode->i_bdev->bd_disk->private_data;
1118         struct hd_driveid ubd_id = {
1119                 .cyls           = 0,
1120                 .heads          = 128,
1121                 .sectors        = 32,
1122         };
1123
1124         switch (cmd) {
1125                 struct cdrom_volctrl volume;
1126         case HDIO_GET_IDENTITY:
1127                 ubd_id.cyls = ubd_dev->size / (128 * 32 * 512);
1128                 if(copy_to_user((char __user *) arg, (char *) &ubd_id,
1129                                  sizeof(ubd_id)))
1130                         return(-EFAULT);
1131                 return(0);
1132
1133         case CDROMVOLREAD:
1134                 if(copy_from_user(&volume, (char __user *) arg, sizeof(volume)))
1135                         return(-EFAULT);
1136                 volume.channel0 = 255;
1137                 volume.channel1 = 255;
1138                 volume.channel2 = 255;
1139                 volume.channel3 = 255;
1140                 if(copy_to_user((char __user *) arg, &volume, sizeof(volume)))
1141                         return(-EFAULT);
1142                 return(0);
1143         }
1144         return(-EINVAL);
1145 }
1146
1147 static int path_requires_switch(char *from_cmdline, char *from_cow, char *cow)
1148 {
1149         struct uml_stat buf1, buf2;
1150         int err;
1151
1152         if(from_cmdline == NULL)
1153                 return 0;
1154         if(!strcmp(from_cmdline, from_cow))
1155                 return 0;
1156
1157         err = os_stat_file(from_cmdline, &buf1);
1158         if(err < 0){
1159                 printk("Couldn't stat '%s', err = %d\n", from_cmdline, -err);
1160                 return 0;
1161         }
1162         err = os_stat_file(from_cow, &buf2);
1163         if(err < 0){
1164                 printk("Couldn't stat '%s', err = %d\n", from_cow, -err);
1165                 return 1;
1166         }
1167         if((buf1.ust_dev == buf2.ust_dev) && (buf1.ust_ino == buf2.ust_ino))
1168                 return 0;
1169
1170         printk("Backing file mismatch - \"%s\" requested,\n"
1171                "\"%s\" specified in COW header of \"%s\"\n",
1172                from_cmdline, from_cow, cow);
1173         return 1;
1174 }
1175
1176 static int backing_file_mismatch(char *file, __u64 size, time_t mtime)
1177 {
1178         unsigned long modtime;
1179         unsigned long long actual;
1180         int err;
1181
1182         err = os_file_modtime(file, &modtime);
1183         if(err < 0){
1184                 printk("Failed to get modification time of backing file "
1185                        "\"%s\", err = %d\n", file, -err);
1186                 return(err);
1187         }
1188
1189         err = os_file_size(file, &actual);
1190         if(err < 0){
1191                 printk("Failed to get size of backing file \"%s\", "
1192                        "err = %d\n", file, -err);
1193                 return(err);
1194         }
1195
1196         if(actual != size){
1197                 /*__u64 can be a long on AMD64 and with %lu GCC complains; so
1198                  * the typecast.*/
1199                 printk("Size mismatch (%llu vs %llu) of COW header vs backing "
1200                        "file\n", (unsigned long long) size, actual);
1201                 return(-EINVAL);
1202         }
1203         if(modtime != mtime){
1204                 printk("mtime mismatch (%ld vs %ld) of COW header vs backing "
1205                        "file\n", mtime, modtime);
1206                 return(-EINVAL);
1207         }
1208         return(0);
1209 }
1210
1211 int read_cow_bitmap(int fd, void *buf, int offset, int len)
1212 {
1213         int err;
1214
1215         err = os_seek_file(fd, offset);
1216         if(err < 0)
1217                 return(err);
1218
1219         err = os_read_file(fd, buf, len);
1220         if(err < 0)
1221                 return(err);
1222
1223         return(0);
1224 }
1225
1226 int open_ubd_file(char *file, struct openflags *openflags, int shared,
1227                   char **backing_file_out, int *bitmap_offset_out,
1228                   unsigned long *bitmap_len_out, int *data_offset_out,
1229                   int *create_cow_out)
1230 {
1231         time_t mtime;
1232         unsigned long long size;
1233         __u32 version, align;
1234         char *backing_file;
1235         int fd, err, sectorsize, asked_switch, mode = 0644;
1236
1237         fd = os_open_file(file, *openflags, mode);
1238         if (fd < 0) {
1239                 if ((fd == -ENOENT) && (create_cow_out != NULL))
1240                         *create_cow_out = 1;
1241                 if (!openflags->w ||
1242                    ((fd != -EROFS) && (fd != -EACCES)))
1243                         return fd;
1244                 openflags->w = 0;
1245                 fd = os_open_file(file, *openflags, mode);
1246                 if (fd < 0)
1247                         return fd;
1248         }
1249
1250         if(shared)
1251                 printk("Not locking \"%s\" on the host\n", file);
1252         else {
1253                 err = os_lock_file(fd, openflags->w);
1254                 if(err < 0){
1255                         printk("Failed to lock '%s', err = %d\n", file, -err);
1256                         goto out_close;
1257                 }
1258         }
1259
1260         /* Successful return case! */
1261         if(backing_file_out == NULL)
1262                 return(fd);
1263
1264         err = read_cow_header(file_reader, &fd, &version, &backing_file, &mtime,
1265                               &size, &sectorsize, &align, bitmap_offset_out);
1266         if(err && (*backing_file_out != NULL)){
1267                 printk("Failed to read COW header from COW file \"%s\", "
1268                        "errno = %d\n", file, -err);
1269                 goto out_close;
1270         }
1271         if(err)
1272                 return(fd);
1273
1274         asked_switch = path_requires_switch(*backing_file_out, backing_file, file);
1275
1276         /* Allow switching only if no mismatch. */
1277         if (asked_switch && !backing_file_mismatch(*backing_file_out, size, mtime)) {
1278                 printk("Switching backing file to '%s'\n", *backing_file_out);
1279                 err = write_cow_header(file, fd, *backing_file_out,
1280                                        sectorsize, align, &size);
1281                 if (err) {
1282                         printk("Switch failed, errno = %d\n", -err);
1283                         goto out_close;
1284                 }
1285         } else {
1286                 *backing_file_out = backing_file;
1287                 err = backing_file_mismatch(*backing_file_out, size, mtime);
1288                 if (err)
1289                         goto out_close;
1290         }
1291
1292         cow_sizes(version, size, sectorsize, align, *bitmap_offset_out,
1293                   bitmap_len_out, data_offset_out);
1294
1295         return fd;
1296  out_close:
1297         os_close_file(fd);
1298         return err;
1299 }
1300
1301 int create_cow_file(char *cow_file, char *backing_file, struct openflags flags,
1302                     int sectorsize, int alignment, int *bitmap_offset_out,
1303                     unsigned long *bitmap_len_out, int *data_offset_out)
1304 {
1305         int err, fd;
1306
1307         flags.c = 1;
1308         fd = open_ubd_file(cow_file, &flags, 0, NULL, NULL, NULL, NULL, NULL);
1309         if(fd < 0){
1310                 err = fd;
1311                 printk("Open of COW file '%s' failed, errno = %d\n", cow_file,
1312                        -err);
1313                 goto out;
1314         }
1315
1316         err = init_cow_file(fd, cow_file, backing_file, sectorsize, alignment,
1317                             bitmap_offset_out, bitmap_len_out,
1318                             data_offset_out);
1319         if(!err)
1320                 return(fd);
1321         os_close_file(fd);
1322  out:
1323         return(err);
1324 }
1325
1326 static int update_bitmap(struct io_thread_req *req)
1327 {
1328         int n;
1329
1330         if(req->cow_offset == -1)
1331                 return(0);
1332
1333         n = os_seek_file(req->fds[1], req->cow_offset);
1334         if(n < 0){
1335                 printk("do_io - bitmap lseek failed : err = %d\n", -n);
1336                 return(1);
1337         }
1338
1339         n = os_write_file(req->fds[1], &req->bitmap_words,
1340                           sizeof(req->bitmap_words));
1341         if(n != sizeof(req->bitmap_words)){
1342                 printk("do_io - bitmap update failed, err = %d fd = %d\n", -n,
1343                        req->fds[1]);
1344                 return(1);
1345         }
1346
1347         return(0);
1348 }
1349
1350 void do_io(struct io_thread_req *req)
1351 {
1352         char *buf;
1353         unsigned long len;
1354         int n, nsectors, start, end, bit;
1355         int err;
1356         __u64 off;
1357
1358         nsectors = req->length / req->sectorsize;
1359         start = 0;
1360         do {
1361                 bit = ubd_test_bit(start, (unsigned char *) &req->sector_mask);
1362                 end = start;
1363                 while((end < nsectors) &&
1364                       (ubd_test_bit(end, (unsigned char *)
1365                                     &req->sector_mask) == bit))
1366                         end++;
1367
1368                 off = req->offset + req->offsets[bit] +
1369                         start * req->sectorsize;
1370                 len = (end - start) * req->sectorsize;
1371                 buf = &req->buffer[start * req->sectorsize];
1372
1373                 err = os_seek_file(req->fds[bit], off);
1374                 if(err < 0){
1375                         printk("do_io - lseek failed : err = %d\n", -err);
1376                         req->error = 1;
1377                         return;
1378                 }
1379                 if(req->op == UBD_READ){
1380                         n = 0;
1381                         do {
1382                                 buf = &buf[n];
1383                                 len -= n;
1384                                 n = os_read_file(req->fds[bit], buf, len);
1385                                 if (n < 0) {
1386                                         printk("do_io - read failed, err = %d "
1387                                                "fd = %d\n", -n, req->fds[bit]);
1388                                         req->error = 1;
1389                                         return;
1390                                 }
1391                         } while((n < len) && (n != 0));
1392                         if (n < len) memset(&buf[n], 0, len - n);
1393                 } else {
1394                         n = os_write_file(req->fds[bit], buf, len);
1395                         if(n != len){
1396                                 printk("do_io - write failed err = %d "
1397                                        "fd = %d\n", -n, req->fds[bit]);
1398                                 req->error = 1;
1399                                 return;
1400                         }
1401                 }
1402
1403                 start = end;
1404         } while(start < nsectors);
1405
1406         req->error = update_bitmap(req);
1407 }
1408
1409 /* Changed in start_io_thread, which is serialized by being called only
1410  * from ubd_init, which is an initcall.
1411  */
1412 int kernel_fd = -1;
1413
1414 /* Only changed by the io thread. XXX: currently unused. */
1415 static int io_count = 0;
1416
1417 int io_thread(void *arg)
1418 {
1419         struct io_thread_req req;
1420         int n;
1421
1422         ignore_sigwinch_sig();
1423         while(1){
1424                 n = os_read_file(kernel_fd, &req, sizeof(req));
1425                 if(n != sizeof(req)){
1426                         if(n < 0)
1427                                 printk("io_thread - read failed, fd = %d, "
1428                                        "err = %d\n", kernel_fd, -n);
1429                         else {
1430                                 printk("io_thread - short read, fd = %d, "
1431                                        "length = %d\n", kernel_fd, n);
1432                         }
1433                         continue;
1434                 }
1435                 io_count++;
1436                 do_io(&req);
1437                 n = os_write_file(kernel_fd, &req, sizeof(req));
1438                 if(n != sizeof(req))
1439                         printk("io_thread - write failed, fd = %d, err = %d\n",
1440                                kernel_fd, -n);
1441         }
1442
1443         return 0;
1444 }