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 MAJOR_NR UBD_MAJOR
  21 #define UBD_SHIFT 4
  22
  23 #include "linux/kernel.h"
  24 #include "linux/module.h"
  25 #include "linux/blkdev.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/ctype.h"
  31 #include "linux/capability.h"
  32 #include "linux/mm.h"
  33 #include "linux/vmalloc.h"
  34 #include "linux/blkpg.h"
  35 #include "linux/genhd.h"
  36 #include "linux/spinlock.h"
  37 #include "linux/platform_device.h"
  38 #include "linux/scatterlist.h"
  39 #include "asm/segment.h"
  40 #include "asm/uaccess.h"
  41 #include "asm/irq.h"
  42 #include "asm/types.h"
  43 #include "asm/tlbflush.h"
  44 #include "mem_user.h"
  45 #include "kern_util.h"
  46 #include "kern.h"
  47 #include "mconsole_kern.h"
  48 #include "init.h"
  49 #include "irq_user.h"
  50 #include "irq_kern.h"
  51 #include "ubd_user.h"
  52 #include "os.h"
  53 #include "mem.h"
  54 #include "mem_kern.h"
  55 #include "cow.h"
  56
  57 enum ubd_req { UBD_READ, UBD_WRITE };
  58
  59 struct io_thread_req {
  60         struct request *req;
  61         enum ubd_req op;
  62         int fds[2];
  63         unsigned long offsets[2];
  64         unsigned long long offset;
  65         unsigned long length;
  66         char *buffer;
  67         int sectorsize;
  68         unsigned long sector_mask;
  69         unsigned long long cow_offset;
  70         unsigned long bitmap_words[2];
  71         int error;
  72 };
  73
  74 extern int open_ubd_file(char *file, struct openflags *openflags, int shared,
  75                          char **backing_file_out, int *bitmap_offset_out,
  76                          unsigned long *bitmap_len_out, int *data_offset_out,
  77                          int *create_cow_out);
  78 extern int create_cow_file(char *cow_file, char *backing_file,
  79                            struct openflags flags, int sectorsize,
  80                            int alignment, int *bitmap_offset_out,
  81                            unsigned long *bitmap_len_out,
  82                            int *data_offset_out);
  83 extern int read_cow_bitmap(int fd, void *buf, int offset, int len);
  84 extern void do_io(struct io_thread_req *req);
  85
  86 static inline int ubd_test_bit(__u64 bit, unsigned char *data)
  87 {
  88         __u64 n;
  89         int bits, off;
  90
  91         bits = sizeof(data[0]) * 8;
  92         n = bit / bits;
  93         off = bit % bits;
  94         return (data[n] & (1 << off)) != 0;
  95 }
  96
  97 static inline void ubd_set_bit(__u64 bit, unsigned char *data)
  98 {
  99         __u64 n;
 100         int bits, off;
 101
 102         bits = sizeof(data[0]) * 8;
 103         n = bit / bits;
 104         off = bit % bits;
 105         data[n] |= (1 << off);
 106 }
 107 /*End stuff from ubd_user.h*/
 108
 109 #define DRIVER_NAME "uml-blkdev"
 110
 111 static DEFINE_MUTEX(ubd_lock);
 112
 113 static int ubd_open(struct inode * inode, struct file * filp);
 114 static int ubd_release(struct inode * inode, struct file * file);
 115 static int ubd_ioctl(struct inode * inode, struct file * file,
 116                      unsigned int cmd, unsigned long arg);
 117 static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo);
 118
 119 #define MAX_DEV (16)
 120
 121 static struct block_device_operations ubd_blops = {
 122         .owner          = THIS_MODULE,
 123         .open           = ubd_open,
 124         .release        = ubd_release,
 125         .ioctl          = ubd_ioctl,
 126         .getgeo         = ubd_getgeo,
 127 };
 128
 129 /* Protected by ubd_lock */
 130 static int fake_major = MAJOR_NR;
 131 static struct gendisk *ubd_gendisk[MAX_DEV];
 132 static struct gendisk *fake_gendisk[MAX_DEV];
 133
 134 #ifdef CONFIG_BLK_DEV_UBD_SYNC
 135 #define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 1, .c = 0, \
 136                                          .cl = 1 })
 137 #else
 138 #define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 0, .c = 0, \
 139                                          .cl = 1 })
 140 #endif
 141 static struct openflags global_openflags = OPEN_FLAGS;
 142
 143 struct cow {
 144         /* backing file name */
 145         char *file;
 146         /* backing file fd */
 147         int fd;
 148         unsigned long *bitmap;
 149         unsigned long bitmap_len;
 150         int bitmap_offset;
 151         int data_offset;
 152 };
 153
 154 #define MAX_SG 64
 155
 156 struct ubd {
 157         struct list_head restart;
 158         /* name (and fd, below) of the file opened for writing, either the
 159          * backing or the cow file. */
 160         char *file;
 161         int count;
 162         int fd;
 163         __u64 size;
 164         struct openflags boot_openflags;
 165         struct openflags openflags;
 166         unsigned shared:1;
 167         unsigned no_cow:1;
 168         struct cow cow;
 169         struct platform_device pdev;
 170         struct request_queue *queue;
 171         spinlock_t lock;
 172         struct scatterlist sg[MAX_SG];
 173         struct request *request;
 174         int start_sg, end_sg;
 175 };
 176
 177 #define DEFAULT_COW { \
 178         .file =                 NULL, \
 179         .fd =                   -1,     \
 180         .bitmap =               NULL, \
 181         .bitmap_offset =        0, \
 182         .data_offset =          0, \
 183 }
 184
 185 #define DEFAULT_UBD { \
 186         .file =                 NULL, \
 187         .count =                0, \
 188         .fd =                   -1, \
 189         .size =                 -1, \
 190         .boot_openflags =       OPEN_FLAGS, \
 191         .openflags =            OPEN_FLAGS, \
 192         .no_cow =               0, \
 193         .shared =               0, \
 194         .cow =                  DEFAULT_COW, \
 195         .lock =                 SPIN_LOCK_UNLOCKED,     \
 196         .request =              NULL, \
 197         .start_sg =             0, \
 198         .end_sg =               0, \
 199 }
 200
 201 /* Protected by ubd_lock */
 202 struct ubd ubd_devs[MAX_DEV] = { [ 0 ... MAX_DEV - 1 ] = DEFAULT_UBD };
 203
 204 /* Only changed by fake_ide_setup which is a setup */
 205 static int fake_ide = 0;
 206 static struct proc_dir_entry *proc_ide_root = NULL;
 207 static struct proc_dir_entry *proc_ide = NULL;
 208
 209 static void make_proc_ide(void)
 210 {
 211         proc_ide_root = proc_mkdir("ide", NULL);
 212         proc_ide = proc_mkdir("ide0", proc_ide_root);
 213 }
 214
 215 static int proc_ide_read_media(char *page, char **start, off_t off, int count,
 216                                int *eof, void *data)
 217 {
 218         int len;
 219
 220         strcpy(page, "disk\n");
 221         len = strlen("disk\n");
 222         len -= off;
 223         if (len < count){
 224                 *eof = 1;
 225                 if (len <= 0) return 0;
 226         }
 227         else len = count;
 228         *start = page + off;
 229         return len;
 230 }
 231
 232 static void make_ide_entries(char *dev_name)
 233 {
 234         struct proc_dir_entry *dir, *ent;
 235         char name[64];
 236
 237         if(proc_ide_root == NULL) make_proc_ide();
 238
 239         dir = proc_mkdir(dev_name, proc_ide);
 240         if(!dir) return;
 241
 242         ent = create_proc_entry("media", S_IFREG|S_IRUGO, dir);
 243         if(!ent) return;
 244         ent->data = NULL;
 245         ent->read_proc = proc_ide_read_media;
 246         ent->write_proc = NULL;
 247         sprintf(name,"ide0/%s", dev_name);
 248         proc_symlink(dev_name, proc_ide_root, name);
 249 }
 250
 251 static int fake_ide_setup(char *str)
 252 {
 253         fake_ide = 1;
 254         return 1;
 255 }
 256
 257 __setup("fake_ide", fake_ide_setup);
 258
 259 __uml_help(fake_ide_setup,
 260 "fake_ide\n"
 261 "    Create ide0 entries that map onto ubd devices.\n\n"
 262 );
 263
 264 static int parse_unit(char **ptr)
 265 {
 266         char *str = *ptr, *end;
 267         int n = -1;
 268
 269         if(isdigit(*str)) {
 270                 n = simple_strtoul(str, &end, 0);
 271                 if(end == str)
 272                         return -1;
 273                 *ptr = end;
 274         }
 275         else if (('a' <= *str) && (*str <= 'z')) {
 276                 n = *str - 'a';
 277                 str++;
 278                 *ptr = str;
 279         }
 280         return n;
 281 }
 282
 283 /* If *index_out == -1 at exit, the passed option was a general one;
 284  * otherwise, the str pointer is used (and owned) inside ubd_devs array, so it
 285  * should not be freed on exit.
 286  */
 287 static int ubd_setup_common(char *str, int *index_out, char **error_out)
 288 {
 289         struct ubd *ubd_dev;
 290         struct openflags flags = global_openflags;
 291         char *backing_file;
 292         int n, err = 0, i;
 293
 294         if(index_out) *index_out = -1;
 295         n = *str;
 296         if(n == '='){
 297                 char *end;
 298                 int major;
 299
 300                 str++;
 301                 if(!strcmp(str, "sync")){
 302                         global_openflags = of_sync(global_openflags);
 303                         goto out1;
 304                 }
 305
 306                 err = -EINVAL;
 307                 major = simple_strtoul(str, &end, 0);
 308                 if((*end != '\0') || (end == str)){
 309                         *error_out = "Didn't parse major number";
 310                         goto out1;
 311                 }
 312
 313                 mutex_lock(&ubd_lock);
 314                 if(fake_major != MAJOR_NR){
 315                         *error_out = "Can't assign a fake major twice";
 316                         goto out1;
 317                 }
 318
 319                 fake_major = major;
 320
 321                 printk(KERN_INFO "Setting extra ubd major number to %d\n",
 322                        major);
 323                 err = 0;
 324         out1:
 325                 mutex_unlock(&ubd_lock);
 326                 return err;
 327         }
 328
 329         n = parse_unit(&str);
 330         if(n < 0){
 331                 *error_out = "Couldn't parse device number";
 332                 return -EINVAL;
 333         }
 334         if(n >= MAX_DEV){
 335                 *error_out = "Device number out of range";
 336                 return 1;
 337         }
 338
 339         err = -EBUSY;
 340         mutex_lock(&ubd_lock);
 341
 342         ubd_dev = &ubd_devs[n];
 343         if(ubd_dev->file != NULL){
 344                 *error_out = "Device is already configured";
 345                 goto out;
 346         }
 347
 348         if (index_out)
 349                 *index_out = n;
 350
 351         err = -EINVAL;
 352         for (i = 0; i < sizeof("rscd="); i++) {
 353                 switch (*str) {
 354                 case 'r':
 355                         flags.w = 0;
 356                         break;
 357                 case 's':
 358                         flags.s = 1;
 359                         break;
 360                 case 'd':
 361                         ubd_dev->no_cow = 1;
 362                         break;
 363                 case 'c':
 364                         ubd_dev->shared = 1;
 365                         break;
 366                 case '=':
 367                         str++;
 368                         goto break_loop;
 369                 default:
 370                         *error_out = "Expected '=' or flag letter "
 371                                 "(r, s, c, or d)";
 372                         goto out;
 373                 }
 374                 str++;
 375         }
 376
 377         if (*str == '=')
 378                 *error_out = "Too many flags specified";
 379         else
 380                 *error_out = "Missing '='";
 381         goto out;
 382
 383 break_loop:
 384         backing_file = strchr(str, ',');
 385
 386         if (backing_file == NULL)
 387                 backing_file = strchr(str, ':');
 388
 389         if(backing_file != NULL){
 390                 if(ubd_dev->no_cow){
 391                         *error_out = "Can't specify both 'd' and a cow file";
 392                         goto out;
 393                 }
 394                 else {
 395                         *backing_file = '\0';
 396                         backing_file++;
 397                 }
 398         }
 399         err = 0;
 400         ubd_dev->file = str;
 401         ubd_dev->cow.file = backing_file;
 402         ubd_dev->boot_openflags = flags;
 403 out:
 404         mutex_unlock(&ubd_lock);
 405         return err;
 406 }
 407
 408 static int ubd_setup(char *str)
 409 {
 410         char *error;
 411         int err;
 412
 413         err = ubd_setup_common(str, NULL, &error);
 414         if(err)
 415                 printk(KERN_ERR "Failed to initialize device with \"%s\" : "
 416                        "%s\n", str, error);
 417         return 1;
 418 }
 419
 420 __setup("ubd", ubd_setup);
 421 __uml_help(ubd_setup,
 422 "ubd<n><flags>=<filename>[(:|,)<filename2>]\n"
 423 "    This is used to associate a device with a file in the underlying\n"
 424 "    filesystem. When specifying two filenames, the first one is the\n"
 425 "    COW name and the second is the backing file name. As separator you can\n"
 426 "    use either a ':' or a ',': the first one allows writing things like;\n"
 427 "       ubd0=~/Uml/root_cow:~/Uml/root_backing_file\n"
 428 "    while with a ',' the shell would not expand the 2nd '~'.\n"
 429 "    When using only one filename, UML will detect whether to treat it like\n"
 430 "    a COW file or a backing file. To override this detection, add the 'd'\n"
 431 "    flag:\n"
 432 "       ubd0d=BackingFile\n"
 433 "    Usually, there is a filesystem in the file, but \n"
 434 "    that's not required. Swap devices containing swap files can be\n"
 435 "    specified like this. Also, a file which doesn't contain a\n"
 436 "    filesystem can have its contents read in the virtual \n"
 437 "    machine by running 'dd' on the device. <n> must be in the range\n"
 438 "    0 to 7. Appending an 'r' to the number will cause that device\n"
 439 "    to be mounted read-only. For example ubd1r=./ext_fs. Appending\n"
 440 "    an 's' will cause data to be written to disk on the host immediately.\n\n"
 441 );
 442
 443 static int udb_setup(char *str)
 444 {
 445         printk("udb%s specified on command line is almost certainly a ubd -> "
 446                "udb TYPO\n", str);
 447         return 1;
 448 }
 449
 450 __setup("udb", udb_setup);
 451 __uml_help(udb_setup,
 452 "udb\n"
 453 "    This option is here solely to catch ubd -> udb typos, which can be\n"
 454 "    to impossible to catch visually unless you specifically look for\n"
 455 "    them.  The only result of any option starting with 'udb' is an error\n"
 456 "    in the boot output.\n\n"
 457 );
 458
 459 static int fakehd_set = 0;
 460 static int fakehd(char *str)
 461 {
 462         printk(KERN_INFO "fakehd : Changing ubd name to \"hd\".\n");
 463         fakehd_set = 1;
 464         return 1;
 465 }
 466
 467 __setup("fakehd", fakehd);
 468 __uml_help(fakehd,
 469 "fakehd\n"
 470 "    Change the ubd device name to \"hd\".\n\n"
 471 );
 472
 473 static void do_ubd_request(struct request_queue * q);
 474
 475 /* Only changed by ubd_init, which is an initcall. */
 476 int thread_fd = -1;
 477
 478 static void ubd_end_request(struct request *req, int bytes, int error)
 479 {
 480         blk_end_request(req, error, bytes);
 481 }
 482
 483 /* Callable only from interrupt context - otherwise you need to do
 484  * spin_lock_irq()/spin_lock_irqsave() */
 485 static inline void ubd_finish(struct request *req, int bytes)
 486 {
 487         if(bytes < 0){
 488                 ubd_end_request(req, 0, -EIO);
 489                 return;
 490         }
 491         ubd_end_request(req, bytes, 0);
 492 }
 493
 494 static LIST_HEAD(restart);
 495
 496 /* XXX - move this inside ubd_intr. */
 497 /* Called without dev->lock held, and only in interrupt context. */
 498 static void ubd_handler(void)
 499 {
 500         struct io_thread_req *req;
 501         struct request *rq;
 502         struct ubd *ubd;
 503         struct list_head *list, *next_ele;
 504         unsigned long flags;
 505         int n;
 506
 507         while(1){
 508                 n = os_read_file(thread_fd, &req,
 509                                  sizeof(struct io_thread_req *));
 510                 if(n != sizeof(req)){
 511                         if(n == -EAGAIN)
 512                                 break;
 513                         printk(KERN_ERR "spurious interrupt in ubd_handler, "
 514                                "err = %d\n", -n);
 515                         return;
 516                 }
 517
 518                 rq = req->req;
 519                 rq->nr_sectors -= req->length >> 9;
 520                 if(rq->nr_sectors == 0)
 521                         ubd_finish(rq, rq->hard_nr_sectors << 9);
 522                 kfree(req);
 523         }
 524         reactivate_fd(thread_fd, UBD_IRQ);
 525
 526         list_for_each_safe(list, next_ele, &restart){
 527                 ubd = container_of(list, struct ubd, restart);
 528                 list_del_init(&ubd->restart);
 529                 spin_lock_irqsave(&ubd->lock, flags);
 530                 do_ubd_request(ubd->queue);
 531                 spin_unlock_irqrestore(&ubd->lock, flags);
 532         }
 533 }
 534
 535 static irqreturn_t ubd_intr(int irq, void *dev)
 536 {
 537         ubd_handler();
 538         return IRQ_HANDLED;
 539 }
 540
 541 /* Only changed by ubd_init, which is an initcall. */
 542 static int io_pid = -1;
 543
 544 void kill_io_thread(void)
 545 {
 546         if(io_pid != -1)
 547                 os_kill_process(io_pid, 1);
 548 }
 549
 550 __uml_exitcall(kill_io_thread);
 551
 552 static inline int ubd_file_size(struct ubd *ubd_dev, __u64 *size_out)
 553 {
 554         char *file;
 555
 556         file = ubd_dev->cow.file ? ubd_dev->cow.file : ubd_dev->file;
 557         return os_file_size(file, size_out);
 558 }
 559
 560 static void ubd_close_dev(struct ubd *ubd_dev)
 561 {
 562         os_close_file(ubd_dev->fd);
 563         if(ubd_dev->cow.file == NULL)
 564                 return;
 565
 566         os_close_file(ubd_dev->cow.fd);
 567         vfree(ubd_dev->cow.bitmap);
 568         ubd_dev->cow.bitmap = NULL;
 569 }
 570
 571 static int ubd_open_dev(struct ubd *ubd_dev)
 572 {
 573         struct openflags flags;
 574         char **back_ptr;
 575         int err, create_cow, *create_ptr;
 576         int fd;
 577
 578         ubd_dev->openflags = ubd_dev->boot_openflags;
 579         create_cow = 0;
 580         create_ptr = (ubd_dev->cow.file != NULL) ? &create_cow : NULL;
 581         back_ptr = ubd_dev->no_cow ? NULL : &ubd_dev->cow.file;
 582
 583         fd = open_ubd_file(ubd_dev->file, &ubd_dev->openflags, ubd_dev->shared,
 584                                 back_ptr, &ubd_dev->cow.bitmap_offset,
 585                                 &ubd_dev->cow.bitmap_len, &ubd_dev->cow.data_offset,
 586                                 create_ptr);
 587
 588         if((fd == -ENOENT) && create_cow){
 589                 fd = create_cow_file(ubd_dev->file, ubd_dev->cow.file,
 590                                           ubd_dev->openflags, 1 << 9, PAGE_SIZE,
 591                                           &ubd_dev->cow.bitmap_offset,
 592                                           &ubd_dev->cow.bitmap_len,
 593                                           &ubd_dev->cow.data_offset);
 594                 if(fd >= 0){
 595                         printk(KERN_INFO "Creating \"%s\" as COW file for "
 596                                "\"%s\"\n", ubd_dev->file, ubd_dev->cow.file);
 597                 }
 598         }
 599
 600         if(fd < 0){
 601                 printk("Failed to open '%s', errno = %d\n", ubd_dev->file,
 602                        -fd);
 603                 return fd;
 604         }
 605         ubd_dev->fd = fd;
 606
 607         if(ubd_dev->cow.file != NULL){
 608                 blk_queue_max_sectors(ubd_dev->queue, 8 * sizeof(long));
 609
 610                 err = -ENOMEM;
 611                 ubd_dev->cow.bitmap = vmalloc(ubd_dev->cow.bitmap_len);
 612                 if(ubd_dev->cow.bitmap == NULL){
 613                         printk(KERN_ERR "Failed to vmalloc COW bitmap\n");
 614                         goto error;
 615                 }
 616                 flush_tlb_kernel_vm();
 617
 618                 err = read_cow_bitmap(ubd_dev->fd, ubd_dev->cow.bitmap,
 619                                       ubd_dev->cow.bitmap_offset,
 620                                       ubd_dev->cow.bitmap_len);
 621                 if(err < 0)
 622                         goto error;
 623
 624                 flags = ubd_dev->openflags;
 625                 flags.w = 0;
 626                 err = open_ubd_file(ubd_dev->cow.file, &flags, ubd_dev->shared, NULL,
 627                                     NULL, NULL, NULL, NULL);
 628                 if(err < 0) goto error;
 629                 ubd_dev->cow.fd = err;
 630         }
 631         return 0;
 632  error:
 633         os_close_file(ubd_dev->fd);
 634         return err;
 635 }
 636
 637 static void ubd_device_release(struct device *dev)
 638 {
 639         struct ubd *ubd_dev = dev->driver_data;
 640
 641         blk_cleanup_queue(ubd_dev->queue);
 642         *ubd_dev = ((struct ubd) DEFAULT_UBD);
 643 }
 644
 645 static int ubd_disk_register(int major, u64 size, int unit,
 646                              struct gendisk **disk_out)
 647 {
 648         struct gendisk *disk;
 649
 650         disk = alloc_disk(1 << UBD_SHIFT);
 651         if(disk == NULL)
 652                 return -ENOMEM;
 653
 654         disk->major = major;
 655         disk->first_minor = unit << UBD_SHIFT;
 656         disk->fops = &ubd_blops;
 657         set_capacity(disk, size / 512);
 658         if(major == MAJOR_NR)
 659                 sprintf(disk->disk_name, "ubd%c", 'a' + unit);
 660         else
 661                 sprintf(disk->disk_name, "ubd_fake%d", unit);
 662
 663         /* sysfs register (not for ide fake devices) */
 664         if (major == MAJOR_NR) {
 665                 ubd_devs[unit].pdev.id   = unit;
 666                 ubd_devs[unit].pdev.name = DRIVER_NAME;
 667                 ubd_devs[unit].pdev.dev.release = ubd_device_release;
 668                 ubd_devs[unit].pdev.dev.driver_data = &ubd_devs[unit];
 669                 platform_device_register(&ubd_devs[unit].pdev);
 670                 disk->driverfs_dev = &ubd_devs[unit].pdev.dev;
 671         }
 672
 673         disk->private_data = &ubd_devs[unit];
 674         disk->queue = ubd_devs[unit].queue;
 675         add_disk(disk);
 676
 677         *disk_out = disk;
 678         return 0;
 679 }
 680
 681 #define ROUND_BLOCK(n) ((n + ((1 << 9) - 1)) & (-1 << 9))
 682
 683 static int ubd_add(int n, char **error_out)
 684 {
 685         struct ubd *ubd_dev = &ubd_devs[n];
 686         int err = 0;
 687
 688         if(ubd_dev->file == NULL)
 689                 goto out;
 690
 691         err = ubd_file_size(ubd_dev, &ubd_dev->size);
 692         if(err < 0){
 693                 *error_out = "Couldn't determine size of device's file";
 694                 goto out;
 695         }
 696
 697         ubd_dev->size = ROUND_BLOCK(ubd_dev->size);
 698
 699         INIT_LIST_HEAD(&ubd_dev->restart);
 700         sg_init_table(ubd_dev->sg, MAX_SG);
 701
 702         err = -ENOMEM;
 703         ubd_dev->queue = blk_init_queue(do_ubd_request, &ubd_dev->lock);
 704         if (ubd_dev->queue == NULL) {
 705                 *error_out = "Failed to initialize device queue";
 706                 goto out;
 707         }
 708         ubd_dev->queue->queuedata = ubd_dev;
 709
 710         blk_queue_max_hw_segments(ubd_dev->queue, MAX_SG);
 711         err = ubd_disk_register(MAJOR_NR, ubd_dev->size, n, &ubd_gendisk[n]);
 712         if(err){
 713                 *error_out = "Failed to register device";
 714                 goto out_cleanup;
 715         }
 716
 717         if(fake_major != MAJOR_NR)
 718                 ubd_disk_register(fake_major, ubd_dev->size, n,
 719                                   &fake_gendisk[n]);
 720
 721         /* perhaps this should also be under the "if (fake_major)" above */
 722         /* using the fake_disk->disk_name and also the fakehd_set name */
 723         if (fake_ide)
 724                 make_ide_entries(ubd_gendisk[n]->disk_name);
 725
 726         err = 0;
 727 out:
 728         return err;
 729
 730 out_cleanup:
 731         blk_cleanup_queue(ubd_dev->queue);
 732         goto out;
 733 }
 734
 735 static int ubd_config(char *str, char **error_out)
 736 {
 737         int n, ret;
 738
 739         /* This string is possibly broken up and stored, so it's only
 740          * freed if ubd_setup_common fails, or if only general options
 741          * were set.
 742          */
 743         str = kstrdup(str, GFP_KERNEL);
 744         if (str == NULL) {
 745                 *error_out = "Failed to allocate memory";
 746                 return -ENOMEM;
 747         }
 748
 749         ret = ubd_setup_common(str, &n, error_out);
 750         if (ret)
 751                 goto err_free;
 752
 753         if (n == -1) {
 754                 ret = 0;
 755                 goto err_free;
 756         }
 757
 758         mutex_lock(&ubd_lock);
 759         ret = ubd_add(n, error_out);
 760         if (ret)
 761                 ubd_devs[n].file = NULL;
 762         mutex_unlock(&ubd_lock);
 763
 764 out:
 765         return ret;
 766
 767 err_free:
 768         kfree(str);
 769         goto out;
 770 }
 771
 772 static int ubd_get_config(char *name, char *str, int size, char **error_out)
 773 {
 774         struct ubd *ubd_dev;
 775         int n, len = 0;
 776
 777         n = parse_unit(&name);
 778         if((n >= MAX_DEV) || (n < 0)){
 779                 *error_out = "ubd_get_config : device number out of range";
 780                 return -1;
 781         }
 782
 783         ubd_dev = &ubd_devs[n];
 784         mutex_lock(&ubd_lock);
 785
 786         if(ubd_dev->file == NULL){
 787                 CONFIG_CHUNK(str, size, len, "", 1);
 788                 goto out;
 789         }
 790
 791         CONFIG_CHUNK(str, size, len, ubd_dev->file, 0);
 792
 793         if(ubd_dev->cow.file != NULL){
 794                 CONFIG_CHUNK(str, size, len, ",", 0);
 795                 CONFIG_CHUNK(str, size, len, ubd_dev->cow.file, 1);
 796         }
 797         else CONFIG_CHUNK(str, size, len, "", 1);
 798
 799  out:
 800         mutex_unlock(&ubd_lock);
 801         return len;
 802 }
 803
 804 static int ubd_id(char **str, int *start_out, int *end_out)
 805 {
 806         int n;
 807
 808         n = parse_unit(str);
 809         *start_out = 0;
 810         *end_out = MAX_DEV - 1;
 811         return n;
 812 }
 813
 814 static int ubd_remove(int n, char **error_out)
 815 {
 816         struct gendisk *disk = ubd_gendisk[n];
 817         struct ubd *ubd_dev;
 818         int err = -ENODEV;
 819
 820         mutex_lock(&ubd_lock);
 821
 822         ubd_dev = &ubd_devs[n];
 823
 824         if(ubd_dev->file == NULL)
 825                 goto out;
 826
 827         /* you cannot remove a open disk */
 828         err = -EBUSY;
 829         if(ubd_dev->count > 0)
 830                 goto out;
 831
 832         ubd_gendisk[n] = NULL;
 833         if(disk != NULL){
 834                 del_gendisk(disk);
 835                 put_disk(disk);
 836         }
 837
 838         if(fake_gendisk[n] != NULL){
 839                 del_gendisk(fake_gendisk[n]);
 840                 put_disk(fake_gendisk[n]);
 841                 fake_gendisk[n] = NULL;
 842         }
 843
 844         err = 0;
 845         platform_device_unregister(&ubd_dev->pdev);
 846 out:
 847         mutex_unlock(&ubd_lock);
 848         return err;
 849 }
 850
 851 /* All these are called by mconsole in process context and without
 852  * ubd-specific locks.  The structure itself is const except for .list.
 853  */
 854 static struct mc_device ubd_mc = {
 855         .list           = LIST_HEAD_INIT(ubd_mc.list),
 856         .name           = "ubd",
 857         .config         = ubd_config,
 858         .get_config     = ubd_get_config,
 859         .id             = ubd_id,
 860         .remove         = ubd_remove,
 861 };
 862
 863 static int __init ubd_mc_init(void)
 864 {
 865         mconsole_register_dev(&ubd_mc);
 866         return 0;
 867 }
 868
 869 __initcall(ubd_mc_init);
 870
 871 static int __init ubd0_init(void)
 872 {
 873         struct ubd *ubd_dev = &ubd_devs[0];
 874
 875         mutex_lock(&ubd_lock);
 876         if(ubd_dev->file == NULL)
 877                 ubd_dev->file = "root_fs";
 878         mutex_unlock(&ubd_lock);
 879
 880         return 0;
 881 }
 882
 883 __initcall(ubd0_init);
 884
 885 /* Used in ubd_init, which is an initcall */
 886 static struct platform_driver ubd_driver = {
 887         .driver = {
 888                 .name  = DRIVER_NAME,
 889         },
 890 };
 891
 892 static int __init ubd_init(void)
 893 {
 894         char *error;
 895         int i, err;
 896
 897         if (register_blkdev(MAJOR_NR, "ubd"))
 898                 return -1;
 899
 900         if (fake_major != MAJOR_NR) {
 901                 char name[sizeof("ubd_nnn\0")];
 902
 903                 snprintf(name, sizeof(name), "ubd_%d", fake_major);
 904                 if (register_blkdev(fake_major, "ubd"))
 905                         return -1;
 906         }
 907         platform_driver_register(&ubd_driver);
 908         mutex_lock(&ubd_lock);
 909         for (i = 0; i < MAX_DEV; i++){
 910                 err = ubd_add(i, &error);
 911                 if(err)
 912                         printk(KERN_ERR "Failed to initialize ubd device %d :"
 913                                "%s\n", i, error);
 914         }
 915         mutex_unlock(&ubd_lock);
 916         return 0;
 917 }
 918
 919 late_initcall(ubd_init);
 920
 921 static int __init ubd_driver_init(void){
 922         unsigned long stack;
 923         int err;
 924
 925         /* Set by CONFIG_BLK_DEV_UBD_SYNC or ubd=sync.*/
 926         if(global_openflags.s){
 927                 printk(KERN_INFO "ubd: Synchronous mode\n");
 928                 /* Letting ubd=sync be like using ubd#s= instead of ubd#= is
 929                  * enough. So use anyway the io thread. */
 930         }
 931         stack = alloc_stack(0, 0);
 932         io_pid = start_io_thread(stack + PAGE_SIZE - sizeof(void *),
 933                                  &thread_fd);
 934         if(io_pid < 0){
 935                 printk(KERN_ERR
 936                        "ubd : Failed to start I/O thread (errno = %d) - "
 937                        "falling back to synchronous I/O\n", -io_pid);
 938                 io_pid = -1;
 939                 return 0;
 940         }
 941         err = um_request_irq(UBD_IRQ, thread_fd, IRQ_READ, ubd_intr,
 942                              IRQF_DISABLED, "ubd", ubd_devs);
 943         if(err != 0)
 944                 printk(KERN_ERR "um_request_irq failed - errno = %d\n", -err);
 945         return 0;
 946 }
 947
 948 device_initcall(ubd_driver_init);
 949
 950 static int ubd_open(struct inode *inode, struct file *filp)
 951 {
 952         struct gendisk *disk = inode->i_bdev->bd_disk;
 953         struct ubd *ubd_dev = disk->private_data;
 954         int err = 0;
 955
 956         if(ubd_dev->count == 0){
 957                 err = ubd_open_dev(ubd_dev);
 958                 if(err){
 959                         printk(KERN_ERR "%s: Can't open \"%s\": errno = %d\n",
 960                                disk->disk_name, ubd_dev->file, -err);
 961                         goto out;
 962                 }
 963         }
 964         ubd_dev->count++;
 965         set_disk_ro(disk, !ubd_dev->openflags.w);
 966
 967         /* This should no more be needed. And it didn't work anyway to exclude
 968          * read-write remounting of filesystems.*/
 969         /*if((filp->f_mode & FMODE_WRITE) && !ubd_dev->openflags.w){
 970                 if(--ubd_dev->count == 0) ubd_close_dev(ubd_dev);
 971                 err = -EROFS;
 972         }*/
 973  out:
 974         return err;
 975 }
 976
 977 static int ubd_release(struct inode * inode, struct file * file)
 978 {
 979         struct gendisk *disk = inode->i_bdev->bd_disk;
 980         struct ubd *ubd_dev = disk->private_data;
 981
 982         if(--ubd_dev->count == 0)
 983                 ubd_close_dev(ubd_dev);
 984         return 0;
 985 }
 986
 987 static void cowify_bitmap(__u64 io_offset, int length, unsigned long *cow_mask,
 988                           __u64 *cow_offset, unsigned long *bitmap,
 989                           __u64 bitmap_offset, unsigned long *bitmap_words,
 990                           __u64 bitmap_len)
 991 {
 992         __u64 sector = io_offset >> 9;
 993         int i, update_bitmap = 0;
 994
 995         for(i = 0; i < length >> 9; i++){
 996                 if(cow_mask != NULL)
 997                         ubd_set_bit(i, (unsigned char *) cow_mask);
 998                 if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
 999                         continue;
1000
1001                 update_bitmap = 1;
1002                 ubd_set_bit(sector + i, (unsigned char *) bitmap);
1003         }
1004
1005         if(!update_bitmap)
1006                 return;
1007
1008         *cow_offset = sector / (sizeof(unsigned long) * 8);
1009
1010         /* This takes care of the case where we're exactly at the end of the
1011          * device, and *cow_offset + 1 is off the end.  So, just back it up
1012          * by one word.  Thanks to Lynn Kerby for the fix and James McMechan
1013          * for the original diagnosis.
1014          */
1015         if(*cow_offset == ((bitmap_len + sizeof(unsigned long) - 1) /
1016                            sizeof(unsigned long) - 1))
1017                 (*cow_offset)--;
1018
1019         bitmap_words[0] = bitmap[*cow_offset];
1020         bitmap_words[1] = bitmap[*cow_offset + 1];
1021
1022         *cow_offset *= sizeof(unsigned long);
1023         *cow_offset += bitmap_offset;
1024 }
1025
1026 static void cowify_req(struct io_thread_req *req, unsigned long *bitmap,
1027                        __u64 bitmap_offset, __u64 bitmap_len)
1028 {
1029         __u64 sector = req->offset >> 9;
1030         int i;
1031
1032         if(req->length > (sizeof(req->sector_mask) * 8) << 9)
1033                 panic("Operation too long");
1034
1035         if(req->op == UBD_READ) {
1036                 for(i = 0; i < req->length >> 9; i++){
1037                         if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
1038                                 ubd_set_bit(i, (unsigned char *)
1039                                             &req->sector_mask);
1040                 }
1041         }
1042         else cowify_bitmap(req->offset, req->length, &req->sector_mask,
1043                            &req->cow_offset, bitmap, bitmap_offset,
1044                            req->bitmap_words, bitmap_len);
1045 }
1046
1047 /* Called with dev->lock held */
1048 static void prepare_request(struct request *req, struct io_thread_req *io_req,
1049                             unsigned long long offset, int page_offset,
1050                             int len, struct page *page)
1051 {
1052         struct gendisk *disk = req->rq_disk;
1053         struct ubd *ubd_dev = disk->private_data;
1054
1055         io_req->req = req;
1056         io_req->fds[0] = (ubd_dev->cow.file != NULL) ? ubd_dev->cow.fd :
1057                 ubd_dev->fd;
1058         io_req->fds[1] = ubd_dev->fd;
1059         io_req->cow_offset = -1;
1060         io_req->offset = offset;
1061         io_req->length = len;
1062         io_req->error = 0;
1063         io_req->sector_mask = 0;
1064
1065         io_req->op = (rq_data_dir(req) == READ) ? UBD_READ : UBD_WRITE;
1066         io_req->offsets[0] = 0;
1067         io_req->offsets[1] = ubd_dev->cow.data_offset;
1068         io_req->buffer = page_address(page) + page_offset;
1069         io_req->sectorsize = 1 << 9;
1070
1071         if(ubd_dev->cow.file != NULL)
1072                 cowify_req(io_req, ubd_dev->cow.bitmap,
1073                            ubd_dev->cow.bitmap_offset, ubd_dev->cow.bitmap_len);
1074
1075 }
1076
1077 /* Called with dev->lock held */
1078 static void do_ubd_request(struct request_queue *q)
1079 {
1080         struct io_thread_req *io_req;
1081         struct request *req;
1082         int n, last_sectors;
1083
1084         while(1){
1085                 struct ubd *dev = q->queuedata;
1086                 if(dev->end_sg == 0){
1087                         struct request *req = elv_next_request(q);
1088                         if(req == NULL)
1089                                 return;
1090
1091                         dev->request = req;
1092                         blkdev_dequeue_request(req);
1093                         dev->start_sg = 0;
1094                         dev->end_sg = blk_rq_map_sg(q, req, dev->sg);
1095                 }
1096
1097                 req = dev->request;
1098                 last_sectors = 0;
1099                 while(dev->start_sg < dev->end_sg){
1100                         struct scatterlist *sg = &dev->sg[dev->start_sg];
1101
1102                         req->sector += last_sectors;
1103                         io_req = kmalloc(sizeof(struct io_thread_req),
1104                                          GFP_ATOMIC);
1105                         if(io_req == NULL){
1106                                 if(list_empty(&dev->restart))
1107                                         list_add(&dev->restart, &restart);
1108                                 return;
1109                         }
1110                         prepare_request(req, io_req,
1111                                         (unsigned long long) req->sector << 9,
1112                                         sg->offset, sg->length, sg_page(sg));
1113
1114                         last_sectors = sg->length >> 9;
1115                         n = os_write_file(thread_fd, &io_req,
1116                                           sizeof(struct io_thread_req *));
1117                         if(n != sizeof(struct io_thread_req *)){
1118                                 if(n != -EAGAIN)
1119                                         printk("write to io thread failed, "
1120                                                "errno = %d\n", -n);
1121                                 else if(list_empty(&dev->restart))
1122                                         list_add(&dev->restart, &restart);
1123                                 kfree(io_req);
1124                                 return;
1125                         }
1126
1127                         dev->start_sg++;
1128                 }
1129                 dev->end_sg = 0;
1130                 dev->request = NULL;
1131         }
1132 }
1133
1134 static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
1135 {
1136         struct ubd *ubd_dev = bdev->bd_disk->private_data;
1137
1138         geo->heads = 128;
1139         geo->sectors = 32;
1140         geo->cylinders = ubd_dev->size / (128 * 32 * 512);
1141         return 0;
1142 }
1143
1144 static int ubd_ioctl(struct inode * inode, struct file * file,
1145                      unsigned int cmd, unsigned long arg)
1146 {
1147         struct ubd *ubd_dev = inode->i_bdev->bd_disk->private_data;
1148         struct hd_driveid ubd_id = {
1149                 .cyls           = 0,
1150                 .heads          = 128,
1151                 .sectors        = 32,
1152         };
1153
1154         switch (cmd) {
1155                 struct cdrom_volctrl volume;
1156         case HDIO_GET_IDENTITY:
1157                 ubd_id.cyls = ubd_dev->size / (128 * 32 * 512);
1158                 if(copy_to_user((char __user *) arg, (char *) &ubd_id,
1159                                  sizeof(ubd_id)))
1160                         return -EFAULT;
1161                 return 0;
1162
1163         case CDROMVOLREAD:
1164                 if(copy_from_user(&volume, (char __user *) arg, sizeof(volume)))
1165                         return -EFAULT;
1166                 volume.channel0 = 255;
1167                 volume.channel1 = 255;
1168                 volume.channel2 = 255;
1169                 volume.channel3 = 255;
1170                 if(copy_to_user((char __user *) arg, &volume, sizeof(volume)))
1171                         return -EFAULT;
1172                 return 0;
1173         }
1174         return -EINVAL;
1175 }
1176
1177 static int path_requires_switch(char *from_cmdline, char *from_cow, char *cow)
1178 {
1179         struct uml_stat buf1, buf2;
1180         int err;
1181
1182         if(from_cmdline == NULL)
1183                 return 0;
1184         if(!strcmp(from_cmdline, from_cow))
1185                 return 0;
1186
1187         err = os_stat_file(from_cmdline, &buf1);
1188         if(err < 0){
1189                 printk("Couldn't stat '%s', err = %d\n", from_cmdline, -err);
1190                 return 0;
1191         }
1192         err = os_stat_file(from_cow, &buf2);
1193         if(err < 0){
1194                 printk("Couldn't stat '%s', err = %d\n", from_cow, -err);
1195                 return 1;
1196         }
1197         if((buf1.ust_dev == buf2.ust_dev) && (buf1.ust_ino == buf2.ust_ino))
1198                 return 0;
1199
1200         printk("Backing file mismatch - \"%s\" requested,\n"
1201                "\"%s\" specified in COW header of \"%s\"\n",
1202                from_cmdline, from_cow, cow);
1203         return 1;
1204 }
1205
1206 static int backing_file_mismatch(char *file, __u64 size, time_t mtime)
1207 {
1208         unsigned long modtime;
1209         unsigned long long actual;
1210         int err;
1211
1212         err = os_file_modtime(file, &modtime);
1213         if(err < 0){
1214                 printk("Failed to get modification time of backing file "
1215                        "\"%s\", err = %d\n", file, -err);
1216                 return err;
1217         }
1218
1219         err = os_file_size(file, &actual);
1220         if(err < 0){
1221                 printk("Failed to get size of backing file \"%s\", "
1222                        "err = %d\n", file, -err);
1223                 return err;
1224         }
1225
1226         if(actual != size){
1227                 /*__u64 can be a long on AMD64 and with %lu GCC complains; so
1228                  * the typecast.*/
1229                 printk("Size mismatch (%llu vs %llu) of COW header vs backing "
1230                        "file\n", (unsigned long long) size, actual);
1231                 return -EINVAL;
1232         }
1233         if(modtime != mtime){
1234                 printk("mtime mismatch (%ld vs %ld) of COW header vs backing "
1235                        "file\n", mtime, modtime);
1236                 return -EINVAL;
1237         }
1238         return 0;
1239 }
1240
1241 int read_cow_bitmap(int fd, void *buf, int offset, int len)
1242 {
1243         int err;
1244
1245         err = os_seek_file(fd, offset);
1246         if(err < 0)
1247                 return err;
1248
1249         err = os_read_file(fd, buf, len);
1250         if(err < 0)
1251                 return err;
1252
1253         return 0;
1254 }
1255
1256 int open_ubd_file(char *file, struct openflags *openflags, int shared,
1257                   char **backing_file_out, int *bitmap_offset_out,
1258                   unsigned long *bitmap_len_out, int *data_offset_out,
1259                   int *create_cow_out)
1260 {
1261         time_t mtime;
1262         unsigned long long size;
1263         __u32 version, align;
1264         char *backing_file;
1265         int fd, err, sectorsize, asked_switch, mode = 0644;
1266
1267         fd = os_open_file(file, *openflags, mode);
1268         if (fd < 0) {
1269                 if ((fd == -ENOENT) && (create_cow_out != NULL))
1270                         *create_cow_out = 1;
1271                 if (!openflags->w ||
1272                     ((fd != -EROFS) && (fd != -EACCES)))
1273                         return fd;
1274                 openflags->w = 0;
1275                 fd = os_open_file(file, *openflags, mode);
1276                 if (fd < 0)
1277                         return fd;
1278         }
1279
1280         if(shared)
1281                 printk("Not locking \"%s\" on the host\n", file);
1282         else {
1283                 err = os_lock_file(fd, openflags->w);
1284                 if(err < 0){
1285                         printk("Failed to lock '%s', err = %d\n", file, -err);
1286                         goto out_close;
1287                 }
1288         }
1289
1290         /* Successful return case! */
1291         if(backing_file_out == NULL)
1292                 return fd;
1293
1294         err = read_cow_header(file_reader, &fd, &version, &backing_file, &mtime,
1295                               &size, &sectorsize, &align, bitmap_offset_out);
1296         if(err && (*backing_file_out != NULL)){
1297                 printk("Failed to read COW header from COW file \"%s\", "
1298                        "errno = %d\n", file, -err);
1299                 goto out_close;
1300         }
1301         if(err)
1302                 return fd;
1303
1304         asked_switch = path_requires_switch(*backing_file_out, backing_file, file);
1305
1306         /* Allow switching only if no mismatch. */
1307         if (asked_switch && !backing_file_mismatch(*backing_file_out, size, mtime)) {
1308                 printk("Switching backing file to '%s'\n", *backing_file_out);
1309                 err = write_cow_header(file, fd, *backing_file_out,
1310                                        sectorsize, align, &size);
1311                 if (err) {
1312                         printk("Switch failed, errno = %d\n", -err);
1313                         goto out_close;
1314                 }
1315         } else {
1316                 *backing_file_out = backing_file;
1317                 err = backing_file_mismatch(*backing_file_out, size, mtime);
1318                 if (err)
1319                         goto out_close;
1320         }
1321
1322         cow_sizes(version, size, sectorsize, align, *bitmap_offset_out,
1323                   bitmap_len_out, data_offset_out);
1324
1325         return fd;
1326  out_close:
1327         os_close_file(fd);
1328         return err;
1329 }
1330
1331 int create_cow_file(char *cow_file, char *backing_file, struct openflags flags,
1332                     int sectorsize, int alignment, int *bitmap_offset_out,
1333                     unsigned long *bitmap_len_out, int *data_offset_out)
1334 {
1335         int err, fd;
1336
1337         flags.c = 1;
1338         fd = open_ubd_file(cow_file, &flags, 0, NULL, NULL, NULL, NULL, NULL);
1339         if(fd < 0){
1340                 err = fd;
1341                 printk("Open of COW file '%s' failed, errno = %d\n", cow_file,
1342                        -err);
1343                 goto out;
1344         }
1345
1346         err = init_cow_file(fd, cow_file, backing_file, sectorsize, alignment,
1347                             bitmap_offset_out, bitmap_len_out,
1348                             data_offset_out);
1349         if(!err)
1350                 return fd;
1351         os_close_file(fd);
1352  out:
1353         return err;
1354 }
1355
1356 static int update_bitmap(struct io_thread_req *req)
1357 {
1358         int n;
1359
1360         if(req->cow_offset == -1)
1361                 return 0;
1362
1363         n = os_seek_file(req->fds[1], req->cow_offset);
1364         if(n < 0){
1365                 printk("do_io - bitmap lseek failed : err = %d\n", -n);
1366                 return 1;
1367         }
1368
1369         n = os_write_file(req->fds[1], &req->bitmap_words,
1370                           sizeof(req->bitmap_words));
1371         if(n != sizeof(req->bitmap_words)){
1372                 printk("do_io - bitmap update failed, err = %d fd = %d\n", -n,
1373                        req->fds[1]);
1374                 return 1;
1375         }
1376
1377         return 0;
1378 }
1379
1380 void do_io(struct io_thread_req *req)
1381 {
1382         char *buf;
1383         unsigned long len;
1384         int n, nsectors, start, end, bit;
1385         int err;
1386         __u64 off;
1387
1388         nsectors = req->length / req->sectorsize;
1389         start = 0;
1390         do {
1391                 bit = ubd_test_bit(start, (unsigned char *) &req->sector_mask);
1392                 end = start;
1393                 while((end < nsectors) &&
1394                       (ubd_test_bit(end, (unsigned char *)
1395                                     &req->sector_mask) == bit))
1396                         end++;
1397
1398                 off = req->offset + req->offsets[bit] +
1399                         start * req->sectorsize;
1400                 len = (end - start) * req->sectorsize;
1401                 buf = &req->buffer[start * req->sectorsize];
1402
1403                 err = os_seek_file(req->fds[bit], off);
1404                 if(err < 0){
1405                         printk("do_io - lseek failed : err = %d\n", -err);
1406                         req->error = 1;
1407                         return;
1408                 }
1409                 if(req->op == UBD_READ){
1410                         n = 0;
1411                         do {
1412                                 buf = &buf[n];
1413                                 len -= n;
1414                                 n = os_read_file(req->fds[bit], buf, len);
1415                                 if (n < 0) {
1416                                         printk("do_io - read failed, err = %d "
1417                                                "fd = %d\n", -n, req->fds[bit]);
1418                                         req->error = 1;
1419                                         return;
1420                                 }
1421                         } while((n < len) && (n != 0));
1422                         if (n < len) memset(&buf[n], 0, len - n);
1423                 } else {
1424                         n = os_write_file(req->fds[bit], buf, len);
1425                         if(n != len){
1426                                 printk("do_io - write failed err = %d "
1427                                        "fd = %d\n", -n, req->fds[bit]);
1428                                 req->error = 1;
1429                                 return;
1430                         }
1431                 }
1432
1433                 start = end;
1434         } while(start < nsectors);
1435
1436         req->error = update_bitmap(req);
1437 }
1438
1439 /* Changed in start_io_thread, which is serialized by being called only
1440  * from ubd_init, which is an initcall.
1441  */
1442 int kernel_fd = -1;
1443
1444 /* Only changed by the io thread. XXX: currently unused. */
1445 static int io_count = 0;
1446
1447 int io_thread(void *arg)
1448 {
1449         struct io_thread_req *req;
1450         int n;
1451
1452         ignore_sigwinch_sig();
1453         while(1){
1454                 n = os_read_file(kernel_fd, &req,
1455                                  sizeof(struct io_thread_req *));
1456                 if(n != sizeof(struct io_thread_req *)){
1457                         if(n < 0)
1458                                 printk("io_thread - read failed, fd = %d, "
1459                                        "err = %d\n", kernel_fd, -n);
1460                         else {
1461                                 printk("io_thread - short read, fd = %d, "
1462                                        "length = %d\n", kernel_fd, n);
1463                         }
1464                         continue;
1465                 }
1466                 io_count++;
1467                 do_io(req);
1468                 n = os_write_file(kernel_fd, &req,
1469                                   sizeof(struct io_thread_req *));
1470                 if(n != sizeof(struct io_thread_req *))
1471                         printk("io_thread - write failed, fd = %d, err = %d\n",
1472                                kernel_fd, -n);
1473         }
1474
1475         return 0;
1476 }