arch/um/drivers/ubd_kern.c

   1 /*
   2  * Copyright (C) 2000 Jeff Dike (jdike@karaya.com)
   3  * Licensed under the GPL
   4  */
   5
   6 /* 2001-09-28...2002-04-17
   7  * Partition stuff by James_McMechan@hotmail.com
   8  * old style ubd by setting UBD_SHIFT to 0
   9  * 2002-09-27...2002-10-18 massive tinkering for 2.5
  10  * partitions have changed in 2.5
  11  * 2003-01-29 more tinkering for 2.5.59-1
  12  * This should now address the sysfs problems and has
  13  * the symlink for devfs to allow for booting with
  14  * the common /dev/ubd/discX/... names rather than
  15  * only /dev/ubdN/discN this version also has lots of
  16  * clean ups preparing for ubd-many.
  17  * James McMechan
  18  */
  19
  20 #define UBD_SHIFT 4
  21
  22 #include "linux/kernel.h"
  23 #include "linux/module.h"
  24 #include "linux/blkdev.h"
  25 #include "linux/ata.h"
  26 #include "linux/hdreg.h"
  27 #include "linux/init.h"
  28 #include "linux/cdrom.h"
  29 #include "linux/proc_fs.h"
  30 #include "linux/seq_file.h"
  31 #include "linux/ctype.h"
  32 #include "linux/capability.h"
  33 #include "linux/mm.h"
  34 #include "linux/slab.h"
  35 #include "linux/vmalloc.h"
  36 #include "linux/mutex.h"
  37 #include "linux/blkpg.h"
  38 #include "linux/genhd.h"
  39 #include "linux/spinlock.h"
  40 #include "linux/platform_device.h"
  41 #include "linux/scatterlist.h"
  42 #include "asm/segment.h"
  43 #include "asm/uaccess.h"
  44 #include "asm/irq.h"
  45 #include "asm/types.h"
  46 #include "asm/tlbflush.h"
  47 #include "mem_user.h"
  48 #include "kern_util.h"
  49 #include "mconsole_kern.h"
  50 #include "init.h"
  51 #include "irq_user.h"
  52 #include "irq_kern.h"
  53 #include "ubd_user.h"
  54 #include "os.h"
  55 #include "mem.h"
  56 #include "cow.h"
  57
  58 enum ubd_req { UBD_READ, UBD_WRITE };
  59
  60 struct io_thread_req {
  61         struct request *req;
  62         enum ubd_req op;
  63         int fds[2];
  64         unsigned long offsets[2];
  65         unsigned long long offset;
  66         unsigned long length;
  67         char *buffer;
  68         int sectorsize;
  69         unsigned long sector_mask;
  70         unsigned long long cow_offset;
  71         unsigned long bitmap_words[2];
  72         int error;
  73 };
  74
  75 static inline int ubd_test_bit(__u64 bit, unsigned char *data)
  76 {
  77         __u64 n;
  78         int bits, off;
  79
  80         bits = sizeof(data[0]) * 8;
  81         n = bit / bits;
  82         off = bit % bits;
  83         return (data[n] & (1 << off)) != 0;
  84 }
  85
  86 static inline void ubd_set_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         data[n] |= (1 << off);
  95 }
  96 /*End stuff from ubd_user.h*/
  97
  98 #define DRIVER_NAME "uml-blkdev"
  99
 100 static DEFINE_MUTEX(ubd_lock);
 101 static DEFINE_MUTEX(ubd_mutex); /* replaces BKL, might not be needed */
 102
 103 static int ubd_open(struct block_device *bdev, fmode_t mode);
 104 static int ubd_release(struct gendisk *disk, fmode_t mode);
 105 static int ubd_ioctl(struct block_device *bdev, fmode_t mode,
 106                      unsigned int cmd, unsigned long arg);
 107 static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo);
 108
 109 #define MAX_DEV (16)
 110
 111 static const struct block_device_operations ubd_blops = {
 112         .owner          = THIS_MODULE,
 113         .open           = ubd_open,
 114         .release        = ubd_release,
 115         .ioctl          = ubd_ioctl,
 116         .getgeo         = ubd_getgeo,
 117 };
 118
 119 /* Protected by ubd_lock */
 120 static int fake_major = UBD_MAJOR;
 121 static struct gendisk *ubd_gendisk[MAX_DEV];
 122 static struct gendisk *fake_gendisk[MAX_DEV];
 123
 124 #ifdef CONFIG_BLK_DEV_UBD_SYNC
 125 #define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 1, .c = 0, \
 126                                          .cl = 1 })
 127 #else
 128 #define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 0, .c = 0, \
 129                                          .cl = 1 })
 130 #endif
 131 static struct openflags global_openflags = OPEN_FLAGS;
 132
 133 struct cow {
 134         /* backing file name */
 135         char *file;
 136         /* backing file fd */
 137         int fd;
 138         unsigned long *bitmap;
 139         unsigned long bitmap_len;
 140         int bitmap_offset;
 141         int data_offset;
 142 };
 143
 144 #define MAX_SG 64
 145
 146 struct ubd {
 147         struct list_head restart;
 148         /* name (and fd, below) of the file opened for writing, either the
 149          * backing or the cow file. */
 150         char *file;
 151         int count;
 152         int fd;
 153         __u64 size;
 154         struct openflags boot_openflags;
 155         struct openflags openflags;
 156         unsigned shared:1;
 157         unsigned no_cow:1;
 158         struct cow cow;
 159         struct platform_device pdev;
 160         struct request_queue *queue;
 161         spinlock_t lock;
 162         struct scatterlist sg[MAX_SG];
 163         struct request *request;
 164         int start_sg, end_sg;
 165         sector_t rq_pos;
 166 };
 167
 168 #define DEFAULT_COW { \
 169         .file =                 NULL, \
 170         .fd =                   -1,     \
 171         .bitmap =               NULL, \
 172         .bitmap_offset =        0, \
 173         .data_offset =          0, \
 174 }
 175
 176 #define DEFAULT_UBD { \
 177         .file =                 NULL, \
 178         .count =                0, \
 179         .fd =                   -1, \
 180         .size =                 -1, \
 181         .boot_openflags =       OPEN_FLAGS, \
 182         .openflags =            OPEN_FLAGS, \
 183         .no_cow =               0, \
 184         .shared =               0, \
 185         .cow =                  DEFAULT_COW, \
 186         .lock =                 __SPIN_LOCK_UNLOCKED(ubd_devs.lock), \
 187         .request =              NULL, \
 188         .start_sg =             0, \
 189         .end_sg =               0, \
 190         .rq_pos =               0, \
 191 }
 192
 193 /* Protected by ubd_lock */
 194 static struct ubd ubd_devs[MAX_DEV] = { [0 ... MAX_DEV - 1] = DEFAULT_UBD };
 195
 196 /* Only changed by fake_ide_setup which is a setup */
 197 static int fake_ide = 0;
 198 static struct proc_dir_entry *proc_ide_root = NULL;
 199 static struct proc_dir_entry *proc_ide = NULL;
 200
 201 static void make_proc_ide(void)
 202 {
 203         proc_ide_root = proc_mkdir("ide", NULL);
 204         proc_ide = proc_mkdir("ide0", proc_ide_root);
 205 }
 206
 207 static int fake_ide_media_proc_show(struct seq_file *m, void *v)
 208 {
 209         seq_puts(m, "disk\n");
 210         return 0;
 211 }
 212
 213 static int fake_ide_media_proc_open(struct inode *inode, struct file *file)
 214 {
 215         return single_open(file, fake_ide_media_proc_show, NULL);
 216 }
 217
 218 static const struct file_operations fake_ide_media_proc_fops = {
 219         .owner          = THIS_MODULE,
 220         .open           = fake_ide_media_proc_open,
 221         .read           = seq_read,
 222         .llseek         = seq_lseek,
 223         .release        = single_release,
 224 };
 225
 226 static void make_ide_entries(const char *dev_name)
 227 {
 228         struct proc_dir_entry *dir, *ent;
 229         char name[64];
 230
 231         if(proc_ide_root == NULL) make_proc_ide();
 232
 233         dir = proc_mkdir(dev_name, proc_ide);
 234         if(!dir) return;
 235
 236         ent = proc_create("media", S_IRUGO, dir, &fake_ide_media_proc_fops);
 237         if(!ent) return;
 238         snprintf(name, sizeof(name), "ide0/%s", dev_name);
 239         proc_symlink(dev_name, proc_ide_root, name);
 240 }
 241
 242 static int fake_ide_setup(char *str)
 243 {
 244         fake_ide = 1;
 245         return 1;
 246 }
 247
 248 __setup("fake_ide", fake_ide_setup);
 249
 250 __uml_help(fake_ide_setup,
 251 "fake_ide\n"
 252 "    Create ide0 entries that map onto ubd devices.\n\n"
 253 );
 254
 255 static int parse_unit(char **ptr)
 256 {
 257         char *str = *ptr, *end;
 258         int n = -1;
 259
 260         if(isdigit(*str)) {
 261                 n = simple_strtoul(str, &end, 0);
 262                 if(end == str)
 263                         return -1;
 264                 *ptr = end;
 265         }
 266         else if (('a' <= *str) && (*str <= 'z')) {
 267                 n = *str - 'a';
 268                 str++;
 269                 *ptr = str;
 270         }
 271         return n;
 272 }
 273
 274 /* If *index_out == -1 at exit, the passed option was a general one;
 275  * otherwise, the str pointer is used (and owned) inside ubd_devs array, so it
 276  * should not be freed on exit.
 277  */
 278 static int ubd_setup_common(char *str, int *index_out, char **error_out)
 279 {
 280         struct ubd *ubd_dev;
 281         struct openflags flags = global_openflags;
 282         char *backing_file;
 283         int n, err = 0, i;
 284
 285         if(index_out) *index_out = -1;
 286         n = *str;
 287         if(n == '='){
 288                 char *end;
 289                 int major;
 290
 291                 str++;
 292                 if(!strcmp(str, "sync")){
 293                         global_openflags = of_sync(global_openflags);
 294                         goto out1;
 295                 }
 296
 297                 err = -EINVAL;
 298                 major = simple_strtoul(str, &end, 0);
 299                 if((*end != '\0') || (end == str)){
 300                         *error_out = "Didn't parse major number";
 301                         goto out1;
 302                 }
 303
 304                 mutex_lock(&ubd_lock);
 305                 if (fake_major != UBD_MAJOR) {
 306                         *error_out = "Can't assign a fake major twice";
 307                         goto out1;
 308                 }
 309
 310                 fake_major = major;
 311
 312                 printk(KERN_INFO "Setting extra ubd major number to %d\n",
 313                        major);
 314                 err = 0;
 315         out1:
 316                 mutex_unlock(&ubd_lock);
 317                 return err;
 318         }
 319
 320         n = parse_unit(&str);
 321         if(n < 0){
 322                 *error_out = "Couldn't parse device number";
 323                 return -EINVAL;
 324         }
 325         if(n >= MAX_DEV){
 326                 *error_out = "Device number out of range";
 327                 return 1;
 328         }
 329
 330         err = -EBUSY;
 331         mutex_lock(&ubd_lock);
 332
 333         ubd_dev = &ubd_devs[n];
 334         if(ubd_dev->file != NULL){
 335                 *error_out = "Device is already configured";
 336                 goto out;
 337         }
 338
 339         if (index_out)
 340                 *index_out = n;
 341
 342         err = -EINVAL;
 343         for (i = 0; i < sizeof("rscd="); i++) {
 344                 switch (*str) {
 345                 case 'r':
 346                         flags.w = 0;
 347                         break;
 348                 case 's':
 349                         flags.s = 1;
 350                         break;
 351                 case 'd':
 352                         ubd_dev->no_cow = 1;
 353                         break;
 354                 case 'c':
 355                         ubd_dev->shared = 1;
 356                         break;
 357                 case '=':
 358                         str++;
 359                         goto break_loop;
 360                 default:
 361                         *error_out = "Expected '=' or flag letter "
 362                                 "(r, s, c, or d)";
 363                         goto out;
 364                 }
 365                 str++;
 366         }
 367
 368         if (*str == '=')
 369                 *error_out = "Too many flags specified";
 370         else
 371                 *error_out = "Missing '='";
 372         goto out;
 373
 374 break_loop:
 375         backing_file = strchr(str, ',');
 376
 377         if (backing_file == NULL)
 378                 backing_file = strchr(str, ':');
 379
 380         if(backing_file != NULL){
 381                 if(ubd_dev->no_cow){
 382                         *error_out = "Can't specify both 'd' and a cow file";
 383                         goto out;
 384                 }
 385                 else {
 386                         *backing_file = '\0';
 387                         backing_file++;
 388                 }
 389         }
 390         err = 0;
 391         ubd_dev->file = str;
 392         ubd_dev->cow.file = backing_file;
 393         ubd_dev->boot_openflags = flags;
 394 out:
 395         mutex_unlock(&ubd_lock);
 396         return err;
 397 }
 398
 399 static int ubd_setup(char *str)
 400 {
 401         char *error;
 402         int err;
 403
 404         err = ubd_setup_common(str, NULL, &error);
 405         if(err)
 406                 printk(KERN_ERR "Failed to initialize device with \"%s\" : "
 407                        "%s\n", str, error);
 408         return 1;
 409 }
 410
 411 __setup("ubd", ubd_setup);
 412 __uml_help(ubd_setup,
 413 "ubd<n><flags>=<filename>[(:|,)<filename2>]\n"
 414 "    This is used to associate a device with a file in the underlying\n"
 415 "    filesystem. When specifying two filenames, the first one is the\n"
 416 "    COW name and the second is the backing file name. As separator you can\n"
 417 "    use either a ':' or a ',': the first one allows writing things like;\n"
 418 "       ubd0=~/Uml/root_cow:~/Uml/root_backing_file\n"
 419 "    while with a ',' the shell would not expand the 2nd '~'.\n"
 420 "    When using only one filename, UML will detect whether to treat it like\n"
 421 "    a COW file or a backing file. To override this detection, add the 'd'\n"
 422 "    flag:\n"
 423 "       ubd0d=BackingFile\n"
 424 "    Usually, there is a filesystem in the file, but \n"
 425 "    that's not required. Swap devices containing swap files can be\n"
 426 "    specified like this. Also, a file which doesn't contain a\n"
 427 "    filesystem can have its contents read in the virtual \n"
 428 "    machine by running 'dd' on the device. <n> must be in the range\n"
 429 "    0 to 7. Appending an 'r' to the number will cause that device\n"
 430 "    to be mounted read-only. For example ubd1r=./ext_fs. Appending\n"
 431 "    an 's' will cause data to be written to disk on the host immediately.\n"
 432 "    'c' will cause the device to be treated as being shared between multiple\n"
 433 "    UMLs and file locking will be turned off - this is appropriate for a\n"
 434 "    cluster filesystem and inappropriate at almost all other times.\n\n"
 435 );
 436
 437 static int udb_setup(char *str)
 438 {
 439         printk("udb%s specified on command line is almost certainly a ubd -> "
 440                "udb TYPO\n", str);
 441         return 1;
 442 }
 443
 444 __setup("udb", udb_setup);
 445 __uml_help(udb_setup,
 446 "udb\n"
 447 "    This option is here solely to catch ubd -> udb typos, which can be\n"
 448 "    to impossible to catch visually unless you specifically look for\n"
 449 "    them.  The only result of any option starting with 'udb' is an error\n"
 450 "    in the boot output.\n\n"
 451 );
 452
 453 static void do_ubd_request(struct request_queue * q);
 454
 455 /* Only changed by ubd_init, which is an initcall. */
 456 static int thread_fd = -1;
 457 static LIST_HEAD(restart);
 458
 459 /* XXX - move this inside ubd_intr. */
 460 /* Called without dev->lock held, and only in interrupt context. */
 461 static void ubd_handler(void)
 462 {
 463         struct io_thread_req *req;
 464         struct ubd *ubd;
 465         struct list_head *list, *next_ele;
 466         unsigned long flags;
 467         int n;
 468
 469         while(1){
 470                 n = os_read_file(thread_fd, &req,
 471                                  sizeof(struct io_thread_req *));
 472                 if(n != sizeof(req)){
 473                         if(n == -EAGAIN)
 474                                 break;
 475                         printk(KERN_ERR "spurious interrupt in ubd_handler, "
 476                                "err = %d\n", -n);
 477                         return;
 478                 }
 479
 480                 blk_end_request(req->req, 0, req->length);
 481                 kfree(req);
 482         }
 483         reactivate_fd(thread_fd, UBD_IRQ);
 484
 485         list_for_each_safe(list, next_ele, &restart){
 486                 ubd = container_of(list, struct ubd, restart);
 487                 list_del_init(&ubd->restart);
 488                 spin_lock_irqsave(&ubd->lock, flags);
 489                 do_ubd_request(ubd->queue);
 490                 spin_unlock_irqrestore(&ubd->lock, flags);
 491         }
 492 }
 493
 494 static irqreturn_t ubd_intr(int irq, void *dev)
 495 {
 496         ubd_handler();
 497         return IRQ_HANDLED;
 498 }
 499
 500 /* Only changed by ubd_init, which is an initcall. */
 501 static int io_pid = -1;
 502
 503 static void kill_io_thread(void)
 504 {
 505         if(io_pid != -1)
 506                 os_kill_process(io_pid, 1);
 507 }
 508
 509 __uml_exitcall(kill_io_thread);
 510
 511 static inline int ubd_file_size(struct ubd *ubd_dev, __u64 *size_out)
 512 {
 513         char *file;
 514
 515         file = ubd_dev->cow.file ? ubd_dev->cow.file : ubd_dev->file;
 516         return os_file_size(file, size_out);
 517 }
 518
 519 static int read_cow_bitmap(int fd, void *buf, int offset, int len)
 520 {
 521         int err;
 522
 523         err = os_seek_file(fd, offset);
 524         if (err < 0)
 525                 return err;
 526
 527         err = os_read_file(fd, buf, len);
 528         if (err < 0)
 529                 return err;
 530
 531         return 0;
 532 }
 533
 534 static int backing_file_mismatch(char *file, __u64 size, time_t mtime)
 535 {
 536         unsigned long modtime;
 537         unsigned long long actual;
 538         int err;
 539
 540         err = os_file_modtime(file, &modtime);
 541         if (err < 0) {
 542                 printk(KERN_ERR "Failed to get modification time of backing "
 543                        "file \"%s\", err = %d\n", file, -err);
 544                 return err;
 545         }
 546
 547         err = os_file_size(file, &actual);
 548         if (err < 0) {
 549                 printk(KERN_ERR "Failed to get size of backing file \"%s\", "
 550                        "err = %d\n", file, -err);
 551                 return err;
 552         }
 553
 554         if (actual != size) {
 555                 /*__u64 can be a long on AMD64 and with %lu GCC complains; so
 556                  * the typecast.*/
 557                 printk(KERN_ERR "Size mismatch (%llu vs %llu) of COW header "
 558                        "vs backing file\n", (unsigned long long) size, actual);
 559                 return -EINVAL;
 560         }
 561         if (modtime != mtime) {
 562                 printk(KERN_ERR "mtime mismatch (%ld vs %ld) of COW header vs "
 563                        "backing file\n", mtime, modtime);
 564                 return -EINVAL;
 565         }
 566         return 0;
 567 }
 568
 569 static int path_requires_switch(char *from_cmdline, char *from_cow, char *cow)
 570 {
 571         struct uml_stat buf1, buf2;
 572         int err;
 573
 574         if (from_cmdline == NULL)
 575                 return 0;
 576         if (!strcmp(from_cmdline, from_cow))
 577                 return 0;
 578
 579         err = os_stat_file(from_cmdline, &buf1);
 580         if (err < 0) {
 581                 printk(KERN_ERR "Couldn't stat '%s', err = %d\n", from_cmdline,
 582                        -err);
 583                 return 0;
 584         }
 585         err = os_stat_file(from_cow, &buf2);
 586         if (err < 0) {
 587                 printk(KERN_ERR "Couldn't stat '%s', err = %d\n", from_cow,
 588                        -err);
 589                 return 1;
 590         }
 591         if ((buf1.ust_dev == buf2.ust_dev) && (buf1.ust_ino == buf2.ust_ino))
 592                 return 0;
 593
 594         printk(KERN_ERR "Backing file mismatch - \"%s\" requested, "
 595                "\"%s\" specified in COW header of \"%s\"\n",
 596                from_cmdline, from_cow, cow);
 597         return 1;
 598 }
 599
 600 static int open_ubd_file(char *file, struct openflags *openflags, int shared,
 601                   char **backing_file_out, int *bitmap_offset_out,
 602                   unsigned long *bitmap_len_out, int *data_offset_out,
 603                   int *create_cow_out)
 604 {
 605         time_t mtime;
 606         unsigned long long size;
 607         __u32 version, align;
 608         char *backing_file;
 609         int fd, err, sectorsize, asked_switch, mode = 0644;
 610
 611         fd = os_open_file(file, *openflags, mode);
 612         if (fd < 0) {
 613                 if ((fd == -ENOENT) && (create_cow_out != NULL))
 614                         *create_cow_out = 1;
 615                 if (!openflags->w ||
 616                     ((fd != -EROFS) && (fd != -EACCES)))
 617                         return fd;
 618                 openflags->w = 0;
 619                 fd = os_open_file(file, *openflags, mode);
 620                 if (fd < 0)
 621                         return fd;
 622         }
 623
 624         if (shared)
 625                 printk(KERN_INFO "Not locking \"%s\" on the host\n", file);
 626         else {
 627                 err = os_lock_file(fd, openflags->w);
 628                 if (err < 0) {
 629                         printk(KERN_ERR "Failed to lock '%s', err = %d\n",
 630                                file, -err);
 631                         goto out_close;
 632                 }
 633         }
 634
 635         /* Successful return case! */
 636         if (backing_file_out == NULL)
 637                 return fd;
 638
 639         err = read_cow_header(file_reader, &fd, &version, &backing_file, &mtime,
 640                               &size, &sectorsize, &align, bitmap_offset_out);
 641         if (err && (*backing_file_out != NULL)) {
 642                 printk(KERN_ERR "Failed to read COW header from COW file "
 643                        "\"%s\", errno = %d\n", file, -err);
 644                 goto out_close;
 645         }
 646         if (err)
 647                 return fd;
 648
 649         asked_switch = path_requires_switch(*backing_file_out, backing_file,
 650                                             file);
 651
 652         /* Allow switching only if no mismatch. */
 653         if (asked_switch && !backing_file_mismatch(*backing_file_out, size,
 654                                                    mtime)) {
 655                 printk(KERN_ERR "Switching backing file to '%s'\n",
 656                        *backing_file_out);
 657                 err = write_cow_header(file, fd, *backing_file_out,
 658                                        sectorsize, align, &size);
 659                 if (err) {
 660                         printk(KERN_ERR "Switch failed, errno = %d\n", -err);
 661                         goto out_close;
 662                 }
 663         } else {
 664                 *backing_file_out = backing_file;
 665                 err = backing_file_mismatch(*backing_file_out, size, mtime);
 666                 if (err)
 667                         goto out_close;
 668         }
 669
 670         cow_sizes(version, size, sectorsize, align, *bitmap_offset_out,
 671                   bitmap_len_out, data_offset_out);
 672
 673         return fd;
 674  out_close:
 675         os_close_file(fd);
 676         return err;
 677 }
 678
 679 static int create_cow_file(char *cow_file, char *backing_file,
 680                     struct openflags flags,
 681                     int sectorsize, int alignment, int *bitmap_offset_out,
 682                     unsigned long *bitmap_len_out, int *data_offset_out)
 683 {
 684         int err, fd;
 685
 686         flags.c = 1;
 687         fd = open_ubd_file(cow_file, &flags, 0, NULL, NULL, NULL, NULL, NULL);
 688         if (fd < 0) {
 689                 err = fd;
 690                 printk(KERN_ERR "Open of COW file '%s' failed, errno = %d\n",
 691                        cow_file, -err);
 692                 goto out;
 693         }
 694
 695         err = init_cow_file(fd, cow_file, backing_file, sectorsize, alignment,
 696                             bitmap_offset_out, bitmap_len_out,
 697                             data_offset_out);
 698         if (!err)
 699                 return fd;
 700         os_close_file(fd);
 701  out:
 702         return err;
 703 }
 704
 705 static void ubd_close_dev(struct ubd *ubd_dev)
 706 {
 707         os_close_file(ubd_dev->fd);
 708         if(ubd_dev->cow.file == NULL)
 709                 return;
 710
 711         os_close_file(ubd_dev->cow.fd);
 712         vfree(ubd_dev->cow.bitmap);
 713         ubd_dev->cow.bitmap = NULL;
 714 }
 715
 716 static int ubd_open_dev(struct ubd *ubd_dev)
 717 {
 718         struct openflags flags;
 719         char **back_ptr;
 720         int err, create_cow, *create_ptr;
 721         int fd;
 722
 723         ubd_dev->openflags = ubd_dev->boot_openflags;
 724         create_cow = 0;
 725         create_ptr = (ubd_dev->cow.file != NULL) ? &create_cow : NULL;
 726         back_ptr = ubd_dev->no_cow ? NULL : &ubd_dev->cow.file;
 727
 728         fd = open_ubd_file(ubd_dev->file, &ubd_dev->openflags, ubd_dev->shared,
 729                                 back_ptr, &ubd_dev->cow.bitmap_offset,
 730                                 &ubd_dev->cow.bitmap_len, &ubd_dev->cow.data_offset,
 731                                 create_ptr);
 732
 733         if((fd == -ENOENT) && create_cow){
 734                 fd = create_cow_file(ubd_dev->file, ubd_dev->cow.file,
 735                                           ubd_dev->openflags, 1 << 9, PAGE_SIZE,
 736                                           &ubd_dev->cow.bitmap_offset,
 737                                           &ubd_dev->cow.bitmap_len,
 738                                           &ubd_dev->cow.data_offset);
 739                 if(fd >= 0){
 740                         printk(KERN_INFO "Creating \"%s\" as COW file for "
 741                                "\"%s\"\n", ubd_dev->file, ubd_dev->cow.file);
 742                 }
 743         }
 744
 745         if(fd < 0){
 746                 printk("Failed to open '%s', errno = %d\n", ubd_dev->file,
 747                        -fd);
 748                 return fd;
 749         }
 750         ubd_dev->fd = fd;
 751
 752         if(ubd_dev->cow.file != NULL){
 753                 blk_queue_max_hw_sectors(ubd_dev->queue, 8 * sizeof(long));
 754
 755                 err = -ENOMEM;
 756                 ubd_dev->cow.bitmap = vmalloc(ubd_dev->cow.bitmap_len);
 757                 if(ubd_dev->cow.bitmap == NULL){
 758                         printk(KERN_ERR "Failed to vmalloc COW bitmap\n");
 759                         goto error;
 760                 }
 761                 flush_tlb_kernel_vm();
 762
 763                 err = read_cow_bitmap(ubd_dev->fd, ubd_dev->cow.bitmap,
 764                                       ubd_dev->cow.bitmap_offset,
 765                                       ubd_dev->cow.bitmap_len);
 766                 if(err < 0)
 767                         goto error;
 768
 769                 flags = ubd_dev->openflags;
 770                 flags.w = 0;
 771                 err = open_ubd_file(ubd_dev->cow.file, &flags, ubd_dev->shared, NULL,
 772                                     NULL, NULL, NULL, NULL);
 773                 if(err < 0) goto error;
 774                 ubd_dev->cow.fd = err;
 775         }
 776         return 0;
 777  error:
 778         os_close_file(ubd_dev->fd);
 779         return err;
 780 }
 781
 782 static void ubd_device_release(struct device *dev)
 783 {
 784         struct ubd *ubd_dev = dev_get_drvdata(dev);
 785
 786         blk_cleanup_queue(ubd_dev->queue);
 787         *ubd_dev = ((struct ubd) DEFAULT_UBD);
 788 }
 789
 790 static int ubd_disk_register(int major, u64 size, int unit,
 791                              struct gendisk **disk_out)
 792 {
 793         struct gendisk *disk;
 794
 795         disk = alloc_disk(1 << UBD_SHIFT);
 796         if(disk == NULL)
 797                 return -ENOMEM;
 798
 799         disk->major = major;
 800         disk->first_minor = unit << UBD_SHIFT;
 801         disk->fops = &ubd_blops;
 802         set_capacity(disk, size / 512);
 803         if (major == UBD_MAJOR)
 804                 sprintf(disk->disk_name, "ubd%c", 'a' + unit);
 805         else
 806                 sprintf(disk->disk_name, "ubd_fake%d", unit);
 807
 808         /* sysfs register (not for ide fake devices) */
 809         if (major == UBD_MAJOR) {
 810                 ubd_devs[unit].pdev.id   = unit;
 811                 ubd_devs[unit].pdev.name = DRIVER_NAME;
 812                 ubd_devs[unit].pdev.dev.release = ubd_device_release;
 813                 dev_set_drvdata(&ubd_devs[unit].pdev.dev, &ubd_devs[unit]);
 814                 platform_device_register(&ubd_devs[unit].pdev);
 815                 disk->driverfs_dev = &ubd_devs[unit].pdev.dev;
 816         }
 817
 818         disk->private_data = &ubd_devs[unit];
 819         disk->queue = ubd_devs[unit].queue;
 820         add_disk(disk);
 821
 822         *disk_out = disk;
 823         return 0;
 824 }
 825
 826 #define ROUND_BLOCK(n) ((n + ((1 << 9) - 1)) & (-1 << 9))
 827
 828 static int ubd_add(int n, char **error_out)
 829 {
 830         struct ubd *ubd_dev = &ubd_devs[n];
 831         int err = 0;
 832
 833         if(ubd_dev->file == NULL)
 834                 goto out;
 835
 836         err = ubd_file_size(ubd_dev, &ubd_dev->size);
 837         if(err < 0){
 838                 *error_out = "Couldn't determine size of device's file";
 839                 goto out;
 840         }
 841
 842         ubd_dev->size = ROUND_BLOCK(ubd_dev->size);
 843
 844         INIT_LIST_HEAD(&ubd_dev->restart);
 845         sg_init_table(ubd_dev->sg, MAX_SG);
 846
 847         err = -ENOMEM;
 848         ubd_dev->queue = blk_init_queue(do_ubd_request, &ubd_dev->lock);
 849         if (ubd_dev->queue == NULL) {
 850                 *error_out = "Failed to initialize device queue";
 851                 goto out;
 852         }
 853         ubd_dev->queue->queuedata = ubd_dev;
 854
 855         blk_queue_max_segments(ubd_dev->queue, MAX_SG);
 856         err = ubd_disk_register(UBD_MAJOR, ubd_dev->size, n, &ubd_gendisk[n]);
 857         if(err){
 858                 *error_out = "Failed to register device";
 859                 goto out_cleanup;
 860         }
 861
 862         if (fake_major != UBD_MAJOR)
 863                 ubd_disk_register(fake_major, ubd_dev->size, n,
 864                                   &fake_gendisk[n]);
 865
 866         /*
 867          * Perhaps this should also be under the "if (fake_major)" above
 868          * using the fake_disk->disk_name
 869          */
 870         if (fake_ide)
 871                 make_ide_entries(ubd_gendisk[n]->disk_name);
 872
 873         err = 0;
 874 out:
 875         return err;
 876
 877 out_cleanup:
 878         blk_cleanup_queue(ubd_dev->queue);
 879         goto out;
 880 }
 881
 882 static int ubd_config(char *str, char **error_out)
 883 {
 884         int n, ret;
 885
 886         /* This string is possibly broken up and stored, so it's only
 887          * freed if ubd_setup_common fails, or if only general options
 888          * were set.
 889          */
 890         str = kstrdup(str, GFP_KERNEL);
 891         if (str == NULL) {
 892                 *error_out = "Failed to allocate memory";
 893                 return -ENOMEM;
 894         }
 895
 896         ret = ubd_setup_common(str, &n, error_out);
 897         if (ret)
 898                 goto err_free;
 899
 900         if (n == -1) {
 901                 ret = 0;
 902                 goto err_free;
 903         }
 904
 905         mutex_lock(&ubd_lock);
 906         ret = ubd_add(n, error_out);
 907         if (ret)
 908                 ubd_devs[n].file = NULL;
 909         mutex_unlock(&ubd_lock);
 910
 911 out:
 912         return ret;
 913
 914 err_free:
 915         kfree(str);
 916         goto out;
 917 }
 918
 919 static int ubd_get_config(char *name, char *str, int size, char **error_out)
 920 {
 921         struct ubd *ubd_dev;
 922         int n, len = 0;
 923
 924         n = parse_unit(&name);
 925         if((n >= MAX_DEV) || (n < 0)){
 926                 *error_out = "ubd_get_config : device number out of range";
 927                 return -1;
 928         }
 929
 930         ubd_dev = &ubd_devs[n];
 931         mutex_lock(&ubd_lock);
 932
 933         if(ubd_dev->file == NULL){
 934                 CONFIG_CHUNK(str, size, len, "", 1);
 935                 goto out;
 936         }
 937
 938         CONFIG_CHUNK(str, size, len, ubd_dev->file, 0);
 939
 940         if(ubd_dev->cow.file != NULL){
 941                 CONFIG_CHUNK(str, size, len, ",", 0);
 942                 CONFIG_CHUNK(str, size, len, ubd_dev->cow.file, 1);
 943         }
 944         else CONFIG_CHUNK(str, size, len, "", 1);
 945
 946  out:
 947         mutex_unlock(&ubd_lock);
 948         return len;
 949 }
 950
 951 static int ubd_id(char **str, int *start_out, int *end_out)
 952 {
 953         int n;
 954
 955         n = parse_unit(str);
 956         *start_out = 0;
 957         *end_out = MAX_DEV - 1;
 958         return n;
 959 }
 960
 961 static int ubd_remove(int n, char **error_out)
 962 {
 963         struct gendisk *disk = ubd_gendisk[n];
 964         struct ubd *ubd_dev;
 965         int err = -ENODEV;
 966
 967         mutex_lock(&ubd_lock);
 968
 969         ubd_dev = &ubd_devs[n];
 970
 971         if(ubd_dev->file == NULL)
 972                 goto out;
 973
 974         /* you cannot remove a open disk */
 975         err = -EBUSY;
 976         if(ubd_dev->count > 0)
 977                 goto out;
 978
 979         ubd_gendisk[n] = NULL;
 980         if(disk != NULL){
 981                 del_gendisk(disk);
 982                 put_disk(disk);
 983         }
 984
 985         if(fake_gendisk[n] != NULL){
 986                 del_gendisk(fake_gendisk[n]);
 987                 put_disk(fake_gendisk[n]);
 988                 fake_gendisk[n] = NULL;
 989         }
 990
 991         err = 0;
 992         platform_device_unregister(&ubd_dev->pdev);
 993 out:
 994         mutex_unlock(&ubd_lock);
 995         return err;
 996 }
 997
 998 /* All these are called by mconsole in process context and without
 999  * ubd-specific locks.  The structure itself is const except for .list.
1000  */
1001 static struct mc_device ubd_mc = {
1002         .list           = LIST_HEAD_INIT(ubd_mc.list),
1003         .name           = "ubd",
1004         .config         = ubd_config,
1005         .get_config     = ubd_get_config,
1006         .id             = ubd_id,
1007         .remove         = ubd_remove,
1008 };
1009
1010 static int __init ubd_mc_init(void)
1011 {
1012         mconsole_register_dev(&ubd_mc);
1013         return 0;
1014 }
1015
1016 __initcall(ubd_mc_init);
1017
1018 static int __init ubd0_init(void)
1019 {
1020         struct ubd *ubd_dev = &ubd_devs[0];
1021
1022         mutex_lock(&ubd_lock);
1023         if(ubd_dev->file == NULL)
1024                 ubd_dev->file = "root_fs";
1025         mutex_unlock(&ubd_lock);
1026
1027         return 0;
1028 }
1029
1030 __initcall(ubd0_init);
1031
1032 /* Used in ubd_init, which is an initcall */
1033 static struct platform_driver ubd_driver = {
1034         .driver = {
1035                 .name  = DRIVER_NAME,
1036         },
1037 };
1038
1039 static int __init ubd_init(void)
1040 {
1041         char *error;
1042         int i, err;
1043
1044         if (register_blkdev(UBD_MAJOR, "ubd"))
1045                 return -1;
1046
1047         if (fake_major != UBD_MAJOR) {
1048                 char name[sizeof("ubd_nnn\0")];
1049
1050                 snprintf(name, sizeof(name), "ubd_%d", fake_major);
1051                 if (register_blkdev(fake_major, "ubd"))
1052                         return -1;
1053         }
1054         platform_driver_register(&ubd_driver);
1055         mutex_lock(&ubd_lock);
1056         for (i = 0; i < MAX_DEV; i++){
1057                 err = ubd_add(i, &error);
1058                 if(err)
1059                         printk(KERN_ERR "Failed to initialize ubd device %d :"
1060                                "%s\n", i, error);
1061         }
1062         mutex_unlock(&ubd_lock);
1063         return 0;
1064 }
1065
1066 late_initcall(ubd_init);
1067
1068 static int __init ubd_driver_init(void){
1069         unsigned long stack;
1070         int err;
1071
1072         /* Set by CONFIG_BLK_DEV_UBD_SYNC or ubd=sync.*/
1073         if(global_openflags.s){
1074                 printk(KERN_INFO "ubd: Synchronous mode\n");
1075                 /* Letting ubd=sync be like using ubd#s= instead of ubd#= is
1076                  * enough. So use anyway the io thread. */
1077         }
1078         stack = alloc_stack(0, 0);
1079         io_pid = start_io_thread(stack + PAGE_SIZE - sizeof(void *),
1080                                  &thread_fd);
1081         if(io_pid < 0){
1082                 printk(KERN_ERR
1083                        "ubd : Failed to start I/O thread (errno = %d) - "
1084                        "falling back to synchronous I/O\n", -io_pid);
1085                 io_pid = -1;
1086                 return 0;
1087         }
1088         err = um_request_irq(UBD_IRQ, thread_fd, IRQ_READ, ubd_intr,
1089                              IRQF_DISABLED, "ubd", ubd_devs);
1090         if(err != 0)
1091                 printk(KERN_ERR "um_request_irq failed - errno = %d\n", -err);
1092         return 0;
1093 }
1094
1095 device_initcall(ubd_driver_init);
1096
1097 static int ubd_open(struct block_device *bdev, fmode_t mode)
1098 {
1099         struct gendisk *disk = bdev->bd_disk;
1100         struct ubd *ubd_dev = disk->private_data;
1101         int err = 0;
1102
1103         mutex_lock(&ubd_mutex);
1104         if(ubd_dev->count == 0){
1105                 err = ubd_open_dev(ubd_dev);
1106                 if(err){
1107                         printk(KERN_ERR "%s: Can't open \"%s\": errno = %d\n",
1108                                disk->disk_name, ubd_dev->file, -err);
1109                         goto out;
1110                 }
1111         }
1112         ubd_dev->count++;
1113         set_disk_ro(disk, !ubd_dev->openflags.w);
1114
1115         /* This should no more be needed. And it didn't work anyway to exclude
1116          * read-write remounting of filesystems.*/
1117         /*if((mode & FMODE_WRITE) && !ubd_dev->openflags.w){
1118                 if(--ubd_dev->count == 0) ubd_close_dev(ubd_dev);
1119                 err = -EROFS;
1120         }*/
1121 out:
1122         mutex_unlock(&ubd_mutex);
1123         return err;
1124 }
1125
1126 static int ubd_release(struct gendisk *disk, fmode_t mode)
1127 {
1128         struct ubd *ubd_dev = disk->private_data;
1129
1130         mutex_lock(&ubd_mutex);
1131         if(--ubd_dev->count == 0)
1132                 ubd_close_dev(ubd_dev);
1133         mutex_unlock(&ubd_mutex);
1134         return 0;
1135 }
1136
1137 static void cowify_bitmap(__u64 io_offset, int length, unsigned long *cow_mask,
1138                           __u64 *cow_offset, unsigned long *bitmap,
1139                           __u64 bitmap_offset, unsigned long *bitmap_words,
1140                           __u64 bitmap_len)
1141 {
1142         __u64 sector = io_offset >> 9;
1143         int i, update_bitmap = 0;
1144
1145         for(i = 0; i < length >> 9; i++){
1146                 if(cow_mask != NULL)
1147                         ubd_set_bit(i, (unsigned char *) cow_mask);
1148                 if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
1149                         continue;
1150
1151                 update_bitmap = 1;
1152                 ubd_set_bit(sector + i, (unsigned char *) bitmap);
1153         }
1154
1155         if(!update_bitmap)
1156                 return;
1157
1158         *cow_offset = sector / (sizeof(unsigned long) * 8);
1159
1160         /* This takes care of the case where we're exactly at the end of the
1161          * device, and *cow_offset + 1 is off the end.  So, just back it up
1162          * by one word.  Thanks to Lynn Kerby for the fix and James McMechan
1163          * for the original diagnosis.
1164          */
1165         if (*cow_offset == (DIV_ROUND_UP(bitmap_len,
1166                                          sizeof(unsigned long)) - 1))
1167                 (*cow_offset)--;
1168
1169         bitmap_words[0] = bitmap[*cow_offset];
1170         bitmap_words[1] = bitmap[*cow_offset + 1];
1171
1172         *cow_offset *= sizeof(unsigned long);
1173         *cow_offset += bitmap_offset;
1174 }
1175
1176 static void cowify_req(struct io_thread_req *req, unsigned long *bitmap,
1177                        __u64 bitmap_offset, __u64 bitmap_len)
1178 {
1179         __u64 sector = req->offset >> 9;
1180         int i;
1181
1182         if(req->length > (sizeof(req->sector_mask) * 8) << 9)
1183                 panic("Operation too long");
1184
1185         if(req->op == UBD_READ) {
1186                 for(i = 0; i < req->length >> 9; i++){
1187                         if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
1188                                 ubd_set_bit(i, (unsigned char *)
1189                                             &req->sector_mask);
1190                 }
1191         }
1192         else cowify_bitmap(req->offset, req->length, &req->sector_mask,
1193                            &req->cow_offset, bitmap, bitmap_offset,
1194                            req->bitmap_words, bitmap_len);
1195 }
1196
1197 /* Called with dev->lock held */
1198 static void prepare_request(struct request *req, struct io_thread_req *io_req,
1199                             unsigned long long offset, int page_offset,
1200                             int len, struct page *page)
1201 {
1202         struct gendisk *disk = req->rq_disk;
1203         struct ubd *ubd_dev = disk->private_data;
1204
1205         io_req->req = req;
1206         io_req->fds[0] = (ubd_dev->cow.file != NULL) ? ubd_dev->cow.fd :
1207                 ubd_dev->fd;
1208         io_req->fds[1] = ubd_dev->fd;
1209         io_req->cow_offset = -1;
1210         io_req->offset = offset;
1211         io_req->length = len;
1212         io_req->error = 0;
1213         io_req->sector_mask = 0;
1214
1215         io_req->op = (rq_data_dir(req) == READ) ? UBD_READ : UBD_WRITE;
1216         io_req->offsets[0] = 0;
1217         io_req->offsets[1] = ubd_dev->cow.data_offset;
1218         io_req->buffer = page_address(page) + page_offset;
1219         io_req->sectorsize = 1 << 9;
1220
1221         if(ubd_dev->cow.file != NULL)
1222                 cowify_req(io_req, ubd_dev->cow.bitmap,
1223                            ubd_dev->cow.bitmap_offset, ubd_dev->cow.bitmap_len);
1224
1225 }
1226
1227 /* Called with dev->lock held */
1228 static void do_ubd_request(struct request_queue *q)
1229 {
1230         struct io_thread_req *io_req;
1231         struct request *req;
1232         int n;
1233
1234         while(1){
1235                 struct ubd *dev = q->queuedata;
1236                 if(dev->end_sg == 0){
1237                         struct request *req = blk_fetch_request(q);
1238                         if(req == NULL)
1239                                 return;
1240
1241                         dev->request = req;
1242                         dev->rq_pos = blk_rq_pos(req);
1243                         dev->start_sg = 0;
1244                         dev->end_sg = blk_rq_map_sg(q, req, dev->sg);
1245                 }
1246
1247                 req = dev->request;
1248                 while(dev->start_sg < dev->end_sg){
1249                         struct scatterlist *sg = &dev->sg[dev->start_sg];
1250
1251                         io_req = kmalloc(sizeof(struct io_thread_req),
1252                                          GFP_ATOMIC);
1253                         if(io_req == NULL){
1254                                 if(list_empty(&dev->restart))
1255                                         list_add(&dev->restart, &restart);
1256                                 return;
1257                         }
1258                         prepare_request(req, io_req,
1259                                         (unsigned long long)dev->rq_pos << 9,
1260                                         sg->offset, sg->length, sg_page(sg));
1261
1262                         n = os_write_file(thread_fd, &io_req,
1263                                           sizeof(struct io_thread_req *));
1264                         if(n != sizeof(struct io_thread_req *)){
1265                                 if(n != -EAGAIN)
1266                                         printk("write to io thread failed, "
1267                                                "errno = %d\n", -n);
1268                                 else if(list_empty(&dev->restart))
1269                                         list_add(&dev->restart, &restart);
1270                                 kfree(io_req);
1271                                 return;
1272                         }
1273
1274                         dev->rq_pos += sg->length >> 9;
1275                         dev->start_sg++;
1276                 }
1277                 dev->end_sg = 0;
1278                 dev->request = NULL;
1279         }
1280 }
1281
1282 static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
1283 {
1284         struct ubd *ubd_dev = bdev->bd_disk->private_data;
1285
1286         geo->heads = 128;
1287         geo->sectors = 32;
1288         geo->cylinders = ubd_dev->size / (128 * 32 * 512);
1289         return 0;
1290 }
1291
1292 static int ubd_ioctl(struct block_device *bdev, fmode_t mode,
1293                      unsigned int cmd, unsigned long arg)
1294 {
1295         struct ubd *ubd_dev = bdev->bd_disk->private_data;
1296         u16 ubd_id[ATA_ID_WORDS];
1297
1298         switch (cmd) {
1299                 struct cdrom_volctrl volume;
1300         case HDIO_GET_IDENTITY:
1301                 memset(&ubd_id, 0, ATA_ID_WORDS * 2);
1302                 ubd_id[ATA_ID_CYLS]     = ubd_dev->size / (128 * 32 * 512);
1303                 ubd_id[ATA_ID_HEADS]    = 128;
1304                 ubd_id[ATA_ID_SECTORS]  = 32;
1305                 if(copy_to_user((char __user *) arg, (char *) &ubd_id,
1306                                  sizeof(ubd_id)))
1307                         return -EFAULT;
1308                 return 0;
1309
1310         case CDROMVOLREAD:
1311                 if(copy_from_user(&volume, (char __user *) arg, sizeof(volume)))
1312                         return -EFAULT;
1313                 volume.channel0 = 255;
1314                 volume.channel1 = 255;
1315                 volume.channel2 = 255;
1316                 volume.channel3 = 255;
1317                 if(copy_to_user((char __user *) arg, &volume, sizeof(volume)))
1318                         return -EFAULT;
1319                 return 0;
1320         }
1321         return -EINVAL;
1322 }
1323
1324 static int update_bitmap(struct io_thread_req *req)
1325 {
1326         int n;
1327
1328         if(req->cow_offset == -1)
1329                 return 0;
1330
1331         n = os_seek_file(req->fds[1], req->cow_offset);
1332         if(n < 0){
1333                 printk("do_io - bitmap lseek failed : err = %d\n", -n);
1334                 return 1;
1335         }
1336
1337         n = os_write_file(req->fds[1], &req->bitmap_words,
1338                           sizeof(req->bitmap_words));
1339         if(n != sizeof(req->bitmap_words)){
1340                 printk("do_io - bitmap update failed, err = %d fd = %d\n", -n,
1341                        req->fds[1]);
1342                 return 1;
1343         }
1344
1345         return 0;
1346 }
1347
1348 static void do_io(struct io_thread_req *req)
1349 {
1350         char *buf;
1351         unsigned long len;
1352         int n, nsectors, start, end, bit;
1353         int err;
1354         __u64 off;
1355
1356         nsectors = req->length / req->sectorsize;
1357         start = 0;
1358         do {
1359                 bit = ubd_test_bit(start, (unsigned char *) &req->sector_mask);
1360                 end = start;
1361                 while((end < nsectors) &&
1362                       (ubd_test_bit(end, (unsigned char *)
1363                                     &req->sector_mask) == bit))
1364                         end++;
1365
1366                 off = req->offset + req->offsets[bit] +
1367                         start * req->sectorsize;
1368                 len = (end - start) * req->sectorsize;
1369                 buf = &req->buffer[start * req->sectorsize];
1370
1371                 err = os_seek_file(req->fds[bit], off);
1372                 if(err < 0){
1373                         printk("do_io - lseek failed : err = %d\n", -err);
1374                         req->error = 1;
1375                         return;
1376                 }
1377                 if(req->op == UBD_READ){
1378                         n = 0;
1379                         do {
1380                                 buf = &buf[n];
1381                                 len -= n;
1382                                 n = os_read_file(req->fds[bit], buf, len);
1383                                 if (n < 0) {
1384                                         printk("do_io - read failed, err = %d "
1385                                                "fd = %d\n", -n, req->fds[bit]);
1386                                         req->error = 1;
1387                                         return;
1388                                 }
1389                         } while((n < len) && (n != 0));
1390                         if (n < len) memset(&buf[n], 0, len - n);
1391                 } else {
1392                         n = os_write_file(req->fds[bit], buf, len);
1393                         if(n != len){
1394                                 printk("do_io - write failed err = %d "
1395                                        "fd = %d\n", -n, req->fds[bit]);
1396                                 req->error = 1;
1397                                 return;
1398                         }
1399                 }
1400
1401                 start = end;
1402         } while(start < nsectors);
1403
1404         req->error = update_bitmap(req);
1405 }
1406
1407 /* Changed in start_io_thread, which is serialized by being called only
1408  * from ubd_init, which is an initcall.
1409  */
1410 int kernel_fd = -1;
1411
1412 /* Only changed by the io thread. XXX: currently unused. */
1413 static int io_count = 0;
1414
1415 int io_thread(void *arg)
1416 {
1417         struct io_thread_req *req;
1418         int n;
1419
1420         ignore_sigwinch_sig();
1421         while(1){
1422                 n = os_read_file(kernel_fd, &req,
1423                                  sizeof(struct io_thread_req *));
1424                 if(n != sizeof(struct io_thread_req *)){
1425                         if(n < 0)
1426                                 printk("io_thread - read failed, fd = %d, "
1427                                        "err = %d\n", kernel_fd, -n);
1428                         else {
1429                                 printk("io_thread - short read, fd = %d, "
1430                                        "length = %d\n", kernel_fd, n);
1431                         }
1432                         continue;
1433                 }
1434                 io_count++;
1435                 do_io(req);
1436                 n = os_write_file(kernel_fd, &req,
1437                                   sizeof(struct io_thread_req *));
1438                 if(n != sizeof(struct io_thread_req *))
1439                         printk("io_thread - write failed, fd = %d, err = %d\n",
1440                                kernel_fd, -n);
1441         }
1442
1443         return 0;
1444 }