arch/um/drivers/ubd_kern.c

   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 UBD_SHIFT 4
  21
  22 #include "linux/kernel.h"
  23 #include "linux/module.h"
  24 #include "linux/blkdev.h"
  25 #include "linux/ata.h"
  26 #include "linux/hdreg.h"
  27 #include "linux/init.h"
  28 #include "linux/cdrom.h"
  29 #include "linux/proc_fs.h"
  30 #include "linux/seq_file.h"
  31 #include "linux/ctype.h"
  32 #include "linux/capability.h"
  33 #include "linux/mm.h"
  34 #include "linux/slab.h"
  35 #include "linux/vmalloc.h"
  36 #include "linux/smp_lock.h"
  37 #include "linux/blkpg.h"
  38 #include "linux/genhd.h"
  39 #include "linux/spinlock.h"
  40 #include "linux/platform_device.h"
  41 #include "linux/scatterlist.h"
  42 #include "asm/segment.h"
  43 #include "asm/uaccess.h"
  44 #include "asm/irq.h"
  45 #include "asm/types.h"
  46 #include "asm/tlbflush.h"
  47 #include "mem_user.h"
  48 #include "kern_util.h"
  49 #include "kern.h"
  50 #include "mconsole_kern.h"
  51 #include "init.h"
  52 #include "irq_user.h"
  53 #include "irq_kern.h"
  54 #include "ubd_user.h"
  55 #include "os.h"
  56 #include "mem.h"
  57 #include "mem_kern.h"
  58 #include "cow.h"
  59
  60 enum ubd_req { UBD_READ, UBD_WRITE };
  61
  62 struct io_thread_req {
  63         struct request *req;
  64         enum ubd_req op;
  65         int fds[2];
  66         unsigned long offsets[2];
  67         unsigned long long offset;
  68         unsigned long length;
  69         char *buffer;
  70         int sectorsize;
  71         unsigned long sector_mask;
  72         unsigned long long cow_offset;
  73         unsigned long bitmap_words[2];
  74         int error;
  75 };
  76
  77 static inline int ubd_test_bit(__u64 bit, unsigned char *data)
  78 {
  79         __u64 n;
  80         int bits, off;
  81
  82         bits = sizeof(data[0]) * 8;
  83         n = bit / bits;
  84         off = bit % bits;
  85         return (data[n] & (1 << off)) != 0;
  86 }
  87
  88 static inline void ubd_set_bit(__u64 bit, unsigned char *data)
  89 {
  90         __u64 n;
  91         int bits, off;
  92
  93         bits = sizeof(data[0]) * 8;
  94         n = bit / bits;
  95         off = bit % bits;
  96         data[n] |= (1 << off);
  97 }
  98 /*End stuff from ubd_user.h*/
  99
 100 #define DRIVER_NAME "uml-blkdev"
 101
 102 static DEFINE_MUTEX(ubd_lock);
 103
 104 static int ubd_open(struct block_device *bdev, fmode_t mode);
 105 static int ubd_release(struct gendisk *disk, fmode_t mode);
 106 static int ubd_ioctl(struct block_device *bdev, fmode_t mode,
 107                      unsigned int cmd, unsigned long arg);
 108 static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo);
 109
 110 #define MAX_DEV (16)
 111
 112 static const struct block_device_operations ubd_blops = {
 113         .owner          = THIS_MODULE,
 114         .open           = ubd_open,
 115         .release        = ubd_release,
 116         .ioctl          = ubd_ioctl,
 117         .getgeo         = ubd_getgeo,
 118 };
 119
 120 /* Protected by ubd_lock */
 121 static int fake_major = UBD_MAJOR;
 122 static struct gendisk *ubd_gendisk[MAX_DEV];
 123 static struct gendisk *fake_gendisk[MAX_DEV];
 124
 125 #ifdef CONFIG_BLK_DEV_UBD_SYNC
 126 #define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 1, .c = 0, \
 127                                          .cl = 1 })
 128 #else
 129 #define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 0, .c = 0, \
 130                                          .cl = 1 })
 131 #endif
 132 static struct openflags global_openflags = OPEN_FLAGS;
 133
 134 struct cow {
 135         /* backing file name */
 136         char *file;
 137         /* backing file fd */
 138         int fd;
 139         unsigned long *bitmap;
 140         unsigned long bitmap_len;
 141         int bitmap_offset;
 142         int data_offset;
 143 };
 144
 145 #define MAX_SG 64
 146
 147 struct ubd {
 148         struct list_head restart;
 149         /* name (and fd, below) of the file opened for writing, either the
 150          * backing or the cow file. */
 151         char *file;
 152         int count;
 153         int fd;
 154         __u64 size;
 155         struct openflags boot_openflags;
 156         struct openflags openflags;
 157         unsigned shared:1;
 158         unsigned no_cow:1;
 159         struct cow cow;
 160         struct platform_device pdev;
 161         struct request_queue *queue;
 162         spinlock_t lock;
 163         struct scatterlist sg[MAX_SG];
 164         struct request *request;
 165         int start_sg, end_sg;
 166 };
 167
 168 #define DEFAULT_COW { \
 169         .file =                 NULL, \
 170         .fd =                   -1,     \
 171         .bitmap =               NULL, \
 172         .bitmap_offset =        0, \
 173         .data_offset =          0, \
 174 }
 175
 176 #define DEFAULT_UBD { \
 177         .file =                 NULL, \
 178         .count =                0, \
 179         .fd =                   -1, \
 180         .size =                 -1, \
 181         .boot_openflags =       OPEN_FLAGS, \
 182         .openflags =            OPEN_FLAGS, \
 183         .no_cow =               0, \
 184         .shared =               0, \
 185         .cow =                  DEFAULT_COW, \
 186         .lock =                 SPIN_LOCK_UNLOCKED,     \
 187         .request =              NULL, \
 188         .start_sg =             0, \
 189         .end_sg =               0, \
 190 }
 191
 192 /* Protected by ubd_lock */
 193 static 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 fake_ide_media_proc_show(struct seq_file *m, void *v)
 207 {
 208         seq_puts(m, "disk\n");
 209         return 0;
 210 }
 211
 212 static int fake_ide_media_proc_open(struct inode *inode, struct file *file)
 213 {
 214         return single_open(file, fake_ide_media_proc_show, NULL);
 215 }
 216
 217 static const struct file_operations fake_ide_media_proc_fops = {
 218         .owner          = THIS_MODULE,
 219         .open           = fake_ide_media_proc_open,
 220         .read           = seq_read,
 221         .llseek         = seq_lseek,
 222         .release        = single_release,
 223 };
 224
 225 static void make_ide_entries(const char *dev_name)
 226 {
 227         struct proc_dir_entry *dir, *ent;
 228         char name[64];
 229
 230         if(proc_ide_root == NULL) make_proc_ide();
 231
 232         dir = proc_mkdir(dev_name, proc_ide);
 233         if(!dir) return;
 234
 235         ent = proc_create("media", S_IRUGO, dir, &fake_ide_media_proc_fops);
 236         if(!ent) return;
 237         snprintf(name, sizeof(name), "ide0/%s", dev_name);
 238         proc_symlink(dev_name, proc_ide_root, name);
 239 }
 240
 241 static int fake_ide_setup(char *str)
 242 {
 243         fake_ide = 1;
 244         return 1;
 245 }
 246
 247 __setup("fake_ide", fake_ide_setup);
 248
 249 __uml_help(fake_ide_setup,
 250 "fake_ide\n"
 251 "    Create ide0 entries that map onto ubd devices.\n\n"
 252 );
 253
 254 static int parse_unit(char **ptr)
 255 {
 256         char *str = *ptr, *end;
 257         int n = -1;
 258
 259         if(isdigit(*str)) {
 260                 n = simple_strtoul(str, &end, 0);
 261                 if(end == str)
 262                         return -1;
 263                 *ptr = end;
 264         }
 265         else if (('a' <= *str) && (*str <= 'z')) {
 266                 n = *str - 'a';
 267                 str++;
 268                 *ptr = str;
 269         }
 270         return n;
 271 }
 272
 273 /* If *index_out == -1 at exit, the passed option was a general one;
 274  * otherwise, the str pointer is used (and owned) inside ubd_devs array, so it
 275  * should not be freed on exit.
 276  */
 277 static int ubd_setup_common(char *str, int *index_out, char **error_out)
 278 {
 279         struct ubd *ubd_dev;
 280         struct openflags flags = global_openflags;
 281         char *backing_file;
 282         int n, err = 0, i;
 283
 284         if(index_out) *index_out = -1;
 285         n = *str;
 286         if(n == '='){
 287                 char *end;
 288                 int major;
 289
 290                 str++;
 291                 if(!strcmp(str, "sync")){
 292                         global_openflags = of_sync(global_openflags);
 293                         goto out1;
 294                 }
 295
 296                 err = -EINVAL;
 297                 major = simple_strtoul(str, &end, 0);
 298                 if((*end != '\0') || (end == str)){
 299                         *error_out = "Didn't parse major number";
 300                         goto out1;
 301                 }
 302
 303                 mutex_lock(&ubd_lock);
 304                 if (fake_major != UBD_MAJOR) {
 305                         *error_out = "Can't assign a fake major twice";
 306                         goto out1;
 307                 }
 308
 309                 fake_major = major;
 310
 311                 printk(KERN_INFO "Setting extra ubd major number to %d\n",
 312                        major);
 313                 err = 0;
 314         out1:
 315                 mutex_unlock(&ubd_lock);
 316                 return err;
 317         }
 318
 319         n = parse_unit(&str);
 320         if(n < 0){
 321                 *error_out = "Couldn't parse device number";
 322                 return -EINVAL;
 323         }
 324         if(n >= MAX_DEV){
 325                 *error_out = "Device number out of range";
 326                 return 1;
 327         }
 328
 329         err = -EBUSY;
 330         mutex_lock(&ubd_lock);
 331
 332         ubd_dev = &ubd_devs[n];
 333         if(ubd_dev->file != NULL){
 334                 *error_out = "Device is already configured";
 335                 goto out;
 336         }
 337
 338         if (index_out)
 339                 *index_out = n;
 340
 341         err = -EINVAL;
 342         for (i = 0; i < sizeof("rscd="); i++) {
 343                 switch (*str) {
 344                 case 'r':
 345                         flags.w = 0;
 346                         break;
 347                 case 's':
 348                         flags.s = 1;
 349                         break;
 350                 case 'd':
 351                         ubd_dev->no_cow = 1;
 352                         break;
 353                 case 'c':
 354                         ubd_dev->shared = 1;
 355                         break;
 356                 case '=':
 357                         str++;
 358                         goto break_loop;
 359                 default:
 360                         *error_out = "Expected '=' or flag letter "
 361                                 "(r, s, c, or d)";
 362                         goto out;
 363                 }
 364                 str++;
 365         }
 366
 367         if (*str == '=')
 368                 *error_out = "Too many flags specified";
 369         else
 370                 *error_out = "Missing '='";
 371         goto out;
 372
 373 break_loop:
 374         backing_file = strchr(str, ',');
 375
 376         if (backing_file == NULL)
 377                 backing_file = strchr(str, ':');
 378
 379         if(backing_file != NULL){
 380                 if(ubd_dev->no_cow){
 381                         *error_out = "Can't specify both 'd' and a cow file";
 382                         goto out;
 383                 }
 384                 else {
 385                         *backing_file = '\0';
 386                         backing_file++;
 387                 }
 388         }
 389         err = 0;
 390         ubd_dev->file = str;
 391         ubd_dev->cow.file = backing_file;
 392         ubd_dev->boot_openflags = flags;
 393 out:
 394         mutex_unlock(&ubd_lock);
 395         return err;
 396 }
 397
 398 static int ubd_setup(char *str)
 399 {
 400         char *error;
 401         int err;
 402
 403         err = ubd_setup_common(str, NULL, &error);
 404         if(err)
 405                 printk(KERN_ERR "Failed to initialize device with \"%s\" : "
 406                        "%s\n", str, error);
 407         return 1;
 408 }
 409
 410 __setup("ubd", ubd_setup);
 411 __uml_help(ubd_setup,
 412 "ubd<n><flags>=<filename>[(:|,)<filename2>]\n"
 413 "    This is used to associate a device with a file in the underlying\n"
 414 "    filesystem. When specifying two filenames, the first one is the\n"
 415 "    COW name and the second is the backing file name. As separator you can\n"
 416 "    use either a ':' or a ',': the first one allows writing things like;\n"
 417 "       ubd0=~/Uml/root_cow:~/Uml/root_backing_file\n"
 418 "    while with a ',' the shell would not expand the 2nd '~'.\n"
 419 "    When using only one filename, UML will detect whether to treat it like\n"
 420 "    a COW file or a backing file. To override this detection, add the 'd'\n"
 421 "    flag:\n"
 422 "       ubd0d=BackingFile\n"
 423 "    Usually, there is a filesystem in the file, but \n"
 424 "    that's not required. Swap devices containing swap files can be\n"
 425 "    specified like this. Also, a file which doesn't contain a\n"
 426 "    filesystem can have its contents read in the virtual \n"
 427 "    machine by running 'dd' on the device. <n> must be in the range\n"
 428 "    0 to 7. Appending an 'r' to the number will cause that device\n"
 429 "    to be mounted read-only. For example ubd1r=./ext_fs. Appending\n"
 430 "    an 's' will cause data to be written to disk on the host immediately.\n"
 431 "    'c' will cause the device to be treated as being shared between multiple\n"
 432 "    UMLs and file locking will be turned off - this is appropriate for a\n"
 433 "    cluster filesystem and inappropriate at almost all other times.\n\n"
 434 );
 435
 436 static int udb_setup(char *str)
 437 {
 438         printk("udb%s specified on command line is almost certainly a ubd -> "
 439                "udb TYPO\n", str);
 440         return 1;
 441 }
 442
 443 __setup("udb", udb_setup);
 444 __uml_help(udb_setup,
 445 "udb\n"
 446 "    This option is here solely to catch ubd -> udb typos, which can be\n"
 447 "    to impossible to catch visually unless you specifically look for\n"
 448 "    them.  The only result of any option starting with 'udb' is an error\n"
 449 "    in the boot output.\n\n"
 450 );
 451
 452 static void do_ubd_request(struct request_queue * q);
 453
 454 /* Only changed by ubd_init, which is an initcall. */
 455 static int thread_fd = -1;
 456 static LIST_HEAD(restart);
 457
 458 /* XXX - move this inside ubd_intr. */
 459 /* Called without dev->lock held, and only in interrupt context. */
 460 static void ubd_handler(void)
 461 {
 462         struct io_thread_req *req;
 463         struct ubd *ubd;
 464         struct list_head *list, *next_ele;
 465         unsigned long flags;
 466         int n;
 467
 468         while(1){
 469                 n = os_read_file(thread_fd, &req,
 470                                  sizeof(struct io_thread_req *));
 471                 if(n != sizeof(req)){
 472                         if(n == -EAGAIN)
 473                                 break;
 474                         printk(KERN_ERR "spurious interrupt in ubd_handler, "
 475                                "err = %d\n", -n);
 476                         return;
 477                 }
 478
 479                 blk_end_request(req->req, 0, req->length);
 480                 kfree(req);
 481         }
 482         reactivate_fd(thread_fd, UBD_IRQ);
 483
 484         list_for_each_safe(list, next_ele, &restart){
 485                 ubd = container_of(list, struct ubd, restart);
 486                 list_del_init(&ubd->restart);
 487                 spin_lock_irqsave(&ubd->lock, flags);
 488                 do_ubd_request(ubd->queue);
 489                 spin_unlock_irqrestore(&ubd->lock, flags);
 490         }
 491 }
 492
 493 static irqreturn_t ubd_intr(int irq, void *dev)
 494 {
 495         ubd_handler();
 496         return IRQ_HANDLED;
 497 }
 498
 499 /* Only changed by ubd_init, which is an initcall. */
 500 static int io_pid = -1;
 501
 502 static void kill_io_thread(void)
 503 {
 504         if(io_pid != -1)
 505                 os_kill_process(io_pid, 1);
 506 }
 507
 508 __uml_exitcall(kill_io_thread);
 509
 510 static inline int ubd_file_size(struct ubd *ubd_dev, __u64 *size_out)
 511 {
 512         char *file;
 513
 514         file = ubd_dev->cow.file ? ubd_dev->cow.file : ubd_dev->file;
 515         return os_file_size(file, size_out);
 516 }
 517
 518 static int read_cow_bitmap(int fd, void *buf, int offset, int len)
 519 {
 520         int err;
 521
 522         err = os_seek_file(fd, offset);
 523         if (err < 0)
 524                 return err;
 525
 526         err = os_read_file(fd, buf, len);
 527         if (err < 0)
 528                 return err;
 529
 530         return 0;
 531 }
 532
 533 static int backing_file_mismatch(char *file, __u64 size, time_t mtime)
 534 {
 535         unsigned long modtime;
 536         unsigned long long actual;
 537         int err;
 538
 539         err = os_file_modtime(file, &modtime);
 540         if (err < 0) {
 541                 printk(KERN_ERR "Failed to get modification time of backing "
 542                        "file \"%s\", err = %d\n", file, -err);
 543                 return err;
 544         }
 545
 546         err = os_file_size(file, &actual);
 547         if (err < 0) {
 548                 printk(KERN_ERR "Failed to get size of backing file \"%s\", "
 549                        "err = %d\n", file, -err);
 550                 return err;
 551         }
 552
 553         if (actual != size) {
 554                 /*__u64 can be a long on AMD64 and with %lu GCC complains; so
 555                  * the typecast.*/
 556                 printk(KERN_ERR "Size mismatch (%llu vs %llu) of COW header "
 557                        "vs backing file\n", (unsigned long long) size, actual);
 558                 return -EINVAL;
 559         }
 560         if (modtime != mtime) {
 561                 printk(KERN_ERR "mtime mismatch (%ld vs %ld) of COW header vs "
 562                        "backing file\n", mtime, modtime);
 563                 return -EINVAL;
 564         }
 565         return 0;
 566 }
 567
 568 static int path_requires_switch(char *from_cmdline, char *from_cow, char *cow)
 569 {
 570         struct uml_stat buf1, buf2;
 571         int err;
 572
 573         if (from_cmdline == NULL)
 574                 return 0;
 575         if (!strcmp(from_cmdline, from_cow))
 576                 return 0;
 577
 578         err = os_stat_file(from_cmdline, &buf1);
 579         if (err < 0) {
 580                 printk(KERN_ERR "Couldn't stat '%s', err = %d\n", from_cmdline,
 581                        -err);
 582                 return 0;
 583         }
 584         err = os_stat_file(from_cow, &buf2);
 585         if (err < 0) {
 586                 printk(KERN_ERR "Couldn't stat '%s', err = %d\n", from_cow,
 587                        -err);
 588                 return 1;
 589         }
 590         if ((buf1.ust_dev == buf2.ust_dev) && (buf1.ust_ino == buf2.ust_ino))
 591                 return 0;
 592
 593         printk(KERN_ERR "Backing file mismatch - \"%s\" requested, "
 594                "\"%s\" specified in COW header of \"%s\"\n",
 595                from_cmdline, from_cow, cow);
 596         return 1;
 597 }
 598
 599 static int open_ubd_file(char *file, struct openflags *openflags, int shared,
 600                   char **backing_file_out, int *bitmap_offset_out,
 601                   unsigned long *bitmap_len_out, int *data_offset_out,
 602                   int *create_cow_out)
 603 {
 604         time_t mtime;
 605         unsigned long long size;
 606         __u32 version, align;
 607         char *backing_file;
 608         int fd, err, sectorsize, asked_switch, mode = 0644;
 609
 610         fd = os_open_file(file, *openflags, mode);
 611         if (fd < 0) {
 612                 if ((fd == -ENOENT) && (create_cow_out != NULL))
 613                         *create_cow_out = 1;
 614                 if (!openflags->w ||
 615                     ((fd != -EROFS) && (fd != -EACCES)))
 616                         return fd;
 617                 openflags->w = 0;
 618                 fd = os_open_file(file, *openflags, mode);
 619                 if (fd < 0)
 620                         return fd;
 621         }
 622
 623         if (shared)
 624                 printk(KERN_INFO "Not locking \"%s\" on the host\n", file);
 625         else {
 626                 err = os_lock_file(fd, openflags->w);
 627                 if (err < 0) {
 628                         printk(KERN_ERR "Failed to lock '%s', err = %d\n",
 629                                file, -err);
 630                         goto out_close;
 631                 }
 632         }
 633
 634         /* Successful return case! */
 635         if (backing_file_out == NULL)
 636                 return fd;
 637
 638         err = read_cow_header(file_reader, &fd, &version, &backing_file, &mtime,
 639                               &size, &sectorsize, &align, bitmap_offset_out);
 640         if (err && (*backing_file_out != NULL)) {
 641                 printk(KERN_ERR "Failed to read COW header from COW file "
 642                        "\"%s\", errno = %d\n", file, -err);
 643                 goto out_close;
 644         }
 645         if (err)
 646                 return fd;
 647
 648         asked_switch = path_requires_switch(*backing_file_out, backing_file,
 649                                             file);
 650
 651         /* Allow switching only if no mismatch. */
 652         if (asked_switch && !backing_file_mismatch(*backing_file_out, size,
 653                                                    mtime)) {
 654                 printk(KERN_ERR "Switching backing file to '%s'\n",
 655                        *backing_file_out);
 656                 err = write_cow_header(file, fd, *backing_file_out,
 657                                        sectorsize, align, &size);
 658                 if (err) {
 659                         printk(KERN_ERR "Switch failed, errno = %d\n", -err);
 660                         goto out_close;
 661                 }
 662         } else {
 663                 *backing_file_out = backing_file;
 664                 err = backing_file_mismatch(*backing_file_out, size, mtime);
 665                 if (err)
 666                         goto out_close;
 667         }
 668
 669         cow_sizes(version, size, sectorsize, align, *bitmap_offset_out,
 670                   bitmap_len_out, data_offset_out);
 671
 672         return fd;
 673  out_close:
 674         os_close_file(fd);
 675         return err;
 676 }
 677
 678 static int create_cow_file(char *cow_file, char *backing_file,
 679                     struct openflags flags,
 680                     int sectorsize, int alignment, int *bitmap_offset_out,
 681                     unsigned long *bitmap_len_out, int *data_offset_out)
 682 {
 683         int err, fd;
 684
 685         flags.c = 1;
 686         fd = open_ubd_file(cow_file, &flags, 0, NULL, NULL, NULL, NULL, NULL);
 687         if (fd < 0) {
 688                 err = fd;
 689                 printk(KERN_ERR "Open of COW file '%s' failed, errno = %d\n",
 690                        cow_file, -err);
 691                 goto out;
 692         }
 693
 694         err = init_cow_file(fd, cow_file, backing_file, sectorsize, alignment,
 695                             bitmap_offset_out, bitmap_len_out,
 696                             data_offset_out);
 697         if (!err)
 698                 return fd;
 699         os_close_file(fd);
 700  out:
 701         return err;
 702 }
 703
 704 static void ubd_close_dev(struct ubd *ubd_dev)
 705 {
 706         os_close_file(ubd_dev->fd);
 707         if(ubd_dev->cow.file == NULL)
 708                 return;
 709
 710         os_close_file(ubd_dev->cow.fd);
 711         vfree(ubd_dev->cow.bitmap);
 712         ubd_dev->cow.bitmap = NULL;
 713 }
 714
 715 static int ubd_open_dev(struct ubd *ubd_dev)
 716 {
 717         struct openflags flags;
 718         char **back_ptr;
 719         int err, create_cow, *create_ptr;
 720         int fd;
 721
 722         ubd_dev->openflags = ubd_dev->boot_openflags;
 723         create_cow = 0;
 724         create_ptr = (ubd_dev->cow.file != NULL) ? &create_cow : NULL;
 725         back_ptr = ubd_dev->no_cow ? NULL : &ubd_dev->cow.file;
 726
 727         fd = open_ubd_file(ubd_dev->file, &ubd_dev->openflags, ubd_dev->shared,
 728                                 back_ptr, &ubd_dev->cow.bitmap_offset,
 729                                 &ubd_dev->cow.bitmap_len, &ubd_dev->cow.data_offset,
 730                                 create_ptr);
 731
 732         if((fd == -ENOENT) && create_cow){
 733                 fd = create_cow_file(ubd_dev->file, ubd_dev->cow.file,
 734                                           ubd_dev->openflags, 1 << 9, PAGE_SIZE,
 735                                           &ubd_dev->cow.bitmap_offset,
 736                                           &ubd_dev->cow.bitmap_len,
 737                                           &ubd_dev->cow.data_offset);
 738                 if(fd >= 0){
 739                         printk(KERN_INFO "Creating \"%s\" as COW file for "
 740                                "\"%s\"\n", ubd_dev->file, ubd_dev->cow.file);
 741                 }
 742         }
 743
 744         if(fd < 0){
 745                 printk("Failed to open '%s', errno = %d\n", ubd_dev->file,
 746                        -fd);
 747                 return fd;
 748         }
 749         ubd_dev->fd = fd;
 750
 751         if(ubd_dev->cow.file != NULL){
 752                 blk_queue_max_hw_sectors(ubd_dev->queue, 8 * sizeof(long));
 753
 754                 err = -ENOMEM;
 755                 ubd_dev->cow.bitmap = vmalloc(ubd_dev->cow.bitmap_len);
 756                 if(ubd_dev->cow.bitmap == NULL){
 757                         printk(KERN_ERR "Failed to vmalloc COW bitmap\n");
 758                         goto error;
 759                 }
 760                 flush_tlb_kernel_vm();
 761
 762                 err = read_cow_bitmap(ubd_dev->fd, ubd_dev->cow.bitmap,
 763                                       ubd_dev->cow.bitmap_offset,
 764                                       ubd_dev->cow.bitmap_len);
 765                 if(err < 0)
 766                         goto error;
 767
 768                 flags = ubd_dev->openflags;
 769                 flags.w = 0;
 770                 err = open_ubd_file(ubd_dev->cow.file, &flags, ubd_dev->shared, NULL,
 771                                     NULL, NULL, NULL, NULL);
 772                 if(err < 0) goto error;
 773                 ubd_dev->cow.fd = err;
 774         }
 775         return 0;
 776  error:
 777         os_close_file(ubd_dev->fd);
 778         return err;
 779 }
 780
 781 static void ubd_device_release(struct device *dev)
 782 {
 783         struct ubd *ubd_dev = dev_get_drvdata(dev);
 784
 785         blk_cleanup_queue(ubd_dev->queue);
 786         *ubd_dev = ((struct ubd) DEFAULT_UBD);
 787 }
 788
 789 static int ubd_disk_register(int major, u64 size, int unit,
 790                              struct gendisk **disk_out)
 791 {
 792         struct gendisk *disk;
 793
 794         disk = alloc_disk(1 << UBD_SHIFT);
 795         if(disk == NULL)
 796                 return -ENOMEM;
 797
 798         disk->major = major;
 799         disk->first_minor = unit << UBD_SHIFT;
 800         disk->fops = &ubd_blops;
 801         set_capacity(disk, size / 512);
 802         if (major == UBD_MAJOR)
 803                 sprintf(disk->disk_name, "ubd%c", 'a' + unit);
 804         else
 805                 sprintf(disk->disk_name, "ubd_fake%d", unit);
 806
 807         /* sysfs register (not for ide fake devices) */
 808         if (major == UBD_MAJOR) {
 809                 ubd_devs[unit].pdev.id   = unit;
 810                 ubd_devs[unit].pdev.name = DRIVER_NAME;
 811                 ubd_devs[unit].pdev.dev.release = ubd_device_release;
 812                 dev_set_drvdata(&ubd_devs[unit].pdev.dev, &ubd_devs[unit]);
 813                 platform_device_register(&ubd_devs[unit].pdev);
 814                 disk->driverfs_dev = &ubd_devs[unit].pdev.dev;
 815         }
 816
 817         disk->private_data = &ubd_devs[unit];
 818         disk->queue = ubd_devs[unit].queue;
 819         add_disk(disk);
 820
 821         *disk_out = disk;
 822         return 0;
 823 }
 824
 825 #define ROUND_BLOCK(n) ((n + ((1 << 9) - 1)) & (-1 << 9))
 826
 827 static int ubd_add(int n, char **error_out)
 828 {
 829         struct ubd *ubd_dev = &ubd_devs[n];
 830         int err = 0;
 831
 832         if(ubd_dev->file == NULL)
 833                 goto out;
 834
 835         err = ubd_file_size(ubd_dev, &ubd_dev->size);
 836         if(err < 0){
 837                 *error_out = "Couldn't determine size of device's file";
 838                 goto out;
 839         }
 840
 841         ubd_dev->size = ROUND_BLOCK(ubd_dev->size);
 842
 843         INIT_LIST_HEAD(&ubd_dev->restart);
 844         sg_init_table(ubd_dev->sg, MAX_SG);
 845
 846         err = -ENOMEM;
 847         ubd_dev->queue = blk_init_queue(do_ubd_request, &ubd_dev->lock);
 848         if (ubd_dev->queue == NULL) {
 849                 *error_out = "Failed to initialize device queue";
 850                 goto out;
 851         }
 852         ubd_dev->queue->queuedata = ubd_dev;
 853
 854         blk_queue_max_segments(ubd_dev->queue, MAX_SG);
 855         err = ubd_disk_register(UBD_MAJOR, ubd_dev->size, n, &ubd_gendisk[n]);
 856         if(err){
 857                 *error_out = "Failed to register device";
 858                 goto out_cleanup;
 859         }
 860
 861         if (fake_major != UBD_MAJOR)
 862                 ubd_disk_register(fake_major, ubd_dev->size, n,
 863                                   &fake_gendisk[n]);
 864
 865         /*
 866          * Perhaps this should also be under the "if (fake_major)" above
 867          * using the fake_disk->disk_name
 868          */
 869         if (fake_ide)
 870                 make_ide_entries(ubd_gendisk[n]->disk_name);
 871
 872         err = 0;
 873 out:
 874         return err;
 875
 876 out_cleanup:
 877         blk_cleanup_queue(ubd_dev->queue);
 878         goto out;
 879 }
 880
 881 static int ubd_config(char *str, char **error_out)
 882 {
 883         int n, ret;
 884
 885         /* This string is possibly broken up and stored, so it's only
 886          * freed if ubd_setup_common fails, or if only general options
 887          * were set.
 888          */
 889         str = kstrdup(str, GFP_KERNEL);
 890         if (str == NULL) {
 891                 *error_out = "Failed to allocate memory";
 892                 return -ENOMEM;
 893         }
 894
 895         ret = ubd_setup_common(str, &n, error_out);
 896         if (ret)
 897                 goto err_free;
 898
 899         if (n == -1) {
 900                 ret = 0;
 901                 goto err_free;
 902         }
 903
 904         mutex_lock(&ubd_lock);
 905         ret = ubd_add(n, error_out);
 906         if (ret)
 907                 ubd_devs[n].file = NULL;
 908         mutex_unlock(&ubd_lock);
 909
 910 out:
 911         return ret;
 912
 913 err_free:
 914         kfree(str);
 915         goto out;
 916 }
 917
 918 static int ubd_get_config(char *name, char *str, int size, char **error_out)
 919 {
 920         struct ubd *ubd_dev;
 921         int n, len = 0;
 922
 923         n = parse_unit(&name);
 924         if((n >= MAX_DEV) || (n < 0)){
 925                 *error_out = "ubd_get_config : device number out of range";
 926                 return -1;
 927         }
 928
 929         ubd_dev = &ubd_devs[n];
 930         mutex_lock(&ubd_lock);
 931
 932         if(ubd_dev->file == NULL){
 933                 CONFIG_CHUNK(str, size, len, "", 1);
 934                 goto out;
 935         }
 936
 937         CONFIG_CHUNK(str, size, len, ubd_dev->file, 0);
 938
 939         if(ubd_dev->cow.file != NULL){
 940                 CONFIG_CHUNK(str, size, len, ",", 0);
 941                 CONFIG_CHUNK(str, size, len, ubd_dev->cow.file, 1);
 942         }
 943         else CONFIG_CHUNK(str, size, len, "", 1);
 944
 945  out:
 946         mutex_unlock(&ubd_lock);
 947         return len;
 948 }
 949
 950 static int ubd_id(char **str, int *start_out, int *end_out)
 951 {
 952         int n;
 953
 954         n = parse_unit(str);
 955         *start_out = 0;
 956         *end_out = MAX_DEV - 1;
 957         return n;
 958 }
 959
 960 static int ubd_remove(int n, char **error_out)
 961 {
 962         struct gendisk *disk = ubd_gendisk[n];
 963         struct ubd *ubd_dev;
 964         int err = -ENODEV;
 965
 966         mutex_lock(&ubd_lock);
 967
 968         ubd_dev = &ubd_devs[n];
 969
 970         if(ubd_dev->file == NULL)
 971                 goto out;
 972
 973         /* you cannot remove a open disk */
 974         err = -EBUSY;
 975         if(ubd_dev->count > 0)
 976                 goto out;
 977
 978         ubd_gendisk[n] = NULL;
 979         if(disk != NULL){
 980                 del_gendisk(disk);
 981                 put_disk(disk);
 982         }
 983
 984         if(fake_gendisk[n] != NULL){
 985                 del_gendisk(fake_gendisk[n]);
 986                 put_disk(fake_gendisk[n]);
 987                 fake_gendisk[n] = NULL;
 988         }
 989
 990         err = 0;
 991         platform_device_unregister(&ubd_dev->pdev);
 992 out:
 993         mutex_unlock(&ubd_lock);
 994         return err;
 995 }
 996
 997 /* All these are called by mconsole in process context and without
 998  * ubd-specific locks.  The structure itself is const except for .list.
 999  */
1000 static struct mc_device ubd_mc = {
1001         .list           = LIST_HEAD_INIT(ubd_mc.list),
1002         .name           = "ubd",
1003         .config         = ubd_config,
1004         .get_config     = ubd_get_config,
1005         .id             = ubd_id,
1006         .remove         = ubd_remove,
1007 };
1008
1009 static int __init ubd_mc_init(void)
1010 {
1011         mconsole_register_dev(&ubd_mc);
1012         return 0;
1013 }
1014
1015 __initcall(ubd_mc_init);
1016
1017 static int __init ubd0_init(void)
1018 {
1019         struct ubd *ubd_dev = &ubd_devs[0];
1020
1021         mutex_lock(&ubd_lock);
1022         if(ubd_dev->file == NULL)
1023                 ubd_dev->file = "root_fs";
1024         mutex_unlock(&ubd_lock);
1025
1026         return 0;
1027 }
1028
1029 __initcall(ubd0_init);
1030
1031 /* Used in ubd_init, which is an initcall */
1032 static struct platform_driver ubd_driver = {
1033         .driver = {
1034                 .name  = DRIVER_NAME,
1035         },
1036 };
1037
1038 static int __init ubd_init(void)
1039 {
1040         char *error;
1041         int i, err;
1042
1043         if (register_blkdev(UBD_MAJOR, "ubd"))
1044                 return -1;
1045
1046         if (fake_major != UBD_MAJOR) {
1047                 char name[sizeof("ubd_nnn\0")];
1048
1049                 snprintf(name, sizeof(name), "ubd_%d", fake_major);
1050                 if (register_blkdev(fake_major, "ubd"))
1051                         return -1;
1052         }
1053         platform_driver_register(&ubd_driver);
1054         mutex_lock(&ubd_lock);
1055         for (i = 0; i < MAX_DEV; i++){
1056                 err = ubd_add(i, &error);
1057                 if(err)
1058                         printk(KERN_ERR "Failed to initialize ubd device %d :"
1059                                "%s\n", i, error);
1060         }
1061         mutex_unlock(&ubd_lock);
1062         return 0;
1063 }
1064
1065 late_initcall(ubd_init);
1066
1067 static int __init ubd_driver_init(void){
1068         unsigned long stack;
1069         int err;
1070
1071         /* Set by CONFIG_BLK_DEV_UBD_SYNC or ubd=sync.*/
1072         if(global_openflags.s){
1073                 printk(KERN_INFO "ubd: Synchronous mode\n");
1074                 /* Letting ubd=sync be like using ubd#s= instead of ubd#= is
1075                  * enough. So use anyway the io thread. */
1076         }
1077         stack = alloc_stack(0, 0);
1078         io_pid = start_io_thread(stack + PAGE_SIZE - sizeof(void *),
1079                                  &thread_fd);
1080         if(io_pid < 0){
1081                 printk(KERN_ERR
1082                        "ubd : Failed to start I/O thread (errno = %d) - "
1083                        "falling back to synchronous I/O\n", -io_pid);
1084                 io_pid = -1;
1085                 return 0;
1086         }
1087         err = um_request_irq(UBD_IRQ, thread_fd, IRQ_READ, ubd_intr,
1088                              IRQF_DISABLED, "ubd", ubd_devs);
1089         if(err != 0)
1090                 printk(KERN_ERR "um_request_irq failed - errno = %d\n", -err);
1091         return 0;
1092 }
1093
1094 device_initcall(ubd_driver_init);
1095
1096 static int ubd_open(struct block_device *bdev, fmode_t mode)
1097 {
1098         struct gendisk *disk = bdev->bd_disk;
1099         struct ubd *ubd_dev = disk->private_data;
1100         int err = 0;
1101
1102         lock_kernel();
1103         if(ubd_dev->count == 0){
1104                 err = ubd_open_dev(ubd_dev);
1105                 if(err){
1106                         printk(KERN_ERR "%s: Can't open \"%s\": errno = %d\n",
1107                                disk->disk_name, ubd_dev->file, -err);
1108                         goto out;
1109                 }
1110         }
1111         ubd_dev->count++;
1112         set_disk_ro(disk, !ubd_dev->openflags.w);
1113
1114         /* This should no more be needed. And it didn't work anyway to exclude
1115          * read-write remounting of filesystems.*/
1116         /*if((mode & FMODE_WRITE) && !ubd_dev->openflags.w){
1117                 if(--ubd_dev->count == 0) ubd_close_dev(ubd_dev);
1118                 err = -EROFS;
1119         }*/
1120 out:
1121         unlock_kernel();
1122         return err;
1123 }
1124
1125 static int ubd_release(struct gendisk *disk, fmode_t mode)
1126 {
1127         struct ubd *ubd_dev = disk->private_data;
1128
1129         lock_kernel();
1130         if(--ubd_dev->count == 0)
1131                 ubd_close_dev(ubd_dev);
1132         unlock_kernel();
1133         return 0;
1134 }
1135
1136 static void cowify_bitmap(__u64 io_offset, int length, unsigned long *cow_mask,
1137                           __u64 *cow_offset, unsigned long *bitmap,
1138                           __u64 bitmap_offset, unsigned long *bitmap_words,
1139                           __u64 bitmap_len)
1140 {
1141         __u64 sector = io_offset >> 9;
1142         int i, update_bitmap = 0;
1143
1144         for(i = 0; i < length >> 9; i++){
1145                 if(cow_mask != NULL)
1146                         ubd_set_bit(i, (unsigned char *) cow_mask);
1147                 if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
1148                         continue;
1149
1150                 update_bitmap = 1;
1151                 ubd_set_bit(sector + i, (unsigned char *) bitmap);
1152         }
1153
1154         if(!update_bitmap)
1155                 return;
1156
1157         *cow_offset = sector / (sizeof(unsigned long) * 8);
1158
1159         /* This takes care of the case where we're exactly at the end of the
1160          * device, and *cow_offset + 1 is off the end.  So, just back it up
1161          * by one word.  Thanks to Lynn Kerby for the fix and James McMechan
1162          * for the original diagnosis.
1163          */
1164         if (*cow_offset == (DIV_ROUND_UP(bitmap_len,
1165                                          sizeof(unsigned long)) - 1))
1166                 (*cow_offset)--;
1167
1168         bitmap_words[0] = bitmap[*cow_offset];
1169         bitmap_words[1] = bitmap[*cow_offset + 1];
1170
1171         *cow_offset *= sizeof(unsigned long);
1172         *cow_offset += bitmap_offset;
1173 }
1174
1175 static void cowify_req(struct io_thread_req *req, unsigned long *bitmap,
1176                        __u64 bitmap_offset, __u64 bitmap_len)
1177 {
1178         __u64 sector = req->offset >> 9;
1179         int i;
1180
1181         if(req->length > (sizeof(req->sector_mask) * 8) << 9)
1182                 panic("Operation too long");
1183
1184         if(req->op == UBD_READ) {
1185                 for(i = 0; i < req->length >> 9; i++){
1186                         if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
1187                                 ubd_set_bit(i, (unsigned char *)
1188                                             &req->sector_mask);
1189                 }
1190         }
1191         else cowify_bitmap(req->offset, req->length, &req->sector_mask,
1192                            &req->cow_offset, bitmap, bitmap_offset,
1193                            req->bitmap_words, bitmap_len);
1194 }
1195
1196 /* Called with dev->lock held */
1197 static void prepare_request(struct request *req, struct io_thread_req *io_req,
1198                             unsigned long long offset, int page_offset,
1199                             int len, struct page *page)
1200 {
1201         struct gendisk *disk = req->rq_disk;
1202         struct ubd *ubd_dev = disk->private_data;
1203
1204         io_req->req = req;
1205         io_req->fds[0] = (ubd_dev->cow.file != NULL) ? ubd_dev->cow.fd :
1206                 ubd_dev->fd;
1207         io_req->fds[1] = ubd_dev->fd;
1208         io_req->cow_offset = -1;
1209         io_req->offset = offset;
1210         io_req->length = len;
1211         io_req->error = 0;
1212         io_req->sector_mask = 0;
1213
1214         io_req->op = (rq_data_dir(req) == READ) ? UBD_READ : UBD_WRITE;
1215         io_req->offsets[0] = 0;
1216         io_req->offsets[1] = ubd_dev->cow.data_offset;
1217         io_req->buffer = page_address(page) + page_offset;
1218         io_req->sectorsize = 1 << 9;
1219
1220         if(ubd_dev->cow.file != NULL)
1221                 cowify_req(io_req, ubd_dev->cow.bitmap,
1222                            ubd_dev->cow.bitmap_offset, ubd_dev->cow.bitmap_len);
1223
1224 }
1225
1226 /* Called with dev->lock held */
1227 static void do_ubd_request(struct request_queue *q)
1228 {
1229         struct io_thread_req *io_req;
1230         struct request *req;
1231         sector_t sector;
1232         int n;
1233
1234         while(1){
1235                 struct ubd *dev = q->queuedata;
1236                 if(dev->end_sg == 0){
1237                         struct request *req = blk_fetch_request(q);
1238                         if(req == NULL)
1239                                 return;
1240
1241                         dev->request = req;
1242                         dev->start_sg = 0;
1243                         dev->end_sg = blk_rq_map_sg(q, req, dev->sg);
1244                 }
1245
1246                 req = dev->request;
1247                 sector = blk_rq_pos(req);
1248                 while(dev->start_sg < dev->end_sg){
1249                         struct scatterlist *sg = &dev->sg[dev->start_sg];
1250
1251                         io_req = kmalloc(sizeof(struct io_thread_req),
1252                                          GFP_ATOMIC);
1253                         if(io_req == NULL){
1254                                 if(list_empty(&dev->restart))
1255                                         list_add(&dev->restart, &restart);
1256                                 return;
1257                         }
1258                         prepare_request(req, io_req,
1259                                         (unsigned long long)sector << 9,
1260                                         sg->offset, sg->length, sg_page(sg));
1261
1262                         sector += sg->length >> 9;
1263                         n = os_write_file(thread_fd, &io_req,
1264                                           sizeof(struct io_thread_req *));
1265                         if(n != sizeof(struct io_thread_req *)){
1266                                 if(n != -EAGAIN)
1267                                         printk("write to io thread failed, "
1268                                                "errno = %d\n", -n);
1269                                 else if(list_empty(&dev->restart))
1270                                         list_add(&dev->restart, &restart);
1271                                 kfree(io_req);
1272                                 return;
1273                         }
1274
1275                         dev->start_sg++;
1276                 }
1277                 dev->end_sg = 0;
1278                 dev->request = NULL;
1279         }
1280 }
1281
1282 static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
1283 {
1284         struct ubd *ubd_dev = bdev->bd_disk->private_data;
1285
1286         geo->heads = 128;
1287         geo->sectors = 32;
1288         geo->cylinders = ubd_dev->size / (128 * 32 * 512);
1289         return 0;
1290 }
1291
1292 static int ubd_ioctl(struct block_device *bdev, fmode_t mode,
1293                      unsigned int cmd, unsigned long arg)
1294 {
1295         struct ubd *ubd_dev = bdev->bd_disk->private_data;
1296         u16 ubd_id[ATA_ID_WORDS];
1297
1298         switch (cmd) {
1299                 struct cdrom_volctrl volume;
1300         case HDIO_GET_IDENTITY:
1301                 memset(&ubd_id, 0, ATA_ID_WORDS * 2);
1302                 ubd_id[ATA_ID_CYLS]     = ubd_dev->size / (128 * 32 * 512);
1303                 ubd_id[ATA_ID_HEADS]    = 128;
1304                 ubd_id[ATA_ID_SECTORS]  = 32;
1305                 if(copy_to_user((char __user *) arg, (char *) &ubd_id,
1306                                  sizeof(ubd_id)))
1307                         return -EFAULT;
1308                 return 0;
1309
1310         case CDROMVOLREAD:
1311                 if(copy_from_user(&volume, (char __user *) arg, sizeof(volume)))
1312                         return -EFAULT;
1313                 volume.channel0 = 255;
1314                 volume.channel1 = 255;
1315                 volume.channel2 = 255;
1316                 volume.channel3 = 255;
1317                 if(copy_to_user((char __user *) arg, &volume, sizeof(volume)))
1318                         return -EFAULT;
1319                 return 0;
1320         }
1321         return -EINVAL;
1322 }
1323
1324 static int update_bitmap(struct io_thread_req *req)
1325 {
1326         int n;
1327
1328         if(req->cow_offset == -1)
1329                 return 0;
1330
1331         n = os_seek_file(req->fds[1], req->cow_offset);
1332         if(n < 0){
1333                 printk("do_io - bitmap lseek failed : err = %d\n", -n);
1334                 return 1;
1335         }
1336
1337         n = os_write_file(req->fds[1], &req->bitmap_words,
1338                           sizeof(req->bitmap_words));
1339         if(n != sizeof(req->bitmap_words)){
1340                 printk("do_io - bitmap update failed, err = %d fd = %d\n", -n,
1341                        req->fds[1]);
1342                 return 1;
1343         }
1344
1345         return 0;
1346 }
1347
1348 static void do_io(struct io_thread_req *req)
1349 {
1350         char *buf;
1351         unsigned long len;
1352         int n, nsectors, start, end, bit;
1353         int err;
1354         __u64 off;
1355
1356         nsectors = req->length / req->sectorsize;
1357         start = 0;
1358         do {
1359                 bit = ubd_test_bit(start, (unsigned char *) &req->sector_mask);
1360                 end = start;
1361                 while((end < nsectors) &&
1362                       (ubd_test_bit(end, (unsigned char *)
1363                                     &req->sector_mask) == bit))
1364                         end++;
1365
1366                 off = req->offset + req->offsets[bit] +
1367                         start * req->sectorsize;
1368                 len = (end - start) * req->sectorsize;
1369                 buf = &req->buffer[start * req->sectorsize];
1370
1371                 err = os_seek_file(req->fds[bit], off);
1372                 if(err < 0){
1373                         printk("do_io - lseek failed : err = %d\n", -err);
1374                         req->error = 1;
1375                         return;
1376                 }
1377                 if(req->op == UBD_READ){
1378                         n = 0;
1379                         do {
1380                                 buf = &buf[n];
1381                                 len -= n;
1382                                 n = os_read_file(req->fds[bit], buf, len);
1383                                 if (n < 0) {
1384                                         printk("do_io - read failed, err = %d "
1385                                                "fd = %d\n", -n, req->fds[bit]);
1386                                         req->error = 1;
1387                                         return;
1388                                 }
1389                         } while((n < len) && (n != 0));
1390                         if (n < len) memset(&buf[n], 0, len - n);
1391                 } else {
1392                         n = os_write_file(req->fds[bit], buf, len);
1393                         if(n != len){
1394                                 printk("do_io - write failed err = %d "
1395                                        "fd = %d\n", -n, req->fds[bit]);
1396                                 req->error = 1;
1397                                 return;
1398                         }
1399                 }
1400
1401                 start = end;
1402         } while(start < nsectors);
1403
1404         req->error = update_bitmap(req);
1405 }
1406
1407 /* Changed in start_io_thread, which is serialized by being called only
1408  * from ubd_init, which is an initcall.
1409  */
1410 int kernel_fd = -1;
1411
1412 /* Only changed by the io thread. XXX: currently unused. */
1413 static int io_count = 0;
1414
1415 int io_thread(void *arg)
1416 {
1417         struct io_thread_req *req;
1418         int n;
1419
1420         ignore_sigwinch_sig();
1421         while(1){
1422                 n = os_read_file(kernel_fd, &req,
1423                                  sizeof(struct io_thread_req *));
1424                 if(n != sizeof(struct io_thread_req *)){
1425                         if(n < 0)
1426                                 printk("io_thread - read failed, fd = %d, "
1427                                        "err = %d\n", kernel_fd, -n);
1428                         else {
1429                                 printk("io_thread - short read, fd = %d, "
1430                                        "length = %d\n", kernel_fd, n);
1431                         }
1432                         continue;
1433                 }
1434                 io_count++;
1435                 do_io(req);
1436                 n = os_write_file(kernel_fd, &req,
1437                                   sizeof(struct io_thread_req *));
1438                 if(n != sizeof(struct io_thread_req *))
1439                         printk("io_thread - write failed, fd = %d, err = %d\n",
1440                                kernel_fd, -n);
1441         }
1442
1443         return 0;
1444 }