drivers/md/dm-io.c

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