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