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         if (client->pool)
  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, int 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, int error)
 138 {
 139         struct io *io;
 140         unsigned region;
 141
 142         if (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         bio_put(bio);
 151
 152         dec_count(io, region, error);
 153 }
 154
 155 /*-----------------------------------------------------------------
 156  * These little objects provide an abstraction for getting a new
 157  * destination page for io.
 158  *---------------------------------------------------------------*/
 159 struct dpages {
 160         void (*get_page)(struct dpages *dp,
 161                          struct page **p, unsigned long *len, unsigned *offset);
 162         void (*next_page)(struct dpages *dp);
 163
 164         unsigned context_u;
 165         void *context_ptr;
 166
 167         void *vma_invalidate_address;
 168         unsigned long vma_invalidate_size;
 169 };
 170
 171 /*
 172  * Functions for getting the pages from a list.
 173  */
 174 static void list_get_page(struct dpages *dp,
 175                   struct page **p, unsigned long *len, unsigned *offset)
 176 {
 177         unsigned o = dp->context_u;
 178         struct page_list *pl = (struct page_list *) dp->context_ptr;
 179
 180         *p = pl->page;
 181         *len = PAGE_SIZE - o;
 182         *offset = o;
 183 }
 184
 185 static void list_next_page(struct dpages *dp)
 186 {
 187         struct page_list *pl = (struct page_list *) dp->context_ptr;
 188         dp->context_ptr = pl->next;
 189         dp->context_u = 0;
 190 }
 191
 192 static void list_dp_init(struct dpages *dp, struct page_list *pl, unsigned offset)
 193 {
 194         dp->get_page = list_get_page;
 195         dp->next_page = list_next_page;
 196         dp->context_u = offset;
 197         dp->context_ptr = pl;
 198 }
 199
 200 /*
 201  * Functions for getting the pages from a bvec.
 202  */
 203 static void bio_get_page(struct dpages *dp, struct page **p,
 204                          unsigned long *len, unsigned *offset)
 205 {
 206         struct bio_vec *bvec = dp->context_ptr;
 207         *p = bvec->bv_page;
 208         *len = bvec->bv_len - dp->context_u;
 209         *offset = bvec->bv_offset + dp->context_u;
 210 }
 211
 212 static void bio_next_page(struct dpages *dp)
 213 {
 214         struct bio_vec *bvec = dp->context_ptr;
 215         dp->context_ptr = bvec + 1;
 216         dp->context_u = 0;
 217 }
 218
 219 static void bio_dp_init(struct dpages *dp, struct bio *bio)
 220 {
 221         dp->get_page = bio_get_page;
 222         dp->next_page = bio_next_page;
 223         dp->context_ptr = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
 224         dp->context_u = bio->bi_iter.bi_bvec_done;
 225 }
 226
 227 /*
 228  * Functions for getting the pages from a VMA.
 229  */
 230 static void vm_get_page(struct dpages *dp,
 231                  struct page **p, unsigned long *len, unsigned *offset)
 232 {
 233         *p = vmalloc_to_page(dp->context_ptr);
 234         *offset = dp->context_u;
 235         *len = PAGE_SIZE - dp->context_u;
 236 }
 237
 238 static void vm_next_page(struct dpages *dp)
 239 {
 240         dp->context_ptr += PAGE_SIZE - dp->context_u;
 241         dp->context_u = 0;
 242 }
 243
 244 static void vm_dp_init(struct dpages *dp, void *data)
 245 {
 246         dp->get_page = vm_get_page;
 247         dp->next_page = vm_next_page;
 248         dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1);
 249         dp->context_ptr = data;
 250 }
 251
 252 /*
 253  * Functions for getting the pages from kernel memory.
 254  */
 255 static void km_get_page(struct dpages *dp, struct page **p, unsigned long *len,
 256                         unsigned *offset)
 257 {
 258         *p = virt_to_page(dp->context_ptr);
 259         *offset = dp->context_u;
 260         *len = PAGE_SIZE - dp->context_u;
 261 }
 262
 263 static void km_next_page(struct dpages *dp)
 264 {
 265         dp->context_ptr += PAGE_SIZE - dp->context_u;
 266         dp->context_u = 0;
 267 }
 268
 269 static void km_dp_init(struct dpages *dp, void *data)
 270 {
 271         dp->get_page = km_get_page;
 272         dp->next_page = km_next_page;
 273         dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1);
 274         dp->context_ptr = data;
 275 }
 276
 277 /*-----------------------------------------------------------------
 278  * IO routines that accept a list of pages.
 279  *---------------------------------------------------------------*/
 280 static void do_region(int rw, unsigned region, struct dm_io_region *where,
 281                       struct dpages *dp, struct io *io)
 282 {
 283         struct bio *bio;
 284         struct page *page;
 285         unsigned long len;
 286         unsigned offset;
 287         unsigned num_bvecs;
 288         sector_t remaining = where->count;
 289         struct request_queue *q = bdev_get_queue(where->bdev);
 290         unsigned short logical_block_size = queue_logical_block_size(q);
 291         sector_t num_sectors;
 292         unsigned int uninitialized_var(special_cmd_max_sectors);
 293
 294         /*
 295          * Reject unsupported discard and write same requests.
 296          */
 297         if (rw & REQ_DISCARD)
 298                 special_cmd_max_sectors = q->limits.max_discard_sectors;
 299         else if (rw & REQ_WRITE_SAME)
 300                 special_cmd_max_sectors = q->limits.max_write_same_sectors;
 301         if ((rw & (REQ_DISCARD | REQ_WRITE_SAME)) && special_cmd_max_sectors == 0) {
 302                 dec_count(io, region, -EOPNOTSUPP);
 303                 return;
 304         }
 305
 306         /*
 307          * where->count may be zero if rw holds a flush and we need to
 308          * send a zero-sized flush.
 309          */
 310         do {
 311                 /*
 312                  * Allocate a suitably sized-bio.
 313                  */
 314                 if ((rw & REQ_DISCARD) || (rw & REQ_WRITE_SAME))
 315                         num_bvecs = 1;
 316                 else
 317                         num_bvecs = min_t(int, bio_get_nr_vecs(where->bdev),
 318                                           dm_sector_div_up(remaining, (PAGE_SIZE >> SECTOR_SHIFT)));
 319
 320                 bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, io->client->bios);
 321                 bio->bi_iter.bi_sector = where->sector + (where->count - remaining);
 322                 bio->bi_bdev = where->bdev;
 323                 bio->bi_end_io = endio;
 324                 store_io_and_region_in_bio(bio, io, region);
 325
 326                 if (rw & REQ_DISCARD) {
 327                         num_sectors = min_t(sector_t, special_cmd_max_sectors, remaining);
 328                         bio->bi_iter.bi_size = num_sectors << SECTOR_SHIFT;
 329                         remaining -= num_sectors;
 330                 } else if (rw & REQ_WRITE_SAME) {
 331                         /*
 332                          * WRITE SAME only uses a single page.
 333                          */
 334                         dp->get_page(dp, &page, &len, &offset);
 335                         bio_add_page(bio, page, logical_block_size, offset);
 336                         num_sectors = min_t(sector_t, special_cmd_max_sectors, remaining);
 337                         bio->bi_iter.bi_size = num_sectors << SECTOR_SHIFT;
 338
 339                         offset = 0;
 340                         remaining -= num_sectors;
 341                         dp->next_page(dp);
 342                 } else while (remaining) {
 343                         /*
 344                          * Try and add as many pages as possible.
 345                          */
 346                         dp->get_page(dp, &page, &len, &offset);
 347                         len = min(len, to_bytes(remaining));
 348                         if (!bio_add_page(bio, page, len, offset))
 349                                 break;
 350
 351                         offset = 0;
 352                         remaining -= to_sector(len);
 353                         dp->next_page(dp);
 354                 }
 355
 356                 atomic_inc(&io->count);
 357                 submit_bio(rw, bio);
 358         } while (remaining);
 359 }
 360
 361 static void dispatch_io(int rw, unsigned int num_regions,
 362                         struct dm_io_region *where, struct dpages *dp,
 363                         struct io *io, int sync)
 364 {
 365         int i;
 366         struct dpages old_pages = *dp;
 367
 368         BUG_ON(num_regions > DM_IO_MAX_REGIONS);
 369
 370         if (sync)
 371                 rw |= REQ_SYNC;
 372
 373         /*
 374          * For multiple regions we need to be careful to rewind
 375          * the dp object for each call to do_region.
 376          */
 377         for (i = 0; i < num_regions; i++) {
 378                 *dp = old_pages;
 379                 if (where[i].count || (rw & REQ_FLUSH))
 380                         do_region(rw, i, where + i, dp, io);
 381         }
 382
 383         /*
 384          * Drop the extra reference that we were holding to avoid
 385          * the io being completed too early.
 386          */
 387         dec_count(io, 0, 0);
 388 }
 389
 390 struct sync_io {
 391         unsigned long error_bits;
 392         struct completion wait;
 393 };
 394
 395 static void sync_io_complete(unsigned long error, void *context)
 396 {
 397         struct sync_io *sio = context;
 398
 399         sio->error_bits = error;
 400         complete(&sio->wait);
 401 }
 402
 403 static int sync_io(struct dm_io_client *client, unsigned int num_regions,
 404                    struct dm_io_region *where, int rw, struct dpages *dp,
 405                    unsigned long *error_bits)
 406 {
 407         struct io *io;
 408         struct sync_io sio;
 409
 410         if (num_regions > 1 && (rw & RW_MASK) != WRITE) {
 411                 WARN_ON(1);
 412                 return -EIO;
 413         }
 414
 415         init_completion(&sio.wait);
 416
 417         io = mempool_alloc(client->pool, GFP_NOIO);
 418         io->error_bits = 0;
 419         atomic_set(&io->count, 1); /* see dispatch_io() */
 420         io->client = client;
 421         io->callback = sync_io_complete;
 422         io->context = &sio;
 423
 424         io->vma_invalidate_address = dp->vma_invalidate_address;
 425         io->vma_invalidate_size = dp->vma_invalidate_size;
 426
 427         dispatch_io(rw, num_regions, where, dp, io, 1);
 428
 429         wait_for_completion_io(&sio.wait);
 430
 431         if (error_bits)
 432                 *error_bits = sio.error_bits;
 433
 434         return sio.error_bits ? -EIO : 0;
 435 }
 436
 437 static int async_io(struct dm_io_client *client, unsigned int num_regions,
 438                     struct dm_io_region *where, int rw, struct dpages *dp,
 439                     io_notify_fn fn, void *context)
 440 {
 441         struct io *io;
 442
 443         if (num_regions > 1 && (rw & RW_MASK) != WRITE) {
 444                 WARN_ON(1);
 445                 fn(1, context);
 446                 return -EIO;
 447         }
 448
 449         io = mempool_alloc(client->pool, GFP_NOIO);
 450         io->error_bits = 0;
 451         atomic_set(&io->count, 1); /* see dispatch_io() */
 452         io->client = client;
 453         io->callback = fn;
 454         io->context = context;
 455
 456         io->vma_invalidate_address = dp->vma_invalidate_address;
 457         io->vma_invalidate_size = dp->vma_invalidate_size;
 458
 459         dispatch_io(rw, num_regions, where, dp, io, 0);
 460         return 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_rw & RW_MASK) == 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 /*
 501  * New collapsed (a)synchronous interface.
 502  *
 503  * If the IO is asynchronous (i.e. it has notify.fn), you must either unplug
 504  * the queue with blk_unplug() some time later or set REQ_SYNC in io_req->bi_rw.
 505  * If you fail to do one of these, the IO will be submitted to the disk after
 506  * q->unplug_delay, which defaults to 3ms in blk-settings.c.
 507  */
 508 int dm_io(struct dm_io_request *io_req, unsigned num_regions,
 509           struct dm_io_region *where, unsigned long *sync_error_bits)
 510 {
 511         int r;
 512         struct dpages dp;
 513
 514         r = dp_init(io_req, &dp, (unsigned long)where->count << SECTOR_SHIFT);
 515         if (r)
 516                 return r;
 517
 518         if (!io_req->notify.fn)
 519                 return sync_io(io_req->client, num_regions, where,
 520                                io_req->bi_rw, &dp, sync_error_bits);
 521
 522         return async_io(io_req->client, num_regions, where, io_req->bi_rw,
 523                         &dp, io_req->notify.fn, io_req->notify.context);
 524 }
 525 EXPORT_SYMBOL(dm_io);
 526
 527 int __init dm_io_init(void)
 528 {
 529         _dm_io_cache = KMEM_CACHE(io, 0);
 530         if (!_dm_io_cache)
 531                 return -ENOMEM;
 532
 533         return 0;
 534 }
 535
 536 void dm_io_exit(void)
 537 {
 538         kmem_cache_destroy(_dm_io_cache);
 539         _dm_io_cache = NULL;
 540 }