1 /* 2 * Copyright (C) 2008 Oracle. All rights reserved. 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public 6 * License v2 as published by the Free Software Foundation. 7 * 8 * This program is distributed in the hope that it will be useful, 9 * but WITHOUT ANY WARRANTY; without even the implied warranty of 10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 11 * General Public License for more details. 12 * 13 * You should have received a copy of the GNU General Public 14 * License along with this program; if not, write to the 15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330, 16 * Boston, MA 021110-1307, USA. 17 */ 18 19 #include <linux/kernel.h> 20 #include <linux/bio.h> 21 #include <linux/buffer_head.h> 22 #include <linux/file.h> 23 #include <linux/fs.h> 24 #include <linux/pagemap.h> 25 #include <linux/highmem.h> 26 #include <linux/time.h> 27 #include <linux/init.h> 28 #include <linux/string.h> 29 #include <linux/backing-dev.h> 30 #include <linux/mpage.h> 31 #include <linux/swap.h> 32 #include <linux/writeback.h> 33 #include <linux/bit_spinlock.h> 34 #include <linux/slab.h> 35 #include "compat.h" 36 #include "ctree.h" 37 #include "disk-io.h" 38 #include "transaction.h" 39 #include "btrfs_inode.h" 40 #include "volumes.h" 41 #include "ordered-data.h" 42 #include "compression.h" 43 #include "extent_io.h" 44 #include "extent_map.h" 45 46 struct compressed_bio { 47 /* number of bios pending for this compressed extent */ 48 atomic_t pending_bios; 49 50 /* the pages with the compressed data on them */ 51 struct page **compressed_pages; 52 53 /* inode that owns this data */ 54 struct inode *inode; 55 56 /* starting offset in the inode for our pages */ 57 u64 start; 58 59 /* number of bytes in the inode we're working on */ 60 unsigned long len; 61 62 /* number of bytes on disk */ 63 unsigned long compressed_len; 64 65 /* the compression algorithm for this bio */ 66 int compress_type; 67 68 /* number of compressed pages in the array */ 69 unsigned long nr_pages; 70 71 /* IO errors */ 72 int errors; 73 int mirror_num; 74 75 /* for reads, this is the bio we are copying the data into */ 76 struct bio *orig_bio; 77 78 /* 79 * the start of a variable length array of checksums only 80 * used by reads 81 */ 82 u32 sums; 83 }; 84 85 static inline int compressed_bio_size(struct btrfs_root *root, 86 unsigned long disk_size) 87 { 88 u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy); 89 90 return sizeof(struct compressed_bio) + 91 ((disk_size + root->sectorsize - 1) / root->sectorsize) * 92 csum_size; 93 } 94 95 static struct bio *compressed_bio_alloc(struct block_device *bdev, 96 u64 first_byte, gfp_t gfp_flags) 97 { 98 int nr_vecs; 99 100 nr_vecs = bio_get_nr_vecs(bdev); 101 return btrfs_bio_alloc(bdev, first_byte >> 9, nr_vecs, gfp_flags); 102 } 103 104 static int check_compressed_csum(struct inode *inode, 105 struct compressed_bio *cb, 106 u64 disk_start) 107 { 108 int ret; 109 struct btrfs_root *root = BTRFS_I(inode)->root; 110 struct page *page; 111 unsigned long i; 112 char *kaddr; 113 u32 csum; 114 u32 *cb_sum = &cb->sums; 115 116 if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM) 117 return 0; 118 119 for (i = 0; i < cb->nr_pages; i++) { 120 page = cb->compressed_pages[i]; 121 csum = ~(u32)0; 122 123 kaddr = kmap_atomic(page, KM_USER0); 124 csum = btrfs_csum_data(root, kaddr, csum, PAGE_CACHE_SIZE); 125 btrfs_csum_final(csum, (char *)&csum); 126 kunmap_atomic(kaddr, KM_USER0); 127 128 if (csum != *cb_sum) { 129 printk(KERN_INFO "btrfs csum failed ino %llu " 130 "extent %llu csum %u " 131 "wanted %u mirror %d\n", 132 (unsigned long long)btrfs_ino(inode), 133 (unsigned long long)disk_start, 134 csum, *cb_sum, cb->mirror_num); 135 ret = -EIO; 136 goto fail; 137 } 138 cb_sum++; 139 140 } 141 ret = 0; 142 fail: 143 return ret; 144 } 145 146 /* when we finish reading compressed pages from the disk, we 147 * decompress them and then run the bio end_io routines on the 148 * decompressed pages (in the inode address space). 149 * 150 * This allows the checksumming and other IO error handling routines 151 * to work normally 152 * 153 * The compressed pages are freed here, and it must be run 154 * in process context 155 */ 156 static void end_compressed_bio_read(struct bio *bio, int err) 157 { 158 struct compressed_bio *cb = bio->bi_private; 159 struct inode *inode; 160 struct page *page; 161 unsigned long index; 162 int ret; 163 164 if (err) 165 cb->errors = 1; 166 167 /* if there are more bios still pending for this compressed 168 * extent, just exit 169 */ 170 if (!atomic_dec_and_test(&cb->pending_bios)) 171 goto out; 172 173 inode = cb->inode; 174 ret = check_compressed_csum(inode, cb, (u64)bio->bi_sector << 9); 175 if (ret) 176 goto csum_failed; 177 178 /* ok, we're the last bio for this extent, lets start 179 * the decompression. 180 */ 181 ret = btrfs_decompress_biovec(cb->compress_type, 182 cb->compressed_pages, 183 cb->start, 184 cb->orig_bio->bi_io_vec, 185 cb->orig_bio->bi_vcnt, 186 cb->compressed_len); 187 csum_failed: 188 if (ret) 189 cb->errors = 1; 190 191 /* release the compressed pages */ 192 index = 0; 193 for (index = 0; index < cb->nr_pages; index++) { 194 page = cb->compressed_pages[index]; 195 page->mapping = NULL; 196 page_cache_release(page); 197 } 198 199 /* do io completion on the original bio */ 200 if (cb->errors) { 201 bio_io_error(cb->orig_bio); 202 } else { 203 int bio_index = 0; 204 struct bio_vec *bvec = cb->orig_bio->bi_io_vec; 205 206 /* 207 * we have verified the checksum already, set page 208 * checked so the end_io handlers know about it 209 */ 210 while (bio_index < cb->orig_bio->bi_vcnt) { 211 SetPageChecked(bvec->bv_page); 212 bvec++; 213 bio_index++; 214 } 215 bio_endio(cb->orig_bio, 0); 216 } 217 218 /* finally free the cb struct */ 219 kfree(cb->compressed_pages); 220 kfree(cb); 221 out: 222 bio_put(bio); 223 } 224 225 /* 226 * Clear the writeback bits on all of the file 227 * pages for a compressed write 228 */ 229 static noinline int end_compressed_writeback(struct inode *inode, u64 start, 230 unsigned long ram_size) 231 { 232 unsigned long index = start >> PAGE_CACHE_SHIFT; 233 unsigned long end_index = (start + ram_size - 1) >> PAGE_CACHE_SHIFT; 234 struct page *pages[16]; 235 unsigned long nr_pages = end_index - index + 1; 236 int i; 237 int ret; 238 239 while (nr_pages > 0) { 240 ret = find_get_pages_contig(inode->i_mapping, index, 241 min_t(unsigned long, 242 nr_pages, ARRAY_SIZE(pages)), pages); 243 if (ret == 0) { 244 nr_pages -= 1; 245 index += 1; 246 continue; 247 } 248 for (i = 0; i < ret; i++) { 249 end_page_writeback(pages[i]); 250 page_cache_release(pages[i]); 251 } 252 nr_pages -= ret; 253 index += ret; 254 } 255 /* the inode may be gone now */ 256 return 0; 257 } 258 259 /* 260 * do the cleanup once all the compressed pages hit the disk. 261 * This will clear writeback on the file pages and free the compressed 262 * pages. 263 * 264 * This also calls the writeback end hooks for the file pages so that 265 * metadata and checksums can be updated in the file. 266 */ 267 static void end_compressed_bio_write(struct bio *bio, int err) 268 { 269 struct extent_io_tree *tree; 270 struct compressed_bio *cb = bio->bi_private; 271 struct inode *inode; 272 struct page *page; 273 unsigned long index; 274 275 if (err) 276 cb->errors = 1; 277 278 /* if there are more bios still pending for this compressed 279 * extent, just exit 280 */ 281 if (!atomic_dec_and_test(&cb->pending_bios)) 282 goto out; 283 284 /* ok, we're the last bio for this extent, step one is to 285 * call back into the FS and do all the end_io operations 286 */ 287 inode = cb->inode; 288 tree = &BTRFS_I(inode)->io_tree; 289 cb->compressed_pages[0]->mapping = cb->inode->i_mapping; 290 tree->ops->writepage_end_io_hook(cb->compressed_pages[0], 291 cb->start, 292 cb->start + cb->len - 1, 293 NULL, 1); 294 cb->compressed_pages[0]->mapping = NULL; 295 296 end_compressed_writeback(inode, cb->start, cb->len); 297 /* note, our inode could be gone now */ 298 299 /* 300 * release the compressed pages, these came from alloc_page and 301 * are not attached to the inode at all 302 */ 303 index = 0; 304 for (index = 0; index < cb->nr_pages; index++) { 305 page = cb->compressed_pages[index]; 306 page->mapping = NULL; 307 page_cache_release(page); 308 } 309 310 /* finally free the cb struct */ 311 kfree(cb->compressed_pages); 312 kfree(cb); 313 out: 314 bio_put(bio); 315 } 316 317 /* 318 * worker function to build and submit bios for previously compressed pages. 319 * The corresponding pages in the inode should be marked for writeback 320 * and the compressed pages should have a reference on them for dropping 321 * when the IO is complete. 322 * 323 * This also checksums the file bytes and gets things ready for 324 * the end io hooks. 325 */ 326 int btrfs_submit_compressed_write(struct inode *inode, u64 start, 327 unsigned long len, u64 disk_start, 328 unsigned long compressed_len, 329 struct page **compressed_pages, 330 unsigned long nr_pages) 331 { 332 struct bio *bio = NULL; 333 struct btrfs_root *root = BTRFS_I(inode)->root; 334 struct compressed_bio *cb; 335 unsigned long bytes_left; 336 struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree; 337 int pg_index = 0; 338 struct page *page; 339 u64 first_byte = disk_start; 340 struct block_device *bdev; 341 int ret; 342 int skip_sum = BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM; 343 344 WARN_ON(start & ((u64)PAGE_CACHE_SIZE - 1)); 345 cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS); 346 if (!cb) 347 return -ENOMEM; 348 atomic_set(&cb->pending_bios, 0); 349 cb->errors = 0; 350 cb->inode = inode; 351 cb->start = start; 352 cb->len = len; 353 cb->mirror_num = 0; 354 cb->compressed_pages = compressed_pages; 355 cb->compressed_len = compressed_len; 356 cb->orig_bio = NULL; 357 cb->nr_pages = nr_pages; 358 359 bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev; 360 361 bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS); 362 if(!bio) { 363 kfree(cb); 364 return -ENOMEM; 365 } 366 bio->bi_private = cb; 367 bio->bi_end_io = end_compressed_bio_write; 368 atomic_inc(&cb->pending_bios); 369 370 /* create and submit bios for the compressed pages */ 371 bytes_left = compressed_len; 372 for (pg_index = 0; pg_index < cb->nr_pages; pg_index++) { 373 page = compressed_pages[pg_index]; 374 page->mapping = inode->i_mapping; 375 if (bio->bi_size) 376 ret = io_tree->ops->merge_bio_hook(page, 0, 377 PAGE_CACHE_SIZE, 378 bio, 0); 379 else 380 ret = 0; 381 382 page->mapping = NULL; 383 if (ret || bio_add_page(bio, page, PAGE_CACHE_SIZE, 0) < 384 PAGE_CACHE_SIZE) { 385 bio_get(bio); 386 387 /* 388 * inc the count before we submit the bio so 389 * we know the end IO handler won't happen before 390 * we inc the count. Otherwise, the cb might get 391 * freed before we're done setting it up 392 */ 393 atomic_inc(&cb->pending_bios); 394 ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0); 395 BUG_ON(ret); 396 397 if (!skip_sum) { 398 ret = btrfs_csum_one_bio(root, inode, bio, 399 start, 1); 400 BUG_ON(ret); 401 } 402 403 ret = btrfs_map_bio(root, WRITE, bio, 0, 1); 404 BUG_ON(ret); 405 406 bio_put(bio); 407 408 bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS); 409 bio->bi_private = cb; 410 bio->bi_end_io = end_compressed_bio_write; 411 bio_add_page(bio, page, PAGE_CACHE_SIZE, 0); 412 } 413 if (bytes_left < PAGE_CACHE_SIZE) { 414 printk("bytes left %lu compress len %lu nr %lu\n", 415 bytes_left, cb->compressed_len, cb->nr_pages); 416 } 417 bytes_left -= PAGE_CACHE_SIZE; 418 first_byte += PAGE_CACHE_SIZE; 419 cond_resched(); 420 } 421 bio_get(bio); 422 423 ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0); 424 BUG_ON(ret); 425 426 if (!skip_sum) { 427 ret = btrfs_csum_one_bio(root, inode, bio, start, 1); 428 BUG_ON(ret); 429 } 430 431 ret = btrfs_map_bio(root, WRITE, bio, 0, 1); 432 BUG_ON(ret); 433 434 bio_put(bio); 435 return 0; 436 } 437 438 static noinline int add_ra_bio_pages(struct inode *inode, 439 u64 compressed_end, 440 struct compressed_bio *cb) 441 { 442 unsigned long end_index; 443 unsigned long pg_index; 444 u64 last_offset; 445 u64 isize = i_size_read(inode); 446 int ret; 447 struct page *page; 448 unsigned long nr_pages = 0; 449 struct extent_map *em; 450 struct address_space *mapping = inode->i_mapping; 451 struct extent_map_tree *em_tree; 452 struct extent_io_tree *tree; 453 u64 end; 454 int misses = 0; 455 456 page = cb->orig_bio->bi_io_vec[cb->orig_bio->bi_vcnt - 1].bv_page; 457 last_offset = (page_offset(page) + PAGE_CACHE_SIZE); 458 em_tree = &BTRFS_I(inode)->extent_tree; 459 tree = &BTRFS_I(inode)->io_tree; 460 461 if (isize == 0) 462 return 0; 463 464 end_index = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT; 465 466 while (last_offset < compressed_end) { 467 pg_index = last_offset >> PAGE_CACHE_SHIFT; 468 469 if (pg_index > end_index) 470 break; 471 472 rcu_read_lock(); 473 page = radix_tree_lookup(&mapping->page_tree, pg_index); 474 rcu_read_unlock(); 475 if (page) { 476 misses++; 477 if (misses > 4) 478 break; 479 goto next; 480 } 481 482 page = __page_cache_alloc(mapping_gfp_mask(mapping) & 483 ~__GFP_FS); 484 if (!page) 485 break; 486 487 if (add_to_page_cache_lru(page, mapping, pg_index, 488 GFP_NOFS)) { 489 page_cache_release(page); 490 goto next; 491 } 492 493 end = last_offset + PAGE_CACHE_SIZE - 1; 494 /* 495 * at this point, we have a locked page in the page cache 496 * for these bytes in the file. But, we have to make 497 * sure they map to this compressed extent on disk. 498 */ 499 set_page_extent_mapped(page); 500 lock_extent(tree, last_offset, end, GFP_NOFS); 501 read_lock(&em_tree->lock); 502 em = lookup_extent_mapping(em_tree, last_offset, 503 PAGE_CACHE_SIZE); 504 read_unlock(&em_tree->lock); 505 506 if (!em || last_offset < em->start || 507 (last_offset + PAGE_CACHE_SIZE > extent_map_end(em)) || 508 (em->block_start >> 9) != cb->orig_bio->bi_sector) { 509 free_extent_map(em); 510 unlock_extent(tree, last_offset, end, GFP_NOFS); 511 unlock_page(page); 512 page_cache_release(page); 513 break; 514 } 515 free_extent_map(em); 516 517 if (page->index == end_index) { 518 char *userpage; 519 size_t zero_offset = isize & (PAGE_CACHE_SIZE - 1); 520 521 if (zero_offset) { 522 int zeros; 523 zeros = PAGE_CACHE_SIZE - zero_offset; 524 userpage = kmap_atomic(page, KM_USER0); 525 memset(userpage + zero_offset, 0, zeros); 526 flush_dcache_page(page); 527 kunmap_atomic(userpage, KM_USER0); 528 } 529 } 530 531 ret = bio_add_page(cb->orig_bio, page, 532 PAGE_CACHE_SIZE, 0); 533 534 if (ret == PAGE_CACHE_SIZE) { 535 nr_pages++; 536 page_cache_release(page); 537 } else { 538 unlock_extent(tree, last_offset, end, GFP_NOFS); 539 unlock_page(page); 540 page_cache_release(page); 541 break; 542 } 543 next: 544 last_offset += PAGE_CACHE_SIZE; 545 } 546 return 0; 547 } 548 549 /* 550 * for a compressed read, the bio we get passed has all the inode pages 551 * in it. We don't actually do IO on those pages but allocate new ones 552 * to hold the compressed pages on disk. 553 * 554 * bio->bi_sector points to the compressed extent on disk 555 * bio->bi_io_vec points to all of the inode pages 556 * bio->bi_vcnt is a count of pages 557 * 558 * After the compressed pages are read, we copy the bytes into the 559 * bio we were passed and then call the bio end_io calls 560 */ 561 int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio, 562 int mirror_num, unsigned long bio_flags) 563 { 564 struct extent_io_tree *tree; 565 struct extent_map_tree *em_tree; 566 struct compressed_bio *cb; 567 struct btrfs_root *root = BTRFS_I(inode)->root; 568 unsigned long uncompressed_len = bio->bi_vcnt * PAGE_CACHE_SIZE; 569 unsigned long compressed_len; 570 unsigned long nr_pages; 571 unsigned long pg_index; 572 struct page *page; 573 struct block_device *bdev; 574 struct bio *comp_bio; 575 u64 cur_disk_byte = (u64)bio->bi_sector << 9; 576 u64 em_len; 577 u64 em_start; 578 struct extent_map *em; 579 int ret = -ENOMEM; 580 u32 *sums; 581 582 tree = &BTRFS_I(inode)->io_tree; 583 em_tree = &BTRFS_I(inode)->extent_tree; 584 585 /* we need the actual starting offset of this extent in the file */ 586 read_lock(&em_tree->lock); 587 em = lookup_extent_mapping(em_tree, 588 page_offset(bio->bi_io_vec->bv_page), 589 PAGE_CACHE_SIZE); 590 read_unlock(&em_tree->lock); 591 if (!em) 592 return -EIO; 593 594 compressed_len = em->block_len; 595 cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS); 596 if (!cb) 597 goto out; 598 599 atomic_set(&cb->pending_bios, 0); 600 cb->errors = 0; 601 cb->inode = inode; 602 cb->mirror_num = mirror_num; 603 sums = &cb->sums; 604 605 cb->start = em->orig_start; 606 em_len = em->len; 607 em_start = em->start; 608 609 free_extent_map(em); 610 em = NULL; 611 612 cb->len = uncompressed_len; 613 cb->compressed_len = compressed_len; 614 cb->compress_type = extent_compress_type(bio_flags); 615 cb->orig_bio = bio; 616 617 nr_pages = (compressed_len + PAGE_CACHE_SIZE - 1) / 618 PAGE_CACHE_SIZE; 619 cb->compressed_pages = kzalloc(sizeof(struct page *) * nr_pages, 620 GFP_NOFS); 621 if (!cb->compressed_pages) 622 goto fail1; 623 624 bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev; 625 626 for (pg_index = 0; pg_index < nr_pages; pg_index++) { 627 cb->compressed_pages[pg_index] = alloc_page(GFP_NOFS | 628 __GFP_HIGHMEM); 629 if (!cb->compressed_pages[pg_index]) 630 goto fail2; 631 } 632 cb->nr_pages = nr_pages; 633 634 add_ra_bio_pages(inode, em_start + em_len, cb); 635 636 /* include any pages we added in add_ra-bio_pages */ 637 uncompressed_len = bio->bi_vcnt * PAGE_CACHE_SIZE; 638 cb->len = uncompressed_len; 639 640 comp_bio = compressed_bio_alloc(bdev, cur_disk_byte, GFP_NOFS); 641 if (!comp_bio) 642 goto fail2; 643 comp_bio->bi_private = cb; 644 comp_bio->bi_end_io = end_compressed_bio_read; 645 atomic_inc(&cb->pending_bios); 646 647 for (pg_index = 0; pg_index < nr_pages; pg_index++) { 648 page = cb->compressed_pages[pg_index]; 649 page->mapping = inode->i_mapping; 650 page->index = em_start >> PAGE_CACHE_SHIFT; 651 652 if (comp_bio->bi_size) 653 ret = tree->ops->merge_bio_hook(page, 0, 654 PAGE_CACHE_SIZE, 655 comp_bio, 0); 656 else 657 ret = 0; 658 659 page->mapping = NULL; 660 if (ret || bio_add_page(comp_bio, page, PAGE_CACHE_SIZE, 0) < 661 PAGE_CACHE_SIZE) { 662 bio_get(comp_bio); 663 664 ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0); 665 BUG_ON(ret); 666 667 /* 668 * inc the count before we submit the bio so 669 * we know the end IO handler won't happen before 670 * we inc the count. Otherwise, the cb might get 671 * freed before we're done setting it up 672 */ 673 atomic_inc(&cb->pending_bios); 674 675 if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) { 676 ret = btrfs_lookup_bio_sums(root, inode, 677 comp_bio, sums); 678 BUG_ON(ret); 679 } 680 sums += (comp_bio->bi_size + root->sectorsize - 1) / 681 root->sectorsize; 682 683 ret = btrfs_map_bio(root, READ, comp_bio, 684 mirror_num, 0); 685 BUG_ON(ret); 686 687 bio_put(comp_bio); 688 689 comp_bio = compressed_bio_alloc(bdev, cur_disk_byte, 690 GFP_NOFS); 691 comp_bio->bi_private = cb; 692 comp_bio->bi_end_io = end_compressed_bio_read; 693 694 bio_add_page(comp_bio, page, PAGE_CACHE_SIZE, 0); 695 } 696 cur_disk_byte += PAGE_CACHE_SIZE; 697 } 698 bio_get(comp_bio); 699 700 ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0); 701 BUG_ON(ret); 702 703 if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) { 704 ret = btrfs_lookup_bio_sums(root, inode, comp_bio, sums); 705 BUG_ON(ret); 706 } 707 708 ret = btrfs_map_bio(root, READ, comp_bio, mirror_num, 0); 709 BUG_ON(ret); 710 711 bio_put(comp_bio); 712 return 0; 713 714 fail2: 715 for (pg_index = 0; pg_index < nr_pages; pg_index++) 716 free_page((unsigned long)cb->compressed_pages[pg_index]); 717 718 kfree(cb->compressed_pages); 719 fail1: 720 kfree(cb); 721 out: 722 free_extent_map(em); 723 return ret; 724 } 725 726 static struct list_head comp_idle_workspace[BTRFS_COMPRESS_TYPES]; 727 static spinlock_t comp_workspace_lock[BTRFS_COMPRESS_TYPES]; 728 static int comp_num_workspace[BTRFS_COMPRESS_TYPES]; 729 static atomic_t comp_alloc_workspace[BTRFS_COMPRESS_TYPES]; 730 static wait_queue_head_t comp_workspace_wait[BTRFS_COMPRESS_TYPES]; 731 732 struct btrfs_compress_op *btrfs_compress_op[] = { 733 &btrfs_zlib_compress, 734 &btrfs_lzo_compress, 735 }; 736 737 int __init btrfs_init_compress(void) 738 { 739 int i; 740 741 for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) { 742 INIT_LIST_HEAD(&comp_idle_workspace[i]); 743 spin_lock_init(&comp_workspace_lock[i]); 744 atomic_set(&comp_alloc_workspace[i], 0); 745 init_waitqueue_head(&comp_workspace_wait[i]); 746 } 747 return 0; 748 } 749 750 /* 751 * this finds an available workspace or allocates a new one 752 * ERR_PTR is returned if things go bad. 753 */ 754 static struct list_head *find_workspace(int type) 755 { 756 struct list_head *workspace; 757 int cpus = num_online_cpus(); 758 int idx = type - 1; 759 760 struct list_head *idle_workspace = &comp_idle_workspace[idx]; 761 spinlock_t *workspace_lock = &comp_workspace_lock[idx]; 762 atomic_t *alloc_workspace = &comp_alloc_workspace[idx]; 763 wait_queue_head_t *workspace_wait = &comp_workspace_wait[idx]; 764 int *num_workspace = &comp_num_workspace[idx]; 765 again: 766 spin_lock(workspace_lock); 767 if (!list_empty(idle_workspace)) { 768 workspace = idle_workspace->next; 769 list_del(workspace); 770 (*num_workspace)--; 771 spin_unlock(workspace_lock); 772 return workspace; 773 774 } 775 if (atomic_read(alloc_workspace) > cpus) { 776 DEFINE_WAIT(wait); 777 778 spin_unlock(workspace_lock); 779 prepare_to_wait(workspace_wait, &wait, TASK_UNINTERRUPTIBLE); 780 if (atomic_read(alloc_workspace) > cpus && !*num_workspace) 781 schedule(); 782 finish_wait(workspace_wait, &wait); 783 goto again; 784 } 785 atomic_inc(alloc_workspace); 786 spin_unlock(workspace_lock); 787 788 workspace = btrfs_compress_op[idx]->alloc_workspace(); 789 if (IS_ERR(workspace)) { 790 atomic_dec(alloc_workspace); 791 wake_up(workspace_wait); 792 } 793 return workspace; 794 } 795 796 /* 797 * put a workspace struct back on the list or free it if we have enough 798 * idle ones sitting around 799 */ 800 static void free_workspace(int type, struct list_head *workspace) 801 { 802 int idx = type - 1; 803 struct list_head *idle_workspace = &comp_idle_workspace[idx]; 804 spinlock_t *workspace_lock = &comp_workspace_lock[idx]; 805 atomic_t *alloc_workspace = &comp_alloc_workspace[idx]; 806 wait_queue_head_t *workspace_wait = &comp_workspace_wait[idx]; 807 int *num_workspace = &comp_num_workspace[idx]; 808 809 spin_lock(workspace_lock); 810 if (*num_workspace < num_online_cpus()) { 811 list_add_tail(workspace, idle_workspace); 812 (*num_workspace)++; 813 spin_unlock(workspace_lock); 814 goto wake; 815 } 816 spin_unlock(workspace_lock); 817 818 btrfs_compress_op[idx]->free_workspace(workspace); 819 atomic_dec(alloc_workspace); 820 wake: 821 if (waitqueue_active(workspace_wait)) 822 wake_up(workspace_wait); 823 } 824 825 /* 826 * cleanup function for module exit 827 */ 828 static void free_workspaces(void) 829 { 830 struct list_head *workspace; 831 int i; 832 833 for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) { 834 while (!list_empty(&comp_idle_workspace[i])) { 835 workspace = comp_idle_workspace[i].next; 836 list_del(workspace); 837 btrfs_compress_op[i]->free_workspace(workspace); 838 atomic_dec(&comp_alloc_workspace[i]); 839 } 840 } 841 } 842 843 /* 844 * given an address space and start/len, compress the bytes. 845 * 846 * pages are allocated to hold the compressed result and stored 847 * in 'pages' 848 * 849 * out_pages is used to return the number of pages allocated. There 850 * may be pages allocated even if we return an error 851 * 852 * total_in is used to return the number of bytes actually read. It 853 * may be smaller then len if we had to exit early because we 854 * ran out of room in the pages array or because we cross the 855 * max_out threshold. 856 * 857 * total_out is used to return the total number of compressed bytes 858 * 859 * max_out tells us the max number of bytes that we're allowed to 860 * stuff into pages 861 */ 862 int btrfs_compress_pages(int type, struct address_space *mapping, 863 u64 start, unsigned long len, 864 struct page **pages, 865 unsigned long nr_dest_pages, 866 unsigned long *out_pages, 867 unsigned long *total_in, 868 unsigned long *total_out, 869 unsigned long max_out) 870 { 871 struct list_head *workspace; 872 int ret; 873 874 workspace = find_workspace(type); 875 if (IS_ERR(workspace)) 876 return -1; 877 878 ret = btrfs_compress_op[type-1]->compress_pages(workspace, mapping, 879 start, len, pages, 880 nr_dest_pages, out_pages, 881 total_in, total_out, 882 max_out); 883 free_workspace(type, workspace); 884 return ret; 885 } 886 887 /* 888 * pages_in is an array of pages with compressed data. 889 * 890 * disk_start is the starting logical offset of this array in the file 891 * 892 * bvec is a bio_vec of pages from the file that we want to decompress into 893 * 894 * vcnt is the count of pages in the biovec 895 * 896 * srclen is the number of bytes in pages_in 897 * 898 * The basic idea is that we have a bio that was created by readpages. 899 * The pages in the bio are for the uncompressed data, and they may not 900 * be contiguous. They all correspond to the range of bytes covered by 901 * the compressed extent. 902 */ 903 int btrfs_decompress_biovec(int type, struct page **pages_in, u64 disk_start, 904 struct bio_vec *bvec, int vcnt, size_t srclen) 905 { 906 struct list_head *workspace; 907 int ret; 908 909 workspace = find_workspace(type); 910 if (IS_ERR(workspace)) 911 return -ENOMEM; 912 913 ret = btrfs_compress_op[type-1]->decompress_biovec(workspace, pages_in, 914 disk_start, 915 bvec, vcnt, srclen); 916 free_workspace(type, workspace); 917 return ret; 918 } 919 920 /* 921 * a less complex decompression routine. Our compressed data fits in a 922 * single page, and we want to read a single page out of it. 923 * start_byte tells us the offset into the compressed data we're interested in 924 */ 925 int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page, 926 unsigned long start_byte, size_t srclen, size_t destlen) 927 { 928 struct list_head *workspace; 929 int ret; 930 931 workspace = find_workspace(type); 932 if (IS_ERR(workspace)) 933 return -ENOMEM; 934 935 ret = btrfs_compress_op[type-1]->decompress(workspace, data_in, 936 dest_page, start_byte, 937 srclen, destlen); 938 939 free_workspace(type, workspace); 940 return ret; 941 } 942 943 void btrfs_exit_compress(void) 944 { 945 free_workspaces(); 946 } 947 948 /* 949 * Copy uncompressed data from working buffer to pages. 950 * 951 * buf_start is the byte offset we're of the start of our workspace buffer. 952 * 953 * total_out is the last byte of the buffer 954 */ 955 int btrfs_decompress_buf2page(char *buf, unsigned long buf_start, 956 unsigned long total_out, u64 disk_start, 957 struct bio_vec *bvec, int vcnt, 958 unsigned long *pg_index, 959 unsigned long *pg_offset) 960 { 961 unsigned long buf_offset; 962 unsigned long current_buf_start; 963 unsigned long start_byte; 964 unsigned long working_bytes = total_out - buf_start; 965 unsigned long bytes; 966 char *kaddr; 967 struct page *page_out = bvec[*pg_index].bv_page; 968 969 /* 970 * start byte is the first byte of the page we're currently 971 * copying into relative to the start of the compressed data. 972 */ 973 start_byte = page_offset(page_out) - disk_start; 974 975 /* we haven't yet hit data corresponding to this page */ 976 if (total_out <= start_byte) 977 return 1; 978 979 /* 980 * the start of the data we care about is offset into 981 * the middle of our working buffer 982 */ 983 if (total_out > start_byte && buf_start < start_byte) { 984 buf_offset = start_byte - buf_start; 985 working_bytes -= buf_offset; 986 } else { 987 buf_offset = 0; 988 } 989 current_buf_start = buf_start; 990 991 /* copy bytes from the working buffer into the pages */ 992 while (working_bytes > 0) { 993 bytes = min(PAGE_CACHE_SIZE - *pg_offset, 994 PAGE_CACHE_SIZE - buf_offset); 995 bytes = min(bytes, working_bytes); 996 kaddr = kmap_atomic(page_out, KM_USER0); 997 memcpy(kaddr + *pg_offset, buf + buf_offset, bytes); 998 kunmap_atomic(kaddr, KM_USER0); 999 flush_dcache_page(page_out); 1000 1001 *pg_offset += bytes; 1002 buf_offset += bytes; 1003 working_bytes -= bytes; 1004 current_buf_start += bytes; 1005 1006 /* check if we need to pick another page */ 1007 if (*pg_offset == PAGE_CACHE_SIZE) { 1008 (*pg_index)++; 1009 if (*pg_index >= vcnt) 1010 return 0; 1011 1012 page_out = bvec[*pg_index].bv_page; 1013 *pg_offset = 0; 1014 start_byte = page_offset(page_out) - disk_start; 1015 1016 /* 1017 * make sure our new page is covered by this 1018 * working buffer 1019 */ 1020 if (total_out <= start_byte) 1021 return 1; 1022 1023 /* 1024 * the next page in the biovec might not be adjacent 1025 * to the last page, but it might still be found 1026 * inside this working buffer. bump our offset pointer 1027 */ 1028 if (total_out > start_byte && 1029 current_buf_start < start_byte) { 1030 buf_offset = start_byte - buf_start; 1031 working_bytes = total_out - start_byte; 1032 current_buf_start = buf_start + buf_offset; 1033 } 1034 } 1035 } 1036 1037 return 1; 1038 } 1039