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