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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2008 Oracle. All rights reserved.
4 */
5
6#include <linux/kernel.h>
7#include <linux/bio.h>
8#include <linux/buffer_head.h>
9#include <linux/file.h>
10#include <linux/fs.h>
11#include <linux/pagemap.h>
12#include <linux/highmem.h>
13#include <linux/time.h>
14#include <linux/init.h>
15#include <linux/string.h>
16#include <linux/backing-dev.h>
17#include <linux/mpage.h>
18#include <linux/swap.h>
19#include <linux/writeback.h>
20#include <linux/bit_spinlock.h>
21#include <linux/slab.h>
22#include <linux/sched/mm.h>
23#include <linux/log2.h>
24#include "ctree.h"
25#include "disk-io.h"
26#include "transaction.h"
27#include "btrfs_inode.h"
28#include "volumes.h"
29#include "ordered-data.h"
30#include "compression.h"
31#include "extent_io.h"
32#include "extent_map.h"
33
34static const char* const btrfs_compress_types[] = { "", "zlib", "lzo", "zstd" };
35
36const char* btrfs_compress_type2str(enum btrfs_compression_type type)
37{
38 switch (type) {
39 case BTRFS_COMPRESS_ZLIB:
40 case BTRFS_COMPRESS_LZO:
41 case BTRFS_COMPRESS_ZSTD:
42 case BTRFS_COMPRESS_NONE:
43 return btrfs_compress_types[type];
44 }
45
46 return NULL;
47}
48
49static int btrfs_decompress_bio(struct compressed_bio *cb);
50
51static inline int compressed_bio_size(struct btrfs_fs_info *fs_info,
52 unsigned long disk_size)
53{
54 u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
55
56 return sizeof(struct compressed_bio) +
57 (DIV_ROUND_UP(disk_size, fs_info->sectorsize)) * csum_size;
58}
59
60static int check_compressed_csum(struct btrfs_inode *inode,
61 struct compressed_bio *cb,
62 u64 disk_start)
63{
64 int ret;
65 struct page *page;
66 unsigned long i;
67 char *kaddr;
68 u32 csum;
69 u32 *cb_sum = &cb->sums;
70
71 if (inode->flags & BTRFS_INODE_NODATASUM)
72 return 0;
73
74 for (i = 0; i < cb->nr_pages; i++) {
75 page = cb->compressed_pages[i];
76 csum = ~(u32)0;
77
78 kaddr = kmap_atomic(page);
79 csum = btrfs_csum_data(kaddr, csum, PAGE_SIZE);
80 btrfs_csum_final(csum, (u8 *)&csum);
81 kunmap_atomic(kaddr);
82
83 if (csum != *cb_sum) {
84 btrfs_print_data_csum_error(inode, disk_start, csum,
85 *cb_sum, cb->mirror_num);
86 ret = -EIO;
87 goto fail;
88 }
89 cb_sum++;
90
91 }
92 ret = 0;
93fail:
94 return ret;
95}
96
97/* when we finish reading compressed pages from the disk, we
98 * decompress them and then run the bio end_io routines on the
99 * decompressed pages (in the inode address space).
100 *
101 * This allows the checksumming and other IO error handling routines
102 * to work normally
103 *
104 * The compressed pages are freed here, and it must be run
105 * in process context
106 */
107static void end_compressed_bio_read(struct bio *bio)
108{
109 struct compressed_bio *cb = bio->bi_private;
110 struct inode *inode;
111 struct page *page;
112 unsigned long index;
113 unsigned int mirror = btrfs_io_bio(bio)->mirror_num;
114 int ret = 0;
115
116 if (bio->bi_status)
117 cb->errors = 1;
118
119 /* if there are more bios still pending for this compressed
120 * extent, just exit
121 */
122 if (!refcount_dec_and_test(&cb->pending_bios))
123 goto out;
124
125 /*
126 * Record the correct mirror_num in cb->orig_bio so that
127 * read-repair can work properly.
128 */
129 ASSERT(btrfs_io_bio(cb->orig_bio));
130 btrfs_io_bio(cb->orig_bio)->mirror_num = mirror;
131 cb->mirror_num = mirror;
132
133 /*
134 * Some IO in this cb have failed, just skip checksum as there
135 * is no way it could be correct.
136 */
137 if (cb->errors == 1)
138 goto csum_failed;
139
140 inode = cb->inode;
141 ret = check_compressed_csum(BTRFS_I(inode), cb,
142 (u64)bio->bi_iter.bi_sector << 9);
143 if (ret)
144 goto csum_failed;
145
146 /* ok, we're the last bio for this extent, lets start
147 * the decompression.
148 */
149 ret = btrfs_decompress_bio(cb);
150
151csum_failed:
152 if (ret)
153 cb->errors = 1;
154
155 /* release the compressed pages */
156 index = 0;
157 for (index = 0; index < cb->nr_pages; index++) {
158 page = cb->compressed_pages[index];
159 page->mapping = NULL;
160 put_page(page);
161 }
162
163 /* do io completion on the original bio */
164 if (cb->errors) {
165 bio_io_error(cb->orig_bio);
166 } else {
167 int i;
168 struct bio_vec *bvec;
169
170 /*
171 * we have verified the checksum already, set page
172 * checked so the end_io handlers know about it
173 */
174 ASSERT(!bio_flagged(bio, BIO_CLONED));
175 bio_for_each_segment_all(bvec, cb->orig_bio, i)
176 SetPageChecked(bvec->bv_page);
177
178 bio_endio(cb->orig_bio);
179 }
180
181 /* finally free the cb struct */
182 kfree(cb->compressed_pages);
183 kfree(cb);
184out:
185 bio_put(bio);
186}
187
188/*
189 * Clear the writeback bits on all of the file
190 * pages for a compressed write
191 */
192static noinline void end_compressed_writeback(struct inode *inode,
193 const struct compressed_bio *cb)
194{
195 unsigned long index = cb->start >> PAGE_SHIFT;
196 unsigned long end_index = (cb->start + cb->len - 1) >> PAGE_SHIFT;
197 struct page *pages[16];
198 unsigned long nr_pages = end_index - index + 1;
199 int i;
200 int ret;
201
202 if (cb->errors)
203 mapping_set_error(inode->i_mapping, -EIO);
204
205 while (nr_pages > 0) {
206 ret = find_get_pages_contig(inode->i_mapping, index,
207 min_t(unsigned long,
208 nr_pages, ARRAY_SIZE(pages)), pages);
209 if (ret == 0) {
210 nr_pages -= 1;
211 index += 1;
212 continue;
213 }
214 for (i = 0; i < ret; i++) {
215 if (cb->errors)
216 SetPageError(pages[i]);
217 end_page_writeback(pages[i]);
218 put_page(pages[i]);
219 }
220 nr_pages -= ret;
221 index += ret;
222 }
223 /* the inode may be gone now */
224}
225
226/*
227 * do the cleanup once all the compressed pages hit the disk.
228 * This will clear writeback on the file pages and free the compressed
229 * pages.
230 *
231 * This also calls the writeback end hooks for the file pages so that
232 * metadata and checksums can be updated in the file.
233 */
234static void end_compressed_bio_write(struct bio *bio)
235{
236 struct extent_io_tree *tree;
237 struct compressed_bio *cb = bio->bi_private;
238 struct inode *inode;
239 struct page *page;
240 unsigned long index;
241
242 if (bio->bi_status)
243 cb->errors = 1;
244
245 /* if there are more bios still pending for this compressed
246 * extent, just exit
247 */
248 if (!refcount_dec_and_test(&cb->pending_bios))
249 goto out;
250
251 /* ok, we're the last bio for this extent, step one is to
252 * call back into the FS and do all the end_io operations
253 */
254 inode = cb->inode;
255 tree = &BTRFS_I(inode)->io_tree;
256 cb->compressed_pages[0]->mapping = cb->inode->i_mapping;
257 tree->ops->writepage_end_io_hook(cb->compressed_pages[0],
258 cb->start,
259 cb->start + cb->len - 1,
260 NULL,
261 bio->bi_status ?
262 BLK_STS_OK : BLK_STS_NOTSUPP);
263 cb->compressed_pages[0]->mapping = NULL;
264
265 end_compressed_writeback(inode, cb);
266 /* note, our inode could be gone now */
267
268 /*
269 * release the compressed pages, these came from alloc_page and
270 * are not attached to the inode at all
271 */
272 index = 0;
273 for (index = 0; index < cb->nr_pages; index++) {
274 page = cb->compressed_pages[index];
275 page->mapping = NULL;
276 put_page(page);
277 }
278
279 /* finally free the cb struct */
280 kfree(cb->compressed_pages);
281 kfree(cb);
282out:
283 bio_put(bio);
284}
285
286/*
287 * worker function to build and submit bios for previously compressed pages.
288 * The corresponding pages in the inode should be marked for writeback
289 * and the compressed pages should have a reference on them for dropping
290 * when the IO is complete.
291 *
292 * This also checksums the file bytes and gets things ready for
293 * the end io hooks.
294 */
295blk_status_t btrfs_submit_compressed_write(struct inode *inode, u64 start,
296 unsigned long len, u64 disk_start,
297 unsigned long compressed_len,
298 struct page **compressed_pages,
299 unsigned long nr_pages,
300 unsigned int write_flags)
301{
302 struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
303 struct bio *bio = NULL;
304 struct compressed_bio *cb;
305 unsigned long bytes_left;
306 struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
307 int pg_index = 0;
308 struct page *page;
309 u64 first_byte = disk_start;
310 struct block_device *bdev;
311 blk_status_t ret;
312 int skip_sum = BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM;
313
314 WARN_ON(start & ((u64)PAGE_SIZE - 1));
315 cb = kmalloc(compressed_bio_size(fs_info, compressed_len), GFP_NOFS);
316 if (!cb)
317 return BLK_STS_RESOURCE;
318 refcount_set(&cb->pending_bios, 0);
319 cb->errors = 0;
320 cb->inode = inode;
321 cb->start = start;
322 cb->len = len;
323 cb->mirror_num = 0;
324 cb->compressed_pages = compressed_pages;
325 cb->compressed_len = compressed_len;
326 cb->orig_bio = NULL;
327 cb->nr_pages = nr_pages;
328
329 bdev = fs_info->fs_devices->latest_bdev;
330
331 bio = btrfs_bio_alloc(bdev, first_byte);
332 bio->bi_opf = REQ_OP_WRITE | write_flags;
333 bio->bi_private = cb;
334 bio->bi_end_io = end_compressed_bio_write;
335 refcount_set(&cb->pending_bios, 1);
336
337 /* create and submit bios for the compressed pages */
338 bytes_left = compressed_len;
339 for (pg_index = 0; pg_index < cb->nr_pages; pg_index++) {
340 int submit = 0;
341
342 page = compressed_pages[pg_index];
343 page->mapping = inode->i_mapping;
344 if (bio->bi_iter.bi_size)
345 submit = io_tree->ops->merge_bio_hook(page, 0,
346 PAGE_SIZE,
347 bio, 0);
348
349 page->mapping = NULL;
350 if (submit || bio_add_page(bio, page, PAGE_SIZE, 0) <
351 PAGE_SIZE) {
352 /*
353 * inc the count before we submit the bio so
354 * we know the end IO handler won't happen before
355 * we inc the count. Otherwise, the cb might get
356 * freed before we're done setting it up
357 */
358 refcount_inc(&cb->pending_bios);
359 ret = btrfs_bio_wq_end_io(fs_info, bio,
360 BTRFS_WQ_ENDIO_DATA);
361 BUG_ON(ret); /* -ENOMEM */
362
363 if (!skip_sum) {
364 ret = btrfs_csum_one_bio(inode, bio, start, 1);
365 BUG_ON(ret); /* -ENOMEM */
366 }
367
368 ret = btrfs_map_bio(fs_info, bio, 0, 1);
369 if (ret) {
370 bio->bi_status = ret;
371 bio_endio(bio);
372 }
373
374 bio = btrfs_bio_alloc(bdev, first_byte);
375 bio->bi_opf = REQ_OP_WRITE | write_flags;
376 bio->bi_private = cb;
377 bio->bi_end_io = end_compressed_bio_write;
378 bio_add_page(bio, page, PAGE_SIZE, 0);
379 }
380 if (bytes_left < PAGE_SIZE) {
381 btrfs_info(fs_info,
382 "bytes left %lu compress len %lu nr %lu",
383 bytes_left, cb->compressed_len, cb->nr_pages);
384 }
385 bytes_left -= PAGE_SIZE;
386 first_byte += PAGE_SIZE;
387 cond_resched();
388 }
389
390 ret = btrfs_bio_wq_end_io(fs_info, bio, BTRFS_WQ_ENDIO_DATA);
391 BUG_ON(ret); /* -ENOMEM */
392
393 if (!skip_sum) {
394 ret = btrfs_csum_one_bio(inode, bio, start, 1);
395 BUG_ON(ret); /* -ENOMEM */
396 }
397
398 ret = btrfs_map_bio(fs_info, bio, 0, 1);
399 if (ret) {
400 bio->bi_status = ret;
401 bio_endio(bio);
402 }
403
404 return 0;
405}
406
407static u64 bio_end_offset(struct bio *bio)
408{
409 struct bio_vec *last = bio_last_bvec_all(bio);
410
411 return page_offset(last->bv_page) + last->bv_len + last->bv_offset;
412}
413
414static noinline int add_ra_bio_pages(struct inode *inode,
415 u64 compressed_end,
416 struct compressed_bio *cb)
417{
418 unsigned long end_index;
419 unsigned long pg_index;
420 u64 last_offset;
421 u64 isize = i_size_read(inode);
422 int ret;
423 struct page *page;
424 unsigned long nr_pages = 0;
425 struct extent_map *em;
426 struct address_space *mapping = inode->i_mapping;
427 struct extent_map_tree *em_tree;
428 struct extent_io_tree *tree;
429 u64 end;
430 int misses = 0;
431
432 last_offset = bio_end_offset(cb->orig_bio);
433 em_tree = &BTRFS_I(inode)->extent_tree;
434 tree = &BTRFS_I(inode)->io_tree;
435
436 if (isize == 0)
437 return 0;
438
439 end_index = (i_size_read(inode) - 1) >> PAGE_SHIFT;
440
441 while (last_offset < compressed_end) {
442 pg_index = last_offset >> PAGE_SHIFT;
443
444 if (pg_index > end_index)
445 break;
446
447 rcu_read_lock();
448 page = radix_tree_lookup(&mapping->i_pages, pg_index);
449 rcu_read_unlock();
450 if (page && !radix_tree_exceptional_entry(page)) {
451 misses++;
452 if (misses > 4)
453 break;
454 goto next;
455 }
456
457 page = __page_cache_alloc(mapping_gfp_constraint(mapping,
458 ~__GFP_FS));
459 if (!page)
460 break;
461
462 if (add_to_page_cache_lru(page, mapping, pg_index, GFP_NOFS)) {
463 put_page(page);
464 goto next;
465 }
466
467 end = last_offset + PAGE_SIZE - 1;
468 /*
469 * at this point, we have a locked page in the page cache
470 * for these bytes in the file. But, we have to make
471 * sure they map to this compressed extent on disk.
472 */
473 set_page_extent_mapped(page);
474 lock_extent(tree, last_offset, end);
475 read_lock(&em_tree->lock);
476 em = lookup_extent_mapping(em_tree, last_offset,
477 PAGE_SIZE);
478 read_unlock(&em_tree->lock);
479
480 if (!em || last_offset < em->start ||
481 (last_offset + PAGE_SIZE > extent_map_end(em)) ||
482 (em->block_start >> 9) != cb->orig_bio->bi_iter.bi_sector) {
483 free_extent_map(em);
484 unlock_extent(tree, last_offset, end);
485 unlock_page(page);
486 put_page(page);
487 break;
488 }
489 free_extent_map(em);
490
491 if (page->index == end_index) {
492 char *userpage;
493 size_t zero_offset = isize & (PAGE_SIZE - 1);
494
495 if (zero_offset) {
496 int zeros;
497 zeros = PAGE_SIZE - zero_offset;
498 userpage = kmap_atomic(page);
499 memset(userpage + zero_offset, 0, zeros);
500 flush_dcache_page(page);
501 kunmap_atomic(userpage);
502 }
503 }
504
505 ret = bio_add_page(cb->orig_bio, page,
506 PAGE_SIZE, 0);
507
508 if (ret == PAGE_SIZE) {
509 nr_pages++;
510 put_page(page);
511 } else {
512 unlock_extent(tree, last_offset, end);
513 unlock_page(page);
514 put_page(page);
515 break;
516 }
517next:
518 last_offset += PAGE_SIZE;
519 }
520 return 0;
521}
522
523/*
524 * for a compressed read, the bio we get passed has all the inode pages
525 * in it. We don't actually do IO on those pages but allocate new ones
526 * to hold the compressed pages on disk.
527 *
528 * bio->bi_iter.bi_sector points to the compressed extent on disk
529 * bio->bi_io_vec points to all of the inode pages
530 *
531 * After the compressed pages are read, we copy the bytes into the
532 * bio we were passed and then call the bio end_io calls
533 */
534blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
535 int mirror_num, unsigned long bio_flags)
536{
537 struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
538 struct extent_io_tree *tree;
539 struct extent_map_tree *em_tree;
540 struct compressed_bio *cb;
541 unsigned long compressed_len;
542 unsigned long nr_pages;
543 unsigned long pg_index;
544 struct page *page;
545 struct block_device *bdev;
546 struct bio *comp_bio;
547 u64 cur_disk_byte = (u64)bio->bi_iter.bi_sector << 9;
548 u64 em_len;
549 u64 em_start;
550 struct extent_map *em;
551 blk_status_t ret = BLK_STS_RESOURCE;
552 int faili = 0;
553 u32 *sums;
554
555 tree = &BTRFS_I(inode)->io_tree;
556 em_tree = &BTRFS_I(inode)->extent_tree;
557
558 /* we need the actual starting offset of this extent in the file */
559 read_lock(&em_tree->lock);
560 em = lookup_extent_mapping(em_tree,
561 page_offset(bio_first_page_all(bio)),
562 PAGE_SIZE);
563 read_unlock(&em_tree->lock);
564 if (!em)
565 return BLK_STS_IOERR;
566
567 compressed_len = em->block_len;
568 cb = kmalloc(compressed_bio_size(fs_info, compressed_len), GFP_NOFS);
569 if (!cb)
570 goto out;
571
572 refcount_set(&cb->pending_bios, 0);
573 cb->errors = 0;
574 cb->inode = inode;
575 cb->mirror_num = mirror_num;
576 sums = &cb->sums;
577
578 cb->start = em->orig_start;
579 em_len = em->len;
580 em_start = em->start;
581
582 free_extent_map(em);
583 em = NULL;
584
585 cb->len = bio->bi_iter.bi_size;
586 cb->compressed_len = compressed_len;
587 cb->compress_type = extent_compress_type(bio_flags);
588 cb->orig_bio = bio;
589
590 nr_pages = DIV_ROUND_UP(compressed_len, PAGE_SIZE);
591 cb->compressed_pages = kcalloc(nr_pages, sizeof(struct page *),
592 GFP_NOFS);
593 if (!cb->compressed_pages)
594 goto fail1;
595
596 bdev = fs_info->fs_devices->latest_bdev;
597
598 for (pg_index = 0; pg_index < nr_pages; pg_index++) {
599 cb->compressed_pages[pg_index] = alloc_page(GFP_NOFS |
600 __GFP_HIGHMEM);
601 if (!cb->compressed_pages[pg_index]) {
602 faili = pg_index - 1;
603 ret = BLK_STS_RESOURCE;
604 goto fail2;
605 }
606 }
607 faili = nr_pages - 1;
608 cb->nr_pages = nr_pages;
609
610 add_ra_bio_pages(inode, em_start + em_len, cb);
611
612 /* include any pages we added in add_ra-bio_pages */
613 cb->len = bio->bi_iter.bi_size;
614
615 comp_bio = btrfs_bio_alloc(bdev, cur_disk_byte);
616 bio_set_op_attrs (comp_bio, REQ_OP_READ, 0);
617 comp_bio->bi_private = cb;
618 comp_bio->bi_end_io = end_compressed_bio_read;
619 refcount_set(&cb->pending_bios, 1);
620
621 for (pg_index = 0; pg_index < nr_pages; pg_index++) {
622 int submit = 0;
623
624 page = cb->compressed_pages[pg_index];
625 page->mapping = inode->i_mapping;
626 page->index = em_start >> PAGE_SHIFT;
627
628 if (comp_bio->bi_iter.bi_size)
629 submit = tree->ops->merge_bio_hook(page, 0,
630 PAGE_SIZE,
631 comp_bio, 0);
632
633 page->mapping = NULL;
634 if (submit || bio_add_page(comp_bio, page, PAGE_SIZE, 0) <
635 PAGE_SIZE) {
636 ret = btrfs_bio_wq_end_io(fs_info, comp_bio,
637 BTRFS_WQ_ENDIO_DATA);
638 BUG_ON(ret); /* -ENOMEM */
639
640 /*
641 * inc the count before we submit the bio so
642 * we know the end IO handler won't happen before
643 * we inc the count. Otherwise, the cb might get
644 * freed before we're done setting it up
645 */
646 refcount_inc(&cb->pending_bios);
647
648 if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
649 ret = btrfs_lookup_bio_sums(inode, comp_bio,
650 sums);
651 BUG_ON(ret); /* -ENOMEM */
652 }
653 sums += DIV_ROUND_UP(comp_bio->bi_iter.bi_size,
654 fs_info->sectorsize);
655
656 ret = btrfs_map_bio(fs_info, comp_bio, mirror_num, 0);
657 if (ret) {
658 comp_bio->bi_status = ret;
659 bio_endio(comp_bio);
660 }
661
662 comp_bio = btrfs_bio_alloc(bdev, cur_disk_byte);
663 bio_set_op_attrs(comp_bio, REQ_OP_READ, 0);
664 comp_bio->bi_private = cb;
665 comp_bio->bi_end_io = end_compressed_bio_read;
666
667 bio_add_page(comp_bio, page, PAGE_SIZE, 0);
668 }
669 cur_disk_byte += PAGE_SIZE;
670 }
671
672 ret = btrfs_bio_wq_end_io(fs_info, comp_bio, BTRFS_WQ_ENDIO_DATA);
673 BUG_ON(ret); /* -ENOMEM */
674
675 if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
676 ret = btrfs_lookup_bio_sums(inode, comp_bio, sums);
677 BUG_ON(ret); /* -ENOMEM */
678 }
679
680 ret = btrfs_map_bio(fs_info, comp_bio, mirror_num, 0);
681 if (ret) {
682 comp_bio->bi_status = ret;
683 bio_endio(comp_bio);
684 }
685
686 return 0;
687
688fail2:
689 while (faili >= 0) {
690 __free_page(cb->compressed_pages[faili]);
691 faili--;
692 }
693
694 kfree(cb->compressed_pages);
695fail1:
696 kfree(cb);
697out:
698 free_extent_map(em);
699 return ret;
700}
701
702/*
703 * Heuristic uses systematic sampling to collect data from the input data
704 * range, the logic can be tuned by the following constants:
705 *
706 * @SAMPLING_READ_SIZE - how many bytes will be copied from for each sample
707 * @SAMPLING_INTERVAL - range from which the sampled data can be collected
708 */
709#define SAMPLING_READ_SIZE (16)
710#define SAMPLING_INTERVAL (256)
711
712/*
713 * For statistical analysis of the input data we consider bytes that form a
714 * Galois Field of 256 objects. Each object has an attribute count, ie. how
715 * many times the object appeared in the sample.
716 */
717#define BUCKET_SIZE (256)
718
719/*
720 * The size of the sample is based on a statistical sampling rule of thumb.
721 * The common way is to perform sampling tests as long as the number of
722 * elements in each cell is at least 5.
723 *
724 * Instead of 5, we choose 32 to obtain more accurate results.
725 * If the data contain the maximum number of symbols, which is 256, we obtain a
726 * sample size bound by 8192.
727 *
728 * For a sample of at most 8KB of data per data range: 16 consecutive bytes
729 * from up to 512 locations.
730 */
731#define MAX_SAMPLE_SIZE (BTRFS_MAX_UNCOMPRESSED * \
732 SAMPLING_READ_SIZE / SAMPLING_INTERVAL)
733
734struct bucket_item {
735 u32 count;
736};
737
738struct heuristic_ws {
739 /* Partial copy of input data */
740 u8 *sample;
741 u32 sample_size;
742 /* Buckets store counters for each byte value */
743 struct bucket_item *bucket;
744 /* Sorting buffer */
745 struct bucket_item *bucket_b;
746 struct list_head list;
747};
748
749static void free_heuristic_ws(struct list_head *ws)
750{
751 struct heuristic_ws *workspace;
752
753 workspace = list_entry(ws, struct heuristic_ws, list);
754
755 kvfree(workspace->sample);
756 kfree(workspace->bucket);
757 kfree(workspace->bucket_b);
758 kfree(workspace);
759}
760
761static struct list_head *alloc_heuristic_ws(void)
762{
763 struct heuristic_ws *ws;
764
765 ws = kzalloc(sizeof(*ws), GFP_KERNEL);
766 if (!ws)
767 return ERR_PTR(-ENOMEM);
768
769 ws->sample = kvmalloc(MAX_SAMPLE_SIZE, GFP_KERNEL);
770 if (!ws->sample)
771 goto fail;
772
773 ws->bucket = kcalloc(BUCKET_SIZE, sizeof(*ws->bucket), GFP_KERNEL);
774 if (!ws->bucket)
775 goto fail;
776
777 ws->bucket_b = kcalloc(BUCKET_SIZE, sizeof(*ws->bucket_b), GFP_KERNEL);
778 if (!ws->bucket_b)
779 goto fail;
780
781 INIT_LIST_HEAD(&ws->list);
782 return &ws->list;
783fail:
784 free_heuristic_ws(&ws->list);
785 return ERR_PTR(-ENOMEM);
786}
787
788struct workspaces_list {
789 struct list_head idle_ws;
790 spinlock_t ws_lock;
791 /* Number of free workspaces */
792 int free_ws;
793 /* Total number of allocated workspaces */
794 atomic_t total_ws;
795 /* Waiters for a free workspace */
796 wait_queue_head_t ws_wait;
797};
798
799static struct workspaces_list btrfs_comp_ws[BTRFS_COMPRESS_TYPES];
800
801static struct workspaces_list btrfs_heuristic_ws;
802
803static const struct btrfs_compress_op * const btrfs_compress_op[] = {
804 &btrfs_zlib_compress,
805 &btrfs_lzo_compress,
806 &btrfs_zstd_compress,
807};
808
809void __init btrfs_init_compress(void)
810{
811 struct list_head *workspace;
812 int i;
813
814 INIT_LIST_HEAD(&btrfs_heuristic_ws.idle_ws);
815 spin_lock_init(&btrfs_heuristic_ws.ws_lock);
816 atomic_set(&btrfs_heuristic_ws.total_ws, 0);
817 init_waitqueue_head(&btrfs_heuristic_ws.ws_wait);
818
819 workspace = alloc_heuristic_ws();
820 if (IS_ERR(workspace)) {
821 pr_warn(
822 "BTRFS: cannot preallocate heuristic workspace, will try later\n");
823 } else {
824 atomic_set(&btrfs_heuristic_ws.total_ws, 1);
825 btrfs_heuristic_ws.free_ws = 1;
826 list_add(workspace, &btrfs_heuristic_ws.idle_ws);
827 }
828
829 for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
830 INIT_LIST_HEAD(&btrfs_comp_ws[i].idle_ws);
831 spin_lock_init(&btrfs_comp_ws[i].ws_lock);
832 atomic_set(&btrfs_comp_ws[i].total_ws, 0);
833 init_waitqueue_head(&btrfs_comp_ws[i].ws_wait);
834
835 /*
836 * Preallocate one workspace for each compression type so
837 * we can guarantee forward progress in the worst case
838 */
839 workspace = btrfs_compress_op[i]->alloc_workspace();
840 if (IS_ERR(workspace)) {
841 pr_warn("BTRFS: cannot preallocate compression workspace, will try later\n");
842 } else {
843 atomic_set(&btrfs_comp_ws[i].total_ws, 1);
844 btrfs_comp_ws[i].free_ws = 1;
845 list_add(workspace, &btrfs_comp_ws[i].idle_ws);
846 }
847 }
848}
849
850/*
851 * This finds an available workspace or allocates a new one.
852 * If it's not possible to allocate a new one, waits until there's one.
853 * Preallocation makes a forward progress guarantees and we do not return
854 * errors.
855 */
856static struct list_head *__find_workspace(int type, bool heuristic)
857{
858 struct list_head *workspace;
859 int cpus = num_online_cpus();
860 int idx = type - 1;
861 unsigned nofs_flag;
862 struct list_head *idle_ws;
863 spinlock_t *ws_lock;
864 atomic_t *total_ws;
865 wait_queue_head_t *ws_wait;
866 int *free_ws;
867
868 if (heuristic) {
869 idle_ws = &btrfs_heuristic_ws.idle_ws;
870 ws_lock = &btrfs_heuristic_ws.ws_lock;
871 total_ws = &btrfs_heuristic_ws.total_ws;
872 ws_wait = &btrfs_heuristic_ws.ws_wait;
873 free_ws = &btrfs_heuristic_ws.free_ws;
874 } else {
875 idle_ws = &btrfs_comp_ws[idx].idle_ws;
876 ws_lock = &btrfs_comp_ws[idx].ws_lock;
877 total_ws = &btrfs_comp_ws[idx].total_ws;
878 ws_wait = &btrfs_comp_ws[idx].ws_wait;
879 free_ws = &btrfs_comp_ws[idx].free_ws;
880 }
881
882again:
883 spin_lock(ws_lock);
884 if (!list_empty(idle_ws)) {
885 workspace = idle_ws->next;
886 list_del(workspace);
887 (*free_ws)--;
888 spin_unlock(ws_lock);
889 return workspace;
890
891 }
892 if (atomic_read(total_ws) > cpus) {
893 DEFINE_WAIT(wait);
894
895 spin_unlock(ws_lock);
896 prepare_to_wait(ws_wait, &wait, TASK_UNINTERRUPTIBLE);
897 if (atomic_read(total_ws) > cpus && !*free_ws)
898 schedule();
899 finish_wait(ws_wait, &wait);
900 goto again;
901 }
902 atomic_inc(total_ws);
903 spin_unlock(ws_lock);
904
905 /*
906 * Allocation helpers call vmalloc that can't use GFP_NOFS, so we have
907 * to turn it off here because we might get called from the restricted
908 * context of btrfs_compress_bio/btrfs_compress_pages
909 */
910 nofs_flag = memalloc_nofs_save();
911 if (heuristic)
912 workspace = alloc_heuristic_ws();
913 else
914 workspace = btrfs_compress_op[idx]->alloc_workspace();
915 memalloc_nofs_restore(nofs_flag);
916
917 if (IS_ERR(workspace)) {
918 atomic_dec(total_ws);
919 wake_up(ws_wait);
920
921 /*
922 * Do not return the error but go back to waiting. There's a
923 * workspace preallocated for each type and the compression
924 * time is bounded so we get to a workspace eventually. This
925 * makes our caller's life easier.
926 *
927 * To prevent silent and low-probability deadlocks (when the
928 * initial preallocation fails), check if there are any
929 * workspaces at all.
930 */
931 if (atomic_read(total_ws) == 0) {
932 static DEFINE_RATELIMIT_STATE(_rs,
933 /* once per minute */ 60 * HZ,
934 /* no burst */ 1);
935
936 if (__ratelimit(&_rs)) {
937 pr_warn("BTRFS: no compression workspaces, low memory, retrying\n");
938 }
939 }
940 goto again;
941 }
942 return workspace;
943}
944
945static struct list_head *find_workspace(int type)
946{
947 return __find_workspace(type, false);
948}
949
950/*
951 * put a workspace struct back on the list or free it if we have enough
952 * idle ones sitting around
953 */
954static void __free_workspace(int type, struct list_head *workspace,
955 bool heuristic)
956{
957 int idx = type - 1;
958 struct list_head *idle_ws;
959 spinlock_t *ws_lock;
960 atomic_t *total_ws;
961 wait_queue_head_t *ws_wait;
962 int *free_ws;
963
964 if (heuristic) {
965 idle_ws = &btrfs_heuristic_ws.idle_ws;
966 ws_lock = &btrfs_heuristic_ws.ws_lock;
967 total_ws = &btrfs_heuristic_ws.total_ws;
968 ws_wait = &btrfs_heuristic_ws.ws_wait;
969 free_ws = &btrfs_heuristic_ws.free_ws;
970 } else {
971 idle_ws = &btrfs_comp_ws[idx].idle_ws;
972 ws_lock = &btrfs_comp_ws[idx].ws_lock;
973 total_ws = &btrfs_comp_ws[idx].total_ws;
974 ws_wait = &btrfs_comp_ws[idx].ws_wait;
975 free_ws = &btrfs_comp_ws[idx].free_ws;
976 }
977
978 spin_lock(ws_lock);
979 if (*free_ws <= num_online_cpus()) {
980 list_add(workspace, idle_ws);
981 (*free_ws)++;
982 spin_unlock(ws_lock);
983 goto wake;
984 }
985 spin_unlock(ws_lock);
986
987 if (heuristic)
988 free_heuristic_ws(workspace);
989 else
990 btrfs_compress_op[idx]->free_workspace(workspace);
991 atomic_dec(total_ws);
992wake:
993 /*
994 * Make sure counter is updated before we wake up waiters.
995 */
996 smp_mb();
997 if (waitqueue_active(ws_wait))
998 wake_up(ws_wait);
999}
1000
1001static void free_workspace(int type, struct list_head *ws)
1002{
1003 return __free_workspace(type, ws, false);
1004}
1005
1006/*
1007 * cleanup function for module exit
1008 */
1009static void free_workspaces(void)
1010{
1011 struct list_head *workspace;
1012 int i;
1013
1014 while (!list_empty(&btrfs_heuristic_ws.idle_ws)) {
1015 workspace = btrfs_heuristic_ws.idle_ws.next;
1016 list_del(workspace);
1017 free_heuristic_ws(workspace);
1018 atomic_dec(&btrfs_heuristic_ws.total_ws);
1019 }
1020
1021 for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
1022 while (!list_empty(&btrfs_comp_ws[i].idle_ws)) {
1023 workspace = btrfs_comp_ws[i].idle_ws.next;
1024 list_del(workspace);
1025 btrfs_compress_op[i]->free_workspace(workspace);
1026 atomic_dec(&btrfs_comp_ws[i].total_ws);
1027 }
1028 }
1029}
1030
1031/*
1032 * Given an address space and start and length, compress the bytes into @pages
1033 * that are allocated on demand.
1034 *
1035 * @type_level is encoded algorithm and level, where level 0 means whatever
1036 * default the algorithm chooses and is opaque here;
1037 * - compression algo are 0-3
1038 * - the level are bits 4-7
1039 *
1040 * @out_pages is an in/out parameter, holds maximum number of pages to allocate
1041 * and returns number of actually allocated pages
1042 *
1043 * @total_in is used to return the number of bytes actually read. It
1044 * may be smaller than the input length if we had to exit early because we
1045 * ran out of room in the pages array or because we cross the
1046 * max_out threshold.
1047 *
1048 * @total_out is an in/out parameter, must be set to the input length and will
1049 * be also used to return the total number of compressed bytes
1050 *
1051 * @max_out tells us the max number of bytes that we're allowed to
1052 * stuff into pages
1053 */
1054int btrfs_compress_pages(unsigned int type_level, struct address_space *mapping,
1055 u64 start, struct page **pages,
1056 unsigned long *out_pages,
1057 unsigned long *total_in,
1058 unsigned long *total_out)
1059{
1060 struct list_head *workspace;
1061 int ret;
1062 int type = type_level & 0xF;
1063
1064 workspace = find_workspace(type);
1065
1066 btrfs_compress_op[type - 1]->set_level(workspace, type_level);
1067 ret = btrfs_compress_op[type-1]->compress_pages(workspace, mapping,
1068 start, pages,
1069 out_pages,
1070 total_in, total_out);
1071 free_workspace(type, workspace);
1072 return ret;
1073}
1074
1075/*
1076 * pages_in is an array of pages with compressed data.
1077 *
1078 * disk_start is the starting logical offset of this array in the file
1079 *
1080 * orig_bio contains the pages from the file that we want to decompress into
1081 *
1082 * srclen is the number of bytes in pages_in
1083 *
1084 * The basic idea is that we have a bio that was created by readpages.
1085 * The pages in the bio are for the uncompressed data, and they may not
1086 * be contiguous. They all correspond to the range of bytes covered by
1087 * the compressed extent.
1088 */
1089static int btrfs_decompress_bio(struct compressed_bio *cb)
1090{
1091 struct list_head *workspace;
1092 int ret;
1093 int type = cb->compress_type;
1094
1095 workspace = find_workspace(type);
1096 ret = btrfs_compress_op[type - 1]->decompress_bio(workspace, cb);
1097 free_workspace(type, workspace);
1098
1099 return ret;
1100}
1101
1102/*
1103 * a less complex decompression routine. Our compressed data fits in a
1104 * single page, and we want to read a single page out of it.
1105 * start_byte tells us the offset into the compressed data we're interested in
1106 */
1107int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
1108 unsigned long start_byte, size_t srclen, size_t destlen)
1109{
1110 struct list_head *workspace;
1111 int ret;
1112
1113 workspace = find_workspace(type);
1114
1115 ret = btrfs_compress_op[type-1]->decompress(workspace, data_in,
1116 dest_page, start_byte,
1117 srclen, destlen);
1118
1119 free_workspace(type, workspace);
1120 return ret;
1121}
1122
1123void __cold btrfs_exit_compress(void)
1124{
1125 free_workspaces();
1126}
1127
1128/*
1129 * Copy uncompressed data from working buffer to pages.
1130 *
1131 * buf_start is the byte offset we're of the start of our workspace buffer.
1132 *
1133 * total_out is the last byte of the buffer
1134 */
1135int btrfs_decompress_buf2page(const char *buf, unsigned long buf_start,
1136 unsigned long total_out, u64 disk_start,
1137 struct bio *bio)
1138{
1139 unsigned long buf_offset;
1140 unsigned long current_buf_start;
1141 unsigned long start_byte;
1142 unsigned long prev_start_byte;
1143 unsigned long working_bytes = total_out - buf_start;
1144 unsigned long bytes;
1145 char *kaddr;
1146 struct bio_vec bvec = bio_iter_iovec(bio, bio->bi_iter);
1147
1148 /*
1149 * start byte is the first byte of the page we're currently
1150 * copying into relative to the start of the compressed data.
1151 */
1152 start_byte = page_offset(bvec.bv_page) - disk_start;
1153
1154 /* we haven't yet hit data corresponding to this page */
1155 if (total_out <= start_byte)
1156 return 1;
1157
1158 /*
1159 * the start of the data we care about is offset into
1160 * the middle of our working buffer
1161 */
1162 if (total_out > start_byte && buf_start < start_byte) {
1163 buf_offset = start_byte - buf_start;
1164 working_bytes -= buf_offset;
1165 } else {
1166 buf_offset = 0;
1167 }
1168 current_buf_start = buf_start;
1169
1170 /* copy bytes from the working buffer into the pages */
1171 while (working_bytes > 0) {
1172 bytes = min_t(unsigned long, bvec.bv_len,
1173 PAGE_SIZE - buf_offset);
1174 bytes = min(bytes, working_bytes);
1175
1176 kaddr = kmap_atomic(bvec.bv_page);
1177 memcpy(kaddr + bvec.bv_offset, buf + buf_offset, bytes);
1178 kunmap_atomic(kaddr);
1179 flush_dcache_page(bvec.bv_page);
1180
1181 buf_offset += bytes;
1182 working_bytes -= bytes;
1183 current_buf_start += bytes;
1184
1185 /* check if we need to pick another page */
1186 bio_advance(bio, bytes);
1187 if (!bio->bi_iter.bi_size)
1188 return 0;
1189 bvec = bio_iter_iovec(bio, bio->bi_iter);
1190 prev_start_byte = start_byte;
1191 start_byte = page_offset(bvec.bv_page) - disk_start;
1192
1193 /*
1194 * We need to make sure we're only adjusting
1195 * our offset into compression working buffer when
1196 * we're switching pages. Otherwise we can incorrectly
1197 * keep copying when we were actually done.
1198 */
1199 if (start_byte != prev_start_byte) {
1200 /*
1201 * make sure our new page is covered by this
1202 * working buffer
1203 */
1204 if (total_out <= start_byte)
1205 return 1;
1206
1207 /*
1208 * the next page in the biovec might not be adjacent
1209 * to the last page, but it might still be found
1210 * inside this working buffer. bump our offset pointer
1211 */
1212 if (total_out > start_byte &&
1213 current_buf_start < start_byte) {
1214 buf_offset = start_byte - buf_start;
1215 working_bytes = total_out - start_byte;
1216 current_buf_start = buf_start + buf_offset;
1217 }
1218 }
1219 }
1220
1221 return 1;
1222}
1223
1224/*
1225 * Shannon Entropy calculation
1226 *
1227 * Pure byte distribution analysis fails to determine compressiability of data.
1228 * Try calculating entropy to estimate the average minimum number of bits
1229 * needed to encode the sampled data.
1230 *
1231 * For convenience, return the percentage of needed bits, instead of amount of
1232 * bits directly.
1233 *
1234 * @ENTROPY_LVL_ACEPTABLE - below that threshold, sample has low byte entropy
1235 * and can be compressible with high probability
1236 *
1237 * @ENTROPY_LVL_HIGH - data are not compressible with high probability
1238 *
1239 * Use of ilog2() decreases precision, we lower the LVL to 5 to compensate.
1240 */
1241#define ENTROPY_LVL_ACEPTABLE (65)
1242#define ENTROPY_LVL_HIGH (80)
1243
1244/*
1245 * For increasead precision in shannon_entropy calculation,
1246 * let's do pow(n, M) to save more digits after comma:
1247 *
1248 * - maximum int bit length is 64
1249 * - ilog2(MAX_SAMPLE_SIZE) -> 13
1250 * - 13 * 4 = 52 < 64 -> M = 4
1251 *
1252 * So use pow(n, 4).
1253 */
1254static inline u32 ilog2_w(u64 n)
1255{
1256 return ilog2(n * n * n * n);
1257}
1258
1259static u32 shannon_entropy(struct heuristic_ws *ws)
1260{
1261 const u32 entropy_max = 8 * ilog2_w(2);
1262 u32 entropy_sum = 0;
1263 u32 p, p_base, sz_base;
1264 u32 i;
1265
1266 sz_base = ilog2_w(ws->sample_size);
1267 for (i = 0; i < BUCKET_SIZE && ws->bucket[i].count > 0; i++) {
1268 p = ws->bucket[i].count;
1269 p_base = ilog2_w(p);
1270 entropy_sum += p * (sz_base - p_base);
1271 }
1272
1273 entropy_sum /= ws->sample_size;
1274 return entropy_sum * 100 / entropy_max;
1275}
1276
1277#define RADIX_BASE 4U
1278#define COUNTERS_SIZE (1U << RADIX_BASE)
1279
1280static u8 get4bits(u64 num, int shift) {
1281 u8 low4bits;
1282
1283 num >>= shift;
1284 /* Reverse order */
1285 low4bits = (COUNTERS_SIZE - 1) - (num % COUNTERS_SIZE);
1286 return low4bits;
1287}
1288
1289/*
1290 * Use 4 bits as radix base
1291 * Use 16 u32 counters for calculating new possition in buf array
1292 *
1293 * @array - array that will be sorted
1294 * @array_buf - buffer array to store sorting results
1295 * must be equal in size to @array
1296 * @num - array size
1297 */
1298static void radix_sort(struct bucket_item *array, struct bucket_item *array_buf,
1299 int num)
1300{
1301 u64 max_num;
1302 u64 buf_num;
1303 u32 counters[COUNTERS_SIZE];
1304 u32 new_addr;
1305 u32 addr;
1306 int bitlen;
1307 int shift;
1308 int i;
1309
1310 /*
1311 * Try avoid useless loop iterations for small numbers stored in big
1312 * counters. Example: 48 33 4 ... in 64bit array
1313 */
1314 max_num = array[0].count;
1315 for (i = 1; i < num; i++) {
1316 buf_num = array[i].count;
1317 if (buf_num > max_num)
1318 max_num = buf_num;
1319 }
1320
1321 buf_num = ilog2(max_num);
1322 bitlen = ALIGN(buf_num, RADIX_BASE * 2);
1323
1324 shift = 0;
1325 while (shift < bitlen) {
1326 memset(counters, 0, sizeof(counters));
1327
1328 for (i = 0; i < num; i++) {
1329 buf_num = array[i].count;
1330 addr = get4bits(buf_num, shift);
1331 counters[addr]++;
1332 }
1333
1334 for (i = 1; i < COUNTERS_SIZE; i++)
1335 counters[i] += counters[i - 1];
1336
1337 for (i = num - 1; i >= 0; i--) {
1338 buf_num = array[i].count;
1339 addr = get4bits(buf_num, shift);
1340 counters[addr]--;
1341 new_addr = counters[addr];
1342 array_buf[new_addr] = array[i];
1343 }
1344
1345 shift += RADIX_BASE;
1346
1347 /*
1348 * Normal radix expects to move data from a temporary array, to
1349 * the main one. But that requires some CPU time. Avoid that
1350 * by doing another sort iteration to original array instead of
1351 * memcpy()
1352 */
1353 memset(counters, 0, sizeof(counters));
1354
1355 for (i = 0; i < num; i ++) {
1356 buf_num = array_buf[i].count;
1357 addr = get4bits(buf_num, shift);
1358 counters[addr]++;
1359 }
1360
1361 for (i = 1; i < COUNTERS_SIZE; i++)
1362 counters[i] += counters[i - 1];
1363
1364 for (i = num - 1; i >= 0; i--) {
1365 buf_num = array_buf[i].count;
1366 addr = get4bits(buf_num, shift);
1367 counters[addr]--;
1368 new_addr = counters[addr];
1369 array[new_addr] = array_buf[i];
1370 }
1371
1372 shift += RADIX_BASE;
1373 }
1374}
1375
1376/*
1377 * Size of the core byte set - how many bytes cover 90% of the sample
1378 *
1379 * There are several types of structured binary data that use nearly all byte
1380 * values. The distribution can be uniform and counts in all buckets will be
1381 * nearly the same (eg. encrypted data). Unlikely to be compressible.
1382 *
1383 * Other possibility is normal (Gaussian) distribution, where the data could
1384 * be potentially compressible, but we have to take a few more steps to decide
1385 * how much.
1386 *
1387 * @BYTE_CORE_SET_LOW - main part of byte values repeated frequently,
1388 * compression algo can easy fix that
1389 * @BYTE_CORE_SET_HIGH - data have uniform distribution and with high
1390 * probability is not compressible
1391 */
1392#define BYTE_CORE_SET_LOW (64)
1393#define BYTE_CORE_SET_HIGH (200)
1394
1395static int byte_core_set_size(struct heuristic_ws *ws)
1396{
1397 u32 i;
1398 u32 coreset_sum = 0;
1399 const u32 core_set_threshold = ws->sample_size * 90 / 100;
1400 struct bucket_item *bucket = ws->bucket;
1401
1402 /* Sort in reverse order */
1403 radix_sort(ws->bucket, ws->bucket_b, BUCKET_SIZE);
1404
1405 for (i = 0; i < BYTE_CORE_SET_LOW; i++)
1406 coreset_sum += bucket[i].count;
1407
1408 if (coreset_sum > core_set_threshold)
1409 return i;
1410
1411 for (; i < BYTE_CORE_SET_HIGH && bucket[i].count > 0; i++) {
1412 coreset_sum += bucket[i].count;
1413 if (coreset_sum > core_set_threshold)
1414 break;
1415 }
1416
1417 return i;
1418}
1419
1420/*
1421 * Count byte values in buckets.
1422 * This heuristic can detect textual data (configs, xml, json, html, etc).
1423 * Because in most text-like data byte set is restricted to limited number of
1424 * possible characters, and that restriction in most cases makes data easy to
1425 * compress.
1426 *
1427 * @BYTE_SET_THRESHOLD - consider all data within this byte set size:
1428 * less - compressible
1429 * more - need additional analysis
1430 */
1431#define BYTE_SET_THRESHOLD (64)
1432
1433static u32 byte_set_size(const struct heuristic_ws *ws)
1434{
1435 u32 i;
1436 u32 byte_set_size = 0;
1437
1438 for (i = 0; i < BYTE_SET_THRESHOLD; i++) {
1439 if (ws->bucket[i].count > 0)
1440 byte_set_size++;
1441 }
1442
1443 /*
1444 * Continue collecting count of byte values in buckets. If the byte
1445 * set size is bigger then the threshold, it's pointless to continue,
1446 * the detection technique would fail for this type of data.
1447 */
1448 for (; i < BUCKET_SIZE; i++) {
1449 if (ws->bucket[i].count > 0) {
1450 byte_set_size++;
1451 if (byte_set_size > BYTE_SET_THRESHOLD)
1452 return byte_set_size;
1453 }
1454 }
1455
1456 return byte_set_size;
1457}
1458
1459static bool sample_repeated_patterns(struct heuristic_ws *ws)
1460{
1461 const u32 half_of_sample = ws->sample_size / 2;
1462 const u8 *data = ws->sample;
1463
1464 return memcmp(&data[0], &data[half_of_sample], half_of_sample) == 0;
1465}
1466
1467static void heuristic_collect_sample(struct inode *inode, u64 start, u64 end,
1468 struct heuristic_ws *ws)
1469{
1470 struct page *page;
1471 u64 index, index_end;
1472 u32 i, curr_sample_pos;
1473 u8 *in_data;
1474
1475 /*
1476 * Compression handles the input data by chunks of 128KiB
1477 * (defined by BTRFS_MAX_UNCOMPRESSED)
1478 *
1479 * We do the same for the heuristic and loop over the whole range.
1480 *
1481 * MAX_SAMPLE_SIZE - calculated under assumption that heuristic will
1482 * process no more than BTRFS_MAX_UNCOMPRESSED at a time.
1483 */
1484 if (end - start > BTRFS_MAX_UNCOMPRESSED)
1485 end = start + BTRFS_MAX_UNCOMPRESSED;
1486
1487 index = start >> PAGE_SHIFT;
1488 index_end = end >> PAGE_SHIFT;
1489
1490 /* Don't miss unaligned end */
1491 if (!IS_ALIGNED(end, PAGE_SIZE))
1492 index_end++;
1493
1494 curr_sample_pos = 0;
1495 while (index < index_end) {
1496 page = find_get_page(inode->i_mapping, index);
1497 in_data = kmap(page);
1498 /* Handle case where the start is not aligned to PAGE_SIZE */
1499 i = start % PAGE_SIZE;
1500 while (i < PAGE_SIZE - SAMPLING_READ_SIZE) {
1501 /* Don't sample any garbage from the last page */
1502 if (start > end - SAMPLING_READ_SIZE)
1503 break;
1504 memcpy(&ws->sample[curr_sample_pos], &in_data[i],
1505 SAMPLING_READ_SIZE);
1506 i += SAMPLING_INTERVAL;
1507 start += SAMPLING_INTERVAL;
1508 curr_sample_pos += SAMPLING_READ_SIZE;
1509 }
1510 kunmap(page);
1511 put_page(page);
1512
1513 index++;
1514 }
1515
1516 ws->sample_size = curr_sample_pos;
1517}
1518
1519/*
1520 * Compression heuristic.
1521 *
1522 * For now is's a naive and optimistic 'return true', we'll extend the logic to
1523 * quickly (compared to direct compression) detect data characteristics
1524 * (compressible/uncompressible) to avoid wasting CPU time on uncompressible
1525 * data.
1526 *
1527 * The following types of analysis can be performed:
1528 * - detect mostly zero data
1529 * - detect data with low "byte set" size (text, etc)
1530 * - detect data with low/high "core byte" set
1531 *
1532 * Return non-zero if the compression should be done, 0 otherwise.
1533 */
1534int btrfs_compress_heuristic(struct inode *inode, u64 start, u64 end)
1535{
1536 struct list_head *ws_list = __find_workspace(0, true);
1537 struct heuristic_ws *ws;
1538 u32 i;
1539 u8 byte;
1540 int ret = 0;
1541
1542 ws = list_entry(ws_list, struct heuristic_ws, list);
1543
1544 heuristic_collect_sample(inode, start, end, ws);
1545
1546 if (sample_repeated_patterns(ws)) {
1547 ret = 1;
1548 goto out;
1549 }
1550
1551 memset(ws->bucket, 0, sizeof(*ws->bucket)*BUCKET_SIZE);
1552
1553 for (i = 0; i < ws->sample_size; i++) {
1554 byte = ws->sample[i];
1555 ws->bucket[byte].count++;
1556 }
1557
1558 i = byte_set_size(ws);
1559 if (i < BYTE_SET_THRESHOLD) {
1560 ret = 2;
1561 goto out;
1562 }
1563
1564 i = byte_core_set_size(ws);
1565 if (i <= BYTE_CORE_SET_LOW) {
1566 ret = 3;
1567 goto out;
1568 }
1569
1570 if (i >= BYTE_CORE_SET_HIGH) {
1571 ret = 0;
1572 goto out;
1573 }
1574
1575 i = shannon_entropy(ws);
1576 if (i <= ENTROPY_LVL_ACEPTABLE) {
1577 ret = 4;
1578 goto out;
1579 }
1580
1581 /*
1582 * For the levels below ENTROPY_LVL_HIGH, additional analysis would be
1583 * needed to give green light to compression.
1584 *
1585 * For now just assume that compression at that level is not worth the
1586 * resources because:
1587 *
1588 * 1. it is possible to defrag the data later
1589 *
1590 * 2. the data would turn out to be hardly compressible, eg. 150 byte
1591 * values, every bucket has counter at level ~54. The heuristic would
1592 * be confused. This can happen when data have some internal repeated
1593 * patterns like "abbacbbc...". This can be detected by analyzing
1594 * pairs of bytes, which is too costly.
1595 */
1596 if (i < ENTROPY_LVL_HIGH) {
1597 ret = 5;
1598 goto out;
1599 } else {
1600 ret = 0;
1601 goto out;
1602 }
1603
1604out:
1605 __free_workspace(0, ws_list, true);
1606 return ret;
1607}
1608
1609unsigned int btrfs_compress_str2level(const char *str)
1610{
1611 if (strncmp(str, "zlib", 4) != 0)
1612 return 0;
1613
1614 /* Accepted form: zlib:1 up to zlib:9 and nothing left after the number */
1615 if (str[4] == ':' && '1' <= str[5] && str[5] <= '9' && str[6] == 0)
1616 return str[5] - '0';
1617
1618 return BTRFS_ZLIB_DEFAULT_LEVEL;
1619}
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 "ctree.h"
36#include "disk-io.h"
37#include "transaction.h"
38#include "btrfs_inode.h"
39#include "volumes.h"
40#include "ordered-data.h"
41#include "compression.h"
42#include "extent_io.h"
43#include "extent_map.h"
44
45struct compressed_bio {
46 /* number of bios pending for this compressed extent */
47 atomic_t pending_bios;
48
49 /* the pages with the compressed data on them */
50 struct page **compressed_pages;
51
52 /* inode that owns this data */
53 struct inode *inode;
54
55 /* starting offset in the inode for our pages */
56 u64 start;
57
58 /* number of bytes in the inode we're working on */
59 unsigned long len;
60
61 /* number of bytes on disk */
62 unsigned long compressed_len;
63
64 /* the compression algorithm for this bio */
65 int compress_type;
66
67 /* number of compressed pages in the array */
68 unsigned long nr_pages;
69
70 /* IO errors */
71 int errors;
72 int mirror_num;
73
74 /* for reads, this is the bio we are copying the data into */
75 struct bio *orig_bio;
76
77 /*
78 * the start of a variable length array of checksums only
79 * used by reads
80 */
81 u32 sums;
82};
83
84static int btrfs_decompress_biovec(int type, struct page **pages_in,
85 u64 disk_start, struct bio_vec *bvec,
86 int vcnt, size_t srclen);
87
88static inline int compressed_bio_size(struct btrfs_root *root,
89 unsigned long disk_size)
90{
91 u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
92
93 return sizeof(struct compressed_bio) +
94 ((disk_size + root->sectorsize - 1) / root->sectorsize) *
95 csum_size;
96}
97
98static struct bio *compressed_bio_alloc(struct block_device *bdev,
99 u64 first_byte, gfp_t gfp_flags)
100{
101 int nr_vecs;
102
103 nr_vecs = bio_get_nr_vecs(bdev);
104 return btrfs_bio_alloc(bdev, first_byte >> 9, nr_vecs, gfp_flags);
105}
106
107static int check_compressed_csum(struct inode *inode,
108 struct compressed_bio *cb,
109 u64 disk_start)
110{
111 int ret;
112 struct page *page;
113 unsigned long i;
114 char *kaddr;
115 u32 csum;
116 u32 *cb_sum = &cb->sums;
117
118 if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)
119 return 0;
120
121 for (i = 0; i < cb->nr_pages; i++) {
122 page = cb->compressed_pages[i];
123 csum = ~(u32)0;
124
125 kaddr = kmap_atomic(page);
126 csum = btrfs_csum_data(kaddr, csum, PAGE_CACHE_SIZE);
127 btrfs_csum_final(csum, (char *)&csum);
128 kunmap_atomic(kaddr);
129
130 if (csum != *cb_sum) {
131 btrfs_info(BTRFS_I(inode)->root->fs_info,
132 "csum failed ino %llu extent %llu csum %u wanted %u mirror %d",
133 btrfs_ino(inode), disk_start, csum, *cb_sum,
134 cb->mirror_num);
135 ret = -EIO;
136 goto fail;
137 }
138 cb_sum++;
139
140 }
141 ret = 0;
142fail:
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 */
156static 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,
175 (u64)bio->bi_iter.bi_sector << 9);
176 if (ret)
177 goto csum_failed;
178
179 /* ok, we're the last bio for this extent, lets start
180 * the decompression.
181 */
182 ret = btrfs_decompress_biovec(cb->compress_type,
183 cb->compressed_pages,
184 cb->start,
185 cb->orig_bio->bi_io_vec,
186 cb->orig_bio->bi_vcnt,
187 cb->compressed_len);
188csum_failed:
189 if (ret)
190 cb->errors = 1;
191
192 /* release the compressed pages */
193 index = 0;
194 for (index = 0; index < cb->nr_pages; index++) {
195 page = cb->compressed_pages[index];
196 page->mapping = NULL;
197 page_cache_release(page);
198 }
199
200 /* do io completion on the original bio */
201 if (cb->errors) {
202 bio_io_error(cb->orig_bio);
203 } else {
204 int i;
205 struct bio_vec *bvec;
206
207 /*
208 * we have verified the checksum already, set page
209 * checked so the end_io handlers know about it
210 */
211 bio_for_each_segment_all(bvec, cb->orig_bio, i)
212 SetPageChecked(bvec->bv_page);
213
214 bio_endio(cb->orig_bio, 0);
215 }
216
217 /* finally free the cb struct */
218 kfree(cb->compressed_pages);
219 kfree(cb);
220out:
221 bio_put(bio);
222}
223
224/*
225 * Clear the writeback bits on all of the file
226 * pages for a compressed write
227 */
228static noinline void 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}
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 */
265static 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);
311out:
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 */
324int 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 pg_index = 0;
336 struct page *page;
337 u64 first_byte = disk_start;
338 struct block_device *bdev;
339 int ret;
340 int skip_sum = BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM;
341
342 WARN_ON(start & ((u64)PAGE_CACHE_SIZE - 1));
343 cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS);
344 if (!cb)
345 return -ENOMEM;
346 atomic_set(&cb->pending_bios, 0);
347 cb->errors = 0;
348 cb->inode = inode;
349 cb->start = start;
350 cb->len = len;
351 cb->mirror_num = 0;
352 cb->compressed_pages = compressed_pages;
353 cb->compressed_len = compressed_len;
354 cb->orig_bio = NULL;
355 cb->nr_pages = nr_pages;
356
357 bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
358
359 bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
360 if (!bio) {
361 kfree(cb);
362 return -ENOMEM;
363 }
364 bio->bi_private = cb;
365 bio->bi_end_io = end_compressed_bio_write;
366 atomic_inc(&cb->pending_bios);
367
368 /* create and submit bios for the compressed pages */
369 bytes_left = compressed_len;
370 for (pg_index = 0; pg_index < cb->nr_pages; pg_index++) {
371 page = compressed_pages[pg_index];
372 page->mapping = inode->i_mapping;
373 if (bio->bi_iter.bi_size)
374 ret = io_tree->ops->merge_bio_hook(WRITE, page, 0,
375 PAGE_CACHE_SIZE,
376 bio, 0);
377 else
378 ret = 0;
379
380 page->mapping = NULL;
381 if (ret || bio_add_page(bio, page, PAGE_CACHE_SIZE, 0) <
382 PAGE_CACHE_SIZE) {
383 bio_get(bio);
384
385 /*
386 * inc the count before we submit the bio so
387 * we know the end IO handler won't happen before
388 * we inc the count. Otherwise, the cb might get
389 * freed before we're done setting it up
390 */
391 atomic_inc(&cb->pending_bios);
392 ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0);
393 BUG_ON(ret); /* -ENOMEM */
394
395 if (!skip_sum) {
396 ret = btrfs_csum_one_bio(root, inode, bio,
397 start, 1);
398 BUG_ON(ret); /* -ENOMEM */
399 }
400
401 ret = btrfs_map_bio(root, WRITE, bio, 0, 1);
402 BUG_ON(ret); /* -ENOMEM */
403
404 bio_put(bio);
405
406 bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
407 BUG_ON(!bio);
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 btrfs_info(BTRFS_I(inode)->root->fs_info,
414 "bytes left %lu compress len %lu nr %lu",
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); /* -ENOMEM */
425
426 if (!skip_sum) {
427 ret = btrfs_csum_one_bio(root, inode, bio, start, 1);
428 BUG_ON(ret); /* -ENOMEM */
429 }
430
431 ret = btrfs_map_bio(root, WRITE, bio, 0, 1);
432 BUG_ON(ret); /* -ENOMEM */
433
434 bio_put(bio);
435 return 0;
436}
437
438static 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 && !radix_tree_exceptional_entry(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);
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_iter.bi_sector) {
509 free_extent_map(em);
510 unlock_extent(tree, last_offset, end);
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);
525 memset(userpage + zero_offset, 0, zeros);
526 flush_dcache_page(page);
527 kunmap_atomic(userpage);
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);
539 unlock_page(page);
540 page_cache_release(page);
541 break;
542 }
543next:
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_iter.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 */
561int 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_iter.bi_sector << 9;
576 u64 em_len;
577 u64 em_start;
578 struct extent_map *em;
579 int ret = -ENOMEM;
580 int faili = 0;
581 u32 *sums;
582
583 tree = &BTRFS_I(inode)->io_tree;
584 em_tree = &BTRFS_I(inode)->extent_tree;
585
586 /* we need the actual starting offset of this extent in the file */
587 read_lock(&em_tree->lock);
588 em = lookup_extent_mapping(em_tree,
589 page_offset(bio->bi_io_vec->bv_page),
590 PAGE_CACHE_SIZE);
591 read_unlock(&em_tree->lock);
592 if (!em)
593 return -EIO;
594
595 compressed_len = em->block_len;
596 cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS);
597 if (!cb)
598 goto out;
599
600 atomic_set(&cb->pending_bios, 0);
601 cb->errors = 0;
602 cb->inode = inode;
603 cb->mirror_num = mirror_num;
604 sums = &cb->sums;
605
606 cb->start = em->orig_start;
607 em_len = em->len;
608 em_start = em->start;
609
610 free_extent_map(em);
611 em = NULL;
612
613 cb->len = uncompressed_len;
614 cb->compressed_len = compressed_len;
615 cb->compress_type = extent_compress_type(bio_flags);
616 cb->orig_bio = bio;
617
618 nr_pages = (compressed_len + PAGE_CACHE_SIZE - 1) /
619 PAGE_CACHE_SIZE;
620 cb->compressed_pages = kzalloc(sizeof(struct page *) * nr_pages,
621 GFP_NOFS);
622 if (!cb->compressed_pages)
623 goto fail1;
624
625 bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
626
627 for (pg_index = 0; pg_index < nr_pages; pg_index++) {
628 cb->compressed_pages[pg_index] = alloc_page(GFP_NOFS |
629 __GFP_HIGHMEM);
630 if (!cb->compressed_pages[pg_index]) {
631 faili = pg_index - 1;
632 ret = -ENOMEM;
633 goto fail2;
634 }
635 }
636 faili = nr_pages - 1;
637 cb->nr_pages = nr_pages;
638
639 /* In the parent-locked case, we only locked the range we are
640 * interested in. In all other cases, we can opportunistically
641 * cache decompressed data that goes beyond the requested range. */
642 if (!(bio_flags & EXTENT_BIO_PARENT_LOCKED))
643 add_ra_bio_pages(inode, em_start + em_len, cb);
644
645 /* include any pages we added in add_ra-bio_pages */
646 uncompressed_len = bio->bi_vcnt * PAGE_CACHE_SIZE;
647 cb->len = uncompressed_len;
648
649 comp_bio = compressed_bio_alloc(bdev, cur_disk_byte, GFP_NOFS);
650 if (!comp_bio)
651 goto fail2;
652 comp_bio->bi_private = cb;
653 comp_bio->bi_end_io = end_compressed_bio_read;
654 atomic_inc(&cb->pending_bios);
655
656 for (pg_index = 0; pg_index < nr_pages; pg_index++) {
657 page = cb->compressed_pages[pg_index];
658 page->mapping = inode->i_mapping;
659 page->index = em_start >> PAGE_CACHE_SHIFT;
660
661 if (comp_bio->bi_iter.bi_size)
662 ret = tree->ops->merge_bio_hook(READ, page, 0,
663 PAGE_CACHE_SIZE,
664 comp_bio, 0);
665 else
666 ret = 0;
667
668 page->mapping = NULL;
669 if (ret || bio_add_page(comp_bio, page, PAGE_CACHE_SIZE, 0) <
670 PAGE_CACHE_SIZE) {
671 bio_get(comp_bio);
672
673 ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0);
674 BUG_ON(ret); /* -ENOMEM */
675
676 /*
677 * inc the count before we submit the bio so
678 * we know the end IO handler won't happen before
679 * we inc the count. Otherwise, the cb might get
680 * freed before we're done setting it up
681 */
682 atomic_inc(&cb->pending_bios);
683
684 if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
685 ret = btrfs_lookup_bio_sums(root, inode,
686 comp_bio, sums);
687 BUG_ON(ret); /* -ENOMEM */
688 }
689 sums += (comp_bio->bi_iter.bi_size +
690 root->sectorsize - 1) / root->sectorsize;
691
692 ret = btrfs_map_bio(root, READ, comp_bio,
693 mirror_num, 0);
694 if (ret)
695 bio_endio(comp_bio, ret);
696
697 bio_put(comp_bio);
698
699 comp_bio = compressed_bio_alloc(bdev, cur_disk_byte,
700 GFP_NOFS);
701 BUG_ON(!comp_bio);
702 comp_bio->bi_private = cb;
703 comp_bio->bi_end_io = end_compressed_bio_read;
704
705 bio_add_page(comp_bio, page, PAGE_CACHE_SIZE, 0);
706 }
707 cur_disk_byte += PAGE_CACHE_SIZE;
708 }
709 bio_get(comp_bio);
710
711 ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0);
712 BUG_ON(ret); /* -ENOMEM */
713
714 if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
715 ret = btrfs_lookup_bio_sums(root, inode, comp_bio, sums);
716 BUG_ON(ret); /* -ENOMEM */
717 }
718
719 ret = btrfs_map_bio(root, READ, comp_bio, mirror_num, 0);
720 if (ret)
721 bio_endio(comp_bio, ret);
722
723 bio_put(comp_bio);
724 return 0;
725
726fail2:
727 while (faili >= 0) {
728 __free_page(cb->compressed_pages[faili]);
729 faili--;
730 }
731
732 kfree(cb->compressed_pages);
733fail1:
734 kfree(cb);
735out:
736 free_extent_map(em);
737 return ret;
738}
739
740static struct list_head comp_idle_workspace[BTRFS_COMPRESS_TYPES];
741static spinlock_t comp_workspace_lock[BTRFS_COMPRESS_TYPES];
742static int comp_num_workspace[BTRFS_COMPRESS_TYPES];
743static atomic_t comp_alloc_workspace[BTRFS_COMPRESS_TYPES];
744static wait_queue_head_t comp_workspace_wait[BTRFS_COMPRESS_TYPES];
745
746static struct btrfs_compress_op *btrfs_compress_op[] = {
747 &btrfs_zlib_compress,
748 &btrfs_lzo_compress,
749};
750
751void __init btrfs_init_compress(void)
752{
753 int i;
754
755 for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
756 INIT_LIST_HEAD(&comp_idle_workspace[i]);
757 spin_lock_init(&comp_workspace_lock[i]);
758 atomic_set(&comp_alloc_workspace[i], 0);
759 init_waitqueue_head(&comp_workspace_wait[i]);
760 }
761}
762
763/*
764 * this finds an available workspace or allocates a new one
765 * ERR_PTR is returned if things go bad.
766 */
767static struct list_head *find_workspace(int type)
768{
769 struct list_head *workspace;
770 int cpus = num_online_cpus();
771 int idx = type - 1;
772
773 struct list_head *idle_workspace = &comp_idle_workspace[idx];
774 spinlock_t *workspace_lock = &comp_workspace_lock[idx];
775 atomic_t *alloc_workspace = &comp_alloc_workspace[idx];
776 wait_queue_head_t *workspace_wait = &comp_workspace_wait[idx];
777 int *num_workspace = &comp_num_workspace[idx];
778again:
779 spin_lock(workspace_lock);
780 if (!list_empty(idle_workspace)) {
781 workspace = idle_workspace->next;
782 list_del(workspace);
783 (*num_workspace)--;
784 spin_unlock(workspace_lock);
785 return workspace;
786
787 }
788 if (atomic_read(alloc_workspace) > cpus) {
789 DEFINE_WAIT(wait);
790
791 spin_unlock(workspace_lock);
792 prepare_to_wait(workspace_wait, &wait, TASK_UNINTERRUPTIBLE);
793 if (atomic_read(alloc_workspace) > cpus && !*num_workspace)
794 schedule();
795 finish_wait(workspace_wait, &wait);
796 goto again;
797 }
798 atomic_inc(alloc_workspace);
799 spin_unlock(workspace_lock);
800
801 workspace = btrfs_compress_op[idx]->alloc_workspace();
802 if (IS_ERR(workspace)) {
803 atomic_dec(alloc_workspace);
804 wake_up(workspace_wait);
805 }
806 return workspace;
807}
808
809/*
810 * put a workspace struct back on the list or free it if we have enough
811 * idle ones sitting around
812 */
813static void free_workspace(int type, struct list_head *workspace)
814{
815 int idx = type - 1;
816 struct list_head *idle_workspace = &comp_idle_workspace[idx];
817 spinlock_t *workspace_lock = &comp_workspace_lock[idx];
818 atomic_t *alloc_workspace = &comp_alloc_workspace[idx];
819 wait_queue_head_t *workspace_wait = &comp_workspace_wait[idx];
820 int *num_workspace = &comp_num_workspace[idx];
821
822 spin_lock(workspace_lock);
823 if (*num_workspace < num_online_cpus()) {
824 list_add_tail(workspace, idle_workspace);
825 (*num_workspace)++;
826 spin_unlock(workspace_lock);
827 goto wake;
828 }
829 spin_unlock(workspace_lock);
830
831 btrfs_compress_op[idx]->free_workspace(workspace);
832 atomic_dec(alloc_workspace);
833wake:
834 smp_mb();
835 if (waitqueue_active(workspace_wait))
836 wake_up(workspace_wait);
837}
838
839/*
840 * cleanup function for module exit
841 */
842static void free_workspaces(void)
843{
844 struct list_head *workspace;
845 int i;
846
847 for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
848 while (!list_empty(&comp_idle_workspace[i])) {
849 workspace = comp_idle_workspace[i].next;
850 list_del(workspace);
851 btrfs_compress_op[i]->free_workspace(workspace);
852 atomic_dec(&comp_alloc_workspace[i]);
853 }
854 }
855}
856
857/*
858 * given an address space and start/len, compress the bytes.
859 *
860 * pages are allocated to hold the compressed result and stored
861 * in 'pages'
862 *
863 * out_pages is used to return the number of pages allocated. There
864 * may be pages allocated even if we return an error
865 *
866 * total_in is used to return the number of bytes actually read. It
867 * may be smaller then len if we had to exit early because we
868 * ran out of room in the pages array or because we cross the
869 * max_out threshold.
870 *
871 * total_out is used to return the total number of compressed bytes
872 *
873 * max_out tells us the max number of bytes that we're allowed to
874 * stuff into pages
875 */
876int btrfs_compress_pages(int type, struct address_space *mapping,
877 u64 start, unsigned long len,
878 struct page **pages,
879 unsigned long nr_dest_pages,
880 unsigned long *out_pages,
881 unsigned long *total_in,
882 unsigned long *total_out,
883 unsigned long max_out)
884{
885 struct list_head *workspace;
886 int ret;
887
888 workspace = find_workspace(type);
889 if (IS_ERR(workspace))
890 return -1;
891
892 ret = btrfs_compress_op[type-1]->compress_pages(workspace, mapping,
893 start, len, pages,
894 nr_dest_pages, out_pages,
895 total_in, total_out,
896 max_out);
897 free_workspace(type, workspace);
898 return ret;
899}
900
901/*
902 * pages_in is an array of pages with compressed data.
903 *
904 * disk_start is the starting logical offset of this array in the file
905 *
906 * bvec is a bio_vec of pages from the file that we want to decompress into
907 *
908 * vcnt is the count of pages in the biovec
909 *
910 * srclen is the number of bytes in pages_in
911 *
912 * The basic idea is that we have a bio that was created by readpages.
913 * The pages in the bio are for the uncompressed data, and they may not
914 * be contiguous. They all correspond to the range of bytes covered by
915 * the compressed extent.
916 */
917static int btrfs_decompress_biovec(int type, struct page **pages_in,
918 u64 disk_start, struct bio_vec *bvec,
919 int vcnt, size_t srclen)
920{
921 struct list_head *workspace;
922 int ret;
923
924 workspace = find_workspace(type);
925 if (IS_ERR(workspace))
926 return -ENOMEM;
927
928 ret = btrfs_compress_op[type-1]->decompress_biovec(workspace, pages_in,
929 disk_start,
930 bvec, vcnt, srclen);
931 free_workspace(type, workspace);
932 return ret;
933}
934
935/*
936 * a less complex decompression routine. Our compressed data fits in a
937 * single page, and we want to read a single page out of it.
938 * start_byte tells us the offset into the compressed data we're interested in
939 */
940int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
941 unsigned long start_byte, size_t srclen, size_t destlen)
942{
943 struct list_head *workspace;
944 int ret;
945
946 workspace = find_workspace(type);
947 if (IS_ERR(workspace))
948 return -ENOMEM;
949
950 ret = btrfs_compress_op[type-1]->decompress(workspace, data_in,
951 dest_page, start_byte,
952 srclen, destlen);
953
954 free_workspace(type, workspace);
955 return ret;
956}
957
958void btrfs_exit_compress(void)
959{
960 free_workspaces();
961}
962
963/*
964 * Copy uncompressed data from working buffer to pages.
965 *
966 * buf_start is the byte offset we're of the start of our workspace buffer.
967 *
968 * total_out is the last byte of the buffer
969 */
970int btrfs_decompress_buf2page(char *buf, unsigned long buf_start,
971 unsigned long total_out, u64 disk_start,
972 struct bio_vec *bvec, int vcnt,
973 unsigned long *pg_index,
974 unsigned long *pg_offset)
975{
976 unsigned long buf_offset;
977 unsigned long current_buf_start;
978 unsigned long start_byte;
979 unsigned long working_bytes = total_out - buf_start;
980 unsigned long bytes;
981 char *kaddr;
982 struct page *page_out = bvec[*pg_index].bv_page;
983
984 /*
985 * start byte is the first byte of the page we're currently
986 * copying into relative to the start of the compressed data.
987 */
988 start_byte = page_offset(page_out) - disk_start;
989
990 /* we haven't yet hit data corresponding to this page */
991 if (total_out <= start_byte)
992 return 1;
993
994 /*
995 * the start of the data we care about is offset into
996 * the middle of our working buffer
997 */
998 if (total_out > start_byte && buf_start < start_byte) {
999 buf_offset = start_byte - buf_start;
1000 working_bytes -= buf_offset;
1001 } else {
1002 buf_offset = 0;
1003 }
1004 current_buf_start = buf_start;
1005
1006 /* copy bytes from the working buffer into the pages */
1007 while (working_bytes > 0) {
1008 bytes = min(PAGE_CACHE_SIZE - *pg_offset,
1009 PAGE_CACHE_SIZE - buf_offset);
1010 bytes = min(bytes, working_bytes);
1011 kaddr = kmap_atomic(page_out);
1012 memcpy(kaddr + *pg_offset, buf + buf_offset, bytes);
1013 if (*pg_index == (vcnt - 1) && *pg_offset == 0)
1014 memset(kaddr + bytes, 0, PAGE_CACHE_SIZE - bytes);
1015 kunmap_atomic(kaddr);
1016 flush_dcache_page(page_out);
1017
1018 *pg_offset += bytes;
1019 buf_offset += bytes;
1020 working_bytes -= bytes;
1021 current_buf_start += bytes;
1022
1023 /* check if we need to pick another page */
1024 if (*pg_offset == PAGE_CACHE_SIZE) {
1025 (*pg_index)++;
1026 if (*pg_index >= vcnt)
1027 return 0;
1028
1029 page_out = bvec[*pg_index].bv_page;
1030 *pg_offset = 0;
1031 start_byte = page_offset(page_out) - disk_start;
1032
1033 /*
1034 * make sure our new page is covered by this
1035 * working buffer
1036 */
1037 if (total_out <= start_byte)
1038 return 1;
1039
1040 /*
1041 * the next page in the biovec might not be adjacent
1042 * to the last page, but it might still be found
1043 * inside this working buffer. bump our offset pointer
1044 */
1045 if (total_out > start_byte &&
1046 current_buf_start < start_byte) {
1047 buf_offset = start_byte - buf_start;
1048 working_bytes = total_out - start_byte;
1049 current_buf_start = buf_start + buf_offset;
1050 }
1051 }
1052 }
1053
1054 return 1;
1055}