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