git.oblomov.eu Git - linux-2.6/blob - arch/um/drivers/ubd_kern.c

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