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