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-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);
  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 op, int op_flags, unsigned region,
 282                       struct dm_io_region *where, struct dpages *dp,
 283                       struct io *io)
 284 {
 285         struct bio *bio;
 286         struct page *page;
 287         unsigned long len;
 288         unsigned offset;
 289         unsigned num_bvecs;
 290         sector_t remaining = where->count;
 291         struct request_queue *q = bdev_get_queue(where->bdev);
 292         unsigned short logical_block_size = queue_logical_block_size(q);
 293         sector_t num_sectors;
 294         unsigned int uninitialized_var(special_cmd_max_sectors);
 295
 296         /*
 297          * Reject unsupported discard and write same requests.
 298          */
 299         if (op == REQ_OP_DISCARD)
 300                 special_cmd_max_sectors = q->limits.max_discard_sectors;
 301         else if (op == REQ_OP_WRITE_SAME)
 302                 special_cmd_max_sectors = q->limits.max_write_same_sectors;
 303         if ((op == REQ_OP_DISCARD || op == REQ_OP_WRITE_SAME) &&
 304             special_cmd_max_sectors == 0) {
 305                 dec_count(io, region, -EOPNOTSUPP);
 306                 return;
 307         }
 308
 309         /*
 310          * where->count may be zero if op holds a flush and we need to
 311          * send a zero-sized flush.
 312          */
 313         do {
 314                 /*
 315                  * Allocate a suitably sized-bio.
 316                  */
 317                 if ((op == REQ_OP_DISCARD) || (op == REQ_OP_WRITE_SAME))
 318                         num_bvecs = 1;
 319                 else
 320                         num_bvecs = min_t(int, BIO_MAX_PAGES,
 321                                           dm_sector_div_up(remaining, (PAGE_SIZE >> SECTOR_SHIFT)));
 322
 323                 bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, io->client->bios);
 324                 bio->bi_iter.bi_sector = where->sector + (where->count - remaining);
 325                 bio->bi_bdev = where->bdev;
 326                 bio->bi_end_io = endio;
 327                 bio_set_op_attrs(bio, op, op_flags);
 328                 store_io_and_region_in_bio(bio, io, region);
 329
 330                 if (op == REQ_OP_DISCARD) {
 331                         num_sectors = min_t(sector_t, special_cmd_max_sectors, remaining);
 332                         bio->bi_iter.bi_size = num_sectors << SECTOR_SHIFT;
 333                         remaining -= num_sectors;
 334                 } else if (op == REQ_OP_WRITE_SAME) {
 335                         /*
 336                          * WRITE SAME only uses a single page.
 337                          */
 338                         dp->get_page(dp, &page, &len, &offset);
 339                         bio_add_page(bio, page, logical_block_size, offset);
 340                         num_sectors = min_t(sector_t, special_cmd_max_sectors, remaining);
 341                         bio->bi_iter.bi_size = num_sectors << SECTOR_SHIFT;
 342
 343                         offset = 0;
 344                         remaining -= num_sectors;
 345                         dp->next_page(dp);
 346                 } else while (remaining) {
 347                         /*
 348                          * Try and add as many pages as possible.
 349                          */
 350                         dp->get_page(dp, &page, &len, &offset);
 351                         len = min(len, to_bytes(remaining));
 352                         if (!bio_add_page(bio, page, len, offset))
 353                                 break;
 354
 355                         offset = 0;
 356                         remaining -= to_sector(len);
 357                         dp->next_page(dp);
 358                 }
 359
 360                 atomic_inc(&io->count);
 361                 submit_bio(bio);
 362         } while (remaining);
 363 }
 364
 365 static void dispatch_io(int op, int op_flags, unsigned int num_regions,
 366                         struct dm_io_region *where, struct dpages *dp,
 367                         struct io *io, int sync)
 368 {
 369         int i;
 370         struct dpages old_pages = *dp;
 371
 372         BUG_ON(num_regions > DM_IO_MAX_REGIONS);
 373
 374         if (sync)
 375                 op_flags |= REQ_SYNC;
 376
 377         /*
 378          * For multiple regions we need to be careful to rewind
 379          * the dp object for each call to do_region.
 380          */
 381         for (i = 0; i < num_regions; i++) {
 382                 *dp = old_pages;
 383                 if (where[i].count || (op_flags & REQ_PREFLUSH))
 384                         do_region(op, op_flags, i, where + i, dp, io);
 385         }
 386
 387         /*
 388          * Drop the extra reference that we were holding to avoid
 389          * the io being completed too early.
 390          */
 391         dec_count(io, 0, 0);
 392 }
 393
 394 struct sync_io {
 395         unsigned long error_bits;
 396         struct completion wait;
 397 };
 398
 399 static void sync_io_complete(unsigned long error, void *context)
 400 {
 401         struct sync_io *sio = context;
 402
 403         sio->error_bits = error;
 404         complete(&sio->wait);
 405 }
 406
 407 static int sync_io(struct dm_io_client *client, unsigned int num_regions,
 408                    struct dm_io_region *where, int op, int op_flags,
 409                    struct dpages *dp, unsigned long *error_bits)
 410 {
 411         struct io *io;
 412         struct sync_io sio;
 413
 414         if (num_regions > 1 && !op_is_write(op)) {
 415                 WARN_ON(1);
 416                 return -EIO;
 417         }
 418
 419         init_completion(&sio.wait);
 420
 421         io = mempool_alloc(client->pool, GFP_NOIO);
 422         io->error_bits = 0;
 423         atomic_set(&io->count, 1); /* see dispatch_io() */
 424         io->client = client;
 425         io->callback = sync_io_complete;
 426         io->context = &sio;
 427
 428         io->vma_invalidate_address = dp->vma_invalidate_address;
 429         io->vma_invalidate_size = dp->vma_invalidate_size;
 430
 431         dispatch_io(op, op_flags, num_regions, where, dp, io, 1);
 432
 433         wait_for_completion_io(&sio.wait);
 434
 435         if (error_bits)
 436                 *error_bits = sio.error_bits;
 437
 438         return sio.error_bits ? -EIO : 0;
 439 }
 440
 441 static int async_io(struct dm_io_client *client, unsigned int num_regions,
 442                     struct dm_io_region *where, int op, int op_flags,
 443                     struct dpages *dp, io_notify_fn fn, void *context)
 444 {
 445         struct io *io;
 446
 447         if (num_regions > 1 && !op_is_write(op)) {
 448                 WARN_ON(1);
 449                 fn(1, context);
 450                 return -EIO;
 451         }
 452
 453         io = mempool_alloc(client->pool, GFP_NOIO);
 454         io->error_bits = 0;
 455         atomic_set(&io->count, 1); /* see dispatch_io() */
 456         io->client = client;
 457         io->callback = fn;
 458         io->context = context;
 459
 460         io->vma_invalidate_address = dp->vma_invalidate_address;
 461         io->vma_invalidate_size = dp->vma_invalidate_size;
 462
 463         dispatch_io(op, op_flags, num_regions, where, dp, io, 0);
 464         return 0;
 465 }
 466
 467 static int dp_init(struct dm_io_request *io_req, struct dpages *dp,
 468                    unsigned long size)
 469 {
 470         /* Set up dpages based on memory type */
 471
 472         dp->vma_invalidate_address = NULL;
 473         dp->vma_invalidate_size = 0;
 474
 475         switch (io_req->mem.type) {
 476         case DM_IO_PAGE_LIST:
 477                 list_dp_init(dp, io_req->mem.ptr.pl, io_req->mem.offset);
 478                 break;
 479
 480         case DM_IO_BIO:
 481                 bio_dp_init(dp, io_req->mem.ptr.bio);
 482                 break;
 483
 484         case DM_IO_VMA:
 485                 flush_kernel_vmap_range(io_req->mem.ptr.vma, size);
 486                 if (io_req->bi_op == REQ_OP_READ) {
 487                         dp->vma_invalidate_address = io_req->mem.ptr.vma;
 488                         dp->vma_invalidate_size = size;
 489                 }
 490                 vm_dp_init(dp, io_req->mem.ptr.vma);
 491                 break;
 492
 493         case DM_IO_KMEM:
 494                 km_dp_init(dp, io_req->mem.ptr.addr);
 495                 break;
 496
 497         default:
 498                 return -EINVAL;
 499         }
 500
 501         return 0;
 502 }
 503
 504 /*
 505  * New collapsed (a)synchronous interface.
 506  *
 507  * If the IO is asynchronous (i.e. it has notify.fn), you must either unplug
 508  * the queue with blk_unplug() some time later or set REQ_SYNC in io_req->bi_rw.
 509  * If you fail to do one of these, the IO will be submitted to the disk after
 510  * q->unplug_delay, which defaults to 3ms in blk-settings.c.
 511  */
 512 int dm_io(struct dm_io_request *io_req, unsigned num_regions,
 513           struct dm_io_region *where, unsigned long *sync_error_bits)
 514 {
 515         int r;
 516         struct dpages dp;
 517
 518         r = dp_init(io_req, &dp, (unsigned long)where->count << SECTOR_SHIFT);
 519         if (r)
 520                 return r;
 521
 522         if (!io_req->notify.fn)
 523                 return sync_io(io_req->client, num_regions, where,
 524                                io_req->bi_op, io_req->bi_op_flags, &dp,
 525                                sync_error_bits);
 526
 527         return async_io(io_req->client, num_regions, where, io_req->bi_op,
 528                         io_req->bi_op_flags, &dp, io_req->notify.fn,
 529                         io_req->notify.context);
 530 }
 531 EXPORT_SYMBOL(dm_io);
 532
 533 int __init dm_io_init(void)
 534 {
 535         _dm_io_cache = KMEM_CACHE(io, 0);
 536         if (!_dm_io_cache)
 537                 return -ENOMEM;
 538
 539         return 0;
 540 }
 541
 542 void dm_io_exit(void)
 543 {
 544         kmem_cache_destroy(_dm_io_cache);
 545         _dm_io_cache = NULL;
 546 }