arch/um/drivers/ubd_kern.c

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