| 1 | /* |
| 2 | * Copyright (C) 2003 Sistina Software |
| 3 | * Copyright (C) 2006 Red Hat GmbH |
| 4 | * |
| 5 | * This file is released under the GPL. |
| 6 | */ |
| 7 | |
| 8 | #include "dm-core.h" |
| 9 | |
| 10 | #include <linux/device-mapper.h> |
| 11 | |
| 12 | #include <linux/bio.h> |
| 13 | #include <linux/completion.h> |
| 14 | #include <linux/mempool.h> |
| 15 | #include <linux/module.h> |
| 16 | #include <linux/sched.h> |
| 17 | #include <linux/slab.h> |
| 18 | #include <linux/dm-io.h> |
| 19 | |
| 20 | #define DM_MSG_PREFIX "io" |
| 21 | |
| 22 | #define DM_IO_MAX_REGIONS BITS_PER_LONG |
| 23 | |
| 24 | struct dm_io_client { |
| 25 | mempool_t *pool; |
| 26 | struct bio_set *bios; |
| 27 | }; |
| 28 | |
| 29 | /* |
| 30 | * Aligning 'struct io' reduces the number of bits required to store |
| 31 | * its address. Refer to store_io_and_region_in_bio() below. |
| 32 | */ |
| 33 | struct io { |
| 34 | unsigned long error_bits; |
| 35 | atomic_t count; |
| 36 | struct dm_io_client *client; |
| 37 | io_notify_fn callback; |
| 38 | void *context; |
| 39 | void *vma_invalidate_address; |
| 40 | unsigned long vma_invalidate_size; |
| 41 | } __attribute__((aligned(DM_IO_MAX_REGIONS))); |
| 42 | |
| 43 | static struct kmem_cache *_dm_io_cache; |
| 44 | |
| 45 | /* |
| 46 | * Create a client with mempool and bioset. |
| 47 | */ |
| 48 | struct dm_io_client *dm_io_client_create(void) |
| 49 | { |
| 50 | struct dm_io_client *client; |
| 51 | unsigned min_ios = dm_get_reserved_bio_based_ios(); |
| 52 | |
| 53 | client = kmalloc(sizeof(*client), GFP_KERNEL); |
| 54 | if (!client) |
| 55 | return ERR_PTR(-ENOMEM); |
| 56 | |
| 57 | client->pool = mempool_create_slab_pool(min_ios, _dm_io_cache); |
| 58 | if (!client->pool) |
| 59 | goto bad; |
| 60 | |
| 61 | client->bios = bioset_create(min_ios, 0, (BIOSET_NEED_BVECS | |
| 62 | BIOSET_NEED_RESCUER)); |
| 63 | if (!client->bios) |
| 64 | goto bad; |
| 65 | |
| 66 | return client; |
| 67 | |
| 68 | bad: |
| 69 | mempool_destroy(client->pool); |
| 70 | kfree(client); |
| 71 | return ERR_PTR(-ENOMEM); |
| 72 | } |
| 73 | EXPORT_SYMBOL(dm_io_client_create); |
| 74 | |
| 75 | void dm_io_client_destroy(struct dm_io_client *client) |
| 76 | { |
| 77 | mempool_destroy(client->pool); |
| 78 | bioset_free(client->bios); |
| 79 | kfree(client); |
| 80 | } |
| 81 | EXPORT_SYMBOL(dm_io_client_destroy); |
| 82 | |
| 83 | /*----------------------------------------------------------------- |
| 84 | * We need to keep track of which region a bio is doing io for. |
| 85 | * To avoid a memory allocation to store just 5 or 6 bits, we |
| 86 | * ensure the 'struct io' pointer is aligned so enough low bits are |
| 87 | * always zero and then combine it with the region number directly in |
| 88 | * bi_private. |
| 89 | *---------------------------------------------------------------*/ |
| 90 | static void store_io_and_region_in_bio(struct bio *bio, struct io *io, |
| 91 | unsigned region) |
| 92 | { |
| 93 | if (unlikely(!IS_ALIGNED((unsigned long)io, DM_IO_MAX_REGIONS))) { |
| 94 | DMCRIT("Unaligned struct io pointer %p", io); |
| 95 | BUG(); |
| 96 | } |
| 97 | |
| 98 | bio->bi_private = (void *)((unsigned long)io | region); |
| 99 | } |
| 100 | |
| 101 | static void retrieve_io_and_region_from_bio(struct bio *bio, struct io **io, |
| 102 | unsigned *region) |
| 103 | { |
| 104 | unsigned long val = (unsigned long)bio->bi_private; |
| 105 | |
| 106 | *io = (void *)(val & -(unsigned long)DM_IO_MAX_REGIONS); |
| 107 | *region = val & (DM_IO_MAX_REGIONS - 1); |
| 108 | } |
| 109 | |
| 110 | /*----------------------------------------------------------------- |
| 111 | * We need an io object to keep track of the number of bios that |
| 112 | * have been dispatched for a particular io. |
| 113 | *---------------------------------------------------------------*/ |
| 114 | static void complete_io(struct io *io) |
| 115 | { |
| 116 | unsigned long error_bits = io->error_bits; |
| 117 | io_notify_fn fn = io->callback; |
| 118 | void *context = io->context; |
| 119 | |
| 120 | if (io->vma_invalidate_size) |
| 121 | invalidate_kernel_vmap_range(io->vma_invalidate_address, |
| 122 | io->vma_invalidate_size); |
| 123 | |
| 124 | mempool_free(io, io->client->pool); |
| 125 | fn(error_bits, context); |
| 126 | } |
| 127 | |
| 128 | static void dec_count(struct io *io, unsigned int region, blk_status_t error) |
| 129 | { |
| 130 | if (error) |
| 131 | set_bit(region, &io->error_bits); |
| 132 | |
| 133 | if (atomic_dec_and_test(&io->count)) |
| 134 | complete_io(io); |
| 135 | } |
| 136 | |
| 137 | static void endio(struct bio *bio) |
| 138 | { |
| 139 | struct io *io; |
| 140 | unsigned region; |
| 141 | blk_status_t error; |
| 142 | |
| 143 | if (bio->bi_status && bio_data_dir(bio) == READ) |
| 144 | zero_fill_bio(bio); |
| 145 | |
| 146 | /* |
| 147 | * The bio destructor in bio_put() may use the io object. |
| 148 | */ |
| 149 | retrieve_io_and_region_from_bio(bio, &io, ®ion); |
| 150 | |
| 151 | error = bio->bi_status; |
| 152 | bio_put(bio); |
| 153 | |
| 154 | dec_count(io, region, error); |
| 155 | } |
| 156 | |
| 157 | /*----------------------------------------------------------------- |
| 158 | * These little objects provide an abstraction for getting a new |
| 159 | * destination page for io. |
| 160 | *---------------------------------------------------------------*/ |
| 161 | struct dpages { |
| 162 | void (*get_page)(struct dpages *dp, |
| 163 | struct page **p, unsigned long *len, unsigned *offset); |
| 164 | void (*next_page)(struct dpages *dp); |
| 165 | |
| 166 | union { |
| 167 | unsigned context_u; |
| 168 | struct bvec_iter context_bi; |
| 169 | }; |
| 170 | void *context_ptr; |
| 171 | |
| 172 | void *vma_invalidate_address; |
| 173 | unsigned long vma_invalidate_size; |
| 174 | }; |
| 175 | |
| 176 | /* |
| 177 | * Functions for getting the pages from a list. |
| 178 | */ |
| 179 | static void list_get_page(struct dpages *dp, |
| 180 | struct page **p, unsigned long *len, unsigned *offset) |
| 181 | { |
| 182 | unsigned o = dp->context_u; |
| 183 | struct page_list *pl = (struct page_list *) dp->context_ptr; |
| 184 | |
| 185 | *p = pl->page; |
| 186 | *len = PAGE_SIZE - o; |
| 187 | *offset = o; |
| 188 | } |
| 189 | |
| 190 | static void list_next_page(struct dpages *dp) |
| 191 | { |
| 192 | struct page_list *pl = (struct page_list *) dp->context_ptr; |
| 193 | dp->context_ptr = pl->next; |
| 194 | dp->context_u = 0; |
| 195 | } |
| 196 | |
| 197 | static void list_dp_init(struct dpages *dp, struct page_list *pl, unsigned offset) |
| 198 | { |
| 199 | dp->get_page = list_get_page; |
| 200 | dp->next_page = list_next_page; |
| 201 | dp->context_u = offset; |
| 202 | dp->context_ptr = pl; |
| 203 | } |
| 204 | |
| 205 | /* |
| 206 | * Functions for getting the pages from a bvec. |
| 207 | */ |
| 208 | static void bio_get_page(struct dpages *dp, struct page **p, |
| 209 | unsigned long *len, unsigned *offset) |
| 210 | { |
| 211 | struct bio_vec bvec = bvec_iter_bvec((struct bio_vec *)dp->context_ptr, |
| 212 | dp->context_bi); |
| 213 | |
| 214 | *p = bvec.bv_page; |
| 215 | *len = bvec.bv_len; |
| 216 | *offset = bvec.bv_offset; |
| 217 | |
| 218 | /* avoid figuring it out again in bio_next_page() */ |
| 219 | dp->context_bi.bi_sector = (sector_t)bvec.bv_len; |
| 220 | } |
| 221 | |
| 222 | static void bio_next_page(struct dpages *dp) |
| 223 | { |
| 224 | unsigned int len = (unsigned int)dp->context_bi.bi_sector; |
| 225 | |
| 226 | bvec_iter_advance((struct bio_vec *)dp->context_ptr, |
| 227 | &dp->context_bi, len); |
| 228 | } |
| 229 | |
| 230 | static void bio_dp_init(struct dpages *dp, struct bio *bio) |
| 231 | { |
| 232 | dp->get_page = bio_get_page; |
| 233 | dp->next_page = bio_next_page; |
| 234 | |
| 235 | /* |
| 236 | * We just use bvec iterator to retrieve pages, so it is ok to |
| 237 | * access the bvec table directly here |
| 238 | */ |
| 239 | dp->context_ptr = bio->bi_io_vec; |
| 240 | dp->context_bi = bio->bi_iter; |
| 241 | } |
| 242 | |
| 243 | /* |
| 244 | * Functions for getting the pages from a VMA. |
| 245 | */ |
| 246 | static void vm_get_page(struct dpages *dp, |
| 247 | struct page **p, unsigned long *len, unsigned *offset) |
| 248 | { |
| 249 | *p = vmalloc_to_page(dp->context_ptr); |
| 250 | *offset = dp->context_u; |
| 251 | *len = PAGE_SIZE - dp->context_u; |
| 252 | } |
| 253 | |
| 254 | static void vm_next_page(struct dpages *dp) |
| 255 | { |
| 256 | dp->context_ptr += PAGE_SIZE - dp->context_u; |
| 257 | dp->context_u = 0; |
| 258 | } |
| 259 | |
| 260 | static void vm_dp_init(struct dpages *dp, void *data) |
| 261 | { |
| 262 | dp->get_page = vm_get_page; |
| 263 | dp->next_page = vm_next_page; |
| 264 | dp->context_u = offset_in_page(data); |
| 265 | dp->context_ptr = data; |
| 266 | } |
| 267 | |
| 268 | /* |
| 269 | * Functions for getting the pages from kernel memory. |
| 270 | */ |
| 271 | static void km_get_page(struct dpages *dp, struct page **p, unsigned long *len, |
| 272 | unsigned *offset) |
| 273 | { |
| 274 | *p = virt_to_page(dp->context_ptr); |
| 275 | *offset = dp->context_u; |
| 276 | *len = PAGE_SIZE - dp->context_u; |
| 277 | } |
| 278 | |
| 279 | static void km_next_page(struct dpages *dp) |
| 280 | { |
| 281 | dp->context_ptr += PAGE_SIZE - dp->context_u; |
| 282 | dp->context_u = 0; |
| 283 | } |
| 284 | |
| 285 | static void km_dp_init(struct dpages *dp, void *data) |
| 286 | { |
| 287 | dp->get_page = km_get_page; |
| 288 | dp->next_page = km_next_page; |
| 289 | dp->context_u = offset_in_page(data); |
| 290 | dp->context_ptr = data; |
| 291 | } |
| 292 | |
| 293 | /*----------------------------------------------------------------- |
| 294 | * IO routines that accept a list of pages. |
| 295 | *---------------------------------------------------------------*/ |
| 296 | static void do_region(int op, int op_flags, unsigned region, |
| 297 | struct dm_io_region *where, struct dpages *dp, |
| 298 | struct io *io) |
| 299 | { |
| 300 | struct bio *bio; |
| 301 | struct page *page; |
| 302 | unsigned long len; |
| 303 | unsigned offset; |
| 304 | unsigned num_bvecs; |
| 305 | sector_t remaining = where->count; |
| 306 | struct request_queue *q = bdev_get_queue(where->bdev); |
| 307 | unsigned short logical_block_size = queue_logical_block_size(q); |
| 308 | sector_t num_sectors; |
| 309 | unsigned int uninitialized_var(special_cmd_max_sectors); |
| 310 | |
| 311 | /* |
| 312 | * Reject unsupported discard and write same requests. |
| 313 | */ |
| 314 | if (op == REQ_OP_DISCARD) |
| 315 | special_cmd_max_sectors = q->limits.max_discard_sectors; |
| 316 | else if (op == REQ_OP_WRITE_ZEROES) |
| 317 | special_cmd_max_sectors = q->limits.max_write_zeroes_sectors; |
| 318 | else if (op == REQ_OP_WRITE_SAME) |
| 319 | special_cmd_max_sectors = q->limits.max_write_same_sectors; |
| 320 | if ((op == REQ_OP_DISCARD || op == REQ_OP_WRITE_ZEROES || |
| 321 | op == REQ_OP_WRITE_SAME) && special_cmd_max_sectors == 0) { |
| 322 | atomic_inc(&io->count); |
| 323 | dec_count(io, region, BLK_STS_NOTSUPP); |
| 324 | return; |
| 325 | } |
| 326 | |
| 327 | /* |
| 328 | * where->count may be zero if op holds a flush and we need to |
| 329 | * send a zero-sized flush. |
| 330 | */ |
| 331 | do { |
| 332 | /* |
| 333 | * Allocate a suitably sized-bio. |
| 334 | */ |
| 335 | switch (op) { |
| 336 | case REQ_OP_DISCARD: |
| 337 | case REQ_OP_WRITE_ZEROES: |
| 338 | num_bvecs = 0; |
| 339 | break; |
| 340 | case REQ_OP_WRITE_SAME: |
| 341 | num_bvecs = 1; |
| 342 | break; |
| 343 | default: |
| 344 | num_bvecs = min_t(int, BIO_MAX_PAGES, |
| 345 | dm_sector_div_up(remaining, (PAGE_SIZE >> SECTOR_SHIFT))); |
| 346 | } |
| 347 | |
| 348 | bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, io->client->bios); |
| 349 | bio->bi_iter.bi_sector = where->sector + (where->count - remaining); |
| 350 | bio_set_dev(bio, where->bdev); |
| 351 | bio->bi_end_io = endio; |
| 352 | bio_set_op_attrs(bio, op, op_flags); |
| 353 | store_io_and_region_in_bio(bio, io, region); |
| 354 | |
| 355 | if (op == REQ_OP_DISCARD || op == REQ_OP_WRITE_ZEROES) { |
| 356 | num_sectors = min_t(sector_t, special_cmd_max_sectors, remaining); |
| 357 | bio->bi_iter.bi_size = num_sectors << SECTOR_SHIFT; |
| 358 | remaining -= num_sectors; |
| 359 | } else if (op == REQ_OP_WRITE_SAME) { |
| 360 | /* |
| 361 | * WRITE SAME only uses a single page. |
| 362 | */ |
| 363 | dp->get_page(dp, &page, &len, &offset); |
| 364 | bio_add_page(bio, page, logical_block_size, offset); |
| 365 | num_sectors = min_t(sector_t, special_cmd_max_sectors, remaining); |
| 366 | bio->bi_iter.bi_size = num_sectors << SECTOR_SHIFT; |
| 367 | |
| 368 | offset = 0; |
| 369 | remaining -= num_sectors; |
| 370 | dp->next_page(dp); |
| 371 | } else while (remaining) { |
| 372 | /* |
| 373 | * Try and add as many pages as possible. |
| 374 | */ |
| 375 | dp->get_page(dp, &page, &len, &offset); |
| 376 | len = min(len, to_bytes(remaining)); |
| 377 | if (!bio_add_page(bio, page, len, offset)) |
| 378 | break; |
| 379 | |
| 380 | offset = 0; |
| 381 | remaining -= to_sector(len); |
| 382 | dp->next_page(dp); |
| 383 | } |
| 384 | |
| 385 | atomic_inc(&io->count); |
| 386 | submit_bio(bio); |
| 387 | } while (remaining); |
| 388 | } |
| 389 | |
| 390 | static void dispatch_io(int op, int op_flags, unsigned int num_regions, |
| 391 | struct dm_io_region *where, struct dpages *dp, |
| 392 | struct io *io, int sync) |
| 393 | { |
| 394 | int i; |
| 395 | struct dpages old_pages = *dp; |
| 396 | |
| 397 | BUG_ON(num_regions > DM_IO_MAX_REGIONS); |
| 398 | |
| 399 | if (sync) |
| 400 | op_flags |= REQ_SYNC; |
| 401 | |
| 402 | /* |
| 403 | * For multiple regions we need to be careful to rewind |
| 404 | * the dp object for each call to do_region. |
| 405 | */ |
| 406 | for (i = 0; i < num_regions; i++) { |
| 407 | *dp = old_pages; |
| 408 | if (where[i].count || (op_flags & REQ_PREFLUSH)) |
| 409 | do_region(op, op_flags, i, where + i, dp, io); |
| 410 | } |
| 411 | |
| 412 | /* |
| 413 | * Drop the extra reference that we were holding to avoid |
| 414 | * the io being completed too early. |
| 415 | */ |
| 416 | dec_count(io, 0, 0); |
| 417 | } |
| 418 | |
| 419 | struct sync_io { |
| 420 | unsigned long error_bits; |
| 421 | struct completion wait; |
| 422 | }; |
| 423 | |
| 424 | static void sync_io_complete(unsigned long error, void *context) |
| 425 | { |
| 426 | struct sync_io *sio = context; |
| 427 | |
| 428 | sio->error_bits = error; |
| 429 | complete(&sio->wait); |
| 430 | } |
| 431 | |
| 432 | static int sync_io(struct dm_io_client *client, unsigned int num_regions, |
| 433 | struct dm_io_region *where, int op, int op_flags, |
| 434 | struct dpages *dp, unsigned long *error_bits) |
| 435 | { |
| 436 | struct io *io; |
| 437 | struct sync_io sio; |
| 438 | |
| 439 | if (num_regions > 1 && !op_is_write(op)) { |
| 440 | WARN_ON(1); |
| 441 | return -EIO; |
| 442 | } |
| 443 | |
| 444 | init_completion(&sio.wait); |
| 445 | |
| 446 | io = mempool_alloc(client->pool, GFP_NOIO); |
| 447 | io->error_bits = 0; |
| 448 | atomic_set(&io->count, 1); /* see dispatch_io() */ |
| 449 | io->client = client; |
| 450 | io->callback = sync_io_complete; |
| 451 | io->context = &sio; |
| 452 | |
| 453 | io->vma_invalidate_address = dp->vma_invalidate_address; |
| 454 | io->vma_invalidate_size = dp->vma_invalidate_size; |
| 455 | |
| 456 | dispatch_io(op, op_flags, num_regions, where, dp, io, 1); |
| 457 | |
| 458 | wait_for_completion_io(&sio.wait); |
| 459 | |
| 460 | if (error_bits) |
| 461 | *error_bits = sio.error_bits; |
| 462 | |
| 463 | return sio.error_bits ? -EIO : 0; |
| 464 | } |
| 465 | |
| 466 | static int async_io(struct dm_io_client *client, unsigned int num_regions, |
| 467 | struct dm_io_region *where, int op, int op_flags, |
| 468 | struct dpages *dp, io_notify_fn fn, void *context) |
| 469 | { |
| 470 | struct io *io; |
| 471 | |
| 472 | if (num_regions > 1 && !op_is_write(op)) { |
| 473 | WARN_ON(1); |
| 474 | fn(1, context); |
| 475 | return -EIO; |
| 476 | } |
| 477 | |
| 478 | io = mempool_alloc(client->pool, GFP_NOIO); |
| 479 | io->error_bits = 0; |
| 480 | atomic_set(&io->count, 1); /* see dispatch_io() */ |
| 481 | io->client = client; |
| 482 | io->callback = fn; |
| 483 | io->context = context; |
| 484 | |
| 485 | io->vma_invalidate_address = dp->vma_invalidate_address; |
| 486 | io->vma_invalidate_size = dp->vma_invalidate_size; |
| 487 | |
| 488 | dispatch_io(op, op_flags, num_regions, where, dp, io, 0); |
| 489 | return 0; |
| 490 | } |
| 491 | |
| 492 | static int dp_init(struct dm_io_request *io_req, struct dpages *dp, |
| 493 | unsigned long size) |
| 494 | { |
| 495 | /* Set up dpages based on memory type */ |
| 496 | |
| 497 | dp->vma_invalidate_address = NULL; |
| 498 | dp->vma_invalidate_size = 0; |
| 499 | |
| 500 | switch (io_req->mem.type) { |
| 501 | case DM_IO_PAGE_LIST: |
| 502 | list_dp_init(dp, io_req->mem.ptr.pl, io_req->mem.offset); |
| 503 | break; |
| 504 | |
| 505 | case DM_IO_BIO: |
| 506 | bio_dp_init(dp, io_req->mem.ptr.bio); |
| 507 | break; |
| 508 | |
| 509 | case DM_IO_VMA: |
| 510 | flush_kernel_vmap_range(io_req->mem.ptr.vma, size); |
| 511 | if (io_req->bi_op == REQ_OP_READ) { |
| 512 | dp->vma_invalidate_address = io_req->mem.ptr.vma; |
| 513 | dp->vma_invalidate_size = size; |
| 514 | } |
| 515 | vm_dp_init(dp, io_req->mem.ptr.vma); |
| 516 | break; |
| 517 | |
| 518 | case DM_IO_KMEM: |
| 519 | km_dp_init(dp, io_req->mem.ptr.addr); |
| 520 | break; |
| 521 | |
| 522 | default: |
| 523 | return -EINVAL; |
| 524 | } |
| 525 | |
| 526 | return 0; |
| 527 | } |
| 528 | |
| 529 | /* |
| 530 | * New collapsed (a)synchronous interface. |
| 531 | * |
| 532 | * If the IO is asynchronous (i.e. it has notify.fn), you must either unplug |
| 533 | * the queue with blk_unplug() some time later or set REQ_SYNC in |
| 534 | * io_req->bi_opf. If you fail to do one of these, the IO will be submitted to |
| 535 | * the disk after q->unplug_delay, which defaults to 3ms in blk-settings.c. |
| 536 | */ |
| 537 | int dm_io(struct dm_io_request *io_req, unsigned num_regions, |
| 538 | struct dm_io_region *where, unsigned long *sync_error_bits) |
| 539 | { |
| 540 | int r; |
| 541 | struct dpages dp; |
| 542 | |
| 543 | r = dp_init(io_req, &dp, (unsigned long)where->count << SECTOR_SHIFT); |
| 544 | if (r) |
| 545 | return r; |
| 546 | |
| 547 | if (!io_req->notify.fn) |
| 548 | return sync_io(io_req->client, num_regions, where, |
| 549 | io_req->bi_op, io_req->bi_op_flags, &dp, |
| 550 | sync_error_bits); |
| 551 | |
| 552 | return async_io(io_req->client, num_regions, where, io_req->bi_op, |
| 553 | io_req->bi_op_flags, &dp, io_req->notify.fn, |
| 554 | io_req->notify.context); |
| 555 | } |
| 556 | EXPORT_SYMBOL(dm_io); |
| 557 | |
| 558 | int __init dm_io_init(void) |
| 559 | { |
| 560 | _dm_io_cache = KMEM_CACHE(io, 0); |
| 561 | if (!_dm_io_cache) |
| 562 | return -ENOMEM; |
| 563 | |
| 564 | return 0; |
| 565 | } |
| 566 | |
| 567 | void dm_io_exit(void) |
| 568 | { |
| 569 | kmem_cache_destroy(_dm_io_cache); |
| 570 | _dm_io_cache = NULL; |
| 571 | } |