err.no 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/config.h"
  24 #include "linux/module.h"
  25 #include "linux/blkdev.h"
  26 #include "linux/hdreg.h"
  27 #include "linux/init.h"
  28 #include "linux/devfs_fs_kernel.h"
  29 #include "linux/cdrom.h"
  30 #include "linux/proc_fs.h"
  31 #include "linux/ctype.h"
  32 #include "linux/capability.h"
  33 #include "linux/mm.h"
  34 #include "linux/vmalloc.h"
  35 #include "linux/blkpg.h"
  36 #include "linux/genhd.h"
  37 #include "linux/spinlock.h"
  38 #include "asm/segment.h"
  39 #include "asm/uaccess.h"
  40 #include "asm/irq.h"
  41 #include "asm/types.h"
  42 #include "asm/tlbflush.h"
  43 #include "user_util.h"
  44 #include "mem_user.h"
  45 #include "kern_util.h"
  46 #include "kern.h"
  47 #include "mconsole_kern.h"
  48 #include "init.h"
  49 #include "irq_user.h"
  50 #include "irq_kern.h"
  51 #include "ubd_user.h"
  52 #include "2_5compat.h"
  53 #include "os.h"
  54 #include "mem.h"
  55 #include "mem_kern.h"
  56 #include "cow.h"
  57
  58 enum ubd_req { UBD_READ, UBD_WRITE, UBD_MMAP };
  59
  60 struct io_thread_req {
  61         enum ubd_req op;
  62         int fds[2];
  63         unsigned long offsets[2];
  64         unsigned long long offset;
  65         unsigned long length;
  66         char *buffer;
  67         int sectorsize;
  68         unsigned long sector_mask;
  69         unsigned long long cow_offset;
  70         unsigned long bitmap_words[2];
  71         int map_fd;
  72         unsigned long long map_offset;
  73         int error;
  74 };
  75
  76 extern int open_ubd_file(char *file, struct openflags *openflags,
  77                          char **backing_file_out, int *bitmap_offset_out,
  78                          unsigned long *bitmap_len_out, int *data_offset_out,
  79                          int *create_cow_out);
  80 extern int create_cow_file(char *cow_file, char *backing_file,
  81                            struct openflags flags, int sectorsize,
  82                            int alignment, int *bitmap_offset_out,
  83                            unsigned long *bitmap_len_out,
  84                            int *data_offset_out);
  85 extern int read_cow_bitmap(int fd, void *buf, int offset, int len);
  86 extern void do_io(struct io_thread_req *req);
  87
  88 static inline int ubd_test_bit(__u64 bit, unsigned char *data)
  89 {
  90         __u64 n;
  91         int bits, off;
  92
  93         bits = sizeof(data[0]) * 8;
  94         n = bit / bits;
  95         off = bit % bits;
  96         return((data[n] & (1 << off)) != 0);
  97 }
  98
  99 static inline void ubd_set_bit(__u64 bit, unsigned char *data)
 100 {
 101         __u64 n;
 102         int bits, off;
 103
 104         bits = sizeof(data[0]) * 8;
 105         n = bit / bits;
 106         off = bit % bits;
 107         data[n] |= (1 << off);
 108 }
 109 /*End stuff from ubd_user.h*/
 110
 111 #define DRIVER_NAME "uml-blkdev"
 112
 113 static DEFINE_SPINLOCK(ubd_io_lock);
 114 static DEFINE_SPINLOCK(ubd_lock);
 115
 116 static void (*do_ubd)(void);
 117
 118 static int ubd_open(struct inode * inode, struct file * filp);
 119 static int ubd_release(struct inode * inode, struct file * file);
 120 static int ubd_ioctl(struct inode * inode, struct file * file,
 121                      unsigned int cmd, unsigned long arg);
 122
 123 #define MAX_DEV (8)
 124
 125 /* Changed in early boot */
 126 static int ubd_do_mmap = 0;
 127 #define UBD_MMAP_BLOCK_SIZE PAGE_SIZE
 128
 129 static struct block_device_operations ubd_blops = {
 130         .owner          = THIS_MODULE,
 131         .open           = ubd_open,
 132         .release        = ubd_release,
 133         .ioctl          = ubd_ioctl,
 134 };
 135
 136 /* Protected by the queue_lock */
 137 static request_queue_t *ubd_queue;
 138
 139 /* Protected by ubd_lock */
 140 static int fake_major = MAJOR_NR;
 141
 142 static struct gendisk *ubd_gendisk[MAX_DEV];
 143 static struct gendisk *fake_gendisk[MAX_DEV];
 144
 145 #ifdef CONFIG_BLK_DEV_UBD_SYNC
 146 #define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 1, .c = 0, \
 147                                          .cl = 1 })
 148 #else
 149 #define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 0, .c = 0, \
 150                                          .cl = 1 })
 151 #endif
 152
 153 /* Not protected - changed only in ubd_setup_common and then only to
 154  * to enable O_SYNC.
 155  */
 156 static struct openflags global_openflags = OPEN_FLAGS;
 157
 158 struct cow {
 159         /* This is the backing file, actually */
 160         char *file;
 161         int fd;
 162         unsigned long *bitmap;
 163         unsigned long bitmap_len;
 164         int bitmap_offset;
 165         int data_offset;
 166 };
 167
 168 struct ubd {
 169         char *file;
 170         int count;
 171         int fd;
 172         __u64 size;
 173         struct openflags boot_openflags;
 174         struct openflags openflags;
 175         int no_cow;
 176         struct cow cow;
 177         struct platform_device pdev;
 178
 179         int map_writes;
 180         int map_reads;
 181         int nomap_writes;
 182         int nomap_reads;
 183         int write_maps;
 184 };
 185
 186 #define DEFAULT_COW { \
 187         .file =                 NULL, \
 188         .fd =                   -1, \
 189         .bitmap =               NULL, \
 190         .bitmap_offset =        0, \
 191         .data_offset =          0, \
 192 }
 193
 194 #define DEFAULT_UBD { \
 195         .file =                 NULL, \
 196         .count =                0, \
 197         .fd =                   -1, \
 198         .size =                 -1, \
 199         .boot_openflags =       OPEN_FLAGS, \
 200         .openflags =            OPEN_FLAGS, \
 201         .no_cow =               0, \
 202         .cow =                  DEFAULT_COW, \
 203         .map_writes             = 0, \
 204         .map_reads              = 0, \
 205         .nomap_writes           = 0, \
 206         .nomap_reads            = 0, \
 207         .write_maps             = 0, \
 208 }
 209
 210 struct ubd ubd_dev[MAX_DEV] = { [ 0 ... MAX_DEV - 1 ] = DEFAULT_UBD };
 211
 212 static int ubd0_init(void)
 213 {
 214         struct ubd *dev = &ubd_dev[0];
 215
 216         if(dev->file == NULL)
 217                 dev->file = "root_fs";
 218         return(0);
 219 }
 220
 221 __initcall(ubd0_init);
 222
 223 /* Only changed by fake_ide_setup which is a setup */
 224 static int fake_ide = 0;
 225 static struct proc_dir_entry *proc_ide_root = NULL;
 226 static struct proc_dir_entry *proc_ide = NULL;
 227
 228 static void make_proc_ide(void)
 229 {
 230         proc_ide_root = proc_mkdir("ide", NULL);
 231         proc_ide = proc_mkdir("ide0", proc_ide_root);
 232 }
 233
 234 static int proc_ide_read_media(char *page, char **start, off_t off, int count,
 235                                int *eof, void *data)
 236 {
 237         int len;
 238
 239         strcpy(page, "disk\n");
 240         len = strlen("disk\n");
 241         len -= off;
 242         if (len < count){
 243                 *eof = 1;
 244                 if (len <= 0) return 0;
 245         }
 246         else len = count;
 247         *start = page + off;
 248         return len;
 249 }
 250
 251 static void make_ide_entries(char *dev_name)
 252 {
 253         struct proc_dir_entry *dir, *ent;
 254         char name[64];
 255
 256         if(proc_ide_root == NULL) make_proc_ide();
 257
 258         dir = proc_mkdir(dev_name, proc_ide);
 259         if(!dir) return;
 260
 261         ent = create_proc_entry("media", S_IFREG|S_IRUGO, dir);
 262         if(!ent) return;
 263         ent->nlink = 1;
 264         ent->data = NULL;
 265         ent->read_proc = proc_ide_read_media;
 266         ent->write_proc = NULL;
 267         sprintf(name,"ide0/%s", dev_name);
 268         proc_symlink(dev_name, proc_ide_root, name);
 269 }
 270
 271 static int fake_ide_setup(char *str)
 272 {
 273         fake_ide = 1;
 274         return(1);
 275 }
 276
 277 __setup("fake_ide", fake_ide_setup);
 278
 279 __uml_help(fake_ide_setup,
 280 "fake_ide\n"
 281 "    Create ide0 entries that map onto ubd devices.\n\n"
 282 );
 283
 284 static int parse_unit(char **ptr)
 285 {
 286         char *str = *ptr, *end;
 287         int n = -1;
 288
 289         if(isdigit(*str)) {
 290                 n = simple_strtoul(str, &end, 0);
 291                 if(end == str)
 292                         return(-1);
 293                 *ptr = end;
 294         }
 295         else if (('a' <= *str) && (*str <= 'h')) {
 296                 n = *str - 'a';
 297                 str++;
 298                 *ptr = str;
 299         }
 300         return(n);
 301 }
 302
 303 static int ubd_setup_common(char *str, int *index_out)
 304 {
 305         struct ubd *dev;
 306         struct openflags flags = global_openflags;
 307         char *backing_file;
 308         int n, err, i;
 309
 310         if(index_out) *index_out = -1;
 311         n = *str;
 312         if(n == '='){
 313                 char *end;
 314                 int major;
 315
 316                 str++;
 317                 if(!strcmp(str, "mmap")){
 318                         CHOOSE_MODE(printk("mmap not supported by the ubd "
 319                                            "driver in tt mode\n"),
 320                                     ubd_do_mmap = 1);
 321                         return(0);
 322                 }
 323
 324                 if(!strcmp(str, "sync")){
 325                         global_openflags = of_sync(global_openflags);
 326                         return(0);
 327                 }
 328                 major = simple_strtoul(str, &end, 0);
 329                 if((*end != '\0') || (end == str)){
 330                         printk(KERN_ERR
 331                                "ubd_setup : didn't parse major number\n");
 332                         return(1);
 333                 }
 334
 335                 err = 1;
 336                 spin_lock(&ubd_lock);
 337                 if(fake_major != MAJOR_NR){
 338                         printk(KERN_ERR "Can't assign a fake major twice\n");
 339                         goto out1;
 340                 }
 341
 342                 fake_major = major;
 343
 344                 printk(KERN_INFO "Setting extra ubd major number to %d\n",
 345                        major);
 346                 err = 0;
 347         out1:
 348                 spin_unlock(&ubd_lock);
 349                 return(err);
 350         }
 351
 352         n = parse_unit(&str);
 353         if(n < 0){
 354                 printk(KERN_ERR "ubd_setup : couldn't parse unit number "
 355                        "'%s'\n", str);
 356                 return(1);
 357         }
 358         if(n >= MAX_DEV){
 359                 printk(KERN_ERR "ubd_setup : index %d out of range "
 360                        "(%d devices, from 0 to %d)\n", n, MAX_DEV, MAX_DEV - 1);
 361                 return(1);
 362         }
 363
 364         err = 1;
 365         spin_lock(&ubd_lock);
 366
 367         dev = &ubd_dev[n];
 368         if(dev->file != NULL){
 369                 printk(KERN_ERR "ubd_setup : device already configured\n");
 370                 goto out;
 371         }
 372
 373         if (index_out)
 374                 *index_out = n;
 375
 376         for (i = 0; i < 4; i++) {
 377                 switch (*str) {
 378                 case 'r':
 379                         flags.w = 0;
 380                         break;
 381                 case 's':
 382                         flags.s = 1;
 383                         break;
 384                 case 'd':
 385                         dev->no_cow = 1;
 386                         break;
 387                 case '=':
 388                         str++;
 389                         goto break_loop;
 390                 default:
 391                         printk(KERN_ERR "ubd_setup : Expected '=' or flag letter (r,s or d)\n");
 392                         goto out;
 393                 }
 394                 str++;
 395         }
 396
 397         if (*str == '=')
 398                 printk(KERN_ERR "ubd_setup : Too many flags specified\n");
 399         else
 400                 printk(KERN_ERR "ubd_setup : Expected '='\n");
 401         goto out;
 402
 403 break_loop:
 404         err = 0;
 405         backing_file = strchr(str, ',');
 406
 407         if (!backing_file) {
 408                 backing_file = strchr(str, ':');
 409         }
 410
 411         if(backing_file){
 412                 if(dev->no_cow)
 413                         printk(KERN_ERR "Can't specify both 'd' and a "
 414                                "cow file\n");
 415                 else {
 416                         *backing_file = '\0';
 417                         backing_file++;
 418                 }
 419         }
 420         dev->file = str;
 421         dev->cow.file = backing_file;
 422         dev->boot_openflags = flags;
 423 out:
 424         spin_unlock(&ubd_lock);
 425         return(err);
 426 }
 427
 428 static int ubd_setup(char *str)
 429 {
 430         ubd_setup_common(str, NULL);
 431         return(1);
 432 }
 433
 434 __setup("ubd", ubd_setup);
 435 __uml_help(ubd_setup,
 436 "ubd<n><flags>=<filename>[(:|,)<filename2>]\n"
 437 "    This is used to associate a device with a file in the underlying\n"
 438 "    filesystem. When specifying two filenames, the first one is the\n"
 439 "    COW name and the second is the backing file name. As separator you can\n"
 440 "    use either a ':' or a ',': the first one allows writing things like;\n"
 441 "       ubd0=~/Uml/root_cow:~/Uml/root_backing_file\n"
 442 "    while with a ',' the shell would not expand the 2nd '~'.\n"
 443 "    When using only one filename, UML will detect whether to thread it like\n"
 444 "    a COW file or a backing file. To override this detection, add the 'd'\n"
 445 "    flag:\n"
 446 "       ubd0d=BackingFile\n"
 447 "    Usually, there is a filesystem in the file, but \n"
 448 "    that's not required. Swap devices containing swap files can be\n"
 449 "    specified like this. Also, a file which doesn't contain a\n"
 450 "    filesystem can have its contents read in the virtual \n"
 451 "    machine by running 'dd' on the device. <n> must be in the range\n"
 452 "    0 to 7. Appending an 'r' to the number will cause that device\n"
 453 "    to be mounted read-only. For example ubd1r=./ext_fs. Appending\n"
 454 "    an 's' will cause data to be written to disk on the host immediately.\n\n"
 455 );
 456
 457 static int udb_setup(char *str)
 458 {
 459         printk("udb%s specified on command line is almost certainly a ubd -> "
 460                "udb TYPO\n", str);
 461         return(1);
 462 }
 463
 464 __setup("udb", udb_setup);
 465 __uml_help(udb_setup,
 466 "udb\n"
 467 "    This option is here solely to catch ubd -> udb typos, which can be\n\n"
 468 "    to impossible to catch visually unless you specifically look for\n\n"
 469 "    them.  The only result of any option starting with 'udb' is an error\n\n"
 470 "    in the boot output.\n\n"
 471 );
 472
 473 static int fakehd_set = 0;
 474 static int fakehd(char *str)
 475 {
 476         printk(KERN_INFO "fakehd : Changing ubd name to \"hd\".\n");
 477         fakehd_set = 1;
 478         return 1;
 479 }
 480
 481 __setup("fakehd", fakehd);
 482 __uml_help(fakehd,
 483 "fakehd\n"
 484 "    Change the ubd device name to \"hd\".\n\n"
 485 );
 486
 487 static void do_ubd_request(request_queue_t * q);
 488
 489 /* Only changed by ubd_init, which is an initcall. */
 490 int thread_fd = -1;
 491
 492 /* Changed by ubd_handler, which is serialized because interrupts only
 493  * happen on CPU 0.
 494  */
 495 int intr_count = 0;
 496
 497 /* call ubd_finish if you need to serialize */
 498 static void __ubd_finish(struct request *req, int error)
 499 {
 500         int nsect;
 501
 502         if(error){
 503                 end_request(req, 0);
 504                 return;
 505         }
 506         nsect = req->current_nr_sectors;
 507         req->sector += nsect;
 508         req->buffer += nsect << 9;
 509         req->errors = 0;
 510         req->nr_sectors -= nsect;
 511         req->current_nr_sectors = 0;
 512         end_request(req, 1);
 513 }
 514
 515 static inline void ubd_finish(struct request *req, int error)
 516 {
 517         spin_lock(&ubd_io_lock);
 518         __ubd_finish(req, error);
 519         spin_unlock(&ubd_io_lock);
 520 }
 521
 522 /* Called without ubd_io_lock held */
 523 static void ubd_handler(void)
 524 {
 525         struct io_thread_req req;
 526         struct request *rq = elv_next_request(ubd_queue);
 527         int n, err;
 528
 529         do_ubd = NULL;
 530         intr_count++;
 531         n = os_read_file(thread_fd, &req, sizeof(req));
 532         if(n != sizeof(req)){
 533                 printk(KERN_ERR "Pid %d - spurious interrupt in ubd_handler, "
 534                        "err = %d\n", os_getpid(), -n);
 535                 spin_lock(&ubd_io_lock);
 536                 end_request(rq, 0);
 537                 spin_unlock(&ubd_io_lock);
 538                 return;
 539         }
 540
 541         if((req.op != UBD_MMAP) &&
 542            ((req.offset != ((__u64) (rq->sector)) << 9) ||
 543             (req.length != (rq->current_nr_sectors) << 9)))
 544                 panic("I/O op mismatch");
 545
 546         if(req.map_fd != -1){
 547                 err = physmem_subst_mapping(req.buffer, req.map_fd,
 548                                             req.map_offset, 1);
 549                 if(err)
 550                         printk("ubd_handler - physmem_subst_mapping failed, "
 551                                "err = %d\n", -err);
 552         }
 553
 554         ubd_finish(rq, req.error);
 555         reactivate_fd(thread_fd, UBD_IRQ);
 556         do_ubd_request(ubd_queue);
 557 }
 558
 559 static irqreturn_t ubd_intr(int irq, void *dev, struct pt_regs *unused)
 560 {
 561         ubd_handler();
 562         return(IRQ_HANDLED);
 563 }
 564
 565 /* Only changed by ubd_init, which is an initcall. */
 566 static int io_pid = -1;
 567
 568 void kill_io_thread(void)
 569 {
 570         if(io_pid != -1)
 571                 os_kill_process(io_pid, 1);
 572 }
 573
 574 __uml_exitcall(kill_io_thread);
 575
 576 static int ubd_file_size(struct ubd *dev, __u64 *size_out)
 577 {
 578         char *file;
 579
 580         file = dev->cow.file ? dev->cow.file : dev->file;
 581         return(os_file_size(file, size_out));
 582 }
 583
 584 static void ubd_close(struct ubd *dev)
 585 {
 586         if(ubd_do_mmap)
 587                 physmem_forget_descriptor(dev->fd);
 588         os_close_file(dev->fd);
 589         if(dev->cow.file == NULL)
 590                 return;
 591
 592         if(ubd_do_mmap)
 593                 physmem_forget_descriptor(dev->cow.fd);
 594         os_close_file(dev->cow.fd);
 595         vfree(dev->cow.bitmap);
 596         dev->cow.bitmap = NULL;
 597 }
 598
 599 static int ubd_open_dev(struct ubd *dev)
 600 {
 601         struct openflags flags;
 602         char **back_ptr;
 603         int err, create_cow, *create_ptr;
 604
 605         dev->openflags = dev->boot_openflags;
 606         create_cow = 0;
 607         create_ptr = (dev->cow.file != NULL) ? &create_cow : NULL;
 608         back_ptr = dev->no_cow ? NULL : &dev->cow.file;
 609         dev->fd = open_ubd_file(dev->file, &dev->openflags, back_ptr,
 610                                 &dev->cow.bitmap_offset, &dev->cow.bitmap_len,
 611                                 &dev->cow.data_offset, create_ptr);
 612
 613         if((dev->fd == -ENOENT) && create_cow){
 614                 dev->fd = create_cow_file(dev->file, dev->cow.file,
 615                                           dev->openflags, 1 << 9, PAGE_SIZE,
 616                                           &dev->cow.bitmap_offset,
 617                                           &dev->cow.bitmap_len,
 618                                           &dev->cow.data_offset);
 619                 if(dev->fd >= 0){
 620                         printk(KERN_INFO "Creating \"%s\" as COW file for "
 621                                "\"%s\"\n", dev->file, dev->cow.file);
 622                 }
 623         }
 624
 625         if(dev->fd < 0){
 626                 printk("Failed to open '%s', errno = %d\n", dev->file,
 627                        -dev->fd);
 628                 return(dev->fd);
 629         }
 630
 631         if(dev->cow.file != NULL){
 632                 err = -ENOMEM;
 633                 dev->cow.bitmap = (void *) vmalloc(dev->cow.bitmap_len);
 634                 if(dev->cow.bitmap == NULL){
 635                         printk(KERN_ERR "Failed to vmalloc COW bitmap\n");
 636                         goto error;
 637                 }
 638                 flush_tlb_kernel_vm();
 639
 640                 err = read_cow_bitmap(dev->fd, dev->cow.bitmap,
 641                                       dev->cow.bitmap_offset,
 642                                       dev->cow.bitmap_len);
 643                 if(err < 0)
 644                         goto error;
 645
 646                 flags = dev->openflags;
 647                 flags.w = 0;
 648                 err = open_ubd_file(dev->cow.file, &flags, NULL, NULL, NULL,
 649                                     NULL, NULL);
 650                 if(err < 0) goto error;
 651                 dev->cow.fd = err;
 652         }
 653         return(0);
 654  error:
 655         os_close_file(dev->fd);
 656         return(err);
 657 }
 658
 659 static int ubd_new_disk(int major, u64 size, int unit,
 660                         struct gendisk **disk_out)
 661
 662 {
 663         struct gendisk *disk;
 664         char from[sizeof("ubd/nnnnn\0")], to[sizeof("discnnnnn/disc\0")];
 665         int err;
 666
 667         disk = alloc_disk(1 << UBD_SHIFT);
 668         if(disk == NULL)
 669                 return(-ENOMEM);
 670
 671         disk->major = major;
 672         disk->first_minor = unit << UBD_SHIFT;
 673         disk->fops = &ubd_blops;
 674         set_capacity(disk, size / 512);
 675         if(major == MAJOR_NR){
 676                 sprintf(disk->disk_name, "ubd%c", 'a' + unit);
 677                 sprintf(disk->devfs_name, "ubd/disc%d", unit);
 678                 sprintf(from, "ubd/%d", unit);
 679                 sprintf(to, "disc%d/disc", unit);
 680                 err = devfs_mk_symlink(from, to);
 681                 if(err)
 682                         printk("ubd_new_disk failed to make link from %s to "
 683                                "%s, error = %d\n", from, to, err);
 684         }
 685         else {
 686                 sprintf(disk->disk_name, "ubd_fake%d", unit);
 687                 sprintf(disk->devfs_name, "ubd_fake/disc%d", unit);
 688         }
 689
 690         /* sysfs register (not for ide fake devices) */
 691         if (major == MAJOR_NR) {
 692                 ubd_dev[unit].pdev.id   = unit;
 693                 ubd_dev[unit].pdev.name = DRIVER_NAME;
 694                 platform_device_register(&ubd_dev[unit].pdev);
 695                 disk->driverfs_dev = &ubd_dev[unit].pdev.dev;
 696         }
 697
 698         disk->private_data = &ubd_dev[unit];
 699         disk->queue = ubd_queue;
 700         add_disk(disk);
 701
 702         *disk_out = disk;
 703         return 0;
 704 }
 705
 706 #define ROUND_BLOCK(n) ((n + ((1 << 9) - 1)) & (-1 << 9))
 707
 708 static int ubd_add(int n)
 709 {
 710         struct ubd *dev = &ubd_dev[n];
 711         int err;
 712
 713         if(dev->file == NULL)
 714                 return(-ENODEV);
 715
 716         if (ubd_open_dev(dev))
 717                 return(-ENODEV);
 718
 719         err = ubd_file_size(dev, &dev->size);
 720         if(err < 0)
 721                 return(err);
 722
 723         dev->size = ROUND_BLOCK(dev->size);
 724
 725         err = ubd_new_disk(MAJOR_NR, dev->size, n, &ubd_gendisk[n]);
 726         if(err)
 727                 return(err);
 728
 729         if(fake_major != MAJOR_NR)
 730                 ubd_new_disk(fake_major, dev->size, n,
 731                              &fake_gendisk[n]);
 732
 733         /* perhaps this should also be under the "if (fake_major)" above */
 734         /* using the fake_disk->disk_name and also the fakehd_set name */
 735         if (fake_ide)
 736                 make_ide_entries(ubd_gendisk[n]->disk_name);
 737
 738         ubd_close(dev);
 739         return 0;
 740 }
 741
 742 static int ubd_config(char *str)
 743 {
 744         int n, err;
 745
 746         str = uml_strdup(str);
 747         if(str == NULL){
 748                 printk(KERN_ERR "ubd_config failed to strdup string\n");
 749                 return(1);
 750         }
 751         err = ubd_setup_common(str, &n);
 752         if(err){
 753                 kfree(str);
 754                 return(-1);
 755         }
 756         if(n == -1) return(0);
 757
 758         spin_lock(&ubd_lock);
 759         err = ubd_add(n);
 760         if(err)
 761                 ubd_dev[n].file = NULL;
 762         spin_unlock(&ubd_lock);
 763
 764         return(err);
 765 }
 766
 767 static int ubd_get_config(char *name, char *str, int size, char **error_out)
 768 {
 769         struct ubd *dev;
 770         int n, len = 0;
 771
 772         n = parse_unit(&name);
 773         if((n >= MAX_DEV) || (n < 0)){
 774                 *error_out = "ubd_get_config : device number out of range";
 775                 return(-1);
 776         }
 777
 778         dev = &ubd_dev[n];
 779         spin_lock(&ubd_lock);
 780
 781         if(dev->file == NULL){
 782                 CONFIG_CHUNK(str, size, len, "", 1);
 783                 goto out;
 784         }
 785
 786         CONFIG_CHUNK(str, size, len, dev->file, 0);
 787
 788         if(dev->cow.file != NULL){
 789                 CONFIG_CHUNK(str, size, len, ",", 0);
 790                 CONFIG_CHUNK(str, size, len, dev->cow.file, 1);
 791         }
 792         else CONFIG_CHUNK(str, size, len, "", 1);
 793
 794  out:
 795         spin_unlock(&ubd_lock);
 796         return(len);
 797 }
 798
 799 static int ubd_remove(char *str)
 800 {
 801         struct ubd *dev;
 802         int n, err = -ENODEV;
 803
 804         n = parse_unit(&str);
 805
 806         if((n < 0) || (n >= MAX_DEV))
 807                 return(err);
 808
 809         dev = &ubd_dev[n];
 810         if(dev->count > 0)
 811                 return(-EBUSY); /* you cannot remove a open disk */
 812
 813         err = 0;
 814         spin_lock(&ubd_lock);
 815
 816         if(ubd_gendisk[n] == NULL)
 817                 goto out;
 818
 819         del_gendisk(ubd_gendisk[n]);
 820         put_disk(ubd_gendisk[n]);
 821         ubd_gendisk[n] = NULL;
 822
 823         if(fake_gendisk[n] != NULL){
 824                 del_gendisk(fake_gendisk[n]);
 825                 put_disk(fake_gendisk[n]);
 826                 fake_gendisk[n] = NULL;
 827         }
 828
 829         platform_device_unregister(&dev->pdev);
 830         *dev = ((struct ubd) DEFAULT_UBD);
 831         err = 0;
 832  out:
 833         spin_unlock(&ubd_lock);
 834         return(err);
 835 }
 836
 837 static struct mc_device ubd_mc = {
 838         .name           = "ubd",
 839         .config         = ubd_config,
 840         .get_config     = ubd_get_config,
 841         .remove         = ubd_remove,
 842 };
 843
 844 static int ubd_mc_init(void)
 845 {
 846         mconsole_register_dev(&ubd_mc);
 847         return 0;
 848 }
 849
 850 __initcall(ubd_mc_init);
 851
 852 static struct device_driver ubd_driver = {
 853         .name  = DRIVER_NAME,
 854         .bus   = &platform_bus_type,
 855 };
 856
 857 int ubd_init(void)
 858 {
 859         int i;
 860
 861         devfs_mk_dir("ubd");
 862         if (register_blkdev(MAJOR_NR, "ubd"))
 863                 return -1;
 864
 865         ubd_queue = blk_init_queue(do_ubd_request, &ubd_io_lock);
 866         if (!ubd_queue) {
 867                 unregister_blkdev(MAJOR_NR, "ubd");
 868                 return -1;
 869         }
 870
 871         if (fake_major != MAJOR_NR) {
 872                 char name[sizeof("ubd_nnn\0")];
 873
 874                 snprintf(name, sizeof(name), "ubd_%d", fake_major);
 875                 devfs_mk_dir(name);
 876                 if (register_blkdev(fake_major, "ubd"))
 877                         return -1;
 878         }
 879         driver_register(&ubd_driver);
 880         for (i = 0; i < MAX_DEV; i++)
 881                 ubd_add(i);
 882         return 0;
 883 }
 884
 885 late_initcall(ubd_init);
 886
 887 int ubd_driver_init(void){
 888         unsigned long stack;
 889         int err;
 890
 891         /* Set by CONFIG_BLK_DEV_UBD_SYNC or ubd=sync.*/
 892         if(global_openflags.s){
 893                 printk(KERN_INFO "ubd: Synchronous mode\n");
 894                 /* Letting ubd=sync be like using ubd#s= instead of ubd#= is
 895                  * enough. So use anyway the io thread. */
 896         }
 897         stack = alloc_stack(0, 0);
 898         io_pid = start_io_thread(stack + PAGE_SIZE - sizeof(void *),
 899                                  &thread_fd);
 900         if(io_pid < 0){
 901                 printk(KERN_ERR
 902                        "ubd : Failed to start I/O thread (errno = %d) - "
 903                        "falling back to synchronous I/O\n", -io_pid);
 904                 io_pid = -1;
 905                 return(0);
 906         }
 907         err = um_request_irq(UBD_IRQ, thread_fd, IRQ_READ, ubd_intr,
 908                              SA_INTERRUPT, "ubd", ubd_dev);
 909         if(err != 0)
 910                 printk(KERN_ERR "um_request_irq failed - errno = %d\n", -err);
 911         return(err);
 912 }
 913
 914 device_initcall(ubd_driver_init);
 915
 916 static int ubd_open(struct inode *inode, struct file *filp)
 917 {
 918         struct gendisk *disk = inode->i_bdev->bd_disk;
 919         struct ubd *dev = disk->private_data;
 920         int err = 0;
 921
 922         if(dev->count == 0){
 923                 err = ubd_open_dev(dev);
 924                 if(err){
 925                         printk(KERN_ERR "%s: Can't open \"%s\": errno = %d\n",
 926                                disk->disk_name, dev->file, -err);
 927                         goto out;
 928                 }
 929         }
 930         dev->count++;
 931         set_disk_ro(disk, !dev->openflags.w);
 932
 933         /* This should no more be needed. And it didn't work anyway to exclude
 934          * read-write remounting of filesystems.*/
 935         /*if((filp->f_mode & FMODE_WRITE) && !dev->openflags.w){
 936                 if(--dev->count == 0) ubd_close(dev);
 937                 err = -EROFS;
 938         }*/
 939  out:
 940         return(err);
 941 }
 942
 943 static int ubd_release(struct inode * inode, struct file * file)
 944 {
 945         struct gendisk *disk = inode->i_bdev->bd_disk;
 946         struct ubd *dev = disk->private_data;
 947
 948         if(--dev->count == 0)
 949                 ubd_close(dev);
 950         return(0);
 951 }
 952
 953 static void cowify_bitmap(__u64 io_offset, int length, unsigned long *cow_mask,
 954                           __u64 *cow_offset, unsigned long *bitmap,
 955                           __u64 bitmap_offset, unsigned long *bitmap_words,
 956                           __u64 bitmap_len)
 957 {
 958         __u64 sector = io_offset >> 9;
 959         int i, update_bitmap = 0;
 960
 961         for(i = 0; i < length >> 9; i++){
 962                 if(cow_mask != NULL)
 963                         ubd_set_bit(i, (unsigned char *) cow_mask);
 964                 if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
 965                         continue;
 966
 967                 update_bitmap = 1;
 968                 ubd_set_bit(sector + i, (unsigned char *) bitmap);
 969         }
 970
 971         if(!update_bitmap)
 972                 return;
 973
 974         *cow_offset = sector / (sizeof(unsigned long) * 8);
 975
 976         /* This takes care of the case where we're exactly at the end of the
 977          * device, and *cow_offset + 1 is off the end.  So, just back it up
 978          * by one word.  Thanks to Lynn Kerby for the fix and James McMechan
 979          * for the original diagnosis.
 980          */
 981         if(*cow_offset == ((bitmap_len + sizeof(unsigned long) - 1) /
 982                            sizeof(unsigned long) - 1))
 983                 (*cow_offset)--;
 984
 985         bitmap_words[0] = bitmap[*cow_offset];
 986         bitmap_words[1] = bitmap[*cow_offset + 1];
 987
 988         *cow_offset *= sizeof(unsigned long);
 989         *cow_offset += bitmap_offset;
 990 }
 991
 992 static void cowify_req(struct io_thread_req *req, unsigned long *bitmap,
 993                        __u64 bitmap_offset, __u64 bitmap_len)
 994 {
 995         __u64 sector = req->offset >> 9;
 996         int i;
 997
 998         if(req->length > (sizeof(req->sector_mask) * 8) << 9)
 999                 panic("Operation too long");
1000
1001         if(req->op == UBD_READ) {
1002                 for(i = 0; i < req->length >> 9; i++){
1003                         if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
1004                                 ubd_set_bit(i, (unsigned char *)
1005                                             &req->sector_mask);
1006                 }
1007         }
1008         else cowify_bitmap(req->offset, req->length, &req->sector_mask,
1009                            &req->cow_offset, bitmap, bitmap_offset,
1010                            req->bitmap_words, bitmap_len);
1011 }
1012
1013 static int mmap_fd(struct request *req, struct ubd *dev, __u64 offset)
1014 {
1015         __u64 sector;
1016         unsigned char *bitmap;
1017         int bit, i;
1018
1019         /* mmap must have been requested on the command line */
1020         if(!ubd_do_mmap)
1021                 return(-1);
1022
1023         /* The buffer must be page aligned */
1024         if(((unsigned long) req->buffer % UBD_MMAP_BLOCK_SIZE) != 0)
1025                 return(-1);
1026
1027         /* The request must be a page long */
1028         if((req->current_nr_sectors << 9) != PAGE_SIZE)
1029                 return(-1);
1030
1031         if(dev->cow.file == NULL)
1032                 return(dev->fd);
1033
1034         sector = offset >> 9;
1035         bitmap = (unsigned char *) dev->cow.bitmap;
1036         bit = ubd_test_bit(sector, bitmap);
1037
1038         for(i = 1; i < req->current_nr_sectors; i++){
1039                 if(ubd_test_bit(sector + i, bitmap) != bit)
1040                         return(-1);
1041         }
1042
1043         if(bit || (rq_data_dir(req) == WRITE))
1044                 offset += dev->cow.data_offset;
1045
1046         /* The data on disk must be page aligned */
1047         if((offset % UBD_MMAP_BLOCK_SIZE) != 0)
1048                 return(-1);
1049
1050         return(bit ? dev->fd : dev->cow.fd);
1051 }
1052
1053 static int prepare_mmap_request(struct ubd *dev, int fd, __u64 offset,
1054                                 struct request *req,
1055                                 struct io_thread_req *io_req)
1056 {
1057         int err;
1058
1059         if(rq_data_dir(req) == WRITE){
1060                 /* Writes are almost no-ops since the new data is already in the
1061                  * host page cache
1062                  */
1063                 dev->map_writes++;
1064                 if(dev->cow.file != NULL)
1065                         cowify_bitmap(io_req->offset, io_req->length,
1066                                       &io_req->sector_mask, &io_req->cow_offset,
1067                                       dev->cow.bitmap, dev->cow.bitmap_offset,
1068                                       io_req->bitmap_words,
1069                                       dev->cow.bitmap_len);
1070         }
1071         else {
1072                 int w;
1073
1074                 if((dev->cow.file != NULL) && (fd == dev->cow.fd))
1075                         w = 0;
1076                 else w = dev->openflags.w;
1077
1078                 if((dev->cow.file != NULL) && (fd == dev->fd))
1079                         offset += dev->cow.data_offset;
1080
1081                 err = physmem_subst_mapping(req->buffer, fd, offset, w);
1082                 if(err){
1083                         printk("physmem_subst_mapping failed, err = %d\n",
1084                                -err);
1085                         return(1);
1086                 }
1087                 dev->map_reads++;
1088         }
1089         io_req->op = UBD_MMAP;
1090         io_req->buffer = req->buffer;
1091         return(0);
1092 }
1093
1094 /* Called with ubd_io_lock held */
1095 static int prepare_request(struct request *req, struct io_thread_req *io_req)
1096 {
1097         struct gendisk *disk = req->rq_disk;
1098         struct ubd *dev = disk->private_data;
1099         __u64 offset;
1100         int len, fd;
1101
1102         if(req->rq_status == RQ_INACTIVE) return(1);
1103
1104         /* This should be impossible now */
1105         if((rq_data_dir(req) == WRITE) && !dev->openflags.w){
1106                 printk("Write attempted on readonly ubd device %s\n",
1107                        disk->disk_name);
1108                 end_request(req, 0);
1109                 return(1);
1110         }
1111
1112         offset = ((__u64) req->sector) << 9;
1113         len = req->current_nr_sectors << 9;
1114
1115         io_req->fds[0] = (dev->cow.file != NULL) ? dev->cow.fd : dev->fd;
1116         io_req->fds[1] = dev->fd;
1117         io_req->map_fd = -1;
1118         io_req->cow_offset = -1;
1119         io_req->offset = offset;
1120         io_req->length = len;
1121         io_req->error = 0;
1122         io_req->sector_mask = 0;
1123
1124         fd = mmap_fd(req, dev, io_req->offset);
1125         if(fd > 0){
1126                 /* If mmapping is otherwise OK, but the first access to the
1127                  * page is a write, then it's not mapped in yet.  So we have
1128                  * to write the data to disk first, then we can map the disk
1129                  * page in and continue normally from there.
1130                  */
1131                 if((rq_data_dir(req) == WRITE) && !is_remapped(req->buffer)){
1132                         io_req->map_fd = dev->fd;
1133                         io_req->map_offset = io_req->offset +
1134                                 dev->cow.data_offset;
1135                         dev->write_maps++;
1136                 }
1137                 else return(prepare_mmap_request(dev, fd, io_req->offset, req,
1138                                                  io_req));
1139         }
1140
1141         if(rq_data_dir(req) == READ)
1142                 dev->nomap_reads++;
1143         else dev->nomap_writes++;
1144
1145         io_req->op = (rq_data_dir(req) == READ) ? UBD_READ : UBD_WRITE;
1146         io_req->offsets[0] = 0;
1147         io_req->offsets[1] = dev->cow.data_offset;
1148         io_req->buffer = req->buffer;
1149         io_req->sectorsize = 1 << 9;
1150
1151         if(dev->cow.file != NULL)
1152                 cowify_req(io_req, dev->cow.bitmap, dev->cow.bitmap_offset,
1153                            dev->cow.bitmap_len);
1154
1155         return(0);
1156 }
1157
1158 /* Called with ubd_io_lock held */
1159 static void do_ubd_request(request_queue_t *q)
1160 {
1161         struct io_thread_req io_req;
1162         struct request *req;
1163         int err, n;
1164
1165         if(thread_fd == -1){
1166                 while((req = elv_next_request(q)) != NULL){
1167                         err = prepare_request(req, &io_req);
1168                         if(!err){
1169                                 do_io(&io_req);
1170                                 __ubd_finish(req, io_req.error);
1171                         }
1172                 }
1173         }
1174         else {
1175                 if(do_ubd || (req = elv_next_request(q)) == NULL)
1176                         return;
1177                 err = prepare_request(req, &io_req);
1178                 if(!err){
1179                         do_ubd = ubd_handler;
1180                         n = os_write_file(thread_fd, (char *) &io_req,
1181                                          sizeof(io_req));
1182                         if(n != sizeof(io_req))
1183                                 printk("write to io thread failed, "
1184                                        "errno = %d\n", -n);
1185                 }
1186         }
1187 }
1188
1189 static int ubd_ioctl(struct inode * inode, struct file * file,
1190                      unsigned int cmd, unsigned long arg)
1191 {
1192         struct hd_geometry __user *loc = (struct hd_geometry __user *) arg;
1193         struct ubd *dev = inode->i_bdev->bd_disk->private_data;
1194         struct hd_driveid ubd_id = {
1195                 .cyls           = 0,
1196                 .heads          = 128,
1197                 .sectors        = 32,
1198         };
1199
1200         switch (cmd) {
1201                 struct hd_geometry g;
1202                 struct cdrom_volctrl volume;
1203         case HDIO_GETGEO:
1204                 if(!loc) return(-EINVAL);
1205                 g.heads = 128;
1206                 g.sectors = 32;
1207                 g.cylinders = dev->size / (128 * 32 * 512);
1208                 g.start = get_start_sect(inode->i_bdev);
1209                 return(copy_to_user(loc, &g, sizeof(g)) ? -EFAULT : 0);
1210
1211         case HDIO_GET_IDENTITY:
1212                 ubd_id.cyls = dev->size / (128 * 32 * 512);
1213                 if(copy_to_user((char __user *) arg, (char *) &ubd_id,
1214                                  sizeof(ubd_id)))
1215                         return(-EFAULT);
1216                 return(0);
1217
1218         case CDROMVOLREAD:
1219                 if(copy_from_user(&volume, (char __user *) arg, sizeof(volume)))
1220                         return(-EFAULT);
1221                 volume.channel0 = 255;
1222                 volume.channel1 = 255;
1223                 volume.channel2 = 255;
1224                 volume.channel3 = 255;
1225                 if(copy_to_user((char __user *) arg, &volume, sizeof(volume)))
1226                         return(-EFAULT);
1227                 return(0);
1228         }
1229         return(-EINVAL);
1230 }
1231
1232 static int ubd_check_remapped(int fd, unsigned long address, int is_write,
1233                               __u64 offset)
1234 {
1235         __u64 bitmap_offset;
1236         unsigned long new_bitmap[2];
1237         int i, err, n;
1238
1239         /* If it's not a write access, we can't do anything about it */
1240         if(!is_write)
1241                 return(0);
1242
1243         /* We have a write */
1244         for(i = 0; i < sizeof(ubd_dev) / sizeof(ubd_dev[0]); i++){
1245                 struct ubd *dev = &ubd_dev[i];
1246
1247                 if((dev->fd != fd) && (dev->cow.fd != fd))
1248                         continue;
1249
1250                 /* It's a write to a ubd device */
1251
1252                 /* This should be impossible now */
1253                 if(!dev->openflags.w){
1254                         /* It's a write access on a read-only device - probably
1255                          * shouldn't happen.  If the kernel is trying to change
1256                          * something with no intention of writing it back out,
1257                          * then this message will clue us in that this needs
1258                          * fixing
1259                          */
1260                         printk("Write access to mapped page from readonly ubd "
1261                                "device %d\n", i);
1262                         return(0);
1263                 }
1264
1265                 /* It's a write to a writeable ubd device - it must be COWed
1266                  * because, otherwise, the page would have been mapped in
1267                  * writeable
1268                  */
1269
1270                 if(!dev->cow.file)
1271                         panic("Write fault on writeable non-COW ubd device %d",
1272                               i);
1273
1274                 /* It should also be an access to the backing file since the
1275                  * COW pages should be mapped in read-write
1276                  */
1277
1278                 if(fd == dev->fd)
1279                         panic("Write fault on a backing page of ubd "
1280                               "device %d\n", i);
1281
1282                 /* So, we do the write, copying the backing data to the COW
1283                  * file...
1284                  */
1285
1286                 err = os_seek_file(dev->fd, offset + dev->cow.data_offset);
1287                 if(err < 0)
1288                         panic("Couldn't seek to %lld in COW file of ubd "
1289                               "device %d, err = %d",
1290                               offset + dev->cow.data_offset, i, -err);
1291
1292                 n = os_write_file(dev->fd, (void *) address, PAGE_SIZE);
1293                 if(n != PAGE_SIZE)
1294                         panic("Couldn't copy data to COW file of ubd "
1295                               "device %d, err = %d", i, -n);
1296
1297                 /* ... updating the COW bitmap... */
1298
1299                 cowify_bitmap(offset, PAGE_SIZE, NULL, &bitmap_offset,
1300                               dev->cow.bitmap, dev->cow.bitmap_offset,
1301                               new_bitmap, dev->cow.bitmap_len);
1302
1303                 err = os_seek_file(dev->fd, bitmap_offset);
1304                 if(err < 0)
1305                         panic("Couldn't seek to %lld in COW file of ubd "
1306                               "device %d, err = %d", bitmap_offset, i, -err);
1307
1308                 n = os_write_file(dev->fd, new_bitmap, sizeof(new_bitmap));
1309                 if(n != sizeof(new_bitmap))
1310                         panic("Couldn't update bitmap  of ubd device %d, "
1311                               "err = %d", i, -n);
1312
1313                 /* Maybe we can map the COW page in, and maybe we can't.  If
1314                  * it is a pre-V3 COW file, we can't, since the alignment will
1315                  * be wrong.  If it is a V3 or later COW file which has been
1316                  * moved to a system with a larger page size, then maybe we
1317                  * can't, depending on the exact location of the page.
1318                  */
1319
1320                 offset += dev->cow.data_offset;
1321
1322                 /* Remove the remapping, putting the original anonymous page
1323                  * back.  If the COW file can be mapped in, that is done.
1324                  * Otherwise, the COW page is read in.
1325                  */
1326
1327                 if(!physmem_remove_mapping((void *) address))
1328                         panic("Address 0x%lx not remapped by ubd device %d",
1329                               address, i);
1330                 if((offset % UBD_MMAP_BLOCK_SIZE) == 0)
1331                         physmem_subst_mapping((void *) address, dev->fd,
1332                                               offset, 1);
1333                 else {
1334                         err = os_seek_file(dev->fd, offset);
1335                         if(err < 0)
1336                                 panic("Couldn't seek to %lld in COW file of "
1337                                       "ubd device %d, err = %d", offset, i,
1338                                       -err);
1339
1340                         n = os_read_file(dev->fd, (void *) address, PAGE_SIZE);
1341                         if(n != PAGE_SIZE)
1342                                 panic("Failed to read page from offset %llx of "
1343                                       "COW file of ubd device %d, err = %d",
1344                                       offset, i, -n);
1345                 }
1346
1347                 return(1);
1348         }
1349
1350         /* It's not a write on a ubd device */
1351         return(0);
1352 }
1353
1354 static struct remapper ubd_remapper = {
1355         .list   = LIST_HEAD_INIT(ubd_remapper.list),
1356         .proc   = ubd_check_remapped,
1357 };
1358
1359 static int ubd_remapper_setup(void)
1360 {
1361         if(ubd_do_mmap)
1362                 register_remapper(&ubd_remapper);
1363
1364         return(0);
1365 }
1366
1367 __initcall(ubd_remapper_setup);
1368
1369 static int same_backing_files(char *from_cmdline, char *from_cow, char *cow)
1370 {
1371         struct uml_stat buf1, buf2;
1372         int err;
1373
1374         if(from_cmdline == NULL) return(1);
1375         if(!strcmp(from_cmdline, from_cow)) return(1);
1376
1377         err = os_stat_file(from_cmdline, &buf1);
1378         if(err < 0){
1379                 printk("Couldn't stat '%s', err = %d\n", from_cmdline, -err);
1380                 return(1);
1381         }
1382         err = os_stat_file(from_cow, &buf2);
1383         if(err < 0){
1384                 printk("Couldn't stat '%s', err = %d\n", from_cow, -err);
1385                 return(1);
1386         }
1387         if((buf1.ust_dev == buf2.ust_dev) && (buf1.ust_ino == buf2.ust_ino))
1388                 return(1);
1389
1390         printk("Backing file mismatch - \"%s\" requested,\n"
1391                "\"%s\" specified in COW header of \"%s\"\n",
1392                from_cmdline, from_cow, cow);
1393         return(0);
1394 }
1395
1396 static int backing_file_mismatch(char *file, __u64 size, time_t mtime)
1397 {
1398         unsigned long modtime;
1399         long long actual;
1400         int err;
1401
1402         err = os_file_modtime(file, &modtime);
1403         if(err < 0){
1404                 printk("Failed to get modification time of backing file "
1405                        "\"%s\", err = %d\n", file, -err);
1406                 return(err);
1407         }
1408
1409         err = os_file_size(file, &actual);
1410         if(err < 0){
1411                 printk("Failed to get size of backing file \"%s\", "
1412                        "err = %d\n", file, -err);
1413                 return(err);
1414         }
1415
1416         if(actual != size){
1417                 /*__u64 can be a long on AMD64 and with %lu GCC complains; so
1418                  * the typecast.*/
1419                 printk("Size mismatch (%llu vs %llu) of COW header vs backing "
1420                        "file\n", (unsigned long long) size, actual);
1421                 return(-EINVAL);
1422         }
1423         if(modtime != mtime){
1424                 printk("mtime mismatch (%ld vs %ld) of COW header vs backing "
1425                        "file\n", mtime, modtime);
1426                 return(-EINVAL);
1427         }
1428         return(0);
1429 }
1430
1431 int read_cow_bitmap(int fd, void *buf, int offset, int len)
1432 {
1433         int err;
1434
1435         err = os_seek_file(fd, offset);
1436         if(err < 0)
1437                 return(err);
1438
1439         err = os_read_file(fd, buf, len);
1440         if(err < 0)
1441                 return(err);
1442
1443         return(0);
1444 }
1445
1446 int open_ubd_file(char *file, struct openflags *openflags,
1447                   char **backing_file_out, int *bitmap_offset_out,
1448                   unsigned long *bitmap_len_out, int *data_offset_out,
1449                   int *create_cow_out)
1450 {
1451         time_t mtime;
1452         unsigned long long size;
1453         __u32 version, align;
1454         char *backing_file;
1455         int fd, err, sectorsize, same, mode = 0644;
1456
1457         fd = os_open_file(file, *openflags, mode);
1458         if(fd < 0){
1459                 if((fd == -ENOENT) && (create_cow_out != NULL))
1460                         *create_cow_out = 1;
1461                 if(!openflags->w ||
1462                    ((fd != -EROFS) && (fd != -EACCES))) return(fd);
1463                 openflags->w = 0;
1464                 fd = os_open_file(file, *openflags, mode);
1465                 if(fd < 0)
1466                         return(fd);
1467         }
1468
1469         err = os_lock_file(fd, openflags->w);
1470         if(err < 0){
1471                 printk("Failed to lock '%s', err = %d\n", file, -err);
1472                 goto out_close;
1473         }
1474
1475         if(backing_file_out == NULL) return(fd);
1476
1477         err = read_cow_header(file_reader, &fd, &version, &backing_file, &mtime,
1478                               &size, &sectorsize, &align, bitmap_offset_out);
1479         if(err && (*backing_file_out != NULL)){
1480                 printk("Failed to read COW header from COW file \"%s\", "
1481                        "errno = %d\n", file, -err);
1482                 goto out_close;
1483         }
1484         if(err) return(fd);
1485
1486         if(backing_file_out == NULL) return(fd);
1487
1488         same = same_backing_files(*backing_file_out, backing_file, file);
1489
1490         if(!same && !backing_file_mismatch(*backing_file_out, size, mtime)){
1491                 printk("Switching backing file to '%s'\n", *backing_file_out);
1492                 err = write_cow_header(file, fd, *backing_file_out,
1493                                        sectorsize, align, &size);
1494                 if(err){
1495                         printk("Switch failed, errno = %d\n", -err);
1496                         return(err);
1497                 }
1498         }
1499         else {
1500                 *backing_file_out = backing_file;
1501                 err = backing_file_mismatch(*backing_file_out, size, mtime);
1502                 if(err) goto out_close;
1503         }
1504
1505         cow_sizes(version, size, sectorsize, align, *bitmap_offset_out,
1506                   bitmap_len_out, data_offset_out);
1507
1508         return(fd);
1509  out_close:
1510         os_close_file(fd);
1511         return(err);
1512 }
1513
1514 int create_cow_file(char *cow_file, char *backing_file, struct openflags flags,
1515                     int sectorsize, int alignment, int *bitmap_offset_out,
1516                     unsigned long *bitmap_len_out, int *data_offset_out)
1517 {
1518         int err, fd;
1519
1520         flags.c = 1;
1521         fd = open_ubd_file(cow_file, &flags, NULL, NULL, NULL, NULL, NULL);
1522         if(fd < 0){
1523                 err = fd;
1524                 printk("Open of COW file '%s' failed, errno = %d\n", cow_file,
1525                        -err);
1526                 goto out;
1527         }
1528
1529         err = init_cow_file(fd, cow_file, backing_file, sectorsize, alignment,
1530                             bitmap_offset_out, bitmap_len_out,
1531                             data_offset_out);
1532         if(!err)
1533                 return(fd);
1534         os_close_file(fd);
1535  out:
1536         return(err);
1537 }
1538
1539 static int update_bitmap(struct io_thread_req *req)
1540 {
1541         int n;
1542
1543         if(req->cow_offset == -1)
1544                 return(0);
1545
1546         n = os_seek_file(req->fds[1], req->cow_offset);
1547         if(n < 0){
1548                 printk("do_io - bitmap lseek failed : err = %d\n", -n);
1549                 return(1);
1550         }
1551
1552         n = os_write_file(req->fds[1], &req->bitmap_words,
1553                           sizeof(req->bitmap_words));
1554         if(n != sizeof(req->bitmap_words)){
1555                 printk("do_io - bitmap update failed, err = %d fd = %d\n", -n,
1556                        req->fds[1]);
1557                 return(1);
1558         }
1559
1560         return(0);
1561 }
1562
1563 void do_io(struct io_thread_req *req)
1564 {
1565         char *buf;
1566         unsigned long len;
1567         int n, nsectors, start, end, bit;
1568         int err;
1569         __u64 off;
1570
1571         if(req->op == UBD_MMAP){
1572                 /* Touch the page to force the host to do any necessary IO to
1573                  * get it into memory
1574                  */
1575                 n = *((volatile int *) req->buffer);
1576                 req->error = update_bitmap(req);
1577                 return;
1578         }
1579
1580         nsectors = req->length / req->sectorsize;
1581         start = 0;
1582         do {
1583                 bit = ubd_test_bit(start, (unsigned char *) &req->sector_mask);
1584                 end = start;
1585                 while((end < nsectors) &&
1586                       (ubd_test_bit(end, (unsigned char *)
1587                                     &req->sector_mask) == bit))
1588                         end++;
1589
1590                 off = req->offset + req->offsets[bit] +
1591                         start * req->sectorsize;
1592                 len = (end - start) * req->sectorsize;
1593                 buf = &req->buffer[start * req->sectorsize];
1594
1595                 err = os_seek_file(req->fds[bit], off);
1596                 if(err < 0){
1597                         printk("do_io - lseek failed : err = %d\n", -err);
1598                         req->error = 1;
1599                         return;
1600                 }
1601                 if(req->op == UBD_READ){
1602                         n = 0;
1603                         do {
1604                                 buf = &buf[n];
1605                                 len -= n;
1606                                 n = os_read_file(req->fds[bit], buf, len);
1607                                 if (n < 0) {
1608                                         printk("do_io - read failed, err = %d "
1609                                                "fd = %d\n", -n, req->fds[bit]);
1610                                         req->error = 1;
1611                                         return;
1612                                 }
1613                         } while((n < len) && (n != 0));
1614                         if (n < len) memset(&buf[n], 0, len - n);
1615                 } else {
1616                         n = os_write_file(req->fds[bit], buf, len);
1617                         if(n != len){
1618                                 printk("do_io - write failed err = %d "
1619                                        "fd = %d\n", -n, req->fds[bit]);
1620                                 req->error = 1;
1621                                 return;
1622                         }
1623                 }
1624
1625                 start = end;
1626         } while(start < nsectors);
1627
1628         req->error = update_bitmap(req);
1629 }
1630
1631 /* Changed in start_io_thread, which is serialized by being called only
1632  * from ubd_init, which is an initcall.
1633  */
1634 int kernel_fd = -1;
1635
1636 /* Only changed by the io thread */
1637 int io_count = 0;
1638
1639 int io_thread(void *arg)
1640 {
1641         struct io_thread_req req;
1642         int n;
1643
1644         ignore_sigwinch_sig();
1645         while(1){
1646                 n = os_read_file(kernel_fd, &req, sizeof(req));
1647                 if(n != sizeof(req)){
1648                         if(n < 0)
1649                                 printk("io_thread - read failed, fd = %d, "
1650                                        "err = %d\n", kernel_fd, -n);
1651                         else {
1652                                 printk("io_thread - short read, fd = %d, "
1653                                        "length = %d\n", kernel_fd, n);
1654                         }
1655                         continue;
1656                 }
1657                 io_count++;
1658                 do_io(&req);
1659                 n = os_write_file(kernel_fd, &req, sizeof(req));
1660                 if(n != sizeof(req))
1661                         printk("io_thread - write failed, fd = %d, err = %d\n",
1662                                kernel_fd, -n);
1663         }
1664 }
1665
1666 /*
1667  * Overrides for Emacs so that we follow Linus's tabbing style.
1668  * Emacs will notice this stuff at the end of the file and automatically
1669  * adjust the settings for this buffer only.  This must remain at the end
1670  * of the file.
1671  * ---------------------------------------------------------------------------
1672  * Local variables:
1673  * c-file-style: "linux"
1674  * End:
1675  */