drivers/md/dm-io.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2003 Sistina Software
   4  * Copyright (C) 2006 Red Hat GmbH
   5  *
   6  * This file is released under the GPL.
   7  */
   8
   9 #include "dm-core.h"
  10
  11 #include <linux/device-mapper.h>
  12
  13 #include <linux/bio.h>
  14 #include <linux/completion.h>
  15 #include <linux/mempool.h>
  16 #include <linux/module.h>
  17 #include <linux/sched.h>
  18 #include <linux/slab.h>
  19 #include <linux/dm-io.h>
  20
  21 #define DM_MSG_PREFIX "io"
  22
  23 #define DM_IO_MAX_REGIONS       BITS_PER_LONG
  24
  25 struct dm_io_client {
  26         mempool_t pool;
  27         struct bio_set bios;
  28 };
  29
  30 /*
  31  * Aligning 'struct io' reduces the number of bits required to store
  32  * its address.  Refer to store_io_and_region_in_bio() below.
  33  */
  34 struct io {
  35         unsigned long error_bits;
  36         atomic_t count;
  37         struct dm_io_client *client;
  38         io_notify_fn callback;
  39         void *context;
  40         void *vma_invalidate_address;
  41         unsigned long vma_invalidate_size;
  42 } __aligned(DM_IO_MAX_REGIONS);
  43
  44 static struct kmem_cache *_dm_io_cache;
  45
  46 /*
  47  * Create a client with mempool and bioset.
  48  */
  49 struct dm_io_client *dm_io_client_create(void)
  50 {
  51         struct dm_io_client *client;
  52         unsigned int min_ios = dm_get_reserved_bio_based_ios();
  53         int ret;
  54
  55         client = kzalloc(sizeof(*client), GFP_KERNEL);
  56         if (!client)
  57                 return ERR_PTR(-ENOMEM);
  58
  59         ret = mempool_init_slab_pool(&client->pool, min_ios, _dm_io_cache);
  60         if (ret)
  61                 goto bad;
  62
  63         ret = bioset_init(&client->bios, min_ios, 0, BIOSET_NEED_BVECS);
  64         if (ret)
  65                 goto bad;
  66
  67         return client;
  68
  69 bad:
  70         mempool_exit(&client->pool);
  71         kfree(client);
  72         return ERR_PTR(ret);
  73 }
  74 EXPORT_SYMBOL(dm_io_client_create);
  75
  76 void dm_io_client_destroy(struct dm_io_client *client)
  77 {
  78         mempool_exit(&client->pool);
  79         bioset_exit(&client->bios);
  80         kfree(client);
  81 }
  82 EXPORT_SYMBOL(dm_io_client_destroy);
  83
  84 /*
  85  *-------------------------------------------------------------------
  86  * We need to keep track of which region a bio is doing io for.
  87  * To avoid a memory allocation to store just 5 or 6 bits, we
  88  * ensure the 'struct io' pointer is aligned so enough low bits are
  89  * always zero and then combine it with the region number directly in
  90  * bi_private.
  91  *-------------------------------------------------------------------
  92  */
  93 static void store_io_and_region_in_bio(struct bio *bio, struct io *io,
  94                                        unsigned int region)
  95 {
  96         if (unlikely(!IS_ALIGNED((unsigned long)io, DM_IO_MAX_REGIONS))) {
  97                 DMCRIT("Unaligned struct io pointer %p", io);
  98                 BUG();
  99         }
 100
 101         bio->bi_private = (void *)((unsigned long)io | region);
 102 }
 103
 104 static void retrieve_io_and_region_from_bio(struct bio *bio, struct io **io,
 105                                        unsigned int *region)
 106 {
 107         unsigned long val = (unsigned long)bio->bi_private;
 108
 109         *io = (void *)(val & -(unsigned long)DM_IO_MAX_REGIONS);
 110         *region = val & (DM_IO_MAX_REGIONS - 1);
 111 }
 112
 113 /*
 114  *--------------------------------------------------------------
 115  * We need an io object to keep track of the number of bios that
 116  * have been dispatched for a particular io.
 117  *--------------------------------------------------------------
 118  */
 119 static void complete_io(struct io *io)
 120 {
 121         unsigned long error_bits = io->error_bits;
 122         io_notify_fn fn = io->callback;
 123         void *context = io->context;
 124
 125         if (io->vma_invalidate_size)
 126                 invalidate_kernel_vmap_range(io->vma_invalidate_address,
 127                                              io->vma_invalidate_size);
 128
 129         mempool_free(io, &io->client->pool);
 130         fn(error_bits, context);
 131 }
 132
 133 static void dec_count(struct io *io, unsigned int region, blk_status_t error)
 134 {
 135         if (error)
 136                 set_bit(region, &io->error_bits);
 137
 138         if (atomic_dec_and_test(&io->count))
 139                 complete_io(io);
 140 }
 141
 142 static void endio(struct bio *bio)
 143 {
 144         struct io *io;
 145         unsigned int region;
 146         blk_status_t error;
 147
 148         if (bio->bi_status && bio_data_dir(bio) == READ)
 149                 zero_fill_bio(bio);
 150
 151         /*
 152          * The bio destructor in bio_put() may use the io object.
 153          */
 154         retrieve_io_and_region_from_bio(bio, &io, &region);
 155
 156         error = bio->bi_status;
 157         bio_put(bio);
 158
 159         dec_count(io, region, error);
 160 }
 161
 162 /*
 163  *--------------------------------------------------------------
 164  * These little objects provide an abstraction for getting a new
 165  * destination page for io.
 166  *--------------------------------------------------------------
 167  */
 168 struct dpages {
 169         void (*get_page)(struct dpages *dp,
 170                          struct page **p, unsigned long *len, unsigned int *offset);
 171         void (*next_page)(struct dpages *dp);
 172
 173         union {
 174                 unsigned int context_u;
 175                 struct bvec_iter context_bi;
 176         };
 177         void *context_ptr;
 178
 179         void *vma_invalidate_address;
 180         unsigned long vma_invalidate_size;
 181 };
 182
 183 /*
 184  * Functions for getting the pages from a list.
 185  */
 186 static void list_get_page(struct dpages *dp,
 187                   struct page **p, unsigned long *len, unsigned int *offset)
 188 {
 189         unsigned int o = dp->context_u;
 190         struct page_list *pl = dp->context_ptr;
 191
 192         *p = pl->page;
 193         *len = PAGE_SIZE - o;
 194         *offset = o;
 195 }
 196
 197 static void list_next_page(struct dpages *dp)
 198 {
 199         struct page_list *pl = dp->context_ptr;
 200
 201         dp->context_ptr = pl->next;
 202         dp->context_u = 0;
 203 }
 204
 205 static void list_dp_init(struct dpages *dp, struct page_list *pl, unsigned int offset)
 206 {
 207         dp->get_page = list_get_page;
 208         dp->next_page = list_next_page;
 209         dp->context_u = offset;
 210         dp->context_ptr = pl;
 211 }
 212
 213 /*
 214  * Functions for getting the pages from a bvec.
 215  */
 216 static void bio_get_page(struct dpages *dp, struct page **p,
 217                          unsigned long *len, unsigned int *offset)
 218 {
 219         struct bio_vec bvec = bvec_iter_bvec((struct bio_vec *)dp->context_ptr,
 220                                              dp->context_bi);
 221
 222         *p = bvec.bv_page;
 223         *len = bvec.bv_len;
 224         *offset = bvec.bv_offset;
 225
 226         /* avoid figuring it out again in bio_next_page() */
 227         dp->context_bi.bi_sector = (sector_t)bvec.bv_len;
 228 }
 229
 230 static void bio_next_page(struct dpages *dp)
 231 {
 232         unsigned int len = (unsigned int)dp->context_bi.bi_sector;
 233
 234         bvec_iter_advance((struct bio_vec *)dp->context_ptr,
 235                           &dp->context_bi, len);
 236 }
 237
 238 static void bio_dp_init(struct dpages *dp, struct bio *bio)
 239 {
 240         dp->get_page = bio_get_page;
 241         dp->next_page = bio_next_page;
 242
 243         /*
 244          * We just use bvec iterator to retrieve pages, so it is ok to
 245          * access the bvec table directly here
 246          */
 247         dp->context_ptr = bio->bi_io_vec;
 248         dp->context_bi = bio->bi_iter;
 249 }
 250
 251 /*
 252  * Functions for getting the pages from a VMA.
 253  */
 254 static void vm_get_page(struct dpages *dp,
 255                  struct page **p, unsigned long *len, unsigned int *offset)
 256 {
 257         *p = vmalloc_to_page(dp->context_ptr);
 258         *offset = dp->context_u;
 259         *len = PAGE_SIZE - dp->context_u;
 260 }
 261
 262 static void vm_next_page(struct dpages *dp)
 263 {
 264         dp->context_ptr += PAGE_SIZE - dp->context_u;
 265         dp->context_u = 0;
 266 }
 267
 268 static void vm_dp_init(struct dpages *dp, void *data)
 269 {
 270         dp->get_page = vm_get_page;
 271         dp->next_page = vm_next_page;
 272         dp->context_u = offset_in_page(data);
 273         dp->context_ptr = data;
 274 }
 275
 276 /*
 277  * Functions for getting the pages from kernel memory.
 278  */
 279 static void km_get_page(struct dpages *dp, struct page **p, unsigned long *len,
 280                         unsigned int *offset)
 281 {
 282         *p = virt_to_page(dp->context_ptr);
 283         *offset = dp->context_u;
 284         *len = PAGE_SIZE - dp->context_u;
 285 }
 286
 287 static void km_next_page(struct dpages *dp)
 288 {
 289         dp->context_ptr += PAGE_SIZE - dp->context_u;
 290         dp->context_u = 0;
 291 }
 292
 293 static void km_dp_init(struct dpages *dp, void *data)
 294 {
 295         dp->get_page = km_get_page;
 296         dp->next_page = km_next_page;
 297         dp->context_u = offset_in_page(data);
 298         dp->context_ptr = data;
 299 }
 300
 301 /*
 302  *---------------------------------------------------------------
 303  * IO routines that accept a list of pages.
 304  *---------------------------------------------------------------
 305  */
 306 static void do_region(const blk_opf_t opf, unsigned int region,
 307                       struct dm_io_region *where, struct dpages *dp,
 308                       struct io *io, unsigned short ioprio)
 309 {
 310         struct bio *bio;
 311         struct page *page;
 312         unsigned long len;
 313         unsigned int offset;
 314         unsigned int num_bvecs;
 315         sector_t remaining = where->count;
 316         struct request_queue *q = bdev_get_queue(where->bdev);
 317         sector_t num_sectors;
 318         unsigned int special_cmd_max_sectors;
 319         const enum req_op op = opf & REQ_OP_MASK;
 320
 321         /*
 322          * Reject unsupported discard and write same requests.
 323          */
 324         if (op == REQ_OP_DISCARD)
 325                 special_cmd_max_sectors = bdev_max_discard_sectors(where->bdev);
 326         else if (op == REQ_OP_WRITE_ZEROES)
 327                 special_cmd_max_sectors = q->limits.max_write_zeroes_sectors;
 328         if ((op == REQ_OP_DISCARD || op == REQ_OP_WRITE_ZEROES) &&
 329             special_cmd_max_sectors == 0) {
 330                 atomic_inc(&io->count);
 331                 dec_count(io, region, BLK_STS_NOTSUPP);
 332                 return;
 333         }
 334
 335         /*
 336          * where->count may be zero if op holds a flush and we need to
 337          * send a zero-sized flush.
 338          */
 339         do {
 340                 /*
 341                  * Allocate a suitably sized-bio.
 342                  */
 343                 switch (op) {
 344                 case REQ_OP_DISCARD:
 345                 case REQ_OP_WRITE_ZEROES:
 346                         num_bvecs = 0;
 347                         break;
 348                 default:
 349                         num_bvecs = bio_max_segs(dm_sector_div_up(remaining,
 350                                                 (PAGE_SIZE >> SECTOR_SHIFT)) + 1);
 351                 }
 352
 353                 bio = bio_alloc_bioset(where->bdev, num_bvecs, opf, GFP_NOIO,
 354                                        &io->client->bios);
 355                 bio->bi_iter.bi_sector = where->sector + (where->count - remaining);
 356                 bio->bi_end_io = endio;
 357                 bio->bi_ioprio = ioprio;
 358                 store_io_and_region_in_bio(bio, io, region);
 359
 360                 if (op == REQ_OP_DISCARD || op == REQ_OP_WRITE_ZEROES) {
 361                         num_sectors = min_t(sector_t, special_cmd_max_sectors, remaining);
 362                         bio->bi_iter.bi_size = num_sectors << SECTOR_SHIFT;
 363                         remaining -= num_sectors;
 364                 } else {
 365                         while (remaining) {
 366                                 /*
 367                                  * Try and add as many pages as possible.
 368                                  */
 369                                 dp->get_page(dp, &page, &len, &offset);
 370                                 len = min(len, to_bytes(remaining));
 371                                 if (!bio_add_page(bio, page, len, offset))
 372                                         break;
 373
 374                                 offset = 0;
 375                                 remaining -= to_sector(len);
 376                                 dp->next_page(dp);
 377                         }
 378                 }
 379
 380                 atomic_inc(&io->count);
 381                 submit_bio(bio);
 382         } while (remaining);
 383 }
 384
 385 static void dispatch_io(blk_opf_t opf, unsigned int num_regions,
 386                         struct dm_io_region *where, struct dpages *dp,
 387                         struct io *io, unsigned short ioprio)
 388 {
 389         int i;
 390         struct dpages old_pages = *dp;
 391
 392         BUG_ON(num_regions > DM_IO_MAX_REGIONS);
 393
 394         /*
 395          * For multiple regions we need to be careful to rewind
 396          * the dp object for each call to do_region.
 397          */
 398         for (i = 0; i < num_regions; i++) {
 399                 *dp = old_pages;
 400                 if (where[i].count || (opf & REQ_PREFLUSH))
 401                         do_region(opf, i, where + i, dp, io, ioprio);
 402         }
 403
 404         /*
 405          * Drop the extra reference that we were holding to avoid
 406          * the io being completed too early.
 407          */
 408         dec_count(io, 0, 0);
 409 }
 410
 411 static void async_io(struct dm_io_client *client, unsigned int num_regions,
 412                      struct dm_io_region *where, blk_opf_t opf,
 413                      struct dpages *dp, io_notify_fn fn, void *context,
 414                      unsigned short ioprio)
 415 {
 416         struct io *io;
 417
 418         io = mempool_alloc(&client->pool, GFP_NOIO);
 419         io->error_bits = 0;
 420         atomic_set(&io->count, 1); /* see dispatch_io() */
 421         io->client = client;
 422         io->callback = fn;
 423         io->context = context;
 424
 425         io->vma_invalidate_address = dp->vma_invalidate_address;
 426         io->vma_invalidate_size = dp->vma_invalidate_size;
 427
 428         dispatch_io(opf, num_regions, where, dp, io, ioprio);
 429 }
 430
 431 struct sync_io {
 432         unsigned long error_bits;
 433         struct completion wait;
 434 };
 435
 436 static void sync_io_complete(unsigned long error, void *context)
 437 {
 438         struct sync_io *sio = context;
 439
 440         sio->error_bits = error;
 441         complete(&sio->wait);
 442 }
 443
 444 static int sync_io(struct dm_io_client *client, unsigned int num_regions,
 445                    struct dm_io_region *where, blk_opf_t opf, struct dpages *dp,
 446                    unsigned long *error_bits, unsigned short ioprio)
 447 {
 448         struct sync_io sio;
 449
 450         init_completion(&sio.wait);
 451
 452         async_io(client, num_regions, where, opf | REQ_SYNC, dp,
 453                  sync_io_complete, &sio, ioprio);
 454
 455         wait_for_completion_io(&sio.wait);
 456
 457         if (error_bits)
 458                 *error_bits = sio.error_bits;
 459
 460         return sio.error_bits ? -EIO : 0;
 461 }
 462
 463 static int dp_init(struct dm_io_request *io_req, struct dpages *dp,
 464                    unsigned long size)
 465 {
 466         /* Set up dpages based on memory type */
 467
 468         dp->vma_invalidate_address = NULL;
 469         dp->vma_invalidate_size = 0;
 470
 471         switch (io_req->mem.type) {
 472         case DM_IO_PAGE_LIST:
 473                 list_dp_init(dp, io_req->mem.ptr.pl, io_req->mem.offset);
 474                 break;
 475
 476         case DM_IO_BIO:
 477                 bio_dp_init(dp, io_req->mem.ptr.bio);
 478                 break;
 479
 480         case DM_IO_VMA:
 481                 flush_kernel_vmap_range(io_req->mem.ptr.vma, size);
 482                 if ((io_req->bi_opf & REQ_OP_MASK) == REQ_OP_READ) {
 483                         dp->vma_invalidate_address = io_req->mem.ptr.vma;
 484                         dp->vma_invalidate_size = size;
 485                 }
 486                 vm_dp_init(dp, io_req->mem.ptr.vma);
 487                 break;
 488
 489         case DM_IO_KMEM:
 490                 km_dp_init(dp, io_req->mem.ptr.addr);
 491                 break;
 492
 493         default:
 494                 return -EINVAL;
 495         }
 496
 497         return 0;
 498 }
 499
 500 int dm_io(struct dm_io_request *io_req, unsigned int num_regions,
 501           struct dm_io_region *where, unsigned long *sync_error_bits,
 502           unsigned short ioprio)
 503 {
 504         int r;
 505         struct dpages dp;
 506
 507         if (num_regions > 1 && !op_is_write(io_req->bi_opf)) {
 508                 WARN_ON(1);
 509                 return -EIO;
 510         }
 511
 512         r = dp_init(io_req, &dp, (unsigned long)where->count << SECTOR_SHIFT);
 513         if (r)
 514                 return r;
 515
 516         if (!io_req->notify.fn)
 517                 return sync_io(io_req->client, num_regions, where,
 518                                io_req->bi_opf, &dp, sync_error_bits, ioprio);
 519
 520         async_io(io_req->client, num_regions, where, io_req->bi_opf, &dp,
 521                  io_req->notify.fn, io_req->notify.context, ioprio);
 522         return 0;
 523 }
 524 EXPORT_SYMBOL(dm_io);
 525
 526 int __init dm_io_init(void)
 527 {
 528         _dm_io_cache = KMEM_CACHE(io, 0);
 529         if (!_dm_io_cache)
 530                 return -ENOMEM;
 531
 532         return 0;
 533 }
 534
 535 void dm_io_exit(void)
 536 {
 537         kmem_cache_destroy(_dm_io_cache);
 538         _dm_io_cache = NULL;
 539 }