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