dm-io.c revision e01fd7eeb00f8078103f4ed3e8ef64474c11f300
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 16struct dm_io_client { 17 mempool_t *pool; 18 struct bio_set *bios; 19}; 20 21/* FIXME: can we shrink this ? */ 22struct io { 23 unsigned long error_bits; 24 atomic_t count; 25 struct task_struct *sleeper; 26 struct dm_io_client *client; 27 io_notify_fn callback; 28 void *context; 29}; 30 31/* 32 * io contexts are only dynamically allocated for asynchronous 33 * io. Since async io is likely to be the majority of io we'll 34 * have the same number of io contexts as bios! (FIXME: must reduce this). 35 */ 36 37static unsigned int pages_to_ios(unsigned int pages) 38{ 39 return 4 * pages; /* too many ? */ 40} 41 42/* 43 * Create a client with mempool and bioset. 44 */ 45struct dm_io_client *dm_io_client_create(unsigned num_pages) 46{ 47 unsigned ios = pages_to_ios(num_pages); 48 struct dm_io_client *client; 49 50 client = kmalloc(sizeof(*client), GFP_KERNEL); 51 if (!client) 52 return ERR_PTR(-ENOMEM); 53 54 client->pool = mempool_create_kmalloc_pool(ios, sizeof(struct io)); 55 if (!client->pool) 56 goto bad; 57 58 client->bios = bioset_create(16, 16); 59 if (!client->bios) 60 goto bad; 61 62 return client; 63 64 bad: 65 if (client->pool) 66 mempool_destroy(client->pool); 67 kfree(client); 68 return ERR_PTR(-ENOMEM); 69} 70EXPORT_SYMBOL(dm_io_client_create); 71 72int dm_io_client_resize(unsigned num_pages, struct dm_io_client *client) 73{ 74 return mempool_resize(client->pool, pages_to_ios(num_pages), 75 GFP_KERNEL); 76} 77EXPORT_SYMBOL(dm_io_client_resize); 78 79void dm_io_client_destroy(struct dm_io_client *client) 80{ 81 mempool_destroy(client->pool); 82 bioset_free(client->bios); 83 kfree(client); 84} 85EXPORT_SYMBOL(dm_io_client_destroy); 86 87/*----------------------------------------------------------------- 88 * We need to keep track of which region a bio is doing io for. 89 * In order to save a memory allocation we store this the last 90 * bvec which we know is unused (blech). 91 * XXX This is ugly and can OOPS with some configs... find another way. 92 *---------------------------------------------------------------*/ 93static inline void bio_set_region(struct bio *bio, unsigned region) 94{ 95 bio->bi_io_vec[bio->bi_max_vecs].bv_len = region; 96} 97 98static inline unsigned bio_get_region(struct bio *bio) 99{ 100 return bio->bi_io_vec[bio->bi_max_vecs].bv_len; 101} 102 103/*----------------------------------------------------------------- 104 * We need an io object to keep track of the number of bios that 105 * have been dispatched for a particular io. 106 *---------------------------------------------------------------*/ 107static void dec_count(struct io *io, unsigned int region, int error) 108{ 109 if (error) 110 set_bit(region, &io->error_bits); 111 112 if (atomic_dec_and_test(&io->count)) { 113 if (io->sleeper) 114 wake_up_process(io->sleeper); 115 116 else { 117 unsigned long r = io->error_bits; 118 io_notify_fn fn = io->callback; 119 void *context = io->context; 120 121 mempool_free(io, io->client->pool); 122 fn(r, context); 123 } 124 } 125} 126 127static void endio(struct bio *bio, int error) 128{ 129 struct io *io; 130 unsigned region; 131 132 if (error && bio_data_dir(bio) == READ) 133 zero_fill_bio(bio); 134 135 /* 136 * The bio destructor in bio_put() may use the io object. 137 */ 138 io = bio->bi_private; 139 region = bio_get_region(bio); 140 141 bio->bi_max_vecs++; 142 bio_put(bio); 143 144 dec_count(io, region, error); 145} 146 147/*----------------------------------------------------------------- 148 * These little objects provide an abstraction for getting a new 149 * destination page for io. 150 *---------------------------------------------------------------*/ 151struct dpages { 152 void (*get_page)(struct dpages *dp, 153 struct page **p, unsigned long *len, unsigned *offset); 154 void (*next_page)(struct dpages *dp); 155 156 unsigned context_u; 157 void *context_ptr; 158}; 159 160/* 161 * Functions for getting the pages from a list. 162 */ 163static void list_get_page(struct dpages *dp, 164 struct page **p, unsigned long *len, unsigned *offset) 165{ 166 unsigned o = dp->context_u; 167 struct page_list *pl = (struct page_list *) dp->context_ptr; 168 169 *p = pl->page; 170 *len = PAGE_SIZE - o; 171 *offset = o; 172} 173 174static void list_next_page(struct dpages *dp) 175{ 176 struct page_list *pl = (struct page_list *) dp->context_ptr; 177 dp->context_ptr = pl->next; 178 dp->context_u = 0; 179} 180 181static void list_dp_init(struct dpages *dp, struct page_list *pl, unsigned offset) 182{ 183 dp->get_page = list_get_page; 184 dp->next_page = list_next_page; 185 dp->context_u = offset; 186 dp->context_ptr = pl; 187} 188 189/* 190 * Functions for getting the pages from a bvec. 191 */ 192static void bvec_get_page(struct dpages *dp, 193 struct page **p, unsigned long *len, unsigned *offset) 194{ 195 struct bio_vec *bvec = (struct bio_vec *) dp->context_ptr; 196 *p = bvec->bv_page; 197 *len = bvec->bv_len; 198 *offset = bvec->bv_offset; 199} 200 201static void bvec_next_page(struct dpages *dp) 202{ 203 struct bio_vec *bvec = (struct bio_vec *) dp->context_ptr; 204 dp->context_ptr = bvec + 1; 205} 206 207static void bvec_dp_init(struct dpages *dp, struct bio_vec *bvec) 208{ 209 dp->get_page = bvec_get_page; 210 dp->next_page = bvec_next_page; 211 dp->context_ptr = bvec; 212} 213 214/* 215 * Functions for getting the pages from a VMA. 216 */ 217static void vm_get_page(struct dpages *dp, 218 struct page **p, unsigned long *len, unsigned *offset) 219{ 220 *p = vmalloc_to_page(dp->context_ptr); 221 *offset = dp->context_u; 222 *len = PAGE_SIZE - dp->context_u; 223} 224 225static void vm_next_page(struct dpages *dp) 226{ 227 dp->context_ptr += PAGE_SIZE - dp->context_u; 228 dp->context_u = 0; 229} 230 231static void vm_dp_init(struct dpages *dp, void *data) 232{ 233 dp->get_page = vm_get_page; 234 dp->next_page = vm_next_page; 235 dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1); 236 dp->context_ptr = data; 237} 238 239static void dm_bio_destructor(struct bio *bio) 240{ 241 struct io *io = bio->bi_private; 242 243 bio_free(bio, io->client->bios); 244} 245 246/* 247 * Functions for getting the pages from kernel memory. 248 */ 249static void km_get_page(struct dpages *dp, struct page **p, unsigned long *len, 250 unsigned *offset) 251{ 252 *p = virt_to_page(dp->context_ptr); 253 *offset = dp->context_u; 254 *len = PAGE_SIZE - dp->context_u; 255} 256 257static void km_next_page(struct dpages *dp) 258{ 259 dp->context_ptr += PAGE_SIZE - dp->context_u; 260 dp->context_u = 0; 261} 262 263static void km_dp_init(struct dpages *dp, void *data) 264{ 265 dp->get_page = km_get_page; 266 dp->next_page = km_next_page; 267 dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1); 268 dp->context_ptr = data; 269} 270 271/*----------------------------------------------------------------- 272 * IO routines that accept a list of pages. 273 *---------------------------------------------------------------*/ 274static void do_region(int rw, unsigned int region, struct io_region *where, 275 struct dpages *dp, struct io *io) 276{ 277 struct bio *bio; 278 struct page *page; 279 unsigned long len; 280 unsigned offset; 281 unsigned num_bvecs; 282 sector_t remaining = where->count; 283 284 while (remaining) { 285 /* 286 * Allocate a suitably sized-bio: we add an extra 287 * bvec for bio_get/set_region() and decrement bi_max_vecs 288 * to hide it from bio_add_page(). 289 */ 290 num_bvecs = dm_sector_div_up(remaining, 291 (PAGE_SIZE >> SECTOR_SHIFT)); 292 num_bvecs = 1 + min_t(int, bio_get_nr_vecs(where->bdev), 293 num_bvecs); 294 bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, io->client->bios); 295 bio->bi_sector = where->sector + (where->count - remaining); 296 bio->bi_bdev = where->bdev; 297 bio->bi_end_io = endio; 298 bio->bi_private = io; 299 bio->bi_destructor = dm_bio_destructor; 300 bio->bi_max_vecs--; 301 bio_set_region(bio, region); 302 303 /* 304 * Try and add as many pages as possible. 305 */ 306 while (remaining) { 307 dp->get_page(dp, &page, &len, &offset); 308 len = min(len, to_bytes(remaining)); 309 if (!bio_add_page(bio, page, len, offset)) 310 break; 311 312 offset = 0; 313 remaining -= to_sector(len); 314 dp->next_page(dp); 315 } 316 317 atomic_inc(&io->count); 318 submit_bio(rw, bio); 319 } 320} 321 322static void dispatch_io(int rw, unsigned int num_regions, 323 struct io_region *where, struct dpages *dp, 324 struct io *io, int sync) 325{ 326 int i; 327 struct dpages old_pages = *dp; 328 329 if (sync) 330 rw |= (1 << BIO_RW_SYNC); 331 332 /* 333 * For multiple regions we need to be careful to rewind 334 * the dp object for each call to do_region. 335 */ 336 for (i = 0; i < num_regions; i++) { 337 *dp = old_pages; 338 if (where[i].count) 339 do_region(rw, i, where + i, dp, io); 340 } 341 342 /* 343 * Drop the extra reference that we were holding to avoid 344 * the io being completed too early. 345 */ 346 dec_count(io, 0, 0); 347} 348 349static int sync_io(struct dm_io_client *client, unsigned int num_regions, 350 struct io_region *where, int rw, struct dpages *dp, 351 unsigned long *error_bits) 352{ 353 struct io io; 354 355 if (num_regions > 1 && rw != WRITE) { 356 WARN_ON(1); 357 return -EIO; 358 } 359 360 io.error_bits = 0; 361 atomic_set(&io.count, 1); /* see dispatch_io() */ 362 io.sleeper = current; 363 io.client = client; 364 365 dispatch_io(rw, num_regions, where, dp, &io, 1); 366 367 while (1) { 368 set_current_state(TASK_UNINTERRUPTIBLE); 369 370 if (!atomic_read(&io.count) || signal_pending(current)) 371 break; 372 373 io_schedule(); 374 } 375 set_current_state(TASK_RUNNING); 376 377 if (atomic_read(&io.count)) 378 return -EINTR; 379 380 if (error_bits) 381 *error_bits = io.error_bits; 382 383 return io.error_bits ? -EIO : 0; 384} 385 386static int async_io(struct dm_io_client *client, unsigned int num_regions, 387 struct io_region *where, int rw, struct dpages *dp, 388 io_notify_fn fn, void *context) 389{ 390 struct io *io; 391 392 if (num_regions > 1 && rw != WRITE) { 393 WARN_ON(1); 394 fn(1, context); 395 return -EIO; 396 } 397 398 io = mempool_alloc(client->pool, GFP_NOIO); 399 io->error_bits = 0; 400 atomic_set(&io->count, 1); /* see dispatch_io() */ 401 io->sleeper = NULL; 402 io->client = client; 403 io->callback = fn; 404 io->context = context; 405 406 dispatch_io(rw, num_regions, where, dp, io, 0); 407 return 0; 408} 409 410static int dp_init(struct dm_io_request *io_req, struct dpages *dp) 411{ 412 /* Set up dpages based on memory type */ 413 switch (io_req->mem.type) { 414 case DM_IO_PAGE_LIST: 415 list_dp_init(dp, io_req->mem.ptr.pl, io_req->mem.offset); 416 break; 417 418 case DM_IO_BVEC: 419 bvec_dp_init(dp, io_req->mem.ptr.bvec); 420 break; 421 422 case DM_IO_VMA: 423 vm_dp_init(dp, io_req->mem.ptr.vma); 424 break; 425 426 case DM_IO_KMEM: 427 km_dp_init(dp, io_req->mem.ptr.addr); 428 break; 429 430 default: 431 return -EINVAL; 432 } 433 434 return 0; 435} 436 437/* 438 * New collapsed (a)synchronous interface 439 */ 440int dm_io(struct dm_io_request *io_req, unsigned num_regions, 441 struct io_region *where, unsigned long *sync_error_bits) 442{ 443 int r; 444 struct dpages dp; 445 446 r = dp_init(io_req, &dp); 447 if (r) 448 return r; 449 450 if (!io_req->notify.fn) 451 return sync_io(io_req->client, num_regions, where, 452 io_req->bi_rw, &dp, sync_error_bits); 453 454 return async_io(io_req->client, num_regions, where, io_req->bi_rw, 455 &dp, io_req->notify.fn, io_req->notify.context); 456} 457EXPORT_SYMBOL(dm_io); 458