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-io.h"
   9
  10 #include <linux/bio.h>
  11 #include <linux/mempool.h>
  12 #include <linux/module.h>
  13 #include <linux/sched.h>
  14 #include <linux/slab.h>
  15
  16 static struct bio_set *_bios;
  17
  18 struct dm_io_client {
  19         mempool_t *pool;
  20         struct bio_set *bios;
  21 };
  22
  23 /* FIXME: can we shrink this ? */
  24 struct io {
  25         unsigned long error;
  26         atomic_t count;
  27         struct task_struct *sleeper;
  28         struct dm_io_client *client;
  29         io_notify_fn callback;
  30         void *context;
  31 };
  32
  33 /*
  34  * io contexts are only dynamically allocated for asynchronous
  35  * io.  Since async io is likely to be the majority of io we'll
  36  * have the same number of io contexts as bios! (FIXME: must reduce this).
  37  */
  38 static unsigned _num_ios;
  39 static mempool_t *_io_pool;
  40
  41 /*
  42  * Temporary functions to allow old and new interfaces to co-exist.
  43  */
  44 static struct bio_set *bios(struct dm_io_client *client)
  45 {
  46         return client ? client->bios : _bios;
  47 }
  48
  49 static mempool_t *io_pool(struct dm_io_client *client)
  50 {
  51         return client ? client->pool : _io_pool;
  52 }
  53
  54 static unsigned int pages_to_ios(unsigned int pages)
  55 {
  56         return 4 * pages;       /* too many ? */
  57 }
  58
  59 static int resize_pool(unsigned int new_ios)
  60 {
  61         int r = 0;
  62
  63         if (_io_pool) {
  64                 if (new_ios == 0) {
  65                         /* free off the pool */
  66                         mempool_destroy(_io_pool);
  67                         _io_pool = NULL;
  68                         bioset_free(_bios);
  69
  70                 } else {
  71                         /* resize the pool */
  72                         r = mempool_resize(_io_pool, new_ios, GFP_KERNEL);
  73                 }
  74
  75         } else {
  76                 /* create new pool */
  77                 _io_pool = mempool_create_kmalloc_pool(new_ios,
  78                                                        sizeof(struct io));
  79                 if (!_io_pool)
  80                         return -ENOMEM;
  81
  82                 _bios = bioset_create(16, 16);
  83                 if (!_bios) {
  84                         mempool_destroy(_io_pool);
  85                         _io_pool = NULL;
  86                         return -ENOMEM;
  87                 }
  88         }
  89
  90         if (!r)
  91                 _num_ios = new_ios;
  92
  93         return r;
  94 }
  95
  96 int dm_io_get(unsigned int num_pages)
  97 {
  98         return resize_pool(_num_ios + pages_to_ios(num_pages));
  99 }
 100
 101 void dm_io_put(unsigned int num_pages)
 102 {
 103         resize_pool(_num_ios - pages_to_ios(num_pages));
 104 }
 105
 106 /*
 107  * Create a client with mempool and bioset.
 108  */
 109 struct dm_io_client *dm_io_client_create(unsigned num_pages)
 110 {
 111         unsigned ios = pages_to_ios(num_pages);
 112         struct dm_io_client *client;
 113
 114         client = kmalloc(sizeof(*client), GFP_KERNEL);
 115         if (!client)
 116                 return ERR_PTR(-ENOMEM);
 117
 118         client->pool = mempool_create_kmalloc_pool(ios, sizeof(struct io));
 119         if (!client->pool)
 120                 goto bad;
 121
 122         client->bios = bioset_create(16, 16);
 123         if (!client->bios)
 124                 goto bad;
 125
 126         return client;
 127
 128    bad:
 129         if (client->pool)
 130                 mempool_destroy(client->pool);
 131         kfree(client);
 132         return ERR_PTR(-ENOMEM);
 133 }
 134 EXPORT_SYMBOL(dm_io_client_create);
 135
 136 int dm_io_client_resize(unsigned num_pages, struct dm_io_client *client)
 137 {
 138         return mempool_resize(client->pool, pages_to_ios(num_pages),
 139                               GFP_KERNEL);
 140 }
 141 EXPORT_SYMBOL(dm_io_client_resize);
 142
 143 void dm_io_client_destroy(struct dm_io_client *client)
 144 {
 145         mempool_destroy(client->pool);
 146         bioset_free(client->bios);
 147         kfree(client);
 148 }
 149 EXPORT_SYMBOL(dm_io_client_destroy);
 150
 151 /*-----------------------------------------------------------------
 152  * We need to keep track of which region a bio is doing io for.
 153  * In order to save a memory allocation we store this the last
 154  * bvec which we know is unused (blech).
 155  * XXX This is ugly and can OOPS with some configs... find another way.
 156  *---------------------------------------------------------------*/
 157 static inline void bio_set_region(struct bio *bio, unsigned region)
 158 {
 159         bio->bi_io_vec[bio->bi_max_vecs].bv_len = region;
 160 }
 161
 162 static inline unsigned bio_get_region(struct bio *bio)
 163 {
 164         return bio->bi_io_vec[bio->bi_max_vecs].bv_len;
 165 }
 166
 167 /*-----------------------------------------------------------------
 168  * We need an io object to keep track of the number of bios that
 169  * have been dispatched for a particular io.
 170  *---------------------------------------------------------------*/
 171 static void dec_count(struct io *io, unsigned int region, int error)
 172 {
 173         if (error)
 174                 set_bit(region, &io->error);
 175
 176         if (atomic_dec_and_test(&io->count)) {
 177                 if (io->sleeper)
 178                         wake_up_process(io->sleeper);
 179
 180                 else {
 181                         int r = io->error;
 182                         io_notify_fn fn = io->callback;
 183                         void *context = io->context;
 184
 185                         mempool_free(io, io_pool(io->client));
 186                         fn(r, context);
 187                 }
 188         }
 189 }
 190
 191 static int endio(struct bio *bio, unsigned int done, int error)
 192 {
 193         struct io *io;
 194         unsigned region;
 195
 196         /* keep going until we've finished */
 197         if (bio->bi_size)
 198                 return 1;
 199
 200         if (error && bio_data_dir(bio) == READ)
 201                 zero_fill_bio(bio);
 202
 203         /*
 204          * The bio destructor in bio_put() may use the io object.
 205          */
 206         io = bio->bi_private;
 207         region = bio_get_region(bio);
 208
 209         bio->bi_max_vecs++;
 210         bio_put(bio);
 211
 212         dec_count(io, region, error);
 213
 214         return 0;
 215 }
 216
 217 /*-----------------------------------------------------------------
 218  * These little objects provide an abstraction for getting a new
 219  * destination page for io.
 220  *---------------------------------------------------------------*/
 221 struct dpages {
 222         void (*get_page)(struct dpages *dp,
 223                          struct page **p, unsigned long *len, unsigned *offset);
 224         void (*next_page)(struct dpages *dp);
 225
 226         unsigned context_u;
 227         void *context_ptr;
 228 };
 229
 230 /*
 231  * Functions for getting the pages from a list.
 232  */
 233 static void list_get_page(struct dpages *dp,
 234                   struct page **p, unsigned long *len, unsigned *offset)
 235 {
 236         unsigned o = dp->context_u;
 237         struct page_list *pl = (struct page_list *) dp->context_ptr;
 238
 239         *p = pl->page;
 240         *len = PAGE_SIZE - o;
 241         *offset = o;
 242 }
 243
 244 static void list_next_page(struct dpages *dp)
 245 {
 246         struct page_list *pl = (struct page_list *) dp->context_ptr;
 247         dp->context_ptr = pl->next;
 248         dp->context_u = 0;
 249 }
 250
 251 static void list_dp_init(struct dpages *dp, struct page_list *pl, unsigned offset)
 252 {
 253         dp->get_page = list_get_page;
 254         dp->next_page = list_next_page;
 255         dp->context_u = offset;
 256         dp->context_ptr = pl;
 257 }
 258
 259 /*
 260  * Functions for getting the pages from a bvec.
 261  */
 262 static void bvec_get_page(struct dpages *dp,
 263                   struct page **p, unsigned long *len, unsigned *offset)
 264 {
 265         struct bio_vec *bvec = (struct bio_vec *) dp->context_ptr;
 266         *p = bvec->bv_page;
 267         *len = bvec->bv_len;
 268         *offset = bvec->bv_offset;
 269 }
 270
 271 static void bvec_next_page(struct dpages *dp)
 272 {
 273         struct bio_vec *bvec = (struct bio_vec *) dp->context_ptr;
 274         dp->context_ptr = bvec + 1;
 275 }
 276
 277 static void bvec_dp_init(struct dpages *dp, struct bio_vec *bvec)
 278 {
 279         dp->get_page = bvec_get_page;
 280         dp->next_page = bvec_next_page;
 281         dp->context_ptr = bvec;
 282 }
 283
 284 /*
 285  * Functions for getting the pages from a VMA.
 286  */
 287 static void vm_get_page(struct dpages *dp,
 288                  struct page **p, unsigned long *len, unsigned *offset)
 289 {
 290         *p = vmalloc_to_page(dp->context_ptr);
 291         *offset = dp->context_u;
 292         *len = PAGE_SIZE - dp->context_u;
 293 }
 294
 295 static void vm_next_page(struct dpages *dp)
 296 {
 297         dp->context_ptr += PAGE_SIZE - dp->context_u;
 298         dp->context_u = 0;
 299 }
 300
 301 static void vm_dp_init(struct dpages *dp, void *data)
 302 {
 303         dp->get_page = vm_get_page;
 304         dp->next_page = vm_next_page;
 305         dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1);
 306         dp->context_ptr = data;
 307 }
 308
 309 static void dm_bio_destructor(struct bio *bio)
 310 {
 311         struct io *io = bio->bi_private;
 312
 313         bio_free(bio, bios(io->client));
 314 }
 315
 316 /*
 317  * Functions for getting the pages from kernel memory.
 318  */
 319 static void km_get_page(struct dpages *dp, struct page **p, unsigned long *len,
 320                         unsigned *offset)
 321 {
 322         *p = virt_to_page(dp->context_ptr);
 323         *offset = dp->context_u;
 324         *len = PAGE_SIZE - dp->context_u;
 325 }
 326
 327 static void km_next_page(struct dpages *dp)
 328 {
 329         dp->context_ptr += PAGE_SIZE - dp->context_u;
 330         dp->context_u = 0;
 331 }
 332
 333 static void km_dp_init(struct dpages *dp, void *data)
 334 {
 335         dp->get_page = km_get_page;
 336         dp->next_page = km_next_page;
 337         dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1);
 338         dp->context_ptr = data;
 339 }
 340
 341 /*-----------------------------------------------------------------
 342  * IO routines that accept a list of pages.
 343  *---------------------------------------------------------------*/
 344 static void do_region(int rw, unsigned int region, struct io_region *where,
 345                       struct dpages *dp, struct io *io)
 346 {
 347         struct bio *bio;
 348         struct page *page;
 349         unsigned long len;
 350         unsigned offset;
 351         unsigned num_bvecs;
 352         sector_t remaining = where->count;
 353
 354         while (remaining) {
 355                 /*
 356                  * Allocate a suitably sized-bio: we add an extra
 357                  * bvec for bio_get/set_region() and decrement bi_max_vecs
 358                  * to hide it from bio_add_page().
 359                  */
 360                 num_bvecs = (remaining / (PAGE_SIZE >> SECTOR_SHIFT)) + 2;
 361                 bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, bios(io->client));
 362                 bio->bi_sector = where->sector + (where->count - remaining);
 363                 bio->bi_bdev = where->bdev;
 364                 bio->bi_end_io = endio;
 365                 bio->bi_private = io;
 366                 bio->bi_destructor = dm_bio_destructor;
 367                 bio->bi_max_vecs--;
 368                 bio_set_region(bio, region);
 369
 370                 /*
 371                  * Try and add as many pages as possible.
 372                  */
 373                 while (remaining) {
 374                         dp->get_page(dp, &page, &len, &offset);
 375                         len = min(len, to_bytes(remaining));
 376                         if (!bio_add_page(bio, page, len, offset))
 377                                 break;
 378
 379                         offset = 0;
 380                         remaining -= to_sector(len);
 381                         dp->next_page(dp);
 382                 }
 383
 384                 atomic_inc(&io->count);
 385                 submit_bio(rw, bio);
 386         }
 387 }
 388
 389 static void dispatch_io(int rw, unsigned int num_regions,
 390                         struct io_region *where, struct dpages *dp,
 391                         struct io *io, int sync)
 392 {
 393         int i;
 394         struct dpages old_pages = *dp;
 395
 396         if (sync)
 397                 rw |= (1 << BIO_RW_SYNC);
 398
 399         /*
 400          * For multiple regions we need to be careful to rewind
 401          * the dp object for each call to do_region.
 402          */
 403         for (i = 0; i < num_regions; i++) {
 404                 *dp = old_pages;
 405                 if (where[i].count)
 406                         do_region(rw, i, where + i, dp, io);
 407         }
 408
 409         /*
 410          * Drop the extra reference that we were holding to avoid
 411          * the io being completed too early.
 412          */
 413         dec_count(io, 0, 0);
 414 }
 415
 416 static int sync_io(struct dm_io_client *client, unsigned int num_regions,
 417                    struct io_region *where, int rw, struct dpages *dp,
 418                    unsigned long *error_bits)
 419 {
 420         struct io io;
 421
 422         if (num_regions > 1 && rw != WRITE) {
 423                 WARN_ON(1);
 424                 return -EIO;
 425         }
 426
 427         io.error = 0;
 428         atomic_set(&io.count, 1); /* see dispatch_io() */
 429         io.sleeper = current;
 430         io.client = client;
 431
 432         dispatch_io(rw, num_regions, where, dp, &io, 1);
 433
 434         while (1) {
 435                 set_current_state(TASK_UNINTERRUPTIBLE);
 436
 437                 if (!atomic_read(&io.count) || signal_pending(current))
 438                         break;
 439
 440                 io_schedule();
 441         }
 442         set_current_state(TASK_RUNNING);
 443
 444         if (atomic_read(&io.count))
 445                 return -EINTR;
 446
 447         if (error_bits)
 448                 *error_bits = io.error;
 449
 450         return io.error ? -EIO : 0;
 451 }
 452
 453 static int async_io(struct dm_io_client *client, unsigned int num_regions,
 454                     struct io_region *where, int rw, struct dpages *dp,
 455                     io_notify_fn fn, void *context)
 456 {
 457         struct io *io;
 458
 459         if (num_regions > 1 && rw != WRITE) {
 460                 WARN_ON(1);
 461                 fn(1, context);
 462                 return -EIO;
 463         }
 464
 465         io = mempool_alloc(io_pool(client), GFP_NOIO);
 466         io->error = 0;
 467         atomic_set(&io->count, 1); /* see dispatch_io() */
 468         io->sleeper = NULL;
 469         io->client = client;
 470         io->callback = fn;
 471         io->context = context;
 472
 473         dispatch_io(rw, num_regions, where, dp, io, 0);
 474         return 0;
 475 }
 476
 477 int dm_io_sync(unsigned int num_regions, struct io_region *where, int rw,
 478                struct page_list *pl, unsigned int offset,
 479                unsigned long *error_bits)
 480 {
 481         struct dpages dp;
 482         list_dp_init(&dp, pl, offset);
 483         return sync_io(NULL, num_regions, where, rw, &dp, error_bits);
 484 }
 485
 486 int dm_io_sync_bvec(unsigned int num_regions, struct io_region *where, int rw,
 487                     struct bio_vec *bvec, unsigned long *error_bits)
 488 {
 489         struct dpages dp;
 490         bvec_dp_init(&dp, bvec);
 491         return sync_io(NULL, num_regions, where, rw, &dp, error_bits);
 492 }
 493
 494 int dm_io_sync_vm(unsigned int num_regions, struct io_region *where, int rw,
 495                   void *data, unsigned long *error_bits)
 496 {
 497         struct dpages dp;
 498         vm_dp_init(&dp, data);
 499         return sync_io(NULL, num_regions, where, rw, &dp, error_bits);
 500 }
 501
 502 int dm_io_async(unsigned int num_regions, struct io_region *where, int rw,
 503                 struct page_list *pl, unsigned int offset,
 504                 io_notify_fn fn, void *context)
 505 {
 506         struct dpages dp;
 507         list_dp_init(&dp, pl, offset);
 508         return async_io(NULL, num_regions, where, rw, &dp, fn, context);
 509 }
 510
 511 int dm_io_async_bvec(unsigned int num_regions, struct io_region *where, int rw,
 512                      struct bio_vec *bvec, io_notify_fn fn, void *context)
 513 {
 514         struct dpages dp;
 515         bvec_dp_init(&dp, bvec);
 516         return async_io(NULL, num_regions, where, rw, &dp, fn, context);
 517 }
 518
 519 int dm_io_async_vm(unsigned int num_regions, struct io_region *where, int rw,
 520                    void *data, io_notify_fn fn, void *context)
 521 {
 522         struct dpages dp;
 523         vm_dp_init(&dp, data);
 524         return async_io(NULL, num_regions, where, rw, &dp, fn, context);
 525 }
 526
 527 static int dp_init(struct dm_io_request *io_req, struct dpages *dp)
 528 {
 529         /* Set up dpages based on memory type */
 530         switch (io_req->mem.type) {
 531         case DM_IO_PAGE_LIST:
 532                 list_dp_init(dp, io_req->mem.ptr.pl, io_req->mem.offset);
 533                 break;
 534
 535         case DM_IO_BVEC:
 536                 bvec_dp_init(dp, io_req->mem.ptr.bvec);
 537                 break;
 538
 539         case DM_IO_VMA:
 540                 vm_dp_init(dp, io_req->mem.ptr.vma);
 541                 break;
 542
 543         case DM_IO_KMEM:
 544                 km_dp_init(dp, io_req->mem.ptr.addr);
 545                 break;
 546
 547         default:
 548                 return -EINVAL;
 549         }
 550
 551         return 0;
 552 }
 553
 554 /*
 555  * New collapsed (a)synchronous interface
 556  */
 557 int dm_io(struct dm_io_request *io_req, unsigned num_regions,
 558           struct io_region *where, unsigned long *sync_error_bits)
 559 {
 560         int r;
 561         struct dpages dp;
 562
 563         r = dp_init(io_req, &dp);
 564         if (r)
 565                 return r;
 566
 567         if (!io_req->notify.fn)
 568                 return sync_io(io_req->client, num_regions, where,
 569                                io_req->bi_rw, &dp, sync_error_bits);
 570
 571         return async_io(io_req->client, num_regions, where, io_req->bi_rw,
 572                         &dp, io_req->notify.fn, io_req->notify.context);
 573 }
 574 EXPORT_SYMBOL(dm_io);
 575
 576 EXPORT_SYMBOL(dm_io_get);
 577 EXPORT_SYMBOL(dm_io_put);
 578 EXPORT_SYMBOL(dm_io_sync);
 579 EXPORT_SYMBOL(dm_io_async);
 580 EXPORT_SYMBOL(dm_io_sync_bvec);
 581 EXPORT_SYMBOL(dm_io_async_bvec);
 582 EXPORT_SYMBOL(dm_io_sync_vm);
 583 EXPORT_SYMBOL(dm_io_async_vm);