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 <linux/device-mapper.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 #include <linux/dm-io.h> 16 17 struct dm_io_client { 18 mempool_t *pool; 19 struct bio_set *bios; 20 }; 21 22 /* FIXME: can we shrink this ? */ 23 struct io { 24 unsigned long error_bits; 25 unsigned long eopnotsupp_bits; 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 39 static unsigned int pages_to_ios(unsigned int pages) 40 { 41 return 4 * pages; /* too many ? */ 42 } 43 44 /* 45 * Create a client with mempool and bioset. 46 */ 47 struct dm_io_client *dm_io_client_create(unsigned num_pages) 48 { 49 unsigned ios = pages_to_ios(num_pages); 50 struct dm_io_client *client; 51 52 client = kmalloc(sizeof(*client), GFP_KERNEL); 53 if (!client) 54 return ERR_PTR(-ENOMEM); 55 56 client->pool = mempool_create_kmalloc_pool(ios, sizeof(struct io)); 57 if (!client->pool) 58 goto bad; 59 60 client->bios = bioset_create(16, 0); 61 if (!client->bios) 62 goto bad; 63 64 return client; 65 66 bad: 67 if (client->pool) 68 mempool_destroy(client->pool); 69 kfree(client); 70 return ERR_PTR(-ENOMEM); 71 } 72 EXPORT_SYMBOL(dm_io_client_create); 73 74 int dm_io_client_resize(unsigned num_pages, struct dm_io_client *client) 75 { 76 return mempool_resize(client->pool, pages_to_ios(num_pages), 77 GFP_KERNEL); 78 } 79 EXPORT_SYMBOL(dm_io_client_resize); 80 81 void dm_io_client_destroy(struct dm_io_client *client) 82 { 83 mempool_destroy(client->pool); 84 bioset_free(client->bios); 85 kfree(client); 86 } 87 EXPORT_SYMBOL(dm_io_client_destroy); 88 89 /*----------------------------------------------------------------- 90 * We need to keep track of which region a bio is doing io for. 91 * In order to save a memory allocation we store this the last 92 * bvec which we know is unused (blech). 93 * XXX This is ugly and can OOPS with some configs... find another way. 94 *---------------------------------------------------------------*/ 95 static inline void bio_set_region(struct bio *bio, unsigned region) 96 { 97 bio->bi_io_vec[bio->bi_max_vecs].bv_len = region; 98 } 99 100 static inline unsigned bio_get_region(struct bio *bio) 101 { 102 return bio->bi_io_vec[bio->bi_max_vecs].bv_len; 103 } 104 105 /*----------------------------------------------------------------- 106 * We need an io object to keep track of the number of bios that 107 * have been dispatched for a particular io. 108 *---------------------------------------------------------------*/ 109 static void dec_count(struct io *io, unsigned int region, int error) 110 { 111 if (error) { 112 set_bit(region, &io->error_bits); 113 if (error == -EOPNOTSUPP) 114 set_bit(region, &io->eopnotsupp_bits); 115 } 116 117 if (atomic_dec_and_test(&io->count)) { 118 if (io->sleeper) 119 wake_up_process(io->sleeper); 120 121 else { 122 unsigned long r = io->error_bits; 123 io_notify_fn fn = io->callback; 124 void *context = io->context; 125 126 mempool_free(io, io->client->pool); 127 fn(r, context); 128 } 129 } 130 } 131 132 static void endio(struct bio *bio, int error) 133 { 134 struct io *io; 135 unsigned region; 136 137 if (error && bio_data_dir(bio) == READ) 138 zero_fill_bio(bio); 139 140 /* 141 * The bio destructor in bio_put() may use the io object. 142 */ 143 io = bio->bi_private; 144 region = bio_get_region(bio); 145 146 bio->bi_max_vecs++; 147 bio_put(bio); 148 149 dec_count(io, region, error); 150 } 151 152 /*----------------------------------------------------------------- 153 * These little objects provide an abstraction for getting a new 154 * destination page for io. 155 *---------------------------------------------------------------*/ 156 struct dpages { 157 void (*get_page)(struct dpages *dp, 158 struct page **p, unsigned long *len, unsigned *offset); 159 void (*next_page)(struct dpages *dp); 160 161 unsigned context_u; 162 void *context_ptr; 163 }; 164 165 /* 166 * Functions for getting the pages from a list. 167 */ 168 static void list_get_page(struct dpages *dp, 169 struct page **p, unsigned long *len, unsigned *offset) 170 { 171 unsigned o = dp->context_u; 172 struct page_list *pl = (struct page_list *) dp->context_ptr; 173 174 *p = pl->page; 175 *len = PAGE_SIZE - o; 176 *offset = o; 177 } 178 179 static void list_next_page(struct dpages *dp) 180 { 181 struct page_list *pl = (struct page_list *) dp->context_ptr; 182 dp->context_ptr = pl->next; 183 dp->context_u = 0; 184 } 185 186 static void list_dp_init(struct dpages *dp, struct page_list *pl, unsigned offset) 187 { 188 dp->get_page = list_get_page; 189 dp->next_page = list_next_page; 190 dp->context_u = offset; 191 dp->context_ptr = pl; 192 } 193 194 /* 195 * Functions for getting the pages from a bvec. 196 */ 197 static void bvec_get_page(struct dpages *dp, 198 struct page **p, unsigned long *len, unsigned *offset) 199 { 200 struct bio_vec *bvec = (struct bio_vec *) dp->context_ptr; 201 *p = bvec->bv_page; 202 *len = bvec->bv_len; 203 *offset = bvec->bv_offset; 204 } 205 206 static void bvec_next_page(struct dpages *dp) 207 { 208 struct bio_vec *bvec = (struct bio_vec *) dp->context_ptr; 209 dp->context_ptr = bvec + 1; 210 } 211 212 static void bvec_dp_init(struct dpages *dp, struct bio_vec *bvec) 213 { 214 dp->get_page = bvec_get_page; 215 dp->next_page = bvec_next_page; 216 dp->context_ptr = bvec; 217 } 218 219 /* 220 * Functions for getting the pages from a VMA. 221 */ 222 static void vm_get_page(struct dpages *dp, 223 struct page **p, unsigned long *len, unsigned *offset) 224 { 225 *p = vmalloc_to_page(dp->context_ptr); 226 *offset = dp->context_u; 227 *len = PAGE_SIZE - dp->context_u; 228 } 229 230 static void vm_next_page(struct dpages *dp) 231 { 232 dp->context_ptr += PAGE_SIZE - dp->context_u; 233 dp->context_u = 0; 234 } 235 236 static void vm_dp_init(struct dpages *dp, void *data) 237 { 238 dp->get_page = vm_get_page; 239 dp->next_page = vm_next_page; 240 dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1); 241 dp->context_ptr = data; 242 } 243 244 static void dm_bio_destructor(struct bio *bio) 245 { 246 struct io *io = bio->bi_private; 247 248 bio_free(bio, io->client->bios); 249 } 250 251 /* 252 * Functions for getting the pages from kernel memory. 253 */ 254 static void km_get_page(struct dpages *dp, struct page **p, unsigned long *len, 255 unsigned *offset) 256 { 257 *p = virt_to_page(dp->context_ptr); 258 *offset = dp->context_u; 259 *len = PAGE_SIZE - dp->context_u; 260 } 261 262 static void km_next_page(struct dpages *dp) 263 { 264 dp->context_ptr += PAGE_SIZE - dp->context_u; 265 dp->context_u = 0; 266 } 267 268 static void km_dp_init(struct dpages *dp, void *data) 269 { 270 dp->get_page = km_get_page; 271 dp->next_page = km_next_page; 272 dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1); 273 dp->context_ptr = data; 274 } 275 276 /*----------------------------------------------------------------- 277 * IO routines that accept a list of pages. 278 *---------------------------------------------------------------*/ 279 static void do_region(int rw, unsigned region, struct dm_io_region *where, 280 struct dpages *dp, struct io *io) 281 { 282 struct bio *bio; 283 struct page *page; 284 unsigned long len; 285 unsigned offset; 286 unsigned num_bvecs; 287 sector_t remaining = where->count; 288 289 while (remaining) { 290 /* 291 * Allocate a suitably sized-bio: we add an extra 292 * bvec for bio_get/set_region() and decrement bi_max_vecs 293 * to hide it from bio_add_page(). 294 */ 295 num_bvecs = dm_sector_div_up(remaining, 296 (PAGE_SIZE >> SECTOR_SHIFT)); 297 num_bvecs = 1 + min_t(int, bio_get_nr_vecs(where->bdev), 298 num_bvecs); 299 if (unlikely(num_bvecs > BIO_MAX_PAGES)) 300 num_bvecs = BIO_MAX_PAGES; 301 bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, io->client->bios); 302 bio->bi_sector = where->sector + (where->count - remaining); 303 bio->bi_bdev = where->bdev; 304 bio->bi_end_io = endio; 305 bio->bi_private = io; 306 bio->bi_destructor = dm_bio_destructor; 307 bio->bi_max_vecs--; 308 bio_set_region(bio, region); 309 310 /* 311 * Try and add as many pages as possible. 312 */ 313 while (remaining) { 314 dp->get_page(dp, &page, &len, &offset); 315 len = min(len, to_bytes(remaining)); 316 if (!bio_add_page(bio, page, len, offset)) 317 break; 318 319 offset = 0; 320 remaining -= to_sector(len); 321 dp->next_page(dp); 322 } 323 324 atomic_inc(&io->count); 325 submit_bio(rw, bio); 326 } 327 } 328 329 static void dispatch_io(int rw, unsigned int num_regions, 330 struct dm_io_region *where, struct dpages *dp, 331 struct io *io, int sync) 332 { 333 int i; 334 struct dpages old_pages = *dp; 335 336 if (sync) 337 rw |= (1 << BIO_RW_SYNCIO) | (1 << BIO_RW_UNPLUG); 338 339 /* 340 * For multiple regions we need to be careful to rewind 341 * the dp object for each call to do_region. 342 */ 343 for (i = 0; i < num_regions; i++) { 344 *dp = old_pages; 345 if (where[i].count) 346 do_region(rw, i, where + i, dp, io); 347 } 348 349 /* 350 * Drop the extra reference that we were holding to avoid 351 * the io being completed too early. 352 */ 353 dec_count(io, 0, 0); 354 } 355 356 static int sync_io(struct dm_io_client *client, unsigned int num_regions, 357 struct dm_io_region *where, int rw, struct dpages *dp, 358 unsigned long *error_bits) 359 { 360 struct io io; 361 362 if (num_regions > 1 && (rw & RW_MASK) != WRITE) { 363 WARN_ON(1); 364 return -EIO; 365 } 366 367 retry: 368 io.error_bits = 0; 369 io.eopnotsupp_bits = 0; 370 atomic_set(&io.count, 1); /* see dispatch_io() */ 371 io.sleeper = current; 372 io.client = client; 373 374 dispatch_io(rw, num_regions, where, dp, &io, 1); 375 376 while (1) { 377 set_current_state(TASK_UNINTERRUPTIBLE); 378 379 if (!atomic_read(&io.count)) 380 break; 381 382 io_schedule(); 383 } 384 set_current_state(TASK_RUNNING); 385 386 if (io.eopnotsupp_bits && (rw & (1 << BIO_RW_BARRIER))) { 387 rw &= ~(1 << BIO_RW_BARRIER); 388 goto retry; 389 } 390 391 if (error_bits) 392 *error_bits = io.error_bits; 393 394 return io.error_bits ? -EIO : 0; 395 } 396 397 static int async_io(struct dm_io_client *client, unsigned int num_regions, 398 struct dm_io_region *where, int rw, struct dpages *dp, 399 io_notify_fn fn, void *context) 400 { 401 struct io *io; 402 403 if (num_regions > 1 && (rw & RW_MASK) != WRITE) { 404 WARN_ON(1); 405 fn(1, context); 406 return -EIO; 407 } 408 409 io = mempool_alloc(client->pool, GFP_NOIO); 410 io->error_bits = 0; 411 io->eopnotsupp_bits = 0; 412 atomic_set(&io->count, 1); /* see dispatch_io() */ 413 io->sleeper = NULL; 414 io->client = client; 415 io->callback = fn; 416 io->context = context; 417 418 dispatch_io(rw, num_regions, where, dp, io, 0); 419 return 0; 420 } 421 422 static int dp_init(struct dm_io_request *io_req, struct dpages *dp) 423 { 424 /* Set up dpages based on memory type */ 425 switch (io_req->mem.type) { 426 case DM_IO_PAGE_LIST: 427 list_dp_init(dp, io_req->mem.ptr.pl, io_req->mem.offset); 428 break; 429 430 case DM_IO_BVEC: 431 bvec_dp_init(dp, io_req->mem.ptr.bvec); 432 break; 433 434 case DM_IO_VMA: 435 vm_dp_init(dp, io_req->mem.ptr.vma); 436 break; 437 438 case DM_IO_KMEM: 439 km_dp_init(dp, io_req->mem.ptr.addr); 440 break; 441 442 default: 443 return -EINVAL; 444 } 445 446 return 0; 447 } 448 449 /* 450 * New collapsed (a)synchronous interface. 451 * 452 * If the IO is asynchronous (i.e. it has notify.fn), you must either unplug 453 * the queue with blk_unplug() some time later or set the BIO_RW_SYNC bit in 454 * io_req->bi_rw. If you fail to do one of these, the IO will be submitted to 455 * the disk after q->unplug_delay, which defaults to 3ms in blk-settings.c. 456 */ 457 int dm_io(struct dm_io_request *io_req, unsigned num_regions, 458 struct dm_io_region *where, unsigned long *sync_error_bits) 459 { 460 int r; 461 struct dpages dp; 462 463 r = dp_init(io_req, &dp); 464 if (r) 465 return r; 466 467 if (!io_req->notify.fn) 468 return sync_io(io_req->client, num_regions, where, 469 io_req->bi_rw, &dp, sync_error_bits); 470 471 return async_io(io_req->client, num_regions, where, io_req->bi_rw, 472 &dp, io_req->notify.fn, io_req->notify.context); 473 } 474 EXPORT_SYMBOL(dm_io); 475