arch/um/drivers/ubd_kern.c

   1 /*
   2  * Copyright (C) 2000 Jeff Dike ([email protected])
   3  * Licensed under the GPL
   4  */
   5
   6 /* 2001-09-28...2002-04-17
   7  * Partition stuff by [email protected]
   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/module.h>
  23 #include <linux/init.h>
  24 #include <linux/blkdev.h>
  25 #include <linux/ata.h>
  26 #include <linux/hdreg.h>
  27 #include <linux/cdrom.h>
  28 #include <linux/proc_fs.h>
  29 #include <linux/seq_file.h>
  30 #include <linux/ctype.h>
  31 #include <linux/slab.h>
  32 #include <linux/vmalloc.h>
  33 #include <linux/platform_device.h>
  34 #include <linux/scatterlist.h>
  35 #include <asm/tlbflush.h>
  36 #include <kern_util.h>
  37 #include "mconsole_kern.h"
  38 #include <init.h>
  39 #include <irq_kern.h>
  40 #include "ubd.h"
  41 #include <os.h>
  42 #include "cow.h"
  43
  44 enum ubd_req { UBD_READ, UBD_WRITE, UBD_FLUSH };
  45
  46 struct io_thread_req {
  47         struct request *req;
  48         enum ubd_req op;
  49         int fds[2];
  50         unsigned long offsets[2];
  51         unsigned long long offset;
  52         unsigned long length;
  53         char *buffer;
  54         int sectorsize;
  55         unsigned long sector_mask;
  56         unsigned long long cow_offset;
  57         unsigned long bitmap_words[2];
  58         int error;
  59 };
  60
  61 static inline int ubd_test_bit(__u64 bit, unsigned char *data)
  62 {
  63         __u64 n;
  64         int bits, off;
  65
  66         bits = sizeof(data[0]) * 8;
  67         n = bit / bits;
  68         off = bit % bits;
  69         return (data[n] & (1 << off)) != 0;
  70 }
  71
  72 static inline void ubd_set_bit(__u64 bit, unsigned char *data)
  73 {
  74         __u64 n;
  75         int bits, off;
  76
  77         bits = sizeof(data[0]) * 8;
  78         n = bit / bits;
  79         off = bit % bits;
  80         data[n] |= (1 << off);
  81 }
  82 /*End stuff from ubd_user.h*/
  83
  84 #define DRIVER_NAME "uml-blkdev"
  85
  86 static DEFINE_MUTEX(ubd_lock);
  87 static DEFINE_MUTEX(ubd_mutex); /* replaces BKL, might not be needed */
  88
  89 static int ubd_open(struct block_device *bdev, fmode_t mode);
  90 static void ubd_release(struct gendisk *disk, fmode_t mode);
  91 static int ubd_ioctl(struct block_device *bdev, fmode_t mode,
  92                      unsigned int cmd, unsigned long arg);
  93 static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo);
  94
  95 #define MAX_DEV (16)
  96
  97 static const struct block_device_operations ubd_blops = {
  98         .owner          = THIS_MODULE,
  99         .open           = ubd_open,
 100         .release        = ubd_release,
 101         .ioctl          = ubd_ioctl,
 102         .getgeo         = ubd_getgeo,
 103 };
 104
 105 /* Protected by ubd_lock */
 106 static int fake_major = UBD_MAJOR;
 107 static struct gendisk *ubd_gendisk[MAX_DEV];
 108 static struct gendisk *fake_gendisk[MAX_DEV];
 109
 110 #ifdef CONFIG_BLK_DEV_UBD_SYNC
 111 #define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 1, .c = 0, \
 112                                          .cl = 1 })
 113 #else
 114 #define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 0, .c = 0, \
 115                                          .cl = 1 })
 116 #endif
 117 static struct openflags global_openflags = OPEN_FLAGS;
 118
 119 struct cow {
 120         /* backing file name */
 121         char *file;
 122         /* backing file fd */
 123         int fd;
 124         unsigned long *bitmap;
 125         unsigned long bitmap_len;
 126         int bitmap_offset;
 127         int data_offset;
 128 };
 129
 130 #define MAX_SG 64
 131
 132 struct ubd {
 133         struct list_head restart;
 134         /* name (and fd, below) of the file opened for writing, either the
 135          * backing or the cow file. */
 136         char *file;
 137         int count;
 138         int fd;
 139         __u64 size;
 140         struct openflags boot_openflags;
 141         struct openflags openflags;
 142         unsigned shared:1;
 143         unsigned no_cow:1;
 144         struct cow cow;
 145         struct platform_device pdev;
 146         struct request_queue *queue;
 147         spinlock_t lock;
 148         struct scatterlist sg[MAX_SG];
 149         struct request *request;
 150         int start_sg, end_sg;
 151         sector_t rq_pos;
 152 };
 153
 154 #define DEFAULT_COW { \
 155         .file =                 NULL, \
 156         .fd =                   -1,     \
 157         .bitmap =               NULL, \
 158         .bitmap_offset =        0, \
 159         .data_offset =          0, \
 160 }
 161
 162 #define DEFAULT_UBD { \
 163         .file =                 NULL, \
 164         .count =                0, \
 165         .fd =                   -1, \
 166         .size =                 -1, \
 167         .boot_openflags =       OPEN_FLAGS, \
 168         .openflags =            OPEN_FLAGS, \
 169         .no_cow =               0, \
 170         .shared =               0, \
 171         .cow =                  DEFAULT_COW, \
 172         .lock =                 __SPIN_LOCK_UNLOCKED(ubd_devs.lock), \
 173         .request =              NULL, \
 174         .start_sg =             0, \
 175         .end_sg =               0, \
 176         .rq_pos =               0, \
 177 }
 178
 179 /* Protected by ubd_lock */
 180 static struct ubd ubd_devs[MAX_DEV] = { [0 ... MAX_DEV - 1] = DEFAULT_UBD };
 181
 182 /* Only changed by fake_ide_setup which is a setup */
 183 static int fake_ide = 0;
 184 static struct proc_dir_entry *proc_ide_root = NULL;
 185 static struct proc_dir_entry *proc_ide = NULL;
 186
 187 static void make_proc_ide(void)
 188 {
 189         proc_ide_root = proc_mkdir("ide", NULL);
 190         proc_ide = proc_mkdir("ide0", proc_ide_root);
 191 }
 192
 193 static int fake_ide_media_proc_show(struct seq_file *m, void *v)
 194 {
 195         seq_puts(m, "disk\n");
 196         return 0;
 197 }
 198
 199 static int fake_ide_media_proc_open(struct inode *inode, struct file *file)
 200 {
 201         return single_open(file, fake_ide_media_proc_show, NULL);
 202 }
 203
 204 static const struct file_operations fake_ide_media_proc_fops = {
 205         .owner          = THIS_MODULE,
 206         .open           = fake_ide_media_proc_open,
 207         .read           = seq_read,
 208         .llseek         = seq_lseek,
 209         .release        = single_release,
 210 };
 211
 212 static void make_ide_entries(const char *dev_name)
 213 {
 214         struct proc_dir_entry *dir, *ent;
 215         char name[64];
 216
 217         if(proc_ide_root == NULL) make_proc_ide();
 218
 219         dir = proc_mkdir(dev_name, proc_ide);
 220         if(!dir) return;
 221
 222         ent = proc_create("media", S_IRUGO, dir, &fake_ide_media_proc_fops);
 223         if(!ent) return;
 224         snprintf(name, sizeof(name), "ide0/%s", dev_name);
 225         proc_symlink(dev_name, proc_ide_root, name);
 226 }
 227
 228 static int fake_ide_setup(char *str)
 229 {
 230         fake_ide = 1;
 231         return 1;
 232 }
 233
 234 __setup("fake_ide", fake_ide_setup);
 235
 236 __uml_help(fake_ide_setup,
 237 "fake_ide\n"
 238 "    Create ide0 entries that map onto ubd devices.\n\n"
 239 );
 240
 241 static int parse_unit(char **ptr)
 242 {
 243         char *str = *ptr, *end;
 244         int n = -1;
 245
 246         if(isdigit(*str)) {
 247                 n = simple_strtoul(str, &end, 0);
 248                 if(end == str)
 249                         return -1;
 250                 *ptr = end;
 251         }
 252         else if (('a' <= *str) && (*str <= 'z')) {
 253                 n = *str - 'a';
 254                 str++;
 255                 *ptr = str;
 256         }
 257         return n;
 258 }
 259
 260 /* If *index_out == -1 at exit, the passed option was a general one;
 261  * otherwise, the str pointer is used (and owned) inside ubd_devs array, so it
 262  * should not be freed on exit.
 263  */
 264 static int ubd_setup_common(char *str, int *index_out, char **error_out)
 265 {
 266         struct ubd *ubd_dev;
 267         struct openflags flags = global_openflags;
 268         char *backing_file;
 269         int n, err = 0, i;
 270
 271         if(index_out) *index_out = -1;
 272         n = *str;
 273         if(n == '='){
 274                 char *end;
 275                 int major;
 276
 277                 str++;
 278                 if(!strcmp(str, "sync")){
 279                         global_openflags = of_sync(global_openflags);
 280                         goto out1;
 281                 }
 282
 283                 err = -EINVAL;
 284                 major = simple_strtoul(str, &end, 0);
 285                 if((*end != '\0') || (end == str)){
 286                         *error_out = "Didn't parse major number";
 287                         goto out1;
 288                 }
 289
 290                 mutex_lock(&ubd_lock);
 291                 if (fake_major != UBD_MAJOR) {
 292                         *error_out = "Can't assign a fake major twice";
 293                         goto out1;
 294                 }
 295
 296                 fake_major = major;
 297
 298                 printk(KERN_INFO "Setting extra ubd major number to %d\n",
 299                        major);
 300                 err = 0;
 301         out1:
 302                 mutex_unlock(&ubd_lock);
 303                 return err;
 304         }
 305
 306         n = parse_unit(&str);
 307         if(n < 0){
 308                 *error_out = "Couldn't parse device number";
 309                 return -EINVAL;
 310         }
 311         if(n >= MAX_DEV){
 312                 *error_out = "Device number out of range";
 313                 return 1;
 314         }
 315
 316         err = -EBUSY;
 317         mutex_lock(&ubd_lock);
 318
 319         ubd_dev = &ubd_devs[n];
 320         if(ubd_dev->file != NULL){
 321                 *error_out = "Device is already configured";
 322                 goto out;
 323         }
 324
 325         if (index_out)
 326                 *index_out = n;
 327
 328         err = -EINVAL;
 329         for (i = 0; i < sizeof("rscd="); i++) {
 330                 switch (*str) {
 331                 case 'r':
 332                         flags.w = 0;
 333                         break;
 334                 case 's':
 335                         flags.s = 1;
 336                         break;
 337                 case 'd':
 338                         ubd_dev->no_cow = 1;
 339                         break;
 340                 case 'c':
 341                         ubd_dev->shared = 1;
 342                         break;
 343                 case '=':
 344                         str++;
 345                         goto break_loop;
 346                 default:
 347                         *error_out = "Expected '=' or flag letter "
 348                                 "(r, s, c, or d)";
 349                         goto out;
 350                 }
 351                 str++;
 352         }
 353
 354         if (*str == '=')
 355                 *error_out = "Too many flags specified";
 356         else
 357                 *error_out = "Missing '='";
 358         goto out;
 359
 360 break_loop:
 361         backing_file = strchr(str, ',');
 362
 363         if (backing_file == NULL)
 364                 backing_file = strchr(str, ':');
 365
 366         if(backing_file != NULL){
 367                 if(ubd_dev->no_cow){
 368                         *error_out = "Can't specify both 'd' and a cow file";
 369                         goto out;
 370                 }
 371                 else {
 372                         *backing_file = '\0';
 373                         backing_file++;
 374                 }
 375         }
 376         err = 0;
 377         ubd_dev->file = str;
 378         ubd_dev->cow.file = backing_file;
 379         ubd_dev->boot_openflags = flags;
 380 out:
 381         mutex_unlock(&ubd_lock);
 382         return err;
 383 }
 384
 385 static int ubd_setup(char *str)
 386 {
 387         char *error;
 388         int err;
 389
 390         err = ubd_setup_common(str, NULL, &error);
 391         if(err)
 392                 printk(KERN_ERR "Failed to initialize device with \"%s\" : "
 393                        "%s\n", str, error);
 394         return 1;
 395 }
 396
 397 __setup("ubd", ubd_setup);
 398 __uml_help(ubd_setup,
 399 "ubd<n><flags>=<filename>[(:|,)<filename2>]\n"
 400 "    This is used to associate a device with a file in the underlying\n"
 401 "    filesystem. When specifying two filenames, the first one is the\n"
 402 "    COW name and the second is the backing file name. As separator you can\n"
 403 "    use either a ':' or a ',': the first one allows writing things like;\n"
 404 "       ubd0=~/Uml/root_cow:~/Uml/root_backing_file\n"
 405 "    while with a ',' the shell would not expand the 2nd '~'.\n"
 406 "    When using only one filename, UML will detect whether to treat it like\n"
 407 "    a COW file or a backing file. To override this detection, add the 'd'\n"
 408 "    flag:\n"
 409 "       ubd0d=BackingFile\n"
 410 "    Usually, there is a filesystem in the file, but \n"
 411 "    that's not required. Swap devices containing swap files can be\n"
 412 "    specified like this. Also, a file which doesn't contain a\n"
 413 "    filesystem can have its contents read in the virtual \n"
 414 "    machine by running 'dd' on the device. <n> must be in the range\n"
 415 "    0 to 7. Appending an 'r' to the number will cause that device\n"
 416 "    to be mounted read-only. For example ubd1r=./ext_fs. Appending\n"
 417 "    an 's' will cause data to be written to disk on the host immediately.\n"
 418 "    'c' will cause the device to be treated as being shared between multiple\n"
 419 "    UMLs and file locking will be turned off - this is appropriate for a\n"
 420 "    cluster filesystem and inappropriate at almost all other times.\n\n"
 421 );
 422
 423 static int udb_setup(char *str)
 424 {
 425         printk("udb%s specified on command line is almost certainly a ubd -> "
 426                "udb TYPO\n", str);
 427         return 1;
 428 }
 429
 430 __setup("udb", udb_setup);
 431 __uml_help(udb_setup,
 432 "udb\n"
 433 "    This option is here solely to catch ubd -> udb typos, which can be\n"
 434 "    to impossible to catch visually unless you specifically look for\n"
 435 "    them.  The only result of any option starting with 'udb' is an error\n"
 436 "    in the boot output.\n\n"
 437 );
 438
 439 static void do_ubd_request(struct request_queue * q);
 440
 441 /* Only changed by ubd_init, which is an initcall. */
 442 static int thread_fd = -1;
 443 static LIST_HEAD(restart);
 444
 445 /* XXX - move this inside ubd_intr. */
 446 /* Called without dev->lock held, and only in interrupt context. */
 447 static void ubd_handler(void)
 448 {
 449         struct io_thread_req *req;
 450         struct ubd *ubd;
 451         struct list_head *list, *next_ele;
 452         unsigned long flags;
 453         int n;
 454
 455         while(1){
 456                 n = os_read_file(thread_fd, &req,
 457                                  sizeof(struct io_thread_req *));
 458                 if(n != sizeof(req)){
 459                         if(n == -EAGAIN)
 460                                 break;
 461                         printk(KERN_ERR "spurious interrupt in ubd_handler, "
 462                                "err = %d\n", -n);
 463                         return;
 464                 }
 465
 466                 blk_end_request(req->req, 0, req->length);
 467                 kfree(req);
 468         }
 469         reactivate_fd(thread_fd, UBD_IRQ);
 470
 471         list_for_each_safe(list, next_ele, &restart){
 472                 ubd = container_of(list, struct ubd, restart);
 473                 list_del_init(&ubd->restart);
 474                 spin_lock_irqsave(&ubd->lock, flags);
 475                 do_ubd_request(ubd->queue);
 476                 spin_unlock_irqrestore(&ubd->lock, flags);
 477         }
 478 }
 479
 480 static irqreturn_t ubd_intr(int irq, void *dev)
 481 {
 482         ubd_handler();
 483         return IRQ_HANDLED;
 484 }
 485
 486 /* Only changed by ubd_init, which is an initcall. */
 487 static int io_pid = -1;
 488
 489 static void kill_io_thread(void)
 490 {
 491         if(io_pid != -1)
 492                 os_kill_process(io_pid, 1);
 493 }
 494
 495 __uml_exitcall(kill_io_thread);
 496
 497 static inline int ubd_file_size(struct ubd *ubd_dev, __u64 *size_out)
 498 {
 499         char *file;
 500         int fd;
 501         int err;
 502
 503         __u32 version;
 504         __u32 align;
 505         char *backing_file;
 506         time_t mtime;
 507         unsigned long long size;
 508         int sector_size;
 509         int bitmap_offset;
 510
 511         if (ubd_dev->file && ubd_dev->cow.file) {
 512                 file = ubd_dev->cow.file;
 513
 514                 goto out;
 515         }
 516
 517         fd = os_open_file(ubd_dev->file, of_read(OPENFLAGS()), 0);
 518         if (fd < 0)
 519                 return fd;
 520
 521         err = read_cow_header(file_reader, &fd, &version, &backing_file, \
 522                 &mtime, &size, &sector_size, &align, &bitmap_offset);
 523         os_close_file(fd);
 524
 525         if(err == -EINVAL)
 526                 file = ubd_dev->file;
 527         else
 528                 file = backing_file;
 529
 530 out:
 531         return os_file_size(file, size_out);
 532 }
 533
 534 static int read_cow_bitmap(int fd, void *buf, int offset, int len)
 535 {
 536         int err;
 537
 538         err = os_seek_file(fd, offset);
 539         if (err < 0)
 540                 return err;
 541
 542         err = os_read_file(fd, buf, len);
 543         if (err < 0)
 544                 return err;
 545
 546         return 0;
 547 }
 548
 549 static int backing_file_mismatch(char *file, __u64 size, time_t mtime)
 550 {
 551         unsigned long modtime;
 552         unsigned long long actual;
 553         int err;
 554
 555         err = os_file_modtime(file, &modtime);
 556         if (err < 0) {
 557                 printk(KERN_ERR "Failed to get modification time of backing "
 558                        "file \"%s\", err = %d\n", file, -err);
 559                 return err;
 560         }
 561
 562         err = os_file_size(file, &actual);
 563         if (err < 0) {
 564                 printk(KERN_ERR "Failed to get size of backing file \"%s\", "
 565                        "err = %d\n", file, -err);
 566                 return err;
 567         }
 568
 569         if (actual != size) {
 570                 /*__u64 can be a long on AMD64 and with %lu GCC complains; so
 571                  * the typecast.*/
 572                 printk(KERN_ERR "Size mismatch (%llu vs %llu) of COW header "
 573                        "vs backing file\n", (unsigned long long) size, actual);
 574                 return -EINVAL;
 575         }
 576         if (modtime != mtime) {
 577                 printk(KERN_ERR "mtime mismatch (%ld vs %ld) of COW header vs "
 578                        "backing file\n", mtime, modtime);
 579                 return -EINVAL;
 580         }
 581         return 0;
 582 }
 583
 584 static int path_requires_switch(char *from_cmdline, char *from_cow, char *cow)
 585 {
 586         struct uml_stat buf1, buf2;
 587         int err;
 588
 589         if (from_cmdline == NULL)
 590                 return 0;
 591         if (!strcmp(from_cmdline, from_cow))
 592                 return 0;
 593
 594         err = os_stat_file(from_cmdline, &buf1);
 595         if (err < 0) {
 596                 printk(KERN_ERR "Couldn't stat '%s', err = %d\n", from_cmdline,
 597                        -err);
 598                 return 0;
 599         }
 600         err = os_stat_file(from_cow, &buf2);
 601         if (err < 0) {
 602                 printk(KERN_ERR "Couldn't stat '%s', err = %d\n", from_cow,
 603                        -err);
 604                 return 1;
 605         }
 606         if ((buf1.ust_dev == buf2.ust_dev) && (buf1.ust_ino == buf2.ust_ino))
 607                 return 0;
 608
 609         printk(KERN_ERR "Backing file mismatch - \"%s\" requested, "
 610                "\"%s\" specified in COW header of \"%s\"\n",
 611                from_cmdline, from_cow, cow);
 612         return 1;
 613 }
 614
 615 static int open_ubd_file(char *file, struct openflags *openflags, int shared,
 616                   char **backing_file_out, int *bitmap_offset_out,
 617                   unsigned long *bitmap_len_out, int *data_offset_out,
 618                   int *create_cow_out)
 619 {
 620         time_t mtime;
 621         unsigned long long size;
 622         __u32 version, align;
 623         char *backing_file;
 624         int fd, err, sectorsize, asked_switch, mode = 0644;
 625
 626         fd = os_open_file(file, *openflags, mode);
 627         if (fd < 0) {
 628                 if ((fd == -ENOENT) && (create_cow_out != NULL))
 629                         *create_cow_out = 1;
 630                 if (!openflags->w ||
 631                     ((fd != -EROFS) && (fd != -EACCES)))
 632                         return fd;
 633                 openflags->w = 0;
 634                 fd = os_open_file(file, *openflags, mode);
 635                 if (fd < 0)
 636                         return fd;
 637         }
 638
 639         if (shared)
 640                 printk(KERN_INFO "Not locking \"%s\" on the host\n", file);
 641         else {
 642                 err = os_lock_file(fd, openflags->w);
 643                 if (err < 0) {
 644                         printk(KERN_ERR "Failed to lock '%s', err = %d\n",
 645                                file, -err);
 646                         goto out_close;
 647                 }
 648         }
 649
 650         /* Successful return case! */
 651         if (backing_file_out == NULL)
 652                 return fd;
 653
 654         err = read_cow_header(file_reader, &fd, &version, &backing_file, &mtime,
 655                               &size, &sectorsize, &align, bitmap_offset_out);
 656         if (err && (*backing_file_out != NULL)) {
 657                 printk(KERN_ERR "Failed to read COW header from COW file "
 658                        "\"%s\", errno = %d\n", file, -err);
 659                 goto out_close;
 660         }
 661         if (err)
 662                 return fd;
 663
 664         asked_switch = path_requires_switch(*backing_file_out, backing_file,
 665                                             file);
 666
 667         /* Allow switching only if no mismatch. */
 668         if (asked_switch && !backing_file_mismatch(*backing_file_out, size,
 669                                                    mtime)) {
 670                 printk(KERN_ERR "Switching backing file to '%s'\n",
 671                        *backing_file_out);
 672                 err = write_cow_header(file, fd, *backing_file_out,
 673                                        sectorsize, align, &size);
 674                 if (err) {
 675                         printk(KERN_ERR "Switch failed, errno = %d\n", -err);
 676                         goto out_close;
 677                 }
 678         } else {
 679                 *backing_file_out = backing_file;
 680                 err = backing_file_mismatch(*backing_file_out, size, mtime);
 681                 if (err)
 682                         goto out_close;
 683         }
 684
 685         cow_sizes(version, size, sectorsize, align, *bitmap_offset_out,
 686                   bitmap_len_out, data_offset_out);
 687
 688         return fd;
 689  out_close:
 690         os_close_file(fd);
 691         return err;
 692 }
 693
 694 static int create_cow_file(char *cow_file, char *backing_file,
 695                     struct openflags flags,
 696                     int sectorsize, int alignment, int *bitmap_offset_out,
 697                     unsigned long *bitmap_len_out, int *data_offset_out)
 698 {
 699         int err, fd;
 700
 701         flags.c = 1;
 702         fd = open_ubd_file(cow_file, &flags, 0, NULL, NULL, NULL, NULL, NULL);
 703         if (fd < 0) {
 704                 err = fd;
 705                 printk(KERN_ERR "Open of COW file '%s' failed, errno = %d\n",
 706                        cow_file, -err);
 707                 goto out;
 708         }
 709
 710         err = init_cow_file(fd, cow_file, backing_file, sectorsize, alignment,
 711                             bitmap_offset_out, bitmap_len_out,
 712                             data_offset_out);
 713         if (!err)
 714                 return fd;
 715         os_close_file(fd);
 716  out:
 717         return err;
 718 }
 719
 720 static void ubd_close_dev(struct ubd *ubd_dev)
 721 {
 722         os_close_file(ubd_dev->fd);
 723         if(ubd_dev->cow.file == NULL)
 724                 return;
 725
 726         os_close_file(ubd_dev->cow.fd);
 727         vfree(ubd_dev->cow.bitmap);
 728         ubd_dev->cow.bitmap = NULL;
 729 }
 730
 731 static int ubd_open_dev(struct ubd *ubd_dev)
 732 {
 733         struct openflags flags;
 734         char **back_ptr;
 735         int err, create_cow, *create_ptr;
 736         int fd;
 737
 738         ubd_dev->openflags = ubd_dev->boot_openflags;
 739         create_cow = 0;
 740         create_ptr = (ubd_dev->cow.file != NULL) ? &create_cow : NULL;
 741         back_ptr = ubd_dev->no_cow ? NULL : &ubd_dev->cow.file;
 742
 743         fd = open_ubd_file(ubd_dev->file, &ubd_dev->openflags, ubd_dev->shared,
 744                                 back_ptr, &ubd_dev->cow.bitmap_offset,
 745                                 &ubd_dev->cow.bitmap_len, &ubd_dev->cow.data_offset,
 746                                 create_ptr);
 747
 748         if((fd == -ENOENT) && create_cow){
 749                 fd = create_cow_file(ubd_dev->file, ubd_dev->cow.file,
 750                                           ubd_dev->openflags, 1 << 9, PAGE_SIZE,
 751                                           &ubd_dev->cow.bitmap_offset,
 752                                           &ubd_dev->cow.bitmap_len,
 753                                           &ubd_dev->cow.data_offset);
 754                 if(fd >= 0){
 755                         printk(KERN_INFO "Creating \"%s\" as COW file for "
 756                                "\"%s\"\n", ubd_dev->file, ubd_dev->cow.file);
 757                 }
 758         }
 759
 760         if(fd < 0){
 761                 printk("Failed to open '%s', errno = %d\n", ubd_dev->file,
 762                        -fd);
 763                 return fd;
 764         }
 765         ubd_dev->fd = fd;
 766
 767         if(ubd_dev->cow.file != NULL){
 768                 blk_queue_max_hw_sectors(ubd_dev->queue, 8 * sizeof(long));
 769
 770                 err = -ENOMEM;
 771                 ubd_dev->cow.bitmap = vmalloc(ubd_dev->cow.bitmap_len);
 772                 if(ubd_dev->cow.bitmap == NULL){
 773                         printk(KERN_ERR "Failed to vmalloc COW bitmap\n");
 774                         goto error;
 775                 }
 776                 flush_tlb_kernel_vm();
 777
 778                 err = read_cow_bitmap(ubd_dev->fd, ubd_dev->cow.bitmap,
 779                                       ubd_dev->cow.bitmap_offset,
 780                                       ubd_dev->cow.bitmap_len);
 781                 if(err < 0)
 782                         goto error;
 783
 784                 flags = ubd_dev->openflags;
 785                 flags.w = 0;
 786                 err = open_ubd_file(ubd_dev->cow.file, &flags, ubd_dev->shared, NULL,
 787                                     NULL, NULL, NULL, NULL);
 788                 if(err < 0) goto error;
 789                 ubd_dev->cow.fd = err;
 790         }
 791         return 0;
 792  error:
 793         os_close_file(ubd_dev->fd);
 794         return err;
 795 }
 796
 797 static void ubd_device_release(struct device *dev)
 798 {
 799         struct ubd *ubd_dev = dev_get_drvdata(dev);
 800
 801         blk_cleanup_queue(ubd_dev->queue);
 802         *ubd_dev = ((struct ubd) DEFAULT_UBD);
 803 }
 804
 805 static int ubd_disk_register(int major, u64 size, int unit,
 806                              struct gendisk **disk_out)
 807 {
 808         struct gendisk *disk;
 809
 810         disk = alloc_disk(1 << UBD_SHIFT);
 811         if(disk == NULL)
 812                 return -ENOMEM;
 813
 814         disk->major = major;
 815         disk->first_minor = unit << UBD_SHIFT;
 816         disk->fops = &ubd_blops;
 817         set_capacity(disk, size / 512);
 818         if (major == UBD_MAJOR)
 819                 sprintf(disk->disk_name, "ubd%c", 'a' + unit);
 820         else
 821                 sprintf(disk->disk_name, "ubd_fake%d", unit);
 822
 823         /* sysfs register (not for ide fake devices) */
 824         if (major == UBD_MAJOR) {
 825                 ubd_devs[unit].pdev.id   = unit;
 826                 ubd_devs[unit].pdev.name = DRIVER_NAME;
 827                 ubd_devs[unit].pdev.dev.release = ubd_device_release;
 828                 dev_set_drvdata(&ubd_devs[unit].pdev.dev, &ubd_devs[unit]);
 829                 platform_device_register(&ubd_devs[unit].pdev);
 830                 disk->driverfs_dev = &ubd_devs[unit].pdev.dev;
 831         }
 832
 833         disk->private_data = &ubd_devs[unit];
 834         disk->queue = ubd_devs[unit].queue;
 835         add_disk(disk);
 836
 837         *disk_out = disk;
 838         return 0;
 839 }
 840
 841 #define ROUND_BLOCK(n) ((n + ((1 << 9) - 1)) & (-1 << 9))
 842
 843 static int ubd_add(int n, char **error_out)
 844 {
 845         struct ubd *ubd_dev = &ubd_devs[n];
 846         int err = 0;
 847
 848         if(ubd_dev->file == NULL)
 849                 goto out;
 850
 851         err = ubd_file_size(ubd_dev, &ubd_dev->size);
 852         if(err < 0){
 853                 *error_out = "Couldn't determine size of device's file";
 854                 goto out;
 855         }
 856
 857         ubd_dev->size = ROUND_BLOCK(ubd_dev->size);
 858
 859         INIT_LIST_HEAD(&ubd_dev->restart);
 860         sg_init_table(ubd_dev->sg, MAX_SG);
 861
 862         err = -ENOMEM;
 863         ubd_dev->queue = blk_init_queue(do_ubd_request, &ubd_dev->lock);
 864         if (ubd_dev->queue == NULL) {
 865                 *error_out = "Failed to initialize device queue";
 866                 goto out;
 867         }
 868         ubd_dev->queue->queuedata = ubd_dev;
 869         blk_queue_flush(ubd_dev->queue, REQ_FLUSH);
 870
 871         blk_queue_max_segments(ubd_dev->queue, MAX_SG);
 872         err = ubd_disk_register(UBD_MAJOR, ubd_dev->size, n, &ubd_gendisk[n]);
 873         if(err){
 874                 *error_out = "Failed to register device";
 875                 goto out_cleanup;
 876         }
 877
 878         if (fake_major != UBD_MAJOR)
 879                 ubd_disk_register(fake_major, ubd_dev->size, n,
 880                                   &fake_gendisk[n]);
 881
 882         /*
 883          * Perhaps this should also be under the "if (fake_major)" above
 884          * using the fake_disk->disk_name
 885          */
 886         if (fake_ide)
 887                 make_ide_entries(ubd_gendisk[n]->disk_name);
 888
 889         err = 0;
 890 out:
 891         return err;
 892
 893 out_cleanup:
 894         blk_cleanup_queue(ubd_dev->queue);
 895         goto out;
 896 }
 897
 898 static int ubd_config(char *str, char **error_out)
 899 {
 900         int n, ret;
 901
 902         /* This string is possibly broken up and stored, so it's only
 903          * freed if ubd_setup_common fails, or if only general options
 904          * were set.
 905          */
 906         str = kstrdup(str, GFP_KERNEL);
 907         if (str == NULL) {
 908                 *error_out = "Failed to allocate memory";
 909                 return -ENOMEM;
 910         }
 911
 912         ret = ubd_setup_common(str, &n, error_out);
 913         if (ret)
 914                 goto err_free;
 915
 916         if (n == -1) {
 917                 ret = 0;
 918                 goto err_free;
 919         }
 920
 921         mutex_lock(&ubd_lock);
 922         ret = ubd_add(n, error_out);
 923         if (ret)
 924                 ubd_devs[n].file = NULL;
 925         mutex_unlock(&ubd_lock);
 926
 927 out:
 928         return ret;
 929
 930 err_free:
 931         kfree(str);
 932         goto out;
 933 }
 934
 935 static int ubd_get_config(char *name, char *str, int size, char **error_out)
 936 {
 937         struct ubd *ubd_dev;
 938         int n, len = 0;
 939
 940         n = parse_unit(&name);
 941         if((n >= MAX_DEV) || (n < 0)){
 942                 *error_out = "ubd_get_config : device number out of range";
 943                 return -1;
 944         }
 945
 946         ubd_dev = &ubd_devs[n];
 947         mutex_lock(&ubd_lock);
 948
 949         if(ubd_dev->file == NULL){
 950                 CONFIG_CHUNK(str, size, len, "", 1);
 951                 goto out;
 952         }
 953
 954         CONFIG_CHUNK(str, size, len, ubd_dev->file, 0);
 955
 956         if(ubd_dev->cow.file != NULL){
 957                 CONFIG_CHUNK(str, size, len, ",", 0);
 958                 CONFIG_CHUNK(str, size, len, ubd_dev->cow.file, 1);
 959         }
 960         else CONFIG_CHUNK(str, size, len, "", 1);
 961
 962  out:
 963         mutex_unlock(&ubd_lock);
 964         return len;
 965 }
 966
 967 static int ubd_id(char **str, int *start_out, int *end_out)
 968 {
 969         int n;
 970
 971         n = parse_unit(str);
 972         *start_out = 0;
 973         *end_out = MAX_DEV - 1;
 974         return n;
 975 }
 976
 977 static int ubd_remove(int n, char **error_out)
 978 {
 979         struct gendisk *disk = ubd_gendisk[n];
 980         struct ubd *ubd_dev;
 981         int err = -ENODEV;
 982
 983         mutex_lock(&ubd_lock);
 984
 985         ubd_dev = &ubd_devs[n];
 986
 987         if(ubd_dev->file == NULL)
 988                 goto out;
 989
 990         /* you cannot remove a open disk */
 991         err = -EBUSY;
 992         if(ubd_dev->count > 0)
 993                 goto out;
 994
 995         ubd_gendisk[n] = NULL;
 996         if(disk != NULL){
 997                 del_gendisk(disk);
 998                 put_disk(disk);
 999         }
1000
1001         if(fake_gendisk[n] != NULL){
1002                 del_gendisk(fake_gendisk[n]);
1003                 put_disk(fake_gendisk[n]);
1004                 fake_gendisk[n] = NULL;
1005         }
1006
1007         err = 0;
1008         platform_device_unregister(&ubd_dev->pdev);
1009 out:
1010         mutex_unlock(&ubd_lock);
1011         return err;
1012 }
1013
1014 /* All these are called by mconsole in process context and without
1015  * ubd-specific locks.  The structure itself is const except for .list.
1016  */
1017 static struct mc_device ubd_mc = {
1018         .list           = LIST_HEAD_INIT(ubd_mc.list),
1019         .name           = "ubd",
1020         .config         = ubd_config,
1021         .get_config     = ubd_get_config,
1022         .id             = ubd_id,
1023         .remove         = ubd_remove,
1024 };
1025
1026 static int __init ubd_mc_init(void)
1027 {
1028         mconsole_register_dev(&ubd_mc);
1029         return 0;
1030 }
1031
1032 __initcall(ubd_mc_init);
1033
1034 static int __init ubd0_init(void)
1035 {
1036         struct ubd *ubd_dev = &ubd_devs[0];
1037
1038         mutex_lock(&ubd_lock);
1039         if(ubd_dev->file == NULL)
1040                 ubd_dev->file = "root_fs";
1041         mutex_unlock(&ubd_lock);
1042
1043         return 0;
1044 }
1045
1046 __initcall(ubd0_init);
1047
1048 /* Used in ubd_init, which is an initcall */
1049 static struct platform_driver ubd_driver = {
1050         .driver = {
1051                 .name  = DRIVER_NAME,
1052         },
1053 };
1054
1055 static int __init ubd_init(void)
1056 {
1057         char *error;
1058         int i, err;
1059
1060         if (register_blkdev(UBD_MAJOR, "ubd"))
1061                 return -1;
1062
1063         if (fake_major != UBD_MAJOR) {
1064                 char name[sizeof("ubd_nnn\0")];
1065
1066                 snprintf(name, sizeof(name), "ubd_%d", fake_major);
1067                 if (register_blkdev(fake_major, "ubd"))
1068                         return -1;
1069         }
1070         platform_driver_register(&ubd_driver);
1071         mutex_lock(&ubd_lock);
1072         for (i = 0; i < MAX_DEV; i++){
1073                 err = ubd_add(i, &error);
1074                 if(err)
1075                         printk(KERN_ERR "Failed to initialize ubd device %d :"
1076                                "%s\n", i, error);
1077         }
1078         mutex_unlock(&ubd_lock);
1079         return 0;
1080 }
1081
1082 late_initcall(ubd_init);
1083
1084 static int __init ubd_driver_init(void){
1085         unsigned long stack;
1086         int err;
1087
1088         /* Set by CONFIG_BLK_DEV_UBD_SYNC or ubd=sync.*/
1089         if(global_openflags.s){
1090                 printk(KERN_INFO "ubd: Synchronous mode\n");
1091                 /* Letting ubd=sync be like using ubd#s= instead of ubd#= is
1092                  * enough. So use anyway the io thread. */
1093         }
1094         stack = alloc_stack(0, 0);
1095         io_pid = start_io_thread(stack + PAGE_SIZE - sizeof(void *),
1096                                  &thread_fd);
1097         if(io_pid < 0){
1098                 printk(KERN_ERR
1099                        "ubd : Failed to start I/O thread (errno = %d) - "
1100                        "falling back to synchronous I/O\n", -io_pid);
1101                 io_pid = -1;
1102                 return 0;
1103         }
1104         err = um_request_irq(UBD_IRQ, thread_fd, IRQ_READ, ubd_intr,
1105                              0, "ubd", ubd_devs);
1106         if(err != 0)
1107                 printk(KERN_ERR "um_request_irq failed - errno = %d\n", -err);
1108         return 0;
1109 }
1110
1111 device_initcall(ubd_driver_init);
1112
1113 static int ubd_open(struct block_device *bdev, fmode_t mode)
1114 {
1115         struct gendisk *disk = bdev->bd_disk;
1116         struct ubd *ubd_dev = disk->private_data;
1117         int err = 0;
1118
1119         mutex_lock(&ubd_mutex);
1120         if(ubd_dev->count == 0){
1121                 err = ubd_open_dev(ubd_dev);
1122                 if(err){
1123                         printk(KERN_ERR "%s: Can't open \"%s\": errno = %d\n",
1124                                disk->disk_name, ubd_dev->file, -err);
1125                         goto out;
1126                 }
1127         }
1128         ubd_dev->count++;
1129         set_disk_ro(disk, !ubd_dev->openflags.w);
1130
1131         /* This should no more be needed. And it didn't work anyway to exclude
1132          * read-write remounting of filesystems.*/
1133         /*if((mode & FMODE_WRITE) && !ubd_dev->openflags.w){
1134                 if(--ubd_dev->count == 0) ubd_close_dev(ubd_dev);
1135                 err = -EROFS;
1136         }*/
1137 out:
1138         mutex_unlock(&ubd_mutex);
1139         return err;
1140 }
1141
1142 static void ubd_release(struct gendisk *disk, fmode_t mode)
1143 {
1144         struct ubd *ubd_dev = disk->private_data;
1145
1146         mutex_lock(&ubd_mutex);
1147         if(--ubd_dev->count == 0)
1148                 ubd_close_dev(ubd_dev);
1149         mutex_unlock(&ubd_mutex);
1150 }
1151
1152 static void cowify_bitmap(__u64 io_offset, int length, unsigned long *cow_mask,
1153                           __u64 *cow_offset, unsigned long *bitmap,
1154                           __u64 bitmap_offset, unsigned long *bitmap_words,
1155                           __u64 bitmap_len)
1156 {
1157         __u64 sector = io_offset >> 9;
1158         int i, update_bitmap = 0;
1159
1160         for(i = 0; i < length >> 9; i++){
1161                 if(cow_mask != NULL)
1162                         ubd_set_bit(i, (unsigned char *) cow_mask);
1163                 if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
1164                         continue;
1165
1166                 update_bitmap = 1;
1167                 ubd_set_bit(sector + i, (unsigned char *) bitmap);
1168         }
1169
1170         if(!update_bitmap)
1171                 return;
1172
1173         *cow_offset = sector / (sizeof(unsigned long) * 8);
1174
1175         /* This takes care of the case where we're exactly at the end of the
1176          * device, and *cow_offset + 1 is off the end.  So, just back it up
1177          * by one word.  Thanks to Lynn Kerby for the fix and James McMechan
1178          * for the original diagnosis.
1179          */
1180         if (*cow_offset == (DIV_ROUND_UP(bitmap_len,
1181                                          sizeof(unsigned long)) - 1))
1182                 (*cow_offset)--;
1183
1184         bitmap_words[0] = bitmap[*cow_offset];
1185         bitmap_words[1] = bitmap[*cow_offset + 1];
1186
1187         *cow_offset *= sizeof(unsigned long);
1188         *cow_offset += bitmap_offset;
1189 }
1190
1191 static void cowify_req(struct io_thread_req *req, unsigned long *bitmap,
1192                        __u64 bitmap_offset, __u64 bitmap_len)
1193 {
1194         __u64 sector = req->offset >> 9;
1195         int i;
1196
1197         if(req->length > (sizeof(req->sector_mask) * 8) << 9)
1198                 panic("Operation too long");
1199
1200         if(req->op == UBD_READ) {
1201                 for(i = 0; i < req->length >> 9; i++){
1202                         if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
1203                                 ubd_set_bit(i, (unsigned char *)
1204                                             &req->sector_mask);
1205                 }
1206         }
1207         else cowify_bitmap(req->offset, req->length, &req->sector_mask,
1208                            &req->cow_offset, bitmap, bitmap_offset,
1209                            req->bitmap_words, bitmap_len);
1210 }
1211
1212 /* Called with dev->lock held */
1213 static void prepare_request(struct request *req, struct io_thread_req *io_req,
1214                             unsigned long long offset, int page_offset,
1215                             int len, struct page *page)
1216 {
1217         struct gendisk *disk = req->rq_disk;
1218         struct ubd *ubd_dev = disk->private_data;
1219
1220         io_req->req = req;
1221         io_req->fds[0] = (ubd_dev->cow.file != NULL) ? ubd_dev->cow.fd :
1222                 ubd_dev->fd;
1223         io_req->fds[1] = ubd_dev->fd;
1224         io_req->cow_offset = -1;
1225         io_req->offset = offset;
1226         io_req->length = len;
1227         io_req->error = 0;
1228         io_req->sector_mask = 0;
1229
1230         io_req->op = (rq_data_dir(req) == READ) ? UBD_READ : UBD_WRITE;
1231         io_req->offsets[0] = 0;
1232         io_req->offsets[1] = ubd_dev->cow.data_offset;
1233         io_req->buffer = page_address(page) + page_offset;
1234         io_req->sectorsize = 1 << 9;
1235
1236         if(ubd_dev->cow.file != NULL)
1237                 cowify_req(io_req, ubd_dev->cow.bitmap,
1238                            ubd_dev->cow.bitmap_offset, ubd_dev->cow.bitmap_len);
1239
1240 }
1241
1242 /* Called with dev->lock held */
1243 static void prepare_flush_request(struct request *req,
1244                                   struct io_thread_req *io_req)
1245 {
1246         struct gendisk *disk = req->rq_disk;
1247         struct ubd *ubd_dev = disk->private_data;
1248
1249         io_req->req = req;
1250         io_req->fds[0] = (ubd_dev->cow.file != NULL) ? ubd_dev->cow.fd :
1251                 ubd_dev->fd;
1252         io_req->op = UBD_FLUSH;
1253 }
1254
1255 static bool submit_request(struct io_thread_req *io_req, struct ubd *dev)
1256 {
1257         int n = os_write_file(thread_fd, &io_req,
1258                              sizeof(io_req));
1259         if (n != sizeof(io_req)) {
1260                 if (n != -EAGAIN)
1261                         printk("write to io thread failed, "
1262                                "errno = %d\n", -n);
1263                 else if (list_empty(&dev->restart))
1264                         list_add(&dev->restart, &restart);
1265
1266                 kfree(io_req);
1267                 return false;
1268         }
1269         return true;
1270 }
1271
1272 /* Called with dev->lock held */
1273 static void do_ubd_request(struct request_queue *q)
1274 {
1275         struct io_thread_req *io_req;
1276         struct request *req;
1277
1278         while(1){
1279                 struct ubd *dev = q->queuedata;
1280                 if(dev->end_sg == 0){
1281                         struct request *req = blk_fetch_request(q);
1282                         if(req == NULL)
1283                                 return;
1284
1285                         dev->request = req;
1286                         dev->rq_pos = blk_rq_pos(req);
1287                         dev->start_sg = 0;
1288                         dev->end_sg = blk_rq_map_sg(q, req, dev->sg);
1289                 }
1290
1291                 req = dev->request;
1292
1293                 if (req->cmd_flags & REQ_FLUSH) {
1294                         io_req = kmalloc(sizeof(struct io_thread_req),
1295                                          GFP_ATOMIC);
1296                         if (io_req == NULL) {
1297                                 if (list_empty(&dev->restart))
1298                                         list_add(&dev->restart, &restart);
1299                                 return;
1300                         }
1301                         prepare_flush_request(req, io_req);
1302                         submit_request(io_req, dev);
1303                 }
1304
1305                 while(dev->start_sg < dev->end_sg){
1306                         struct scatterlist *sg = &dev->sg[dev->start_sg];
1307
1308                         io_req = kmalloc(sizeof(struct io_thread_req),
1309                                          GFP_ATOMIC);
1310                         if(io_req == NULL){
1311                                 if(list_empty(&dev->restart))
1312                                         list_add(&dev->restart, &restart);
1313                                 return;
1314                         }
1315                         prepare_request(req, io_req,
1316                                         (unsigned long long)dev->rq_pos << 9,
1317                                         sg->offset, sg->length, sg_page(sg));
1318
1319                         if (submit_request(io_req, dev) == false)
1320                                 return;
1321
1322                         dev->rq_pos += sg->length >> 9;
1323                         dev->start_sg++;
1324                 }
1325                 dev->end_sg = 0;
1326                 dev->request = NULL;
1327         }
1328 }
1329
1330 static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
1331 {
1332         struct ubd *ubd_dev = bdev->bd_disk->private_data;
1333
1334         geo->heads = 128;
1335         geo->sectors = 32;
1336         geo->cylinders = ubd_dev->size / (128 * 32 * 512);
1337         return 0;
1338 }
1339
1340 static int ubd_ioctl(struct block_device *bdev, fmode_t mode,
1341                      unsigned int cmd, unsigned long arg)
1342 {
1343         struct ubd *ubd_dev = bdev->bd_disk->private_data;
1344         u16 ubd_id[ATA_ID_WORDS];
1345
1346         switch (cmd) {
1347                 struct cdrom_volctrl volume;
1348         case HDIO_GET_IDENTITY:
1349                 memset(&ubd_id, 0, ATA_ID_WORDS * 2);
1350                 ubd_id[ATA_ID_CYLS]     = ubd_dev->size / (128 * 32 * 512);
1351                 ubd_id[ATA_ID_HEADS]    = 128;
1352                 ubd_id[ATA_ID_SECTORS]  = 32;
1353                 if(copy_to_user((char __user *) arg, (char *) &ubd_id,
1354                                  sizeof(ubd_id)))
1355                         return -EFAULT;
1356                 return 0;
1357
1358         case CDROMVOLREAD:
1359                 if(copy_from_user(&volume, (char __user *) arg, sizeof(volume)))
1360                         return -EFAULT;
1361                 volume.channel0 = 255;
1362                 volume.channel1 = 255;
1363                 volume.channel2 = 255;
1364                 volume.channel3 = 255;
1365                 if(copy_to_user((char __user *) arg, &volume, sizeof(volume)))
1366                         return -EFAULT;
1367                 return 0;
1368         }
1369         return -EINVAL;
1370 }
1371
1372 static int update_bitmap(struct io_thread_req *req)
1373 {
1374         int n;
1375
1376         if(req->cow_offset == -1)
1377                 return 0;
1378
1379         n = os_seek_file(req->fds[1], req->cow_offset);
1380         if(n < 0){
1381                 printk("do_io - bitmap lseek failed : err = %d\n", -n);
1382                 return 1;
1383         }
1384
1385         n = os_write_file(req->fds[1], &req->bitmap_words,
1386                           sizeof(req->bitmap_words));
1387         if(n != sizeof(req->bitmap_words)){
1388                 printk("do_io - bitmap update failed, err = %d fd = %d\n", -n,
1389                        req->fds[1]);
1390                 return 1;
1391         }
1392
1393         return 0;
1394 }
1395
1396 static void do_io(struct io_thread_req *req)
1397 {
1398         char *buf;
1399         unsigned long len;
1400         int n, nsectors, start, end, bit;
1401         int err;
1402         __u64 off;
1403
1404         if (req->op == UBD_FLUSH) {
1405                 /* fds[0] is always either the rw image or our cow file */
1406                 n = os_sync_file(req->fds[0]);
1407                 if (n != 0) {
1408                         printk("do_io - sync failed err = %d "
1409                                "fd = %d\n", -n, req->fds[0]);
1410                         req->error = 1;
1411                 }
1412                 return;
1413         }
1414
1415         nsectors = req->length / req->sectorsize;
1416         start = 0;
1417         do {
1418                 bit = ubd_test_bit(start, (unsigned char *) &req->sector_mask);
1419                 end = start;
1420                 while((end < nsectors) &&
1421                       (ubd_test_bit(end, (unsigned char *)
1422                                     &req->sector_mask) == bit))
1423                         end++;
1424
1425                 off = req->offset + req->offsets[bit] +
1426                         start * req->sectorsize;
1427                 len = (end - start) * req->sectorsize;
1428                 buf = &req->buffer[start * req->sectorsize];
1429
1430                 err = os_seek_file(req->fds[bit], off);
1431                 if(err < 0){
1432                         printk("do_io - lseek failed : err = %d\n", -err);
1433                         req->error = 1;
1434                         return;
1435                 }
1436                 if(req->op == UBD_READ){
1437                         n = 0;
1438                         do {
1439                                 buf = &buf[n];
1440                                 len -= n;
1441                                 n = os_read_file(req->fds[bit], buf, len);
1442                                 if (n < 0) {
1443                                         printk("do_io - read failed, err = %d "
1444                                                "fd = %d\n", -n, req->fds[bit]);
1445                                         req->error = 1;
1446                                         return;
1447                                 }
1448                         } while((n < len) && (n != 0));
1449                         if (n < len) memset(&buf[n], 0, len - n);
1450                 } else {
1451                         n = os_write_file(req->fds[bit], buf, len);
1452                         if(n != len){
1453                                 printk("do_io - write failed err = %d "
1454                                        "fd = %d\n", -n, req->fds[bit]);
1455                                 req->error = 1;
1456                                 return;
1457                         }
1458                 }
1459
1460                 start = end;
1461         } while(start < nsectors);
1462
1463         req->error = update_bitmap(req);
1464 }
1465
1466 /* Changed in start_io_thread, which is serialized by being called only
1467  * from ubd_init, which is an initcall.
1468  */
1469 int kernel_fd = -1;
1470
1471 /* Only changed by the io thread. XXX: currently unused. */
1472 static int io_count = 0;
1473
1474 int io_thread(void *arg)
1475 {
1476         struct io_thread_req *req;
1477         int n;
1478
1479         os_fix_helper_signals();
1480
1481         while(1){
1482                 n = os_read_file(kernel_fd, &req,
1483                                  sizeof(struct io_thread_req *));
1484                 if(n != sizeof(struct io_thread_req *)){
1485                         if(n < 0)
1486                                 printk("io_thread - read failed, fd = %d, "
1487                                        "err = %d\n", kernel_fd, -n);
1488                         else {
1489                                 printk("io_thread - short read, fd = %d, "
1490                                        "length = %d\n", kernel_fd, n);
1491                         }
1492                         continue;
1493                 }
1494                 io_count++;
1495                 do_io(req);
1496                 n = os_write_file(kernel_fd, &req,
1497                                   sizeof(struct io_thread_req *));
1498                 if(n != sizeof(struct io_thread_req *))
1499                         printk("io_thread - write failed, fd = %d, err = %d\n",
1500                                kernel_fd, -n);
1501         }
1502
1503         return 0;
1504 }