arch/um/drivers/ubd_kern.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2018 Cambridge Greys Ltd
   4  * Copyright (C) 2015-2016 Anton Ivanov (aivanov@brocade.com)
   5  * Copyright (C) 2000 Jeff Dike (jdike@karaya.com)
   6  */
   7
   8 /* 2001-09-28...2002-04-17
   9  * Partition stuff by James_McMechan@hotmail.com
  10  * old style ubd by setting UBD_SHIFT to 0
  11  * 2002-09-27...2002-10-18 massive tinkering for 2.5
  12  * partitions have changed in 2.5
  13  * 2003-01-29 more tinkering for 2.5.59-1
  14  * This should now address the sysfs problems and has
  15  * the symlink for devfs to allow for booting with
  16  * the common /dev/ubd/discX/... names rather than
  17  * only /dev/ubdN/discN this version also has lots of
  18  * clean ups preparing for ubd-many.
  19  * James McMechan
  20  */
  21
  22 #define UBD_SHIFT 4
  23
  24 #include <linux/module.h>
  25 #include <linux/init.h>
  26 #include <linux/blkdev.h>
  27 #include <linux/blk-mq.h>
  28 #include <linux/ata.h>
  29 #include <linux/hdreg.h>
  30 #include <linux/cdrom.h>
  31 #include <linux/proc_fs.h>
  32 #include <linux/seq_file.h>
  33 #include <linux/ctype.h>
  34 #include <linux/slab.h>
  35 #include <linux/vmalloc.h>
  36 #include <linux/platform_device.h>
  37 #include <linux/scatterlist.h>
  38 #include <asm/tlbflush.h>
  39 #include <kern_util.h>
  40 #include "mconsole_kern.h"
  41 #include <init.h>
  42 #include <irq_kern.h>
  43 #include "ubd.h"
  44 #include <os.h>
  45 #include "cow.h"
  46
  47 /* Max request size is determined by sector mask - 32K */
  48 #define UBD_MAX_REQUEST (8 * sizeof(long))
  49
  50 struct io_desc {
  51         char *buffer;
  52         unsigned long length;
  53         unsigned long sector_mask;
  54         unsigned long long cow_offset;
  55         unsigned long bitmap_words[2];
  56 };
  57
  58 struct io_thread_req {
  59         struct request *req;
  60         int fds[2];
  61         unsigned long offsets[2];
  62         unsigned long long offset;
  63         int sectorsize;
  64         int error;
  65
  66         int desc_cnt;
  67         /* io_desc has to be the last element of the struct */
  68         struct io_desc io_desc[];
  69 };
  70
  71
  72 static struct io_thread_req * (*irq_req_buffer)[];
  73 static struct io_thread_req *irq_remainder;
  74 static int irq_remainder_size;
  75
  76 static struct io_thread_req * (*io_req_buffer)[];
  77 static struct io_thread_req *io_remainder;
  78 static int io_remainder_size;
  79
  80
  81
  82 static inline int ubd_test_bit(__u64 bit, unsigned char *data)
  83 {
  84         __u64 n;
  85         int bits, off;
  86
  87         bits = sizeof(data[0]) * 8;
  88         n = bit / bits;
  89         off = bit % bits;
  90         return (data[n] & (1 << off)) != 0;
  91 }
  92
  93 static inline void ubd_set_bit(__u64 bit, unsigned char *data)
  94 {
  95         __u64 n;
  96         int bits, off;
  97
  98         bits = sizeof(data[0]) * 8;
  99         n = bit / bits;
 100         off = bit % bits;
 101         data[n] |= (1 << off);
 102 }
 103 /*End stuff from ubd_user.h*/
 104
 105 #define DRIVER_NAME "uml-blkdev"
 106
 107 static DEFINE_MUTEX(ubd_lock);
 108 static DEFINE_MUTEX(ubd_mutex); /* replaces BKL, might not be needed */
 109
 110 static int ubd_open(struct block_device *bdev, fmode_t mode);
 111 static void ubd_release(struct gendisk *disk, fmode_t mode);
 112 static int ubd_ioctl(struct block_device *bdev, fmode_t mode,
 113                      unsigned int cmd, unsigned long arg);
 114 static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo);
 115
 116 #define MAX_DEV (16)
 117
 118 static const struct block_device_operations ubd_blops = {
 119         .owner          = THIS_MODULE,
 120         .open           = ubd_open,
 121         .release        = ubd_release,
 122         .ioctl          = ubd_ioctl,
 123         .compat_ioctl   = blkdev_compat_ptr_ioctl,
 124         .getgeo         = ubd_getgeo,
 125 };
 126
 127 /* Protected by ubd_lock */
 128 static int fake_major = UBD_MAJOR;
 129 static struct gendisk *ubd_gendisk[MAX_DEV];
 130 static struct gendisk *fake_gendisk[MAX_DEV];
 131
 132 #ifdef CONFIG_BLK_DEV_UBD_SYNC
 133 #define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 1, .c = 0, \
 134                                          .cl = 1 })
 135 #else
 136 #define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 0, .c = 0, \
 137                                          .cl = 1 })
 138 #endif
 139 static struct openflags global_openflags = OPEN_FLAGS;
 140
 141 struct cow {
 142         /* backing file name */
 143         char *file;
 144         /* backing file fd */
 145         int fd;
 146         unsigned long *bitmap;
 147         unsigned long bitmap_len;
 148         int bitmap_offset;
 149         int data_offset;
 150 };
 151
 152 #define MAX_SG 64
 153
 154 struct ubd {
 155         /* name (and fd, below) of the file opened for writing, either the
 156          * backing or the cow file. */
 157         char *file;
 158         char *serial;
 159         int count;
 160         int fd;
 161         __u64 size;
 162         struct openflags boot_openflags;
 163         struct openflags openflags;
 164         unsigned shared:1;
 165         unsigned no_cow:1;
 166         unsigned no_trim:1;
 167         struct cow cow;
 168         struct platform_device pdev;
 169         struct request_queue *queue;
 170         struct blk_mq_tag_set tag_set;
 171         spinlock_t lock;
 172 };
 173
 174 #define DEFAULT_COW { \
 175         .file =                 NULL, \
 176         .fd =                   -1,     \
 177         .bitmap =               NULL, \
 178         .bitmap_offset =        0, \
 179         .data_offset =          0, \
 180 }
 181
 182 #define DEFAULT_UBD { \
 183         .file =                 NULL, \
 184         .serial =               NULL, \
 185         .count =                0, \
 186         .fd =                   -1, \
 187         .size =                 -1, \
 188         .boot_openflags =       OPEN_FLAGS, \
 189         .openflags =            OPEN_FLAGS, \
 190         .no_cow =               0, \
 191         .no_trim =              0, \
 192         .shared =               0, \
 193         .cow =                  DEFAULT_COW, \
 194         .lock =                 __SPIN_LOCK_UNLOCKED(ubd_devs.lock), \
 195 }
 196
 197 /* Protected by ubd_lock */
 198 static struct ubd ubd_devs[MAX_DEV] = { [0 ... MAX_DEV - 1] = DEFAULT_UBD };
 199
 200 /* Only changed by fake_ide_setup which is a setup */
 201 static int fake_ide = 0;
 202 static struct proc_dir_entry *proc_ide_root = NULL;
 203 static struct proc_dir_entry *proc_ide = NULL;
 204
 205 static blk_status_t ubd_queue_rq(struct blk_mq_hw_ctx *hctx,
 206                                  const struct blk_mq_queue_data *bd);
 207
 208 static void make_proc_ide(void)
 209 {
 210         proc_ide_root = proc_mkdir("ide", NULL);
 211         proc_ide = proc_mkdir("ide0", proc_ide_root);
 212 }
 213
 214 static int fake_ide_media_proc_show(struct seq_file *m, void *v)
 215 {
 216         seq_puts(m, "disk\n");
 217         return 0;
 218 }
 219
 220 static void make_ide_entries(const char *dev_name)
 221 {
 222         struct proc_dir_entry *dir, *ent;
 223         char name[64];
 224
 225         if(proc_ide_root == NULL) make_proc_ide();
 226
 227         dir = proc_mkdir(dev_name, proc_ide);
 228         if(!dir) return;
 229
 230         ent = proc_create_single("media", S_IRUGO, dir,
 231                         fake_ide_media_proc_show);
 232         if(!ent) return;
 233         snprintf(name, sizeof(name), "ide0/%s", dev_name);
 234         proc_symlink(dev_name, proc_ide_root, name);
 235 }
 236
 237 static int fake_ide_setup(char *str)
 238 {
 239         fake_ide = 1;
 240         return 1;
 241 }
 242
 243 __setup("fake_ide", fake_ide_setup);
 244
 245 __uml_help(fake_ide_setup,
 246 "fake_ide\n"
 247 "    Create ide0 entries that map onto ubd devices.\n\n"
 248 );
 249
 250 static int parse_unit(char **ptr)
 251 {
 252         char *str = *ptr, *end;
 253         int n = -1;
 254
 255         if(isdigit(*str)) {
 256                 n = simple_strtoul(str, &end, 0);
 257                 if(end == str)
 258                         return -1;
 259                 *ptr = end;
 260         }
 261         else if (('a' <= *str) && (*str <= 'z')) {
 262                 n = *str - 'a';
 263                 str++;
 264                 *ptr = str;
 265         }
 266         return n;
 267 }
 268
 269 /* If *index_out == -1 at exit, the passed option was a general one;
 270  * otherwise, the str pointer is used (and owned) inside ubd_devs array, so it
 271  * should not be freed on exit.
 272  */
 273 static int ubd_setup_common(char *str, int *index_out, char **error_out)
 274 {
 275         struct ubd *ubd_dev;
 276         struct openflags flags = global_openflags;
 277         char *file, *backing_file, *serial;
 278         int n, err = 0, i;
 279
 280         if(index_out) *index_out = -1;
 281         n = *str;
 282         if(n == '='){
 283                 char *end;
 284                 int major;
 285
 286                 str++;
 287                 if(!strcmp(str, "sync")){
 288                         global_openflags = of_sync(global_openflags);
 289                         return err;
 290                 }
 291
 292                 err = -EINVAL;
 293                 major = simple_strtoul(str, &end, 0);
 294                 if((*end != '\0') || (end == str)){
 295                         *error_out = "Didn't parse major number";
 296                         return err;
 297                 }
 298
 299                 mutex_lock(&ubd_lock);
 300                 if (fake_major != UBD_MAJOR) {
 301                         *error_out = "Can't assign a fake major twice";
 302                         goto out1;
 303                 }
 304
 305                 fake_major = major;
 306
 307                 printk(KERN_INFO "Setting extra ubd major number to %d\n",
 308                        major);
 309                 err = 0;
 310         out1:
 311                 mutex_unlock(&ubd_lock);
 312                 return err;
 313         }
 314
 315         n = parse_unit(&str);
 316         if(n < 0){
 317                 *error_out = "Couldn't parse device number";
 318                 return -EINVAL;
 319         }
 320         if(n >= MAX_DEV){
 321                 *error_out = "Device number out of range";
 322                 return 1;
 323         }
 324
 325         err = -EBUSY;
 326         mutex_lock(&ubd_lock);
 327
 328         ubd_dev = &ubd_devs[n];
 329         if(ubd_dev->file != NULL){
 330                 *error_out = "Device is already configured";
 331                 goto out;
 332         }
 333
 334         if (index_out)
 335                 *index_out = n;
 336
 337         err = -EINVAL;
 338         for (i = 0; i < sizeof("rscdt="); i++) {
 339                 switch (*str) {
 340                 case 'r':
 341                         flags.w = 0;
 342                         break;
 343                 case 's':
 344                         flags.s = 1;
 345                         break;
 346                 case 'd':
 347                         ubd_dev->no_cow = 1;
 348                         break;
 349                 case 'c':
 350                         ubd_dev->shared = 1;
 351                         break;
 352                 case 't':
 353                         ubd_dev->no_trim = 1;
 354                         break;
 355                 case '=':
 356                         str++;
 357                         goto break_loop;
 358                 default:
 359                         *error_out = "Expected '=' or flag letter "
 360                                 "(r, s, c, t or d)";
 361                         goto out;
 362                 }
 363                 str++;
 364         }
 365
 366         if (*str == '=')
 367                 *error_out = "Too many flags specified";
 368         else
 369                 *error_out = "Missing '='";
 370         goto out;
 371
 372 break_loop:
 373         file = strsep(&str, ",:");
 374         if (*file == '\0')
 375                 file = NULL;
 376
 377         backing_file = strsep(&str, ",:");
 378         if (*backing_file == '\0')
 379                 backing_file = NULL;
 380
 381         serial = strsep(&str, ",:");
 382         if (*serial == '\0')
 383                 serial = NULL;
 384
 385         if (backing_file && ubd_dev->no_cow) {
 386                 *error_out = "Can't specify both 'd' and a cow file";
 387                 goto out;
 388         }
 389
 390         err = 0;
 391         ubd_dev->file = file;
 392         ubd_dev->cow.file = backing_file;
 393         ubd_dev->serial = serial;
 394         ubd_dev->boot_openflags = flags;
 395 out:
 396         mutex_unlock(&ubd_lock);
 397         return err;
 398 }
 399
 400 static int ubd_setup(char *str)
 401 {
 402         char *error;
 403         int err;
 404
 405         err = ubd_setup_common(str, NULL, &error);
 406         if(err)
 407                 printk(KERN_ERR "Failed to initialize device with \"%s\" : "
 408                        "%s\n", str, error);
 409         return 1;
 410 }
 411
 412 __setup("ubd", ubd_setup);
 413 __uml_help(ubd_setup,
 414 "ubd<n><flags>=<filename>[(:|,)<filename2>][(:|,)<serial>]\n"
 415 "    This is used to associate a device with a file in the underlying\n"
 416 "    filesystem. When specifying two filenames, the first one is the\n"
 417 "    COW name and the second is the backing file name. As separator you can\n"
 418 "    use either a ':' or a ',': the first one allows writing things like;\n"
 419 "       ubd0=~/Uml/root_cow:~/Uml/root_backing_file\n"
 420 "    while with a ',' the shell would not expand the 2nd '~'.\n"
 421 "    When using only one filename, UML will detect whether to treat it like\n"
 422 "    a COW file or a backing file. To override this detection, add the 'd'\n"
 423 "    flag:\n"
 424 "       ubd0d=BackingFile\n"
 425 "    Usually, there is a filesystem in the file, but \n"
 426 "    that's not required. Swap devices containing swap files can be\n"
 427 "    specified like this. Also, a file which doesn't contain a\n"
 428 "    filesystem can have its contents read in the virtual \n"
 429 "    machine by running 'dd' on the device. <n> must be in the range\n"
 430 "    0 to 7. Appending an 'r' to the number will cause that device\n"
 431 "    to be mounted read-only. For example ubd1r=./ext_fs. Appending\n"
 432 "    an 's' will cause data to be written to disk on the host immediately.\n"
 433 "    'c' will cause the device to be treated as being shared between multiple\n"
 434 "    UMLs and file locking will be turned off - this is appropriate for a\n"
 435 "    cluster filesystem and inappropriate at almost all other times.\n\n"
 436 "    't' will disable trim/discard support on the device (enabled by default).\n\n"
 437 "    An optional device serial number can be exposed using the serial parameter\n"
 438 "    on the cmdline which is exposed as a sysfs entry. This is particularly\n"
 439 "    useful when a unique number should be given to the device. Note when\n"
 440 "    specifying a label, the filename2 must be also presented. It can be\n"
 441 "    an empty string, in which case the backing file is not used:\n"
 442 "       ubd0=File,,Serial\n"
 443 );
 444
 445 static int udb_setup(char *str)
 446 {
 447         printk("udb%s specified on command line is almost certainly a ubd -> "
 448                "udb TYPO\n", str);
 449         return 1;
 450 }
 451
 452 __setup("udb", udb_setup);
 453 __uml_help(udb_setup,
 454 "udb\n"
 455 "    This option is here solely to catch ubd -> udb typos, which can be\n"
 456 "    to impossible to catch visually unless you specifically look for\n"
 457 "    them.  The only result of any option starting with 'udb' is an error\n"
 458 "    in the boot output.\n\n"
 459 );
 460
 461 /* Only changed by ubd_init, which is an initcall. */
 462 static int thread_fd = -1;
 463
 464 /* Function to read several request pointers at a time
 465 * handling fractional reads if (and as) needed
 466 */
 467
 468 static int bulk_req_safe_read(
 469         int fd,
 470         struct io_thread_req * (*request_buffer)[],
 471         struct io_thread_req **remainder,
 472         int *remainder_size,
 473         int max_recs
 474         )
 475 {
 476         int n = 0;
 477         int res = 0;
 478
 479         if (*remainder_size > 0) {
 480                 memmove(
 481                         (char *) request_buffer,
 482                         (char *) remainder, *remainder_size
 483                 );
 484                 n = *remainder_size;
 485         }
 486
 487         res = os_read_file(
 488                         fd,
 489                         ((char *) request_buffer) + *remainder_size,
 490                         sizeof(struct io_thread_req *)*max_recs
 491                                 - *remainder_size
 492                 );
 493         if (res > 0) {
 494                 n += res;
 495                 if ((n % sizeof(struct io_thread_req *)) > 0) {
 496                         /*
 497                         * Read somehow returned not a multiple of dword
 498                         * theoretically possible, but never observed in the
 499                         * wild, so read routine must be able to handle it
 500                         */
 501                         *remainder_size = n % sizeof(struct io_thread_req *);
 502                         WARN(*remainder_size > 0, "UBD IPC read returned a partial result");
 503                         memmove(
 504                                 remainder,
 505                                 ((char *) request_buffer) +
 506                                         (n/sizeof(struct io_thread_req *))*sizeof(struct io_thread_req *),
 507                                 *remainder_size
 508                         );
 509                         n = n - *remainder_size;
 510                 }
 511         } else {
 512                 n = res;
 513         }
 514         return n;
 515 }
 516
 517 /* Called without dev->lock held, and only in interrupt context. */
 518 static void ubd_handler(void)
 519 {
 520         int n;
 521         int count;
 522
 523         while(1){
 524                 n = bulk_req_safe_read(
 525                         thread_fd,
 526                         irq_req_buffer,
 527                         &irq_remainder,
 528                         &irq_remainder_size,
 529                         UBD_REQ_BUFFER_SIZE
 530                 );
 531                 if (n < 0) {
 532                         if(n == -EAGAIN)
 533                                 break;
 534                         printk(KERN_ERR "spurious interrupt in ubd_handler, "
 535                                "err = %d\n", -n);
 536                         return;
 537                 }
 538                 for (count = 0; count < n/sizeof(struct io_thread_req *); count++) {
 539                         struct io_thread_req *io_req = (*irq_req_buffer)[count];
 540
 541                         if ((io_req->error == BLK_STS_NOTSUPP) && (req_op(io_req->req) == REQ_OP_DISCARD)) {
 542                                 blk_queue_max_discard_sectors(io_req->req->q, 0);
 543                                 blk_queue_max_write_zeroes_sectors(io_req->req->q, 0);
 544                                 blk_queue_flag_clear(QUEUE_FLAG_DISCARD, io_req->req->q);
 545                         }
 546                         blk_mq_end_request(io_req->req, io_req->error);
 547                         kfree(io_req);
 548                 }
 549         }
 550 }
 551
 552 static irqreturn_t ubd_intr(int irq, void *dev)
 553 {
 554         ubd_handler();
 555         return IRQ_HANDLED;
 556 }
 557
 558 /* Only changed by ubd_init, which is an initcall. */
 559 static int io_pid = -1;
 560
 561 static void kill_io_thread(void)
 562 {
 563         if(io_pid != -1)
 564                 os_kill_process(io_pid, 1);
 565 }
 566
 567 __uml_exitcall(kill_io_thread);
 568
 569 static inline int ubd_file_size(struct ubd *ubd_dev, __u64 *size_out)
 570 {
 571         char *file;
 572         int fd;
 573         int err;
 574
 575         __u32 version;
 576         __u32 align;
 577         char *backing_file;
 578         time64_t mtime;
 579         unsigned long long size;
 580         int sector_size;
 581         int bitmap_offset;
 582
 583         if (ubd_dev->file && ubd_dev->cow.file) {
 584                 file = ubd_dev->cow.file;
 585
 586                 goto out;
 587         }
 588
 589         fd = os_open_file(ubd_dev->file, of_read(OPENFLAGS()), 0);
 590         if (fd < 0)
 591                 return fd;
 592
 593         err = read_cow_header(file_reader, &fd, &version, &backing_file, \
 594                 &mtime, &size, &sector_size, &align, &bitmap_offset);
 595         os_close_file(fd);
 596
 597         if(err == -EINVAL)
 598                 file = ubd_dev->file;
 599         else
 600                 file = backing_file;
 601
 602 out:
 603         return os_file_size(file, size_out);
 604 }
 605
 606 static int read_cow_bitmap(int fd, void *buf, int offset, int len)
 607 {
 608         int err;
 609
 610         err = os_pread_file(fd, buf, len, offset);
 611         if (err < 0)
 612                 return err;
 613
 614         return 0;
 615 }
 616
 617 static int backing_file_mismatch(char *file, __u64 size, time64_t mtime)
 618 {
 619         time64_t modtime;
 620         unsigned long long actual;
 621         int err;
 622
 623         err = os_file_modtime(file, &modtime);
 624         if (err < 0) {
 625                 printk(KERN_ERR "Failed to get modification time of backing "
 626                        "file \"%s\", err = %d\n", file, -err);
 627                 return err;
 628         }
 629
 630         err = os_file_size(file, &actual);
 631         if (err < 0) {
 632                 printk(KERN_ERR "Failed to get size of backing file \"%s\", "
 633                        "err = %d\n", file, -err);
 634                 return err;
 635         }
 636
 637         if (actual != size) {
 638                 /*__u64 can be a long on AMD64 and with %lu GCC complains; so
 639                  * the typecast.*/
 640                 printk(KERN_ERR "Size mismatch (%llu vs %llu) of COW header "
 641                        "vs backing file\n", (unsigned long long) size, actual);
 642                 return -EINVAL;
 643         }
 644         if (modtime != mtime) {
 645                 printk(KERN_ERR "mtime mismatch (%lld vs %lld) of COW header vs "
 646                        "backing file\n", mtime, modtime);
 647                 return -EINVAL;
 648         }
 649         return 0;
 650 }
 651
 652 static int path_requires_switch(char *from_cmdline, char *from_cow, char *cow)
 653 {
 654         struct uml_stat buf1, buf2;
 655         int err;
 656
 657         if (from_cmdline == NULL)
 658                 return 0;
 659         if (!strcmp(from_cmdline, from_cow))
 660                 return 0;
 661
 662         err = os_stat_file(from_cmdline, &buf1);
 663         if (err < 0) {
 664                 printk(KERN_ERR "Couldn't stat '%s', err = %d\n", from_cmdline,
 665                        -err);
 666                 return 0;
 667         }
 668         err = os_stat_file(from_cow, &buf2);
 669         if (err < 0) {
 670                 printk(KERN_ERR "Couldn't stat '%s', err = %d\n", from_cow,
 671                        -err);
 672                 return 1;
 673         }
 674         if ((buf1.ust_dev == buf2.ust_dev) && (buf1.ust_ino == buf2.ust_ino))
 675                 return 0;
 676
 677         printk(KERN_ERR "Backing file mismatch - \"%s\" requested, "
 678                "\"%s\" specified in COW header of \"%s\"\n",
 679                from_cmdline, from_cow, cow);
 680         return 1;
 681 }
 682
 683 static int open_ubd_file(char *file, struct openflags *openflags, int shared,
 684                   char **backing_file_out, int *bitmap_offset_out,
 685                   unsigned long *bitmap_len_out, int *data_offset_out,
 686                   int *create_cow_out)
 687 {
 688         time64_t mtime;
 689         unsigned long long size;
 690         __u32 version, align;
 691         char *backing_file;
 692         int fd, err, sectorsize, asked_switch, mode = 0644;
 693
 694         fd = os_open_file(file, *openflags, mode);
 695         if (fd < 0) {
 696                 if ((fd == -ENOENT) && (create_cow_out != NULL))
 697                         *create_cow_out = 1;
 698                 if (!openflags->w ||
 699                     ((fd != -EROFS) && (fd != -EACCES)))
 700                         return fd;
 701                 openflags->w = 0;
 702                 fd = os_open_file(file, *openflags, mode);
 703                 if (fd < 0)
 704                         return fd;
 705         }
 706
 707         if (shared)
 708                 printk(KERN_INFO "Not locking \"%s\" on the host\n", file);
 709         else {
 710                 err = os_lock_file(fd, openflags->w);
 711                 if (err < 0) {
 712                         printk(KERN_ERR "Failed to lock '%s', err = %d\n",
 713                                file, -err);
 714                         goto out_close;
 715                 }
 716         }
 717
 718         /* Successful return case! */
 719         if (backing_file_out == NULL)
 720                 return fd;
 721
 722         err = read_cow_header(file_reader, &fd, &version, &backing_file, &mtime,
 723                               &size, &sectorsize, &align, bitmap_offset_out);
 724         if (err && (*backing_file_out != NULL)) {
 725                 printk(KERN_ERR "Failed to read COW header from COW file "
 726                        "\"%s\", errno = %d\n", file, -err);
 727                 goto out_close;
 728         }
 729         if (err)
 730                 return fd;
 731
 732         asked_switch = path_requires_switch(*backing_file_out, backing_file,
 733                                             file);
 734
 735         /* Allow switching only if no mismatch. */
 736         if (asked_switch && !backing_file_mismatch(*backing_file_out, size,
 737                                                    mtime)) {
 738                 printk(KERN_ERR "Switching backing file to '%s'\n",
 739                        *backing_file_out);
 740                 err = write_cow_header(file, fd, *backing_file_out,
 741                                        sectorsize, align, &size);
 742                 if (err) {
 743                         printk(KERN_ERR "Switch failed, errno = %d\n", -err);
 744                         goto out_close;
 745                 }
 746         } else {
 747                 *backing_file_out = backing_file;
 748                 err = backing_file_mismatch(*backing_file_out, size, mtime);
 749                 if (err)
 750                         goto out_close;
 751         }
 752
 753         cow_sizes(version, size, sectorsize, align, *bitmap_offset_out,
 754                   bitmap_len_out, data_offset_out);
 755
 756         return fd;
 757  out_close:
 758         os_close_file(fd);
 759         return err;
 760 }
 761
 762 static int create_cow_file(char *cow_file, char *backing_file,
 763                     struct openflags flags,
 764                     int sectorsize, int alignment, int *bitmap_offset_out,
 765                     unsigned long *bitmap_len_out, int *data_offset_out)
 766 {
 767         int err, fd;
 768
 769         flags.c = 1;
 770         fd = open_ubd_file(cow_file, &flags, 0, NULL, NULL, NULL, NULL, NULL);
 771         if (fd < 0) {
 772                 err = fd;
 773                 printk(KERN_ERR "Open of COW file '%s' failed, errno = %d\n",
 774                        cow_file, -err);
 775                 goto out;
 776         }
 777
 778         err = init_cow_file(fd, cow_file, backing_file, sectorsize, alignment,
 779                             bitmap_offset_out, bitmap_len_out,
 780                             data_offset_out);
 781         if (!err)
 782                 return fd;
 783         os_close_file(fd);
 784  out:
 785         return err;
 786 }
 787
 788 static void ubd_close_dev(struct ubd *ubd_dev)
 789 {
 790         os_close_file(ubd_dev->fd);
 791         if(ubd_dev->cow.file == NULL)
 792                 return;
 793
 794         os_close_file(ubd_dev->cow.fd);
 795         vfree(ubd_dev->cow.bitmap);
 796         ubd_dev->cow.bitmap = NULL;
 797 }
 798
 799 static int ubd_open_dev(struct ubd *ubd_dev)
 800 {
 801         struct openflags flags;
 802         char **back_ptr;
 803         int err, create_cow, *create_ptr;
 804         int fd;
 805
 806         ubd_dev->openflags = ubd_dev->boot_openflags;
 807         create_cow = 0;
 808         create_ptr = (ubd_dev->cow.file != NULL) ? &create_cow : NULL;
 809         back_ptr = ubd_dev->no_cow ? NULL : &ubd_dev->cow.file;
 810
 811         fd = open_ubd_file(ubd_dev->file, &ubd_dev->openflags, ubd_dev->shared,
 812                                 back_ptr, &ubd_dev->cow.bitmap_offset,
 813                                 &ubd_dev->cow.bitmap_len, &ubd_dev->cow.data_offset,
 814                                 create_ptr);
 815
 816         if((fd == -ENOENT) && create_cow){
 817                 fd = create_cow_file(ubd_dev->file, ubd_dev->cow.file,
 818                                           ubd_dev->openflags, SECTOR_SIZE, PAGE_SIZE,
 819                                           &ubd_dev->cow.bitmap_offset,
 820                                           &ubd_dev->cow.bitmap_len,
 821                                           &ubd_dev->cow.data_offset);
 822                 if(fd >= 0){
 823                         printk(KERN_INFO "Creating \"%s\" as COW file for "
 824                                "\"%s\"\n", ubd_dev->file, ubd_dev->cow.file);
 825                 }
 826         }
 827
 828         if(fd < 0){
 829                 printk("Failed to open '%s', errno = %d\n", ubd_dev->file,
 830                        -fd);
 831                 return fd;
 832         }
 833         ubd_dev->fd = fd;
 834
 835         if(ubd_dev->cow.file != NULL){
 836                 blk_queue_max_hw_sectors(ubd_dev->queue, 8 * sizeof(long));
 837
 838                 err = -ENOMEM;
 839                 ubd_dev->cow.bitmap = vmalloc(ubd_dev->cow.bitmap_len);
 840                 if(ubd_dev->cow.bitmap == NULL){
 841                         printk(KERN_ERR "Failed to vmalloc COW bitmap\n");
 842                         goto error;
 843                 }
 844                 flush_tlb_kernel_vm();
 845
 846                 err = read_cow_bitmap(ubd_dev->fd, ubd_dev->cow.bitmap,
 847                                       ubd_dev->cow.bitmap_offset,
 848                                       ubd_dev->cow.bitmap_len);
 849                 if(err < 0)
 850                         goto error;
 851
 852                 flags = ubd_dev->openflags;
 853                 flags.w = 0;
 854                 err = open_ubd_file(ubd_dev->cow.file, &flags, ubd_dev->shared, NULL,
 855                                     NULL, NULL, NULL, NULL);
 856                 if(err < 0) goto error;
 857                 ubd_dev->cow.fd = err;
 858         }
 859         if (ubd_dev->no_trim == 0) {
 860                 ubd_dev->queue->limits.discard_granularity = SECTOR_SIZE;
 861                 ubd_dev->queue->limits.discard_alignment = SECTOR_SIZE;
 862                 blk_queue_max_discard_sectors(ubd_dev->queue, UBD_MAX_REQUEST);
 863                 blk_queue_max_write_zeroes_sectors(ubd_dev->queue, UBD_MAX_REQUEST);
 864                 blk_queue_flag_set(QUEUE_FLAG_DISCARD, ubd_dev->queue);
 865         }
 866         blk_queue_flag_set(QUEUE_FLAG_NONROT, ubd_dev->queue);
 867         return 0;
 868  error:
 869         os_close_file(ubd_dev->fd);
 870         return err;
 871 }
 872
 873 static void ubd_device_release(struct device *dev)
 874 {
 875         struct ubd *ubd_dev = dev_get_drvdata(dev);
 876
 877         blk_cleanup_queue(ubd_dev->queue);
 878         blk_mq_free_tag_set(&ubd_dev->tag_set);
 879         *ubd_dev = ((struct ubd) DEFAULT_UBD);
 880 }
 881
 882 static ssize_t serial_show(struct device *dev,
 883                            struct device_attribute *attr, char *buf)
 884 {
 885         struct gendisk *disk = dev_to_disk(dev);
 886         struct ubd *ubd_dev = disk->private_data;
 887
 888         if (!ubd_dev)
 889                 return 0;
 890
 891         return sprintf(buf, "%s", ubd_dev->serial);
 892 }
 893
 894 static DEVICE_ATTR_RO(serial);
 895
 896 static struct attribute *ubd_attrs[] = {
 897         &dev_attr_serial.attr,
 898         NULL,
 899 };
 900
 901 static umode_t ubd_attrs_are_visible(struct kobject *kobj,
 902                                      struct attribute *a, int n)
 903 {
 904         return a->mode;
 905 }
 906
 907 static const struct attribute_group ubd_attr_group = {
 908         .attrs = ubd_attrs,
 909         .is_visible = ubd_attrs_are_visible,
 910 };
 911
 912 static const struct attribute_group *ubd_attr_groups[] = {
 913         &ubd_attr_group,
 914         NULL,
 915 };
 916
 917 static int ubd_disk_register(int major, u64 size, int unit,
 918                              struct gendisk **disk_out)
 919 {
 920         struct device *parent = NULL;
 921         struct gendisk *disk;
 922
 923         disk = alloc_disk(1 << UBD_SHIFT);
 924         if(disk == NULL)
 925                 return -ENOMEM;
 926
 927         disk->major = major;
 928         disk->first_minor = unit << UBD_SHIFT;
 929         disk->fops = &ubd_blops;
 930         set_capacity(disk, size / 512);
 931         if (major == UBD_MAJOR)
 932                 sprintf(disk->disk_name, "ubd%c", 'a' + unit);
 933         else
 934                 sprintf(disk->disk_name, "ubd_fake%d", unit);
 935
 936         /* sysfs register (not for ide fake devices) */
 937         if (major == UBD_MAJOR) {
 938                 ubd_devs[unit].pdev.id   = unit;
 939                 ubd_devs[unit].pdev.name = DRIVER_NAME;
 940                 ubd_devs[unit].pdev.dev.release = ubd_device_release;
 941                 dev_set_drvdata(&ubd_devs[unit].pdev.dev, &ubd_devs[unit]);
 942                 platform_device_register(&ubd_devs[unit].pdev);
 943                 parent = &ubd_devs[unit].pdev.dev;
 944         }
 945
 946         disk->private_data = &ubd_devs[unit];
 947         disk->queue = ubd_devs[unit].queue;
 948         device_add_disk(parent, disk, ubd_attr_groups);
 949
 950         *disk_out = disk;
 951         return 0;
 952 }
 953
 954 #define ROUND_BLOCK(n) ((n + (SECTOR_SIZE - 1)) & (-SECTOR_SIZE))
 955
 956 static const struct blk_mq_ops ubd_mq_ops = {
 957         .queue_rq = ubd_queue_rq,
 958 };
 959
 960 static int ubd_add(int n, char **error_out)
 961 {
 962         struct ubd *ubd_dev = &ubd_devs[n];
 963         int err = 0;
 964
 965         if(ubd_dev->file == NULL)
 966                 goto out;
 967
 968         err = ubd_file_size(ubd_dev, &ubd_dev->size);
 969         if(err < 0){
 970                 *error_out = "Couldn't determine size of device's file";
 971                 goto out;
 972         }
 973
 974         ubd_dev->size = ROUND_BLOCK(ubd_dev->size);
 975
 976         ubd_dev->tag_set.ops = &ubd_mq_ops;
 977         ubd_dev->tag_set.queue_depth = 64;
 978         ubd_dev->tag_set.numa_node = NUMA_NO_NODE;
 979         ubd_dev->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
 980         ubd_dev->tag_set.driver_data = ubd_dev;
 981         ubd_dev->tag_set.nr_hw_queues = 1;
 982
 983         err = blk_mq_alloc_tag_set(&ubd_dev->tag_set);
 984         if (err)
 985                 goto out;
 986
 987         ubd_dev->queue = blk_mq_init_queue(&ubd_dev->tag_set);
 988         if (IS_ERR(ubd_dev->queue)) {
 989                 err = PTR_ERR(ubd_dev->queue);
 990                 goto out_cleanup_tags;
 991         }
 992
 993         ubd_dev->queue->queuedata = ubd_dev;
 994         blk_queue_write_cache(ubd_dev->queue, true, false);
 995
 996         blk_queue_max_segments(ubd_dev->queue, MAX_SG);
 997         blk_queue_segment_boundary(ubd_dev->queue, PAGE_SIZE - 1);
 998         err = ubd_disk_register(UBD_MAJOR, ubd_dev->size, n, &ubd_gendisk[n]);
 999         if(err){
1000                 *error_out = "Failed to register device";
1001                 goto out_cleanup_tags;
1002         }
1003
1004         if (fake_major != UBD_MAJOR)
1005                 ubd_disk_register(fake_major, ubd_dev->size, n,
1006                                   &fake_gendisk[n]);
1007
1008         /*
1009          * Perhaps this should also be under the "if (fake_major)" above
1010          * using the fake_disk->disk_name
1011          */
1012         if (fake_ide)
1013                 make_ide_entries(ubd_gendisk[n]->disk_name);
1014
1015         err = 0;
1016 out:
1017         return err;
1018
1019 out_cleanup_tags:
1020         blk_mq_free_tag_set(&ubd_dev->tag_set);
1021         if (!(IS_ERR(ubd_dev->queue)))
1022                 blk_cleanup_queue(ubd_dev->queue);
1023         goto out;
1024 }
1025
1026 static int ubd_config(char *str, char **error_out)
1027 {
1028         int n, ret;
1029
1030         /* This string is possibly broken up and stored, so it's only
1031          * freed if ubd_setup_common fails, or if only general options
1032          * were set.
1033          */
1034         str = kstrdup(str, GFP_KERNEL);
1035         if (str == NULL) {
1036                 *error_out = "Failed to allocate memory";
1037                 return -ENOMEM;
1038         }
1039
1040         ret = ubd_setup_common(str, &n, error_out);
1041         if (ret)
1042                 goto err_free;
1043
1044         if (n == -1) {
1045                 ret = 0;
1046                 goto err_free;
1047         }
1048
1049         mutex_lock(&ubd_lock);
1050         ret = ubd_add(n, error_out);
1051         if (ret)
1052                 ubd_devs[n].file = NULL;
1053         mutex_unlock(&ubd_lock);
1054
1055 out:
1056         return ret;
1057
1058 err_free:
1059         kfree(str);
1060         goto out;
1061 }
1062
1063 static int ubd_get_config(char *name, char *str, int size, char **error_out)
1064 {
1065         struct ubd *ubd_dev;
1066         int n, len = 0;
1067
1068         n = parse_unit(&name);
1069         if((n >= MAX_DEV) || (n < 0)){
1070                 *error_out = "ubd_get_config : device number out of range";
1071                 return -1;
1072         }
1073
1074         ubd_dev = &ubd_devs[n];
1075         mutex_lock(&ubd_lock);
1076
1077         if(ubd_dev->file == NULL){
1078                 CONFIG_CHUNK(str, size, len, "", 1);
1079                 goto out;
1080         }
1081
1082         CONFIG_CHUNK(str, size, len, ubd_dev->file, 0);
1083
1084         if(ubd_dev->cow.file != NULL){
1085                 CONFIG_CHUNK(str, size, len, ",", 0);
1086                 CONFIG_CHUNK(str, size, len, ubd_dev->cow.file, 1);
1087         }
1088         else CONFIG_CHUNK(str, size, len, "", 1);
1089
1090  out:
1091         mutex_unlock(&ubd_lock);
1092         return len;
1093 }
1094
1095 static int ubd_id(char **str, int *start_out, int *end_out)
1096 {
1097         int n;
1098
1099         n = parse_unit(str);
1100         *start_out = 0;
1101         *end_out = MAX_DEV - 1;
1102         return n;
1103 }
1104
1105 static int ubd_remove(int n, char **error_out)
1106 {
1107         struct gendisk *disk = ubd_gendisk[n];
1108         struct ubd *ubd_dev;
1109         int err = -ENODEV;
1110
1111         mutex_lock(&ubd_lock);
1112
1113         ubd_dev = &ubd_devs[n];
1114
1115         if(ubd_dev->file == NULL)
1116                 goto out;
1117
1118         /* you cannot remove a open disk */
1119         err = -EBUSY;
1120         if(ubd_dev->count > 0)
1121                 goto out;
1122
1123         ubd_gendisk[n] = NULL;
1124         if(disk != NULL){
1125                 del_gendisk(disk);
1126                 put_disk(disk);
1127         }
1128
1129         if(fake_gendisk[n] != NULL){
1130                 del_gendisk(fake_gendisk[n]);
1131                 put_disk(fake_gendisk[n]);
1132                 fake_gendisk[n] = NULL;
1133         }
1134
1135         err = 0;
1136         platform_device_unregister(&ubd_dev->pdev);
1137 out:
1138         mutex_unlock(&ubd_lock);
1139         return err;
1140 }
1141
1142 /* All these are called by mconsole in process context and without
1143  * ubd-specific locks.  The structure itself is const except for .list.
1144  */
1145 static struct mc_device ubd_mc = {
1146         .list           = LIST_HEAD_INIT(ubd_mc.list),
1147         .name           = "ubd",
1148         .config         = ubd_config,
1149         .get_config     = ubd_get_config,
1150         .id             = ubd_id,
1151         .remove         = ubd_remove,
1152 };
1153
1154 static int __init ubd_mc_init(void)
1155 {
1156         mconsole_register_dev(&ubd_mc);
1157         return 0;
1158 }
1159
1160 __initcall(ubd_mc_init);
1161
1162 static int __init ubd0_init(void)
1163 {
1164         struct ubd *ubd_dev = &ubd_devs[0];
1165
1166         mutex_lock(&ubd_lock);
1167         if(ubd_dev->file == NULL)
1168                 ubd_dev->file = "root_fs";
1169         mutex_unlock(&ubd_lock);
1170
1171         return 0;
1172 }
1173
1174 __initcall(ubd0_init);
1175
1176 /* Used in ubd_init, which is an initcall */
1177 static struct platform_driver ubd_driver = {
1178         .driver = {
1179                 .name  = DRIVER_NAME,
1180         },
1181 };
1182
1183 static int __init ubd_init(void)
1184 {
1185         char *error;
1186         int i, err;
1187
1188         if (register_blkdev(UBD_MAJOR, "ubd"))
1189                 return -1;
1190
1191         if (fake_major != UBD_MAJOR) {
1192                 char name[sizeof("ubd_nnn\0")];
1193
1194                 snprintf(name, sizeof(name), "ubd_%d", fake_major);
1195                 if (register_blkdev(fake_major, "ubd"))
1196                         return -1;
1197         }
1198
1199         irq_req_buffer = kmalloc_array(UBD_REQ_BUFFER_SIZE,
1200                                        sizeof(struct io_thread_req *),
1201                                        GFP_KERNEL
1202                 );
1203         irq_remainder = 0;
1204
1205         if (irq_req_buffer == NULL) {
1206                 printk(KERN_ERR "Failed to initialize ubd buffering\n");
1207                 return -1;
1208         }
1209         io_req_buffer = kmalloc_array(UBD_REQ_BUFFER_SIZE,
1210                                       sizeof(struct io_thread_req *),
1211                                       GFP_KERNEL
1212                 );
1213
1214         io_remainder = 0;
1215
1216         if (io_req_buffer == NULL) {
1217                 printk(KERN_ERR "Failed to initialize ubd buffering\n");
1218                 return -1;
1219         }
1220         platform_driver_register(&ubd_driver);
1221         mutex_lock(&ubd_lock);
1222         for (i = 0; i < MAX_DEV; i++){
1223                 err = ubd_add(i, &error);
1224                 if(err)
1225                         printk(KERN_ERR "Failed to initialize ubd device %d :"
1226                                "%s\n", i, error);
1227         }
1228         mutex_unlock(&ubd_lock);
1229         return 0;
1230 }
1231
1232 late_initcall(ubd_init);
1233
1234 static int __init ubd_driver_init(void){
1235         unsigned long stack;
1236         int err;
1237
1238         /* Set by CONFIG_BLK_DEV_UBD_SYNC or ubd=sync.*/
1239         if(global_openflags.s){
1240                 printk(KERN_INFO "ubd: Synchronous mode\n");
1241                 /* Letting ubd=sync be like using ubd#s= instead of ubd#= is
1242                  * enough. So use anyway the io thread. */
1243         }
1244         stack = alloc_stack(0);
1245         io_pid = start_io_thread(stack + PAGE_SIZE - sizeof(void *),
1246                                  &thread_fd);
1247         if(io_pid < 0){
1248                 printk(KERN_ERR
1249                        "ubd : Failed to start I/O thread (errno = %d) - "
1250                        "falling back to synchronous I/O\n", -io_pid);
1251                 io_pid = -1;
1252                 return 0;
1253         }
1254         err = um_request_irq(UBD_IRQ, thread_fd, IRQ_READ, ubd_intr,
1255                              0, "ubd", ubd_devs);
1256         if(err < 0)
1257                 printk(KERN_ERR "um_request_irq failed - errno = %d\n", -err);
1258         return 0;
1259 }
1260
1261 device_initcall(ubd_driver_init);
1262
1263 static int ubd_open(struct block_device *bdev, fmode_t mode)
1264 {
1265         struct gendisk *disk = bdev->bd_disk;
1266         struct ubd *ubd_dev = disk->private_data;
1267         int err = 0;
1268
1269         mutex_lock(&ubd_mutex);
1270         if(ubd_dev->count == 0){
1271                 err = ubd_open_dev(ubd_dev);
1272                 if(err){
1273                         printk(KERN_ERR "%s: Can't open \"%s\": errno = %d\n",
1274                                disk->disk_name, ubd_dev->file, -err);
1275                         goto out;
1276                 }
1277         }
1278         ubd_dev->count++;
1279         set_disk_ro(disk, !ubd_dev->openflags.w);
1280
1281         /* This should no more be needed. And it didn't work anyway to exclude
1282          * read-write remounting of filesystems.*/
1283         /*if((mode & FMODE_WRITE) && !ubd_dev->openflags.w){
1284                 if(--ubd_dev->count == 0) ubd_close_dev(ubd_dev);
1285                 err = -EROFS;
1286         }*/
1287 out:
1288         mutex_unlock(&ubd_mutex);
1289         return err;
1290 }
1291
1292 static void ubd_release(struct gendisk *disk, fmode_t mode)
1293 {
1294         struct ubd *ubd_dev = disk->private_data;
1295
1296         mutex_lock(&ubd_mutex);
1297         if(--ubd_dev->count == 0)
1298                 ubd_close_dev(ubd_dev);
1299         mutex_unlock(&ubd_mutex);
1300 }
1301
1302 static void cowify_bitmap(__u64 io_offset, int length, unsigned long *cow_mask,
1303                           __u64 *cow_offset, unsigned long *bitmap,
1304                           __u64 bitmap_offset, unsigned long *bitmap_words,
1305                           __u64 bitmap_len)
1306 {
1307         __u64 sector = io_offset >> SECTOR_SHIFT;
1308         int i, update_bitmap = 0;
1309
1310         for (i = 0; i < length >> SECTOR_SHIFT; i++) {
1311                 if(cow_mask != NULL)
1312                         ubd_set_bit(i, (unsigned char *) cow_mask);
1313                 if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
1314                         continue;
1315
1316                 update_bitmap = 1;
1317                 ubd_set_bit(sector + i, (unsigned char *) bitmap);
1318         }
1319
1320         if(!update_bitmap)
1321                 return;
1322
1323         *cow_offset = sector / (sizeof(unsigned long) * 8);
1324
1325         /* This takes care of the case where we're exactly at the end of the
1326          * device, and *cow_offset + 1 is off the end.  So, just back it up
1327          * by one word.  Thanks to Lynn Kerby for the fix and James McMechan
1328          * for the original diagnosis.
1329          */
1330         if (*cow_offset == (DIV_ROUND_UP(bitmap_len,
1331                                          sizeof(unsigned long)) - 1))
1332                 (*cow_offset)--;
1333
1334         bitmap_words[0] = bitmap[*cow_offset];
1335         bitmap_words[1] = bitmap[*cow_offset + 1];
1336
1337         *cow_offset *= sizeof(unsigned long);
1338         *cow_offset += bitmap_offset;
1339 }
1340
1341 static void cowify_req(struct io_thread_req *req, struct io_desc *segment,
1342                        unsigned long offset, unsigned long *bitmap,
1343                        __u64 bitmap_offset, __u64 bitmap_len)
1344 {
1345         __u64 sector = offset >> SECTOR_SHIFT;
1346         int i;
1347
1348         if (segment->length > (sizeof(segment->sector_mask) * 8) << SECTOR_SHIFT)
1349                 panic("Operation too long");
1350
1351         if (req_op(req->req) == REQ_OP_READ) {
1352                 for (i = 0; i < segment->length >> SECTOR_SHIFT; i++) {
1353                         if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
1354                                 ubd_set_bit(i, (unsigned char *)
1355                                             &segment->sector_mask);
1356                 }
1357         } else {
1358                 cowify_bitmap(offset, segment->length, &segment->sector_mask,
1359                               &segment->cow_offset, bitmap, bitmap_offset,
1360                               segment->bitmap_words, bitmap_len);
1361         }
1362 }
1363
1364 static void ubd_map_req(struct ubd *dev, struct io_thread_req *io_req,
1365                         struct request *req)
1366 {
1367         struct bio_vec bvec;
1368         struct req_iterator iter;
1369         int i = 0;
1370         unsigned long byte_offset = io_req->offset;
1371         int op = req_op(req);
1372
1373         if (op == REQ_OP_WRITE_ZEROES || op == REQ_OP_DISCARD) {
1374                 io_req->io_desc[0].buffer = NULL;
1375                 io_req->io_desc[0].length = blk_rq_bytes(req);
1376         } else {
1377                 rq_for_each_segment(bvec, req, iter) {
1378                         BUG_ON(i >= io_req->desc_cnt);
1379
1380                         io_req->io_desc[i].buffer =
1381                                 page_address(bvec.bv_page) + bvec.bv_offset;
1382                         io_req->io_desc[i].length = bvec.bv_len;
1383                         i++;
1384                 }
1385         }
1386
1387         if (dev->cow.file) {
1388                 for (i = 0; i < io_req->desc_cnt; i++) {
1389                         cowify_req(io_req, &io_req->io_desc[i], byte_offset,
1390                                    dev->cow.bitmap, dev->cow.bitmap_offset,
1391                                    dev->cow.bitmap_len);
1392                         byte_offset += io_req->io_desc[i].length;
1393                 }
1394
1395         }
1396 }
1397
1398 static struct io_thread_req *ubd_alloc_req(struct ubd *dev, struct request *req,
1399                                            int desc_cnt)
1400 {
1401         struct io_thread_req *io_req;
1402         int i;
1403
1404         io_req = kmalloc(sizeof(*io_req) +
1405                          (desc_cnt * sizeof(struct io_desc)),
1406                          GFP_ATOMIC);
1407         if (!io_req)
1408                 return NULL;
1409
1410         io_req->req = req;
1411         if (dev->cow.file)
1412                 io_req->fds[0] = dev->cow.fd;
1413         else
1414                 io_req->fds[0] = dev->fd;
1415         io_req->error = 0;
1416         io_req->sectorsize = SECTOR_SIZE;
1417         io_req->fds[1] = dev->fd;
1418         io_req->offset = (u64) blk_rq_pos(req) << SECTOR_SHIFT;
1419         io_req->offsets[0] = 0;
1420         io_req->offsets[1] = dev->cow.data_offset;
1421
1422         for (i = 0 ; i < desc_cnt; i++) {
1423                 io_req->io_desc[i].sector_mask = 0;
1424                 io_req->io_desc[i].cow_offset = -1;
1425         }
1426
1427         return io_req;
1428 }
1429
1430 static int ubd_submit_request(struct ubd *dev, struct request *req)
1431 {
1432         int segs = 0;
1433         struct io_thread_req *io_req;
1434         int ret;
1435         int op = req_op(req);
1436
1437         if (op == REQ_OP_FLUSH)
1438                 segs = 0;
1439         else if (op == REQ_OP_WRITE_ZEROES || op == REQ_OP_DISCARD)
1440                 segs = 1;
1441         else
1442                 segs = blk_rq_nr_phys_segments(req);
1443
1444         io_req = ubd_alloc_req(dev, req, segs);
1445         if (!io_req)
1446                 return -ENOMEM;
1447
1448         io_req->desc_cnt = segs;
1449         if (segs)
1450                 ubd_map_req(dev, io_req, req);
1451
1452         ret = os_write_file(thread_fd, &io_req, sizeof(io_req));
1453         if (ret != sizeof(io_req)) {
1454                 if (ret != -EAGAIN)
1455                         pr_err("write to io thread failed: %d\n", -ret);
1456                 kfree(io_req);
1457         }
1458         return ret;
1459 }
1460
1461 static blk_status_t ubd_queue_rq(struct blk_mq_hw_ctx *hctx,
1462                                  const struct blk_mq_queue_data *bd)
1463 {
1464         struct ubd *ubd_dev = hctx->queue->queuedata;
1465         struct request *req = bd->rq;
1466         int ret = 0, res = BLK_STS_OK;
1467
1468         blk_mq_start_request(req);
1469
1470         spin_lock_irq(&ubd_dev->lock);
1471
1472         switch (req_op(req)) {
1473         case REQ_OP_FLUSH:
1474         case REQ_OP_READ:
1475         case REQ_OP_WRITE:
1476         case REQ_OP_DISCARD:
1477         case REQ_OP_WRITE_ZEROES:
1478                 ret = ubd_submit_request(ubd_dev, req);
1479                 break;
1480         default:
1481                 WARN_ON_ONCE(1);
1482                 res = BLK_STS_NOTSUPP;
1483         }
1484
1485         spin_unlock_irq(&ubd_dev->lock);
1486
1487         if (ret < 0) {
1488                 if (ret == -ENOMEM)
1489                         res = BLK_STS_RESOURCE;
1490                 else
1491                         res = BLK_STS_DEV_RESOURCE;
1492         }
1493
1494         return res;
1495 }
1496
1497 static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
1498 {
1499         struct ubd *ubd_dev = bdev->bd_disk->private_data;
1500
1501         geo->heads = 128;
1502         geo->sectors = 32;
1503         geo->cylinders = ubd_dev->size / (128 * 32 * 512);
1504         return 0;
1505 }
1506
1507 static int ubd_ioctl(struct block_device *bdev, fmode_t mode,
1508                      unsigned int cmd, unsigned long arg)
1509 {
1510         struct ubd *ubd_dev = bdev->bd_disk->private_data;
1511         u16 ubd_id[ATA_ID_WORDS];
1512
1513         switch (cmd) {
1514                 struct cdrom_volctrl volume;
1515         case HDIO_GET_IDENTITY:
1516                 memset(&ubd_id, 0, ATA_ID_WORDS * 2);
1517                 ubd_id[ATA_ID_CYLS]     = ubd_dev->size / (128 * 32 * 512);
1518                 ubd_id[ATA_ID_HEADS]    = 128;
1519                 ubd_id[ATA_ID_SECTORS]  = 32;
1520                 if(copy_to_user((char __user *) arg, (char *) &ubd_id,
1521                                  sizeof(ubd_id)))
1522                         return -EFAULT;
1523                 return 0;
1524
1525         case CDROMVOLREAD:
1526                 if(copy_from_user(&volume, (char __user *) arg, sizeof(volume)))
1527                         return -EFAULT;
1528                 volume.channel0 = 255;
1529                 volume.channel1 = 255;
1530                 volume.channel2 = 255;
1531                 volume.channel3 = 255;
1532                 if(copy_to_user((char __user *) arg, &volume, sizeof(volume)))
1533                         return -EFAULT;
1534                 return 0;
1535         }
1536         return -EINVAL;
1537 }
1538
1539 static int map_error(int error_code)
1540 {
1541         switch (error_code) {
1542         case 0:
1543                 return BLK_STS_OK;
1544         case ENOSYS:
1545         case EOPNOTSUPP:
1546                 return BLK_STS_NOTSUPP;
1547         case ENOSPC:
1548                 return BLK_STS_NOSPC;
1549         }
1550         return BLK_STS_IOERR;
1551 }
1552
1553 /*
1554  * Everything from here onwards *IS NOT PART OF THE KERNEL*
1555  *
1556  * The following functions are part of UML hypervisor code.
1557  * All functions from here onwards are executed as a helper
1558  * thread and are not allowed to execute any kernel functions.
1559  *
1560  * Any communication must occur strictly via shared memory and IPC.
1561  *
1562  * Do not add printks, locks, kernel memory operations, etc - it
1563  * will result in unpredictable behaviour and/or crashes.
1564  */
1565
1566 static int update_bitmap(struct io_thread_req *req, struct io_desc *segment)
1567 {
1568         int n;
1569
1570         if (segment->cow_offset == -1)
1571                 return map_error(0);
1572
1573         n = os_pwrite_file(req->fds[1], &segment->bitmap_words,
1574                           sizeof(segment->bitmap_words), segment->cow_offset);
1575         if (n != sizeof(segment->bitmap_words))
1576                 return map_error(-n);
1577
1578         return map_error(0);
1579 }
1580
1581 static void do_io(struct io_thread_req *req, struct io_desc *desc)
1582 {
1583         char *buf = NULL;
1584         unsigned long len;
1585         int n, nsectors, start, end, bit;
1586         __u64 off;
1587
1588         /* FLUSH is really a special case, we cannot "case" it with others */
1589
1590         if (req_op(req->req) == REQ_OP_FLUSH) {
1591                 /* fds[0] is always either the rw image or our cow file */
1592                 req->error = map_error(-os_sync_file(req->fds[0]));
1593                 return;
1594         }
1595
1596         nsectors = desc->length / req->sectorsize;
1597         start = 0;
1598         do {
1599                 bit = ubd_test_bit(start, (unsigned char *) &desc->sector_mask);
1600                 end = start;
1601                 while((end < nsectors) &&
1602                       (ubd_test_bit(end, (unsigned char *) &desc->sector_mask) == bit))
1603                         end++;
1604
1605                 off = req->offset + req->offsets[bit] +
1606                         start * req->sectorsize;
1607                 len = (end - start) * req->sectorsize;
1608                 if (desc->buffer != NULL)
1609                         buf = &desc->buffer[start * req->sectorsize];
1610
1611                 switch (req_op(req->req)) {
1612                 case REQ_OP_READ:
1613                         n = 0;
1614                         do {
1615                                 buf = &buf[n];
1616                                 len -= n;
1617                                 n = os_pread_file(req->fds[bit], buf, len, off);
1618                                 if (n < 0) {
1619                                         req->error = map_error(-n);
1620                                         return;
1621                                 }
1622                         } while((n < len) && (n != 0));
1623                         if (n < len) memset(&buf[n], 0, len - n);
1624                         break;
1625                 case REQ_OP_WRITE:
1626                         n = os_pwrite_file(req->fds[bit], buf, len, off);
1627                         if(n != len){
1628                                 req->error = map_error(-n);
1629                                 return;
1630                         }
1631                         break;
1632                 case REQ_OP_DISCARD:
1633                 case REQ_OP_WRITE_ZEROES:
1634                         n = os_falloc_punch(req->fds[bit], off, len);
1635                         if (n) {
1636                                 req->error = map_error(-n);
1637                                 return;
1638                         }
1639                         break;
1640                 default:
1641                         WARN_ON_ONCE(1);
1642                         req->error = BLK_STS_NOTSUPP;
1643                         return;
1644                 }
1645
1646                 start = end;
1647         } while(start < nsectors);
1648
1649         req->offset += len;
1650         req->error = update_bitmap(req, desc);
1651 }
1652
1653 /* Changed in start_io_thread, which is serialized by being called only
1654  * from ubd_init, which is an initcall.
1655  */
1656 int kernel_fd = -1;
1657
1658 /* Only changed by the io thread. XXX: currently unused. */
1659 static int io_count = 0;
1660
1661 int io_thread(void *arg)
1662 {
1663         int n, count, written, res;
1664
1665         os_fix_helper_signals();
1666
1667         while(1){
1668                 n = bulk_req_safe_read(
1669                         kernel_fd,
1670                         io_req_buffer,
1671                         &io_remainder,
1672                         &io_remainder_size,
1673                         UBD_REQ_BUFFER_SIZE
1674                 );
1675                 if (n <= 0) {
1676                         if (n == -EAGAIN)
1677                                 ubd_read_poll(-1);
1678
1679                         continue;
1680                 }
1681
1682                 for (count = 0; count < n/sizeof(struct io_thread_req *); count++) {
1683                         struct io_thread_req *req = (*io_req_buffer)[count];
1684                         int i;
1685
1686                         io_count++;
1687                         for (i = 0; !req->error && i < req->desc_cnt; i++)
1688                                 do_io(req, &(req->io_desc[i]));
1689
1690                 }
1691
1692                 written = 0;
1693
1694                 do {
1695                         res = os_write_file(kernel_fd,
1696                                             ((char *) io_req_buffer) + written,
1697                                             n - written);
1698                         if (res >= 0) {
1699                                 written += res;
1700                         }
1701                         if (written < n) {
1702                                 ubd_write_poll(-1);
1703                         }
1704                 } while (written < n);
1705         }
1706
1707         return 0;
1708 }