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