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