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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/file.h>
9#include <linux/fs.h>
10#include <linux/pagemap.h>
11#include <linux/pagevec.h>
12#include <linux/highmem.h>
13#include <linux/kthread.h>
14#include <linux/time.h>
15#include <linux/init.h>
16#include <linux/string.h>
17#include <linux/backing-dev.h>
18#include <linux/writeback.h>
19#include <linux/psi.h>
20#include <linux/slab.h>
21#include <linux/sched/mm.h>
22#include <linux/log2.h>
23#include <linux/shrinker.h>
24#include <crypto/hash.h>
25#include "misc.h"
26#include "ctree.h"
27#include "fs.h"
28#include "disk-io.h"
29#include "transaction.h"
30#include "btrfs_inode.h"
31#include "bio.h"
32#include "ordered-data.h"
33#include "compression.h"
34#include "extent_io.h"
35#include "extent_map.h"
36#include "subpage.h"
37#include "zoned.h"
38#include "file-item.h"
39#include "super.h"
40
41static struct bio_set btrfs_compressed_bioset;
42
43static const char* const btrfs_compress_types[] = { "", "zlib", "lzo", "zstd" };
44
45const char* btrfs_compress_type2str(enum btrfs_compression_type type)
46{
47 switch (type) {
48 case BTRFS_COMPRESS_ZLIB:
49 case BTRFS_COMPRESS_LZO:
50 case BTRFS_COMPRESS_ZSTD:
51 case BTRFS_COMPRESS_NONE:
52 return btrfs_compress_types[type];
53 default:
54 break;
55 }
56
57 return NULL;
58}
59
60static inline struct compressed_bio *to_compressed_bio(struct btrfs_bio *bbio)
61{
62 return container_of(bbio, struct compressed_bio, bbio);
63}
64
65static struct compressed_bio *alloc_compressed_bio(struct btrfs_inode *inode,
66 u64 start, blk_opf_t op,
67 btrfs_bio_end_io_t end_io)
68{
69 struct btrfs_bio *bbio;
70
71 bbio = btrfs_bio(bio_alloc_bioset(NULL, BTRFS_MAX_COMPRESSED_PAGES, op,
72 GFP_NOFS, &btrfs_compressed_bioset));
73 btrfs_bio_init(bbio, inode->root->fs_info, end_io, NULL);
74 bbio->inode = inode;
75 bbio->file_offset = start;
76 return to_compressed_bio(bbio);
77}
78
79bool btrfs_compress_is_valid_type(const char *str, size_t len)
80{
81 int i;
82
83 for (i = 1; i < ARRAY_SIZE(btrfs_compress_types); i++) {
84 size_t comp_len = strlen(btrfs_compress_types[i]);
85
86 if (len < comp_len)
87 continue;
88
89 if (!strncmp(btrfs_compress_types[i], str, comp_len))
90 return true;
91 }
92 return false;
93}
94
95static int compression_compress_pages(int type, struct list_head *ws,
96 struct address_space *mapping, u64 start, struct page **pages,
97 unsigned long *out_pages, unsigned long *total_in,
98 unsigned long *total_out)
99{
100 switch (type) {
101 case BTRFS_COMPRESS_ZLIB:
102 return zlib_compress_pages(ws, mapping, start, pages,
103 out_pages, total_in, total_out);
104 case BTRFS_COMPRESS_LZO:
105 return lzo_compress_pages(ws, mapping, start, pages,
106 out_pages, total_in, total_out);
107 case BTRFS_COMPRESS_ZSTD:
108 return zstd_compress_pages(ws, mapping, start, pages,
109 out_pages, total_in, total_out);
110 case BTRFS_COMPRESS_NONE:
111 default:
112 /*
113 * This can happen when compression races with remount setting
114 * it to 'no compress', while caller doesn't call
115 * inode_need_compress() to check if we really need to
116 * compress.
117 *
118 * Not a big deal, just need to inform caller that we
119 * haven't allocated any pages yet.
120 */
121 *out_pages = 0;
122 return -E2BIG;
123 }
124}
125
126static int compression_decompress_bio(struct list_head *ws,
127 struct compressed_bio *cb)
128{
129 switch (cb->compress_type) {
130 case BTRFS_COMPRESS_ZLIB: return zlib_decompress_bio(ws, cb);
131 case BTRFS_COMPRESS_LZO: return lzo_decompress_bio(ws, cb);
132 case BTRFS_COMPRESS_ZSTD: return zstd_decompress_bio(ws, cb);
133 case BTRFS_COMPRESS_NONE:
134 default:
135 /*
136 * This can't happen, the type is validated several times
137 * before we get here.
138 */
139 BUG();
140 }
141}
142
143static int compression_decompress(int type, struct list_head *ws,
144 const u8 *data_in, struct page *dest_page,
145 unsigned long dest_pgoff, size_t srclen, size_t destlen)
146{
147 switch (type) {
148 case BTRFS_COMPRESS_ZLIB: return zlib_decompress(ws, data_in, dest_page,
149 dest_pgoff, srclen, destlen);
150 case BTRFS_COMPRESS_LZO: return lzo_decompress(ws, data_in, dest_page,
151 dest_pgoff, srclen, destlen);
152 case BTRFS_COMPRESS_ZSTD: return zstd_decompress(ws, data_in, dest_page,
153 dest_pgoff, srclen, destlen);
154 case BTRFS_COMPRESS_NONE:
155 default:
156 /*
157 * This can't happen, the type is validated several times
158 * before we get here.
159 */
160 BUG();
161 }
162}
163
164static void btrfs_free_compressed_pages(struct compressed_bio *cb)
165{
166 for (unsigned int i = 0; i < cb->nr_pages; i++)
167 btrfs_free_compr_page(cb->compressed_pages[i]);
168 kfree(cb->compressed_pages);
169}
170
171static int btrfs_decompress_bio(struct compressed_bio *cb);
172
173/*
174 * Global cache of last unused pages for compression/decompression.
175 */
176static struct btrfs_compr_pool {
177 struct shrinker *shrinker;
178 spinlock_t lock;
179 struct list_head list;
180 int count;
181 int thresh;
182} compr_pool;
183
184static unsigned long btrfs_compr_pool_count(struct shrinker *sh, struct shrink_control *sc)
185{
186 int ret;
187
188 /*
189 * We must not read the values more than once if 'ret' gets expanded in
190 * the return statement so we don't accidentally return a negative
191 * number, even if the first condition finds it positive.
192 */
193 ret = READ_ONCE(compr_pool.count) - READ_ONCE(compr_pool.thresh);
194
195 return ret > 0 ? ret : 0;
196}
197
198static unsigned long btrfs_compr_pool_scan(struct shrinker *sh, struct shrink_control *sc)
199{
200 struct list_head remove;
201 struct list_head *tmp, *next;
202 int freed;
203
204 if (compr_pool.count == 0)
205 return SHRINK_STOP;
206
207 INIT_LIST_HEAD(&remove);
208
209 /* For now, just simply drain the whole list. */
210 spin_lock(&compr_pool.lock);
211 list_splice_init(&compr_pool.list, &remove);
212 freed = compr_pool.count;
213 compr_pool.count = 0;
214 spin_unlock(&compr_pool.lock);
215
216 list_for_each_safe(tmp, next, &remove) {
217 struct page *page = list_entry(tmp, struct page, lru);
218
219 ASSERT(page_ref_count(page) == 1);
220 put_page(page);
221 }
222
223 return freed;
224}
225
226/*
227 * Common wrappers for page allocation from compression wrappers
228 */
229struct page *btrfs_alloc_compr_page(void)
230{
231 struct page *page = NULL;
232
233 spin_lock(&compr_pool.lock);
234 if (compr_pool.count > 0) {
235 page = list_first_entry(&compr_pool.list, struct page, lru);
236 list_del_init(&page->lru);
237 compr_pool.count--;
238 }
239 spin_unlock(&compr_pool.lock);
240
241 if (page)
242 return page;
243
244 return alloc_page(GFP_NOFS);
245}
246
247void btrfs_free_compr_page(struct page *page)
248{
249 bool do_free = false;
250
251 spin_lock(&compr_pool.lock);
252 if (compr_pool.count > compr_pool.thresh) {
253 do_free = true;
254 } else {
255 list_add(&page->lru, &compr_pool.list);
256 compr_pool.count++;
257 }
258 spin_unlock(&compr_pool.lock);
259
260 if (!do_free)
261 return;
262
263 ASSERT(page_ref_count(page) == 1);
264 put_page(page);
265}
266
267static void end_bbio_comprssed_read(struct btrfs_bio *bbio)
268{
269 struct compressed_bio *cb = to_compressed_bio(bbio);
270 blk_status_t status = bbio->bio.bi_status;
271
272 if (!status)
273 status = errno_to_blk_status(btrfs_decompress_bio(cb));
274
275 btrfs_free_compressed_pages(cb);
276 btrfs_bio_end_io(cb->orig_bbio, status);
277 bio_put(&bbio->bio);
278}
279
280/*
281 * Clear the writeback bits on all of the file
282 * pages for a compressed write
283 */
284static noinline void end_compressed_writeback(const struct compressed_bio *cb)
285{
286 struct inode *inode = &cb->bbio.inode->vfs_inode;
287 struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
288 unsigned long index = cb->start >> PAGE_SHIFT;
289 unsigned long end_index = (cb->start + cb->len - 1) >> PAGE_SHIFT;
290 struct folio_batch fbatch;
291 const int error = blk_status_to_errno(cb->bbio.bio.bi_status);
292 int i;
293 int ret;
294
295 if (error)
296 mapping_set_error(inode->i_mapping, error);
297
298 folio_batch_init(&fbatch);
299 while (index <= end_index) {
300 ret = filemap_get_folios(inode->i_mapping, &index, end_index,
301 &fbatch);
302
303 if (ret == 0)
304 return;
305
306 for (i = 0; i < ret; i++) {
307 struct folio *folio = fbatch.folios[i];
308
309 btrfs_folio_clamp_clear_writeback(fs_info, folio,
310 cb->start, cb->len);
311 }
312 folio_batch_release(&fbatch);
313 }
314 /* the inode may be gone now */
315}
316
317static void btrfs_finish_compressed_write_work(struct work_struct *work)
318{
319 struct compressed_bio *cb =
320 container_of(work, struct compressed_bio, write_end_work);
321
322 btrfs_finish_ordered_extent(cb->bbio.ordered, NULL, cb->start, cb->len,
323 cb->bbio.bio.bi_status == BLK_STS_OK);
324
325 if (cb->writeback)
326 end_compressed_writeback(cb);
327 /* Note, our inode could be gone now */
328
329 btrfs_free_compressed_pages(cb);
330 bio_put(&cb->bbio.bio);
331}
332
333/*
334 * Do the cleanup once all the compressed pages hit the disk. This will clear
335 * writeback on the file pages and free the compressed pages.
336 *
337 * This also calls the writeback end hooks for the file pages so that metadata
338 * and checksums can be updated in the file.
339 */
340static void end_bbio_comprssed_write(struct btrfs_bio *bbio)
341{
342 struct compressed_bio *cb = to_compressed_bio(bbio);
343 struct btrfs_fs_info *fs_info = bbio->inode->root->fs_info;
344
345 queue_work(fs_info->compressed_write_workers, &cb->write_end_work);
346}
347
348static void btrfs_add_compressed_bio_pages(struct compressed_bio *cb)
349{
350 struct bio *bio = &cb->bbio.bio;
351 u32 offset = 0;
352
353 while (offset < cb->compressed_len) {
354 u32 len = min_t(u32, cb->compressed_len - offset, PAGE_SIZE);
355
356 /* Maximum compressed extent is smaller than bio size limit. */
357 __bio_add_page(bio, cb->compressed_pages[offset >> PAGE_SHIFT],
358 len, 0);
359 offset += len;
360 }
361}
362
363/*
364 * worker function to build and submit bios for previously compressed pages.
365 * The corresponding pages in the inode should be marked for writeback
366 * and the compressed pages should have a reference on them for dropping
367 * when the IO is complete.
368 *
369 * This also checksums the file bytes and gets things ready for
370 * the end io hooks.
371 */
372void btrfs_submit_compressed_write(struct btrfs_ordered_extent *ordered,
373 struct page **compressed_pages,
374 unsigned int nr_pages,
375 blk_opf_t write_flags,
376 bool writeback)
377{
378 struct btrfs_inode *inode = BTRFS_I(ordered->inode);
379 struct btrfs_fs_info *fs_info = inode->root->fs_info;
380 struct compressed_bio *cb;
381
382 ASSERT(IS_ALIGNED(ordered->file_offset, fs_info->sectorsize));
383 ASSERT(IS_ALIGNED(ordered->num_bytes, fs_info->sectorsize));
384
385 cb = alloc_compressed_bio(inode, ordered->file_offset,
386 REQ_OP_WRITE | write_flags,
387 end_bbio_comprssed_write);
388 cb->start = ordered->file_offset;
389 cb->len = ordered->num_bytes;
390 cb->compressed_pages = compressed_pages;
391 cb->compressed_len = ordered->disk_num_bytes;
392 cb->writeback = writeback;
393 INIT_WORK(&cb->write_end_work, btrfs_finish_compressed_write_work);
394 cb->nr_pages = nr_pages;
395 cb->bbio.bio.bi_iter.bi_sector = ordered->disk_bytenr >> SECTOR_SHIFT;
396 cb->bbio.ordered = ordered;
397 btrfs_add_compressed_bio_pages(cb);
398
399 btrfs_submit_bio(&cb->bbio, 0);
400}
401
402/*
403 * Add extra pages in the same compressed file extent so that we don't need to
404 * re-read the same extent again and again.
405 *
406 * NOTE: this won't work well for subpage, as for subpage read, we lock the
407 * full page then submit bio for each compressed/regular extents.
408 *
409 * This means, if we have several sectors in the same page points to the same
410 * on-disk compressed data, we will re-read the same extent many times and
411 * this function can only help for the next page.
412 */
413static noinline int add_ra_bio_pages(struct inode *inode,
414 u64 compressed_end,
415 struct compressed_bio *cb,
416 int *memstall, unsigned long *pflags)
417{
418 struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
419 unsigned long end_index;
420 struct bio *orig_bio = &cb->orig_bbio->bio;
421 u64 cur = cb->orig_bbio->file_offset + orig_bio->bi_iter.bi_size;
422 u64 isize = i_size_read(inode);
423 int ret;
424 struct page *page;
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 int sectors_missed = 0;
430
431 em_tree = &BTRFS_I(inode)->extent_tree;
432 tree = &BTRFS_I(inode)->io_tree;
433
434 if (isize == 0)
435 return 0;
436
437 /*
438 * For current subpage support, we only support 64K page size,
439 * which means maximum compressed extent size (128K) is just 2x page
440 * size.
441 * This makes readahead less effective, so here disable readahead for
442 * subpage for now, until full compressed write is supported.
443 */
444 if (btrfs_sb(inode->i_sb)->sectorsize < PAGE_SIZE)
445 return 0;
446
447 end_index = (i_size_read(inode) - 1) >> PAGE_SHIFT;
448
449 while (cur < compressed_end) {
450 u64 page_end;
451 u64 pg_index = cur >> PAGE_SHIFT;
452 u32 add_size;
453
454 if (pg_index > end_index)
455 break;
456
457 page = xa_load(&mapping->i_pages, pg_index);
458 if (page && !xa_is_value(page)) {
459 sectors_missed += (PAGE_SIZE - offset_in_page(cur)) >>
460 fs_info->sectorsize_bits;
461
462 /* Beyond threshold, no need to continue */
463 if (sectors_missed > 4)
464 break;
465
466 /*
467 * Jump to next page start as we already have page for
468 * current offset.
469 */
470 cur = (pg_index << PAGE_SHIFT) + PAGE_SIZE;
471 continue;
472 }
473
474 page = __page_cache_alloc(mapping_gfp_constraint(mapping,
475 ~__GFP_FS));
476 if (!page)
477 break;
478
479 if (add_to_page_cache_lru(page, mapping, pg_index, GFP_NOFS)) {
480 put_page(page);
481 /* There is already a page, skip to page end */
482 cur = (pg_index << PAGE_SHIFT) + PAGE_SIZE;
483 continue;
484 }
485
486 if (!*memstall && PageWorkingset(page)) {
487 psi_memstall_enter(pflags);
488 *memstall = 1;
489 }
490
491 ret = set_page_extent_mapped(page);
492 if (ret < 0) {
493 unlock_page(page);
494 put_page(page);
495 break;
496 }
497
498 page_end = (pg_index << PAGE_SHIFT) + PAGE_SIZE - 1;
499 lock_extent(tree, cur, page_end, NULL);
500 read_lock(&em_tree->lock);
501 em = lookup_extent_mapping(em_tree, cur, page_end + 1 - cur);
502 read_unlock(&em_tree->lock);
503
504 /*
505 * At this point, we have a locked page in the page cache for
506 * these bytes in the file. But, we have to make sure they map
507 * to this compressed extent on disk.
508 */
509 if (!em || cur < em->start ||
510 (cur + fs_info->sectorsize > extent_map_end(em)) ||
511 (em->block_start >> SECTOR_SHIFT) != orig_bio->bi_iter.bi_sector) {
512 free_extent_map(em);
513 unlock_extent(tree, cur, page_end, NULL);
514 unlock_page(page);
515 put_page(page);
516 break;
517 }
518 free_extent_map(em);
519
520 if (page->index == end_index) {
521 size_t zero_offset = offset_in_page(isize);
522
523 if (zero_offset) {
524 int zeros;
525 zeros = PAGE_SIZE - zero_offset;
526 memzero_page(page, zero_offset, zeros);
527 }
528 }
529
530 add_size = min(em->start + em->len, page_end + 1) - cur;
531 ret = bio_add_page(orig_bio, page, add_size, offset_in_page(cur));
532 if (ret != add_size) {
533 unlock_extent(tree, cur, page_end, NULL);
534 unlock_page(page);
535 put_page(page);
536 break;
537 }
538 /*
539 * If it's subpage, we also need to increase its
540 * subpage::readers number, as at endio we will decrease
541 * subpage::readers and to unlock the page.
542 */
543 if (fs_info->sectorsize < PAGE_SIZE)
544 btrfs_subpage_start_reader(fs_info, page_folio(page),
545 cur, add_size);
546 put_page(page);
547 cur += add_size;
548 }
549 return 0;
550}
551
552/*
553 * for a compressed read, the bio we get passed has all the inode pages
554 * in it. We don't actually do IO on those pages but allocate new ones
555 * to hold the compressed pages on disk.
556 *
557 * bio->bi_iter.bi_sector points to the compressed extent on disk
558 * bio->bi_io_vec points to all of the inode pages
559 *
560 * After the compressed pages are read, we copy the bytes into the
561 * bio we were passed and then call the bio end_io calls
562 */
563void btrfs_submit_compressed_read(struct btrfs_bio *bbio)
564{
565 struct btrfs_inode *inode = bbio->inode;
566 struct btrfs_fs_info *fs_info = inode->root->fs_info;
567 struct extent_map_tree *em_tree = &inode->extent_tree;
568 struct compressed_bio *cb;
569 unsigned int compressed_len;
570 u64 file_offset = bbio->file_offset;
571 u64 em_len;
572 u64 em_start;
573 struct extent_map *em;
574 unsigned long pflags;
575 int memstall = 0;
576 blk_status_t ret;
577 int ret2;
578
579 /* we need the actual starting offset of this extent in the file */
580 read_lock(&em_tree->lock);
581 em = lookup_extent_mapping(em_tree, file_offset, fs_info->sectorsize);
582 read_unlock(&em_tree->lock);
583 if (!em) {
584 ret = BLK_STS_IOERR;
585 goto out;
586 }
587
588 ASSERT(extent_map_is_compressed(em));
589 compressed_len = em->block_len;
590
591 cb = alloc_compressed_bio(inode, file_offset, REQ_OP_READ,
592 end_bbio_comprssed_read);
593
594 cb->start = em->orig_start;
595 em_len = em->len;
596 em_start = em->start;
597
598 cb->len = bbio->bio.bi_iter.bi_size;
599 cb->compressed_len = compressed_len;
600 cb->compress_type = extent_map_compression(em);
601 cb->orig_bbio = bbio;
602
603 free_extent_map(em);
604
605 cb->nr_pages = DIV_ROUND_UP(compressed_len, PAGE_SIZE);
606 cb->compressed_pages = kcalloc(cb->nr_pages, sizeof(struct page *), GFP_NOFS);
607 if (!cb->compressed_pages) {
608 ret = BLK_STS_RESOURCE;
609 goto out_free_bio;
610 }
611
612 ret2 = btrfs_alloc_page_array(cb->nr_pages, cb->compressed_pages, 0);
613 if (ret2) {
614 ret = BLK_STS_RESOURCE;
615 goto out_free_compressed_pages;
616 }
617
618 add_ra_bio_pages(&inode->vfs_inode, em_start + em_len, cb, &memstall,
619 &pflags);
620
621 /* include any pages we added in add_ra-bio_pages */
622 cb->len = bbio->bio.bi_iter.bi_size;
623 cb->bbio.bio.bi_iter.bi_sector = bbio->bio.bi_iter.bi_sector;
624 btrfs_add_compressed_bio_pages(cb);
625
626 if (memstall)
627 psi_memstall_leave(&pflags);
628
629 btrfs_submit_bio(&cb->bbio, 0);
630 return;
631
632out_free_compressed_pages:
633 kfree(cb->compressed_pages);
634out_free_bio:
635 bio_put(&cb->bbio.bio);
636out:
637 btrfs_bio_end_io(bbio, ret);
638}
639
640/*
641 * Heuristic uses systematic sampling to collect data from the input data
642 * range, the logic can be tuned by the following constants:
643 *
644 * @SAMPLING_READ_SIZE - how many bytes will be copied from for each sample
645 * @SAMPLING_INTERVAL - range from which the sampled data can be collected
646 */
647#define SAMPLING_READ_SIZE (16)
648#define SAMPLING_INTERVAL (256)
649
650/*
651 * For statistical analysis of the input data we consider bytes that form a
652 * Galois Field of 256 objects. Each object has an attribute count, ie. how
653 * many times the object appeared in the sample.
654 */
655#define BUCKET_SIZE (256)
656
657/*
658 * The size of the sample is based on a statistical sampling rule of thumb.
659 * The common way is to perform sampling tests as long as the number of
660 * elements in each cell is at least 5.
661 *
662 * Instead of 5, we choose 32 to obtain more accurate results.
663 * If the data contain the maximum number of symbols, which is 256, we obtain a
664 * sample size bound by 8192.
665 *
666 * For a sample of at most 8KB of data per data range: 16 consecutive bytes
667 * from up to 512 locations.
668 */
669#define MAX_SAMPLE_SIZE (BTRFS_MAX_UNCOMPRESSED * \
670 SAMPLING_READ_SIZE / SAMPLING_INTERVAL)
671
672struct bucket_item {
673 u32 count;
674};
675
676struct heuristic_ws {
677 /* Partial copy of input data */
678 u8 *sample;
679 u32 sample_size;
680 /* Buckets store counters for each byte value */
681 struct bucket_item *bucket;
682 /* Sorting buffer */
683 struct bucket_item *bucket_b;
684 struct list_head list;
685};
686
687static struct workspace_manager heuristic_wsm;
688
689static void free_heuristic_ws(struct list_head *ws)
690{
691 struct heuristic_ws *workspace;
692
693 workspace = list_entry(ws, struct heuristic_ws, list);
694
695 kvfree(workspace->sample);
696 kfree(workspace->bucket);
697 kfree(workspace->bucket_b);
698 kfree(workspace);
699}
700
701static struct list_head *alloc_heuristic_ws(unsigned int level)
702{
703 struct heuristic_ws *ws;
704
705 ws = kzalloc(sizeof(*ws), GFP_KERNEL);
706 if (!ws)
707 return ERR_PTR(-ENOMEM);
708
709 ws->sample = kvmalloc(MAX_SAMPLE_SIZE, GFP_KERNEL);
710 if (!ws->sample)
711 goto fail;
712
713 ws->bucket = kcalloc(BUCKET_SIZE, sizeof(*ws->bucket), GFP_KERNEL);
714 if (!ws->bucket)
715 goto fail;
716
717 ws->bucket_b = kcalloc(BUCKET_SIZE, sizeof(*ws->bucket_b), GFP_KERNEL);
718 if (!ws->bucket_b)
719 goto fail;
720
721 INIT_LIST_HEAD(&ws->list);
722 return &ws->list;
723fail:
724 free_heuristic_ws(&ws->list);
725 return ERR_PTR(-ENOMEM);
726}
727
728const struct btrfs_compress_op btrfs_heuristic_compress = {
729 .workspace_manager = &heuristic_wsm,
730};
731
732static const struct btrfs_compress_op * const btrfs_compress_op[] = {
733 /* The heuristic is represented as compression type 0 */
734 &btrfs_heuristic_compress,
735 &btrfs_zlib_compress,
736 &btrfs_lzo_compress,
737 &btrfs_zstd_compress,
738};
739
740static struct list_head *alloc_workspace(int type, unsigned int level)
741{
742 switch (type) {
743 case BTRFS_COMPRESS_NONE: return alloc_heuristic_ws(level);
744 case BTRFS_COMPRESS_ZLIB: return zlib_alloc_workspace(level);
745 case BTRFS_COMPRESS_LZO: return lzo_alloc_workspace(level);
746 case BTRFS_COMPRESS_ZSTD: return zstd_alloc_workspace(level);
747 default:
748 /*
749 * This can't happen, the type is validated several times
750 * before we get here.
751 */
752 BUG();
753 }
754}
755
756static void free_workspace(int type, struct list_head *ws)
757{
758 switch (type) {
759 case BTRFS_COMPRESS_NONE: return free_heuristic_ws(ws);
760 case BTRFS_COMPRESS_ZLIB: return zlib_free_workspace(ws);
761 case BTRFS_COMPRESS_LZO: return lzo_free_workspace(ws);
762 case BTRFS_COMPRESS_ZSTD: return zstd_free_workspace(ws);
763 default:
764 /*
765 * This can't happen, the type is validated several times
766 * before we get here.
767 */
768 BUG();
769 }
770}
771
772static void btrfs_init_workspace_manager(int type)
773{
774 struct workspace_manager *wsm;
775 struct list_head *workspace;
776
777 wsm = btrfs_compress_op[type]->workspace_manager;
778 INIT_LIST_HEAD(&wsm->idle_ws);
779 spin_lock_init(&wsm->ws_lock);
780 atomic_set(&wsm->total_ws, 0);
781 init_waitqueue_head(&wsm->ws_wait);
782
783 /*
784 * Preallocate one workspace for each compression type so we can
785 * guarantee forward progress in the worst case
786 */
787 workspace = alloc_workspace(type, 0);
788 if (IS_ERR(workspace)) {
789 pr_warn(
790 "BTRFS: cannot preallocate compression workspace, will try later\n");
791 } else {
792 atomic_set(&wsm->total_ws, 1);
793 wsm->free_ws = 1;
794 list_add(workspace, &wsm->idle_ws);
795 }
796}
797
798static void btrfs_cleanup_workspace_manager(int type)
799{
800 struct workspace_manager *wsman;
801 struct list_head *ws;
802
803 wsman = btrfs_compress_op[type]->workspace_manager;
804 while (!list_empty(&wsman->idle_ws)) {
805 ws = wsman->idle_ws.next;
806 list_del(ws);
807 free_workspace(type, ws);
808 atomic_dec(&wsman->total_ws);
809 }
810}
811
812/*
813 * This finds an available workspace or allocates a new one.
814 * If it's not possible to allocate a new one, waits until there's one.
815 * Preallocation makes a forward progress guarantees and we do not return
816 * errors.
817 */
818struct list_head *btrfs_get_workspace(int type, unsigned int level)
819{
820 struct workspace_manager *wsm;
821 struct list_head *workspace;
822 int cpus = num_online_cpus();
823 unsigned nofs_flag;
824 struct list_head *idle_ws;
825 spinlock_t *ws_lock;
826 atomic_t *total_ws;
827 wait_queue_head_t *ws_wait;
828 int *free_ws;
829
830 wsm = btrfs_compress_op[type]->workspace_manager;
831 idle_ws = &wsm->idle_ws;
832 ws_lock = &wsm->ws_lock;
833 total_ws = &wsm->total_ws;
834 ws_wait = &wsm->ws_wait;
835 free_ws = &wsm->free_ws;
836
837again:
838 spin_lock(ws_lock);
839 if (!list_empty(idle_ws)) {
840 workspace = idle_ws->next;
841 list_del(workspace);
842 (*free_ws)--;
843 spin_unlock(ws_lock);
844 return workspace;
845
846 }
847 if (atomic_read(total_ws) > cpus) {
848 DEFINE_WAIT(wait);
849
850 spin_unlock(ws_lock);
851 prepare_to_wait(ws_wait, &wait, TASK_UNINTERRUPTIBLE);
852 if (atomic_read(total_ws) > cpus && !*free_ws)
853 schedule();
854 finish_wait(ws_wait, &wait);
855 goto again;
856 }
857 atomic_inc(total_ws);
858 spin_unlock(ws_lock);
859
860 /*
861 * Allocation helpers call vmalloc that can't use GFP_NOFS, so we have
862 * to turn it off here because we might get called from the restricted
863 * context of btrfs_compress_bio/btrfs_compress_pages
864 */
865 nofs_flag = memalloc_nofs_save();
866 workspace = alloc_workspace(type, level);
867 memalloc_nofs_restore(nofs_flag);
868
869 if (IS_ERR(workspace)) {
870 atomic_dec(total_ws);
871 wake_up(ws_wait);
872
873 /*
874 * Do not return the error but go back to waiting. There's a
875 * workspace preallocated for each type and the compression
876 * time is bounded so we get to a workspace eventually. This
877 * makes our caller's life easier.
878 *
879 * To prevent silent and low-probability deadlocks (when the
880 * initial preallocation fails), check if there are any
881 * workspaces at all.
882 */
883 if (atomic_read(total_ws) == 0) {
884 static DEFINE_RATELIMIT_STATE(_rs,
885 /* once per minute */ 60 * HZ,
886 /* no burst */ 1);
887
888 if (__ratelimit(&_rs)) {
889 pr_warn("BTRFS: no compression workspaces, low memory, retrying\n");
890 }
891 }
892 goto again;
893 }
894 return workspace;
895}
896
897static struct list_head *get_workspace(int type, int level)
898{
899 switch (type) {
900 case BTRFS_COMPRESS_NONE: return btrfs_get_workspace(type, level);
901 case BTRFS_COMPRESS_ZLIB: return zlib_get_workspace(level);
902 case BTRFS_COMPRESS_LZO: return btrfs_get_workspace(type, level);
903 case BTRFS_COMPRESS_ZSTD: return zstd_get_workspace(level);
904 default:
905 /*
906 * This can't happen, the type is validated several times
907 * before we get here.
908 */
909 BUG();
910 }
911}
912
913/*
914 * put a workspace struct back on the list or free it if we have enough
915 * idle ones sitting around
916 */
917void btrfs_put_workspace(int type, struct list_head *ws)
918{
919 struct workspace_manager *wsm;
920 struct list_head *idle_ws;
921 spinlock_t *ws_lock;
922 atomic_t *total_ws;
923 wait_queue_head_t *ws_wait;
924 int *free_ws;
925
926 wsm = btrfs_compress_op[type]->workspace_manager;
927 idle_ws = &wsm->idle_ws;
928 ws_lock = &wsm->ws_lock;
929 total_ws = &wsm->total_ws;
930 ws_wait = &wsm->ws_wait;
931 free_ws = &wsm->free_ws;
932
933 spin_lock(ws_lock);
934 if (*free_ws <= num_online_cpus()) {
935 list_add(ws, idle_ws);
936 (*free_ws)++;
937 spin_unlock(ws_lock);
938 goto wake;
939 }
940 spin_unlock(ws_lock);
941
942 free_workspace(type, ws);
943 atomic_dec(total_ws);
944wake:
945 cond_wake_up(ws_wait);
946}
947
948static void put_workspace(int type, struct list_head *ws)
949{
950 switch (type) {
951 case BTRFS_COMPRESS_NONE: return btrfs_put_workspace(type, ws);
952 case BTRFS_COMPRESS_ZLIB: return btrfs_put_workspace(type, ws);
953 case BTRFS_COMPRESS_LZO: return btrfs_put_workspace(type, ws);
954 case BTRFS_COMPRESS_ZSTD: return zstd_put_workspace(ws);
955 default:
956 /*
957 * This can't happen, the type is validated several times
958 * before we get here.
959 */
960 BUG();
961 }
962}
963
964/*
965 * Adjust @level according to the limits of the compression algorithm or
966 * fallback to default
967 */
968static unsigned int btrfs_compress_set_level(int type, unsigned level)
969{
970 const struct btrfs_compress_op *ops = btrfs_compress_op[type];
971
972 if (level == 0)
973 level = ops->default_level;
974 else
975 level = min(level, ops->max_level);
976
977 return level;
978}
979
980/*
981 * Given an address space and start and length, compress the bytes into @pages
982 * that are allocated on demand.
983 *
984 * @type_level is encoded algorithm and level, where level 0 means whatever
985 * default the algorithm chooses and is opaque here;
986 * - compression algo are 0-3
987 * - the level are bits 4-7
988 *
989 * @out_pages is an in/out parameter, holds maximum number of pages to allocate
990 * and returns number of actually allocated pages
991 *
992 * @total_in is used to return the number of bytes actually read. It
993 * may be smaller than the input length if we had to exit early because we
994 * ran out of room in the pages array or because we cross the
995 * max_out threshold.
996 *
997 * @total_out is an in/out parameter, must be set to the input length and will
998 * be also used to return the total number of compressed bytes
999 */
1000int btrfs_compress_pages(unsigned int type_level, struct address_space *mapping,
1001 u64 start, struct page **pages,
1002 unsigned long *out_pages,
1003 unsigned long *total_in,
1004 unsigned long *total_out)
1005{
1006 int type = btrfs_compress_type(type_level);
1007 int level = btrfs_compress_level(type_level);
1008 struct list_head *workspace;
1009 int ret;
1010
1011 level = btrfs_compress_set_level(type, level);
1012 workspace = get_workspace(type, level);
1013 ret = compression_compress_pages(type, workspace, mapping, start, pages,
1014 out_pages, total_in, total_out);
1015 put_workspace(type, workspace);
1016 return ret;
1017}
1018
1019static int btrfs_decompress_bio(struct compressed_bio *cb)
1020{
1021 struct list_head *workspace;
1022 int ret;
1023 int type = cb->compress_type;
1024
1025 workspace = get_workspace(type, 0);
1026 ret = compression_decompress_bio(workspace, cb);
1027 put_workspace(type, workspace);
1028
1029 if (!ret)
1030 zero_fill_bio(&cb->orig_bbio->bio);
1031 return ret;
1032}
1033
1034/*
1035 * a less complex decompression routine. Our compressed data fits in a
1036 * single page, and we want to read a single page out of it.
1037 * start_byte tells us the offset into the compressed data we're interested in
1038 */
1039int btrfs_decompress(int type, const u8 *data_in, struct page *dest_page,
1040 unsigned long dest_pgoff, size_t srclen, size_t destlen)
1041{
1042 struct btrfs_fs_info *fs_info = btrfs_sb(dest_page->mapping->host->i_sb);
1043 struct list_head *workspace;
1044 const u32 sectorsize = fs_info->sectorsize;
1045 int ret;
1046
1047 /*
1048 * The full destination page range should not exceed the page size.
1049 * And the @destlen should not exceed sectorsize, as this is only called for
1050 * inline file extents, which should not exceed sectorsize.
1051 */
1052 ASSERT(dest_pgoff + destlen <= PAGE_SIZE && destlen <= sectorsize);
1053
1054 workspace = get_workspace(type, 0);
1055 ret = compression_decompress(type, workspace, data_in, dest_page,
1056 dest_pgoff, srclen, destlen);
1057 put_workspace(type, workspace);
1058
1059 return ret;
1060}
1061
1062int __init btrfs_init_compress(void)
1063{
1064 if (bioset_init(&btrfs_compressed_bioset, BIO_POOL_SIZE,
1065 offsetof(struct compressed_bio, bbio.bio),
1066 BIOSET_NEED_BVECS))
1067 return -ENOMEM;
1068
1069 compr_pool.shrinker = shrinker_alloc(SHRINKER_NONSLAB, "btrfs-compr-pages");
1070 if (!compr_pool.shrinker)
1071 return -ENOMEM;
1072
1073 btrfs_init_workspace_manager(BTRFS_COMPRESS_NONE);
1074 btrfs_init_workspace_manager(BTRFS_COMPRESS_ZLIB);
1075 btrfs_init_workspace_manager(BTRFS_COMPRESS_LZO);
1076 zstd_init_workspace_manager();
1077
1078 spin_lock_init(&compr_pool.lock);
1079 INIT_LIST_HEAD(&compr_pool.list);
1080 compr_pool.count = 0;
1081 /* 128K / 4K = 32, for 8 threads is 256 pages. */
1082 compr_pool.thresh = BTRFS_MAX_COMPRESSED / PAGE_SIZE * 8;
1083 compr_pool.shrinker->count_objects = btrfs_compr_pool_count;
1084 compr_pool.shrinker->scan_objects = btrfs_compr_pool_scan;
1085 compr_pool.shrinker->batch = 32;
1086 compr_pool.shrinker->seeks = DEFAULT_SEEKS;
1087 shrinker_register(compr_pool.shrinker);
1088
1089 return 0;
1090}
1091
1092void __cold btrfs_exit_compress(void)
1093{
1094 /* For now scan drains all pages and does not touch the parameters. */
1095 btrfs_compr_pool_scan(NULL, NULL);
1096 shrinker_free(compr_pool.shrinker);
1097
1098 btrfs_cleanup_workspace_manager(BTRFS_COMPRESS_NONE);
1099 btrfs_cleanup_workspace_manager(BTRFS_COMPRESS_ZLIB);
1100 btrfs_cleanup_workspace_manager(BTRFS_COMPRESS_LZO);
1101 zstd_cleanup_workspace_manager();
1102 bioset_exit(&btrfs_compressed_bioset);
1103}
1104
1105/*
1106 * Copy decompressed data from working buffer to pages.
1107 *
1108 * @buf: The decompressed data buffer
1109 * @buf_len: The decompressed data length
1110 * @decompressed: Number of bytes that are already decompressed inside the
1111 * compressed extent
1112 * @cb: The compressed extent descriptor
1113 * @orig_bio: The original bio that the caller wants to read for
1114 *
1115 * An easier to understand graph is like below:
1116 *
1117 * |<- orig_bio ->| |<- orig_bio->|
1118 * |<------- full decompressed extent ----->|
1119 * |<----------- @cb range ---->|
1120 * | |<-- @buf_len -->|
1121 * |<--- @decompressed --->|
1122 *
1123 * Note that, @cb can be a subpage of the full decompressed extent, but
1124 * @cb->start always has the same as the orig_file_offset value of the full
1125 * decompressed extent.
1126 *
1127 * When reading compressed extent, we have to read the full compressed extent,
1128 * while @orig_bio may only want part of the range.
1129 * Thus this function will ensure only data covered by @orig_bio will be copied
1130 * to.
1131 *
1132 * Return 0 if we have copied all needed contents for @orig_bio.
1133 * Return >0 if we need continue decompress.
1134 */
1135int btrfs_decompress_buf2page(const char *buf, u32 buf_len,
1136 struct compressed_bio *cb, u32 decompressed)
1137{
1138 struct bio *orig_bio = &cb->orig_bbio->bio;
1139 /* Offset inside the full decompressed extent */
1140 u32 cur_offset;
1141
1142 cur_offset = decompressed;
1143 /* The main loop to do the copy */
1144 while (cur_offset < decompressed + buf_len) {
1145 struct bio_vec bvec;
1146 size_t copy_len;
1147 u32 copy_start;
1148 /* Offset inside the full decompressed extent */
1149 u32 bvec_offset;
1150
1151 bvec = bio_iter_iovec(orig_bio, orig_bio->bi_iter);
1152 /*
1153 * cb->start may underflow, but subtracting that value can still
1154 * give us correct offset inside the full decompressed extent.
1155 */
1156 bvec_offset = page_offset(bvec.bv_page) + bvec.bv_offset - cb->start;
1157
1158 /* Haven't reached the bvec range, exit */
1159 if (decompressed + buf_len <= bvec_offset)
1160 return 1;
1161
1162 copy_start = max(cur_offset, bvec_offset);
1163 copy_len = min(bvec_offset + bvec.bv_len,
1164 decompressed + buf_len) - copy_start;
1165 ASSERT(copy_len);
1166
1167 /*
1168 * Extra range check to ensure we didn't go beyond
1169 * @buf + @buf_len.
1170 */
1171 ASSERT(copy_start - decompressed < buf_len);
1172 memcpy_to_page(bvec.bv_page, bvec.bv_offset,
1173 buf + copy_start - decompressed, copy_len);
1174 cur_offset += copy_len;
1175
1176 bio_advance(orig_bio, copy_len);
1177 /* Finished the bio */
1178 if (!orig_bio->bi_iter.bi_size)
1179 return 0;
1180 }
1181 return 1;
1182}
1183
1184/*
1185 * Shannon Entropy calculation
1186 *
1187 * Pure byte distribution analysis fails to determine compressibility of data.
1188 * Try calculating entropy to estimate the average minimum number of bits
1189 * needed to encode the sampled data.
1190 *
1191 * For convenience, return the percentage of needed bits, instead of amount of
1192 * bits directly.
1193 *
1194 * @ENTROPY_LVL_ACEPTABLE - below that threshold, sample has low byte entropy
1195 * and can be compressible with high probability
1196 *
1197 * @ENTROPY_LVL_HIGH - data are not compressible with high probability
1198 *
1199 * Use of ilog2() decreases precision, we lower the LVL to 5 to compensate.
1200 */
1201#define ENTROPY_LVL_ACEPTABLE (65)
1202#define ENTROPY_LVL_HIGH (80)
1203
1204/*
1205 * For increasead precision in shannon_entropy calculation,
1206 * let's do pow(n, M) to save more digits after comma:
1207 *
1208 * - maximum int bit length is 64
1209 * - ilog2(MAX_SAMPLE_SIZE) -> 13
1210 * - 13 * 4 = 52 < 64 -> M = 4
1211 *
1212 * So use pow(n, 4).
1213 */
1214static inline u32 ilog2_w(u64 n)
1215{
1216 return ilog2(n * n * n * n);
1217}
1218
1219static u32 shannon_entropy(struct heuristic_ws *ws)
1220{
1221 const u32 entropy_max = 8 * ilog2_w(2);
1222 u32 entropy_sum = 0;
1223 u32 p, p_base, sz_base;
1224 u32 i;
1225
1226 sz_base = ilog2_w(ws->sample_size);
1227 for (i = 0; i < BUCKET_SIZE && ws->bucket[i].count > 0; i++) {
1228 p = ws->bucket[i].count;
1229 p_base = ilog2_w(p);
1230 entropy_sum += p * (sz_base - p_base);
1231 }
1232
1233 entropy_sum /= ws->sample_size;
1234 return entropy_sum * 100 / entropy_max;
1235}
1236
1237#define RADIX_BASE 4U
1238#define COUNTERS_SIZE (1U << RADIX_BASE)
1239
1240static u8 get4bits(u64 num, int shift) {
1241 u8 low4bits;
1242
1243 num >>= shift;
1244 /* Reverse order */
1245 low4bits = (COUNTERS_SIZE - 1) - (num % COUNTERS_SIZE);
1246 return low4bits;
1247}
1248
1249/*
1250 * Use 4 bits as radix base
1251 * Use 16 u32 counters for calculating new position in buf array
1252 *
1253 * @array - array that will be sorted
1254 * @array_buf - buffer array to store sorting results
1255 * must be equal in size to @array
1256 * @num - array size
1257 */
1258static void radix_sort(struct bucket_item *array, struct bucket_item *array_buf,
1259 int num)
1260{
1261 u64 max_num;
1262 u64 buf_num;
1263 u32 counters[COUNTERS_SIZE];
1264 u32 new_addr;
1265 u32 addr;
1266 int bitlen;
1267 int shift;
1268 int i;
1269
1270 /*
1271 * Try avoid useless loop iterations for small numbers stored in big
1272 * counters. Example: 48 33 4 ... in 64bit array
1273 */
1274 max_num = array[0].count;
1275 for (i = 1; i < num; i++) {
1276 buf_num = array[i].count;
1277 if (buf_num > max_num)
1278 max_num = buf_num;
1279 }
1280
1281 buf_num = ilog2(max_num);
1282 bitlen = ALIGN(buf_num, RADIX_BASE * 2);
1283
1284 shift = 0;
1285 while (shift < bitlen) {
1286 memset(counters, 0, sizeof(counters));
1287
1288 for (i = 0; i < num; i++) {
1289 buf_num = array[i].count;
1290 addr = get4bits(buf_num, shift);
1291 counters[addr]++;
1292 }
1293
1294 for (i = 1; i < COUNTERS_SIZE; i++)
1295 counters[i] += counters[i - 1];
1296
1297 for (i = num - 1; i >= 0; i--) {
1298 buf_num = array[i].count;
1299 addr = get4bits(buf_num, shift);
1300 counters[addr]--;
1301 new_addr = counters[addr];
1302 array_buf[new_addr] = array[i];
1303 }
1304
1305 shift += RADIX_BASE;
1306
1307 /*
1308 * Normal radix expects to move data from a temporary array, to
1309 * the main one. But that requires some CPU time. Avoid that
1310 * by doing another sort iteration to original array instead of
1311 * memcpy()
1312 */
1313 memset(counters, 0, sizeof(counters));
1314
1315 for (i = 0; i < num; i ++) {
1316 buf_num = array_buf[i].count;
1317 addr = get4bits(buf_num, shift);
1318 counters[addr]++;
1319 }
1320
1321 for (i = 1; i < COUNTERS_SIZE; i++)
1322 counters[i] += counters[i - 1];
1323
1324 for (i = num - 1; i >= 0; i--) {
1325 buf_num = array_buf[i].count;
1326 addr = get4bits(buf_num, shift);
1327 counters[addr]--;
1328 new_addr = counters[addr];
1329 array[new_addr] = array_buf[i];
1330 }
1331
1332 shift += RADIX_BASE;
1333 }
1334}
1335
1336/*
1337 * Size of the core byte set - how many bytes cover 90% of the sample
1338 *
1339 * There are several types of structured binary data that use nearly all byte
1340 * values. The distribution can be uniform and counts in all buckets will be
1341 * nearly the same (eg. encrypted data). Unlikely to be compressible.
1342 *
1343 * Other possibility is normal (Gaussian) distribution, where the data could
1344 * be potentially compressible, but we have to take a few more steps to decide
1345 * how much.
1346 *
1347 * @BYTE_CORE_SET_LOW - main part of byte values repeated frequently,
1348 * compression algo can easy fix that
1349 * @BYTE_CORE_SET_HIGH - data have uniform distribution and with high
1350 * probability is not compressible
1351 */
1352#define BYTE_CORE_SET_LOW (64)
1353#define BYTE_CORE_SET_HIGH (200)
1354
1355static int byte_core_set_size(struct heuristic_ws *ws)
1356{
1357 u32 i;
1358 u32 coreset_sum = 0;
1359 const u32 core_set_threshold = ws->sample_size * 90 / 100;
1360 struct bucket_item *bucket = ws->bucket;
1361
1362 /* Sort in reverse order */
1363 radix_sort(ws->bucket, ws->bucket_b, BUCKET_SIZE);
1364
1365 for (i = 0; i < BYTE_CORE_SET_LOW; i++)
1366 coreset_sum += bucket[i].count;
1367
1368 if (coreset_sum > core_set_threshold)
1369 return i;
1370
1371 for (; i < BYTE_CORE_SET_HIGH && bucket[i].count > 0; i++) {
1372 coreset_sum += bucket[i].count;
1373 if (coreset_sum > core_set_threshold)
1374 break;
1375 }
1376
1377 return i;
1378}
1379
1380/*
1381 * Count byte values in buckets.
1382 * This heuristic can detect textual data (configs, xml, json, html, etc).
1383 * Because in most text-like data byte set is restricted to limited number of
1384 * possible characters, and that restriction in most cases makes data easy to
1385 * compress.
1386 *
1387 * @BYTE_SET_THRESHOLD - consider all data within this byte set size:
1388 * less - compressible
1389 * more - need additional analysis
1390 */
1391#define BYTE_SET_THRESHOLD (64)
1392
1393static u32 byte_set_size(const struct heuristic_ws *ws)
1394{
1395 u32 i;
1396 u32 byte_set_size = 0;
1397
1398 for (i = 0; i < BYTE_SET_THRESHOLD; i++) {
1399 if (ws->bucket[i].count > 0)
1400 byte_set_size++;
1401 }
1402
1403 /*
1404 * Continue collecting count of byte values in buckets. If the byte
1405 * set size is bigger then the threshold, it's pointless to continue,
1406 * the detection technique would fail for this type of data.
1407 */
1408 for (; i < BUCKET_SIZE; i++) {
1409 if (ws->bucket[i].count > 0) {
1410 byte_set_size++;
1411 if (byte_set_size > BYTE_SET_THRESHOLD)
1412 return byte_set_size;
1413 }
1414 }
1415
1416 return byte_set_size;
1417}
1418
1419static bool sample_repeated_patterns(struct heuristic_ws *ws)
1420{
1421 const u32 half_of_sample = ws->sample_size / 2;
1422 const u8 *data = ws->sample;
1423
1424 return memcmp(&data[0], &data[half_of_sample], half_of_sample) == 0;
1425}
1426
1427static void heuristic_collect_sample(struct inode *inode, u64 start, u64 end,
1428 struct heuristic_ws *ws)
1429{
1430 struct page *page;
1431 u64 index, index_end;
1432 u32 i, curr_sample_pos;
1433 u8 *in_data;
1434
1435 /*
1436 * Compression handles the input data by chunks of 128KiB
1437 * (defined by BTRFS_MAX_UNCOMPRESSED)
1438 *
1439 * We do the same for the heuristic and loop over the whole range.
1440 *
1441 * MAX_SAMPLE_SIZE - calculated under assumption that heuristic will
1442 * process no more than BTRFS_MAX_UNCOMPRESSED at a time.
1443 */
1444 if (end - start > BTRFS_MAX_UNCOMPRESSED)
1445 end = start + BTRFS_MAX_UNCOMPRESSED;
1446
1447 index = start >> PAGE_SHIFT;
1448 index_end = end >> PAGE_SHIFT;
1449
1450 /* Don't miss unaligned end */
1451 if (!PAGE_ALIGNED(end))
1452 index_end++;
1453
1454 curr_sample_pos = 0;
1455 while (index < index_end) {
1456 page = find_get_page(inode->i_mapping, index);
1457 in_data = kmap_local_page(page);
1458 /* Handle case where the start is not aligned to PAGE_SIZE */
1459 i = start % PAGE_SIZE;
1460 while (i < PAGE_SIZE - SAMPLING_READ_SIZE) {
1461 /* Don't sample any garbage from the last page */
1462 if (start > end - SAMPLING_READ_SIZE)
1463 break;
1464 memcpy(&ws->sample[curr_sample_pos], &in_data[i],
1465 SAMPLING_READ_SIZE);
1466 i += SAMPLING_INTERVAL;
1467 start += SAMPLING_INTERVAL;
1468 curr_sample_pos += SAMPLING_READ_SIZE;
1469 }
1470 kunmap_local(in_data);
1471 put_page(page);
1472
1473 index++;
1474 }
1475
1476 ws->sample_size = curr_sample_pos;
1477}
1478
1479/*
1480 * Compression heuristic.
1481 *
1482 * For now is's a naive and optimistic 'return true', we'll extend the logic to
1483 * quickly (compared to direct compression) detect data characteristics
1484 * (compressible/incompressible) to avoid wasting CPU time on incompressible
1485 * data.
1486 *
1487 * The following types of analysis can be performed:
1488 * - detect mostly zero data
1489 * - detect data with low "byte set" size (text, etc)
1490 * - detect data with low/high "core byte" set
1491 *
1492 * Return non-zero if the compression should be done, 0 otherwise.
1493 */
1494int btrfs_compress_heuristic(struct inode *inode, u64 start, u64 end)
1495{
1496 struct list_head *ws_list = get_workspace(0, 0);
1497 struct heuristic_ws *ws;
1498 u32 i;
1499 u8 byte;
1500 int ret = 0;
1501
1502 ws = list_entry(ws_list, struct heuristic_ws, list);
1503
1504 heuristic_collect_sample(inode, start, end, ws);
1505
1506 if (sample_repeated_patterns(ws)) {
1507 ret = 1;
1508 goto out;
1509 }
1510
1511 memset(ws->bucket, 0, sizeof(*ws->bucket)*BUCKET_SIZE);
1512
1513 for (i = 0; i < ws->sample_size; i++) {
1514 byte = ws->sample[i];
1515 ws->bucket[byte].count++;
1516 }
1517
1518 i = byte_set_size(ws);
1519 if (i < BYTE_SET_THRESHOLD) {
1520 ret = 2;
1521 goto out;
1522 }
1523
1524 i = byte_core_set_size(ws);
1525 if (i <= BYTE_CORE_SET_LOW) {
1526 ret = 3;
1527 goto out;
1528 }
1529
1530 if (i >= BYTE_CORE_SET_HIGH) {
1531 ret = 0;
1532 goto out;
1533 }
1534
1535 i = shannon_entropy(ws);
1536 if (i <= ENTROPY_LVL_ACEPTABLE) {
1537 ret = 4;
1538 goto out;
1539 }
1540
1541 /*
1542 * For the levels below ENTROPY_LVL_HIGH, additional analysis would be
1543 * needed to give green light to compression.
1544 *
1545 * For now just assume that compression at that level is not worth the
1546 * resources because:
1547 *
1548 * 1. it is possible to defrag the data later
1549 *
1550 * 2. the data would turn out to be hardly compressible, eg. 150 byte
1551 * values, every bucket has counter at level ~54. The heuristic would
1552 * be confused. This can happen when data have some internal repeated
1553 * patterns like "abbacbbc...". This can be detected by analyzing
1554 * pairs of bytes, which is too costly.
1555 */
1556 if (i < ENTROPY_LVL_HIGH) {
1557 ret = 5;
1558 goto out;
1559 } else {
1560 ret = 0;
1561 goto out;
1562 }
1563
1564out:
1565 put_workspace(0, ws_list);
1566 return ret;
1567}
1568
1569/*
1570 * Convert the compression suffix (eg. after "zlib" starting with ":") to
1571 * level, unrecognized string will set the default level
1572 */
1573unsigned int btrfs_compress_str2level(unsigned int type, const char *str)
1574{
1575 unsigned int level = 0;
1576 int ret;
1577
1578 if (!type)
1579 return 0;
1580
1581 if (str[0] == ':') {
1582 ret = kstrtouint(str + 1, 10, &level);
1583 if (ret)
1584 level = 0;
1585 }
1586
1587 level = btrfs_compress_set_level(type, level);
1588
1589 return level;
1590}
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_bio(int type, struct page **pages_in,
85 u64 disk_start, struct bio *orig_bio,
86 size_t srclen);
87
88static inline int compressed_bio_size(struct btrfs_fs_info *fs_info,
89 unsigned long disk_size)
90{
91 u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
92
93 return sizeof(struct compressed_bio) +
94 (DIV_ROUND_UP(disk_size, fs_info->sectorsize)) * csum_size;
95}
96
97static struct bio *compressed_bio_alloc(struct block_device *bdev,
98 u64 first_byte, gfp_t gfp_flags)
99{
100 return btrfs_bio_alloc(bdev, first_byte >> 9, BIO_MAX_PAGES, gfp_flags);
101}
102
103static int check_compressed_csum(struct inode *inode,
104 struct compressed_bio *cb,
105 u64 disk_start)
106{
107 int ret;
108 struct page *page;
109 unsigned long i;
110 char *kaddr;
111 u32 csum;
112 u32 *cb_sum = &cb->sums;
113
114 if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)
115 return 0;
116
117 for (i = 0; i < cb->nr_pages; i++) {
118 page = cb->compressed_pages[i];
119 csum = ~(u32)0;
120
121 kaddr = kmap_atomic(page);
122 csum = btrfs_csum_data(kaddr, csum, PAGE_SIZE);
123 btrfs_csum_final(csum, (u8 *)&csum);
124 kunmap_atomic(kaddr);
125
126 if (csum != *cb_sum) {
127 btrfs_info(BTRFS_I(inode)->root->fs_info,
128 "csum failed ino %llu extent %llu csum %u wanted %u mirror %d",
129 btrfs_ino(inode), disk_start, csum, *cb_sum,
130 cb->mirror_num);
131 ret = -EIO;
132 goto fail;
133 }
134 cb_sum++;
135
136 }
137 ret = 0;
138fail:
139 return ret;
140}
141
142/* when we finish reading compressed pages from the disk, we
143 * decompress them and then run the bio end_io routines on the
144 * decompressed pages (in the inode address space).
145 *
146 * This allows the checksumming and other IO error handling routines
147 * to work normally
148 *
149 * The compressed pages are freed here, and it must be run
150 * in process context
151 */
152static void end_compressed_bio_read(struct bio *bio)
153{
154 struct compressed_bio *cb = bio->bi_private;
155 struct inode *inode;
156 struct page *page;
157 unsigned long index;
158 int ret;
159
160 if (bio->bi_error)
161 cb->errors = 1;
162
163 /* if there are more bios still pending for this compressed
164 * extent, just exit
165 */
166 if (!atomic_dec_and_test(&cb->pending_bios))
167 goto out;
168
169 inode = cb->inode;
170 ret = check_compressed_csum(inode, cb,
171 (u64)bio->bi_iter.bi_sector << 9);
172 if (ret)
173 goto csum_failed;
174
175 /* ok, we're the last bio for this extent, lets start
176 * the decompression.
177 */
178 ret = btrfs_decompress_bio(cb->compress_type,
179 cb->compressed_pages,
180 cb->start,
181 cb->orig_bio,
182 cb->compressed_len);
183csum_failed:
184 if (ret)
185 cb->errors = 1;
186
187 /* release the compressed pages */
188 index = 0;
189 for (index = 0; index < cb->nr_pages; index++) {
190 page = cb->compressed_pages[index];
191 page->mapping = NULL;
192 put_page(page);
193 }
194
195 /* do io completion on the original bio */
196 if (cb->errors) {
197 bio_io_error(cb->orig_bio);
198 } else {
199 int i;
200 struct bio_vec *bvec;
201
202 /*
203 * we have verified the checksum already, set page
204 * checked so the end_io handlers know about it
205 */
206 bio_for_each_segment_all(bvec, cb->orig_bio, i)
207 SetPageChecked(bvec->bv_page);
208
209 bio_endio(cb->orig_bio);
210 }
211
212 /* finally free the cb struct */
213 kfree(cb->compressed_pages);
214 kfree(cb);
215out:
216 bio_put(bio);
217}
218
219/*
220 * Clear the writeback bits on all of the file
221 * pages for a compressed write
222 */
223static noinline void end_compressed_writeback(struct inode *inode,
224 const struct compressed_bio *cb)
225{
226 unsigned long index = cb->start >> PAGE_SHIFT;
227 unsigned long end_index = (cb->start + cb->len - 1) >> PAGE_SHIFT;
228 struct page *pages[16];
229 unsigned long nr_pages = end_index - index + 1;
230 int i;
231 int ret;
232
233 if (cb->errors)
234 mapping_set_error(inode->i_mapping, -EIO);
235
236 while (nr_pages > 0) {
237 ret = find_get_pages_contig(inode->i_mapping, index,
238 min_t(unsigned long,
239 nr_pages, ARRAY_SIZE(pages)), pages);
240 if (ret == 0) {
241 nr_pages -= 1;
242 index += 1;
243 continue;
244 }
245 for (i = 0; i < ret; i++) {
246 if (cb->errors)
247 SetPageError(pages[i]);
248 end_page_writeback(pages[i]);
249 put_page(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)
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 (bio->bi_error)
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,
292 bio->bi_error ? 0 : 1);
293 cb->compressed_pages[0]->mapping = NULL;
294
295 end_compressed_writeback(inode, cb);
296 /* note, our inode could be gone now */
297
298 /*
299 * release the compressed pages, these came from alloc_page and
300 * are not attached to the inode at all
301 */
302 index = 0;
303 for (index = 0; index < cb->nr_pages; index++) {
304 page = cb->compressed_pages[index];
305 page->mapping = NULL;
306 put_page(page);
307 }
308
309 /* finally free the cb struct */
310 kfree(cb->compressed_pages);
311 kfree(cb);
312out:
313 bio_put(bio);
314}
315
316/*
317 * worker function to build and submit bios for previously compressed pages.
318 * The corresponding pages in the inode should be marked for writeback
319 * and the compressed pages should have a reference on them for dropping
320 * when the IO is complete.
321 *
322 * This also checksums the file bytes and gets things ready for
323 * the end io hooks.
324 */
325int btrfs_submit_compressed_write(struct inode *inode, u64 start,
326 unsigned long len, u64 disk_start,
327 unsigned long compressed_len,
328 struct page **compressed_pages,
329 unsigned long nr_pages)
330{
331 struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
332 struct bio *bio = NULL;
333 struct compressed_bio *cb;
334 unsigned long bytes_left;
335 struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
336 int pg_index = 0;
337 struct page *page;
338 u64 first_byte = disk_start;
339 struct block_device *bdev;
340 int ret;
341 int skip_sum = BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM;
342
343 WARN_ON(start & ((u64)PAGE_SIZE - 1));
344 cb = kmalloc(compressed_bio_size(fs_info, compressed_len), GFP_NOFS);
345 if (!cb)
346 return -ENOMEM;
347 atomic_set(&cb->pending_bios, 0);
348 cb->errors = 0;
349 cb->inode = inode;
350 cb->start = start;
351 cb->len = len;
352 cb->mirror_num = 0;
353 cb->compressed_pages = compressed_pages;
354 cb->compressed_len = compressed_len;
355 cb->orig_bio = NULL;
356 cb->nr_pages = nr_pages;
357
358 bdev = fs_info->fs_devices->latest_bdev;
359
360 bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
361 if (!bio) {
362 kfree(cb);
363 return -ENOMEM;
364 }
365 bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
366 bio->bi_private = cb;
367 bio->bi_end_io = end_compressed_bio_write;
368 atomic_inc(&cb->pending_bios);
369
370 /* create and submit bios for the compressed pages */
371 bytes_left = compressed_len;
372 for (pg_index = 0; pg_index < cb->nr_pages; pg_index++) {
373 page = compressed_pages[pg_index];
374 page->mapping = inode->i_mapping;
375 if (bio->bi_iter.bi_size)
376 ret = io_tree->ops->merge_bio_hook(page, 0,
377 PAGE_SIZE,
378 bio, 0);
379 else
380 ret = 0;
381
382 page->mapping = NULL;
383 if (ret || bio_add_page(bio, page, PAGE_SIZE, 0) <
384 PAGE_SIZE) {
385 bio_get(bio);
386
387 /*
388 * inc the count before we submit the bio so
389 * we know the end IO handler won't happen before
390 * we inc the count. Otherwise, the cb might get
391 * freed before we're done setting it up
392 */
393 atomic_inc(&cb->pending_bios);
394 ret = btrfs_bio_wq_end_io(fs_info, bio,
395 BTRFS_WQ_ENDIO_DATA);
396 BUG_ON(ret); /* -ENOMEM */
397
398 if (!skip_sum) {
399 ret = btrfs_csum_one_bio(inode, bio, start, 1);
400 BUG_ON(ret); /* -ENOMEM */
401 }
402
403 ret = btrfs_map_bio(fs_info, bio, 0, 1);
404 if (ret) {
405 bio->bi_error = ret;
406 bio_endio(bio);
407 }
408
409 bio_put(bio);
410
411 bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
412 BUG_ON(!bio);
413 bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
414 bio->bi_private = cb;
415 bio->bi_end_io = end_compressed_bio_write;
416 bio_add_page(bio, page, PAGE_SIZE, 0);
417 }
418 if (bytes_left < PAGE_SIZE) {
419 btrfs_info(fs_info,
420 "bytes left %lu compress len %lu nr %lu",
421 bytes_left, cb->compressed_len, cb->nr_pages);
422 }
423 bytes_left -= PAGE_SIZE;
424 first_byte += PAGE_SIZE;
425 cond_resched();
426 }
427 bio_get(bio);
428
429 ret = btrfs_bio_wq_end_io(fs_info, bio, BTRFS_WQ_ENDIO_DATA);
430 BUG_ON(ret); /* -ENOMEM */
431
432 if (!skip_sum) {
433 ret = btrfs_csum_one_bio(inode, bio, start, 1);
434 BUG_ON(ret); /* -ENOMEM */
435 }
436
437 ret = btrfs_map_bio(fs_info, bio, 0, 1);
438 if (ret) {
439 bio->bi_error = ret;
440 bio_endio(bio);
441 }
442
443 bio_put(bio);
444 return 0;
445}
446
447static u64 bio_end_offset(struct bio *bio)
448{
449 struct bio_vec *last = &bio->bi_io_vec[bio->bi_vcnt - 1];
450
451 return page_offset(last->bv_page) + last->bv_len + last->bv_offset;
452}
453
454static noinline int add_ra_bio_pages(struct inode *inode,
455 u64 compressed_end,
456 struct compressed_bio *cb)
457{
458 unsigned long end_index;
459 unsigned long pg_index;
460 u64 last_offset;
461 u64 isize = i_size_read(inode);
462 int ret;
463 struct page *page;
464 unsigned long nr_pages = 0;
465 struct extent_map *em;
466 struct address_space *mapping = inode->i_mapping;
467 struct extent_map_tree *em_tree;
468 struct extent_io_tree *tree;
469 u64 end;
470 int misses = 0;
471
472 last_offset = bio_end_offset(cb->orig_bio);
473 em_tree = &BTRFS_I(inode)->extent_tree;
474 tree = &BTRFS_I(inode)->io_tree;
475
476 if (isize == 0)
477 return 0;
478
479 end_index = (i_size_read(inode) - 1) >> PAGE_SHIFT;
480
481 while (last_offset < compressed_end) {
482 pg_index = last_offset >> PAGE_SHIFT;
483
484 if (pg_index > end_index)
485 break;
486
487 rcu_read_lock();
488 page = radix_tree_lookup(&mapping->page_tree, pg_index);
489 rcu_read_unlock();
490 if (page && !radix_tree_exceptional_entry(page)) {
491 misses++;
492 if (misses > 4)
493 break;
494 goto next;
495 }
496
497 page = __page_cache_alloc(mapping_gfp_constraint(mapping,
498 ~__GFP_FS));
499 if (!page)
500 break;
501
502 if (add_to_page_cache_lru(page, mapping, pg_index, GFP_NOFS)) {
503 put_page(page);
504 goto next;
505 }
506
507 end = last_offset + PAGE_SIZE - 1;
508 /*
509 * at this point, we have a locked page in the page cache
510 * for these bytes in the file. But, we have to make
511 * sure they map to this compressed extent on disk.
512 */
513 set_page_extent_mapped(page);
514 lock_extent(tree, last_offset, end);
515 read_lock(&em_tree->lock);
516 em = lookup_extent_mapping(em_tree, last_offset,
517 PAGE_SIZE);
518 read_unlock(&em_tree->lock);
519
520 if (!em || last_offset < em->start ||
521 (last_offset + PAGE_SIZE > extent_map_end(em)) ||
522 (em->block_start >> 9) != cb->orig_bio->bi_iter.bi_sector) {
523 free_extent_map(em);
524 unlock_extent(tree, last_offset, end);
525 unlock_page(page);
526 put_page(page);
527 break;
528 }
529 free_extent_map(em);
530
531 if (page->index == end_index) {
532 char *userpage;
533 size_t zero_offset = isize & (PAGE_SIZE - 1);
534
535 if (zero_offset) {
536 int zeros;
537 zeros = PAGE_SIZE - zero_offset;
538 userpage = kmap_atomic(page);
539 memset(userpage + zero_offset, 0, zeros);
540 flush_dcache_page(page);
541 kunmap_atomic(userpage);
542 }
543 }
544
545 ret = bio_add_page(cb->orig_bio, page,
546 PAGE_SIZE, 0);
547
548 if (ret == PAGE_SIZE) {
549 nr_pages++;
550 put_page(page);
551 } else {
552 unlock_extent(tree, last_offset, end);
553 unlock_page(page);
554 put_page(page);
555 break;
556 }
557next:
558 last_offset += PAGE_SIZE;
559 }
560 return 0;
561}
562
563/*
564 * for a compressed read, the bio we get passed has all the inode pages
565 * in it. We don't actually do IO on those pages but allocate new ones
566 * to hold the compressed pages on disk.
567 *
568 * bio->bi_iter.bi_sector points to the compressed extent on disk
569 * bio->bi_io_vec points to all of the inode pages
570 *
571 * After the compressed pages are read, we copy the bytes into the
572 * bio we were passed and then call the bio end_io calls
573 */
574int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
575 int mirror_num, unsigned long bio_flags)
576{
577 struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
578 struct extent_io_tree *tree;
579 struct extent_map_tree *em_tree;
580 struct compressed_bio *cb;
581 unsigned long compressed_len;
582 unsigned long nr_pages;
583 unsigned long pg_index;
584 struct page *page;
585 struct block_device *bdev;
586 struct bio *comp_bio;
587 u64 cur_disk_byte = (u64)bio->bi_iter.bi_sector << 9;
588 u64 em_len;
589 u64 em_start;
590 struct extent_map *em;
591 int ret = -ENOMEM;
592 int faili = 0;
593 u32 *sums;
594
595 tree = &BTRFS_I(inode)->io_tree;
596 em_tree = &BTRFS_I(inode)->extent_tree;
597
598 /* we need the actual starting offset of this extent in the file */
599 read_lock(&em_tree->lock);
600 em = lookup_extent_mapping(em_tree,
601 page_offset(bio->bi_io_vec->bv_page),
602 PAGE_SIZE);
603 read_unlock(&em_tree->lock);
604 if (!em)
605 return -EIO;
606
607 compressed_len = em->block_len;
608 cb = kmalloc(compressed_bio_size(fs_info, compressed_len), GFP_NOFS);
609 if (!cb)
610 goto out;
611
612 atomic_set(&cb->pending_bios, 0);
613 cb->errors = 0;
614 cb->inode = inode;
615 cb->mirror_num = mirror_num;
616 sums = &cb->sums;
617
618 cb->start = em->orig_start;
619 em_len = em->len;
620 em_start = em->start;
621
622 free_extent_map(em);
623 em = NULL;
624
625 cb->len = bio->bi_iter.bi_size;
626 cb->compressed_len = compressed_len;
627 cb->compress_type = extent_compress_type(bio_flags);
628 cb->orig_bio = bio;
629
630 nr_pages = DIV_ROUND_UP(compressed_len, PAGE_SIZE);
631 cb->compressed_pages = kcalloc(nr_pages, sizeof(struct page *),
632 GFP_NOFS);
633 if (!cb->compressed_pages)
634 goto fail1;
635
636 bdev = fs_info->fs_devices->latest_bdev;
637
638 for (pg_index = 0; pg_index < nr_pages; pg_index++) {
639 cb->compressed_pages[pg_index] = alloc_page(GFP_NOFS |
640 __GFP_HIGHMEM);
641 if (!cb->compressed_pages[pg_index]) {
642 faili = pg_index - 1;
643 ret = -ENOMEM;
644 goto fail2;
645 }
646 }
647 faili = nr_pages - 1;
648 cb->nr_pages = nr_pages;
649
650 add_ra_bio_pages(inode, em_start + em_len, cb);
651
652 /* include any pages we added in add_ra-bio_pages */
653 cb->len = bio->bi_iter.bi_size;
654
655 comp_bio = compressed_bio_alloc(bdev, cur_disk_byte, GFP_NOFS);
656 if (!comp_bio)
657 goto fail2;
658 bio_set_op_attrs (comp_bio, REQ_OP_READ, 0);
659 comp_bio->bi_private = cb;
660 comp_bio->bi_end_io = end_compressed_bio_read;
661 atomic_inc(&cb->pending_bios);
662
663 for (pg_index = 0; pg_index < nr_pages; pg_index++) {
664 page = cb->compressed_pages[pg_index];
665 page->mapping = inode->i_mapping;
666 page->index = em_start >> PAGE_SHIFT;
667
668 if (comp_bio->bi_iter.bi_size)
669 ret = tree->ops->merge_bio_hook(page, 0,
670 PAGE_SIZE,
671 comp_bio, 0);
672 else
673 ret = 0;
674
675 page->mapping = NULL;
676 if (ret || bio_add_page(comp_bio, page, PAGE_SIZE, 0) <
677 PAGE_SIZE) {
678 bio_get(comp_bio);
679
680 ret = btrfs_bio_wq_end_io(fs_info, comp_bio,
681 BTRFS_WQ_ENDIO_DATA);
682 BUG_ON(ret); /* -ENOMEM */
683
684 /*
685 * inc the count before we submit the bio so
686 * we know the end IO handler won't happen before
687 * we inc the count. Otherwise, the cb might get
688 * freed before we're done setting it up
689 */
690 atomic_inc(&cb->pending_bios);
691
692 if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
693 ret = btrfs_lookup_bio_sums(inode, comp_bio,
694 sums);
695 BUG_ON(ret); /* -ENOMEM */
696 }
697 sums += DIV_ROUND_UP(comp_bio->bi_iter.bi_size,
698 fs_info->sectorsize);
699
700 ret = btrfs_map_bio(fs_info, comp_bio, mirror_num, 0);
701 if (ret) {
702 comp_bio->bi_error = ret;
703 bio_endio(comp_bio);
704 }
705
706 bio_put(comp_bio);
707
708 comp_bio = compressed_bio_alloc(bdev, cur_disk_byte,
709 GFP_NOFS);
710 BUG_ON(!comp_bio);
711 bio_set_op_attrs(comp_bio, REQ_OP_READ, 0);
712 comp_bio->bi_private = cb;
713 comp_bio->bi_end_io = end_compressed_bio_read;
714
715 bio_add_page(comp_bio, page, PAGE_SIZE, 0);
716 }
717 cur_disk_byte += PAGE_SIZE;
718 }
719 bio_get(comp_bio);
720
721 ret = btrfs_bio_wq_end_io(fs_info, comp_bio, BTRFS_WQ_ENDIO_DATA);
722 BUG_ON(ret); /* -ENOMEM */
723
724 if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
725 ret = btrfs_lookup_bio_sums(inode, comp_bio, sums);
726 BUG_ON(ret); /* -ENOMEM */
727 }
728
729 ret = btrfs_map_bio(fs_info, comp_bio, mirror_num, 0);
730 if (ret) {
731 comp_bio->bi_error = ret;
732 bio_endio(comp_bio);
733 }
734
735 bio_put(comp_bio);
736 return 0;
737
738fail2:
739 while (faili >= 0) {
740 __free_page(cb->compressed_pages[faili]);
741 faili--;
742 }
743
744 kfree(cb->compressed_pages);
745fail1:
746 kfree(cb);
747out:
748 free_extent_map(em);
749 return ret;
750}
751
752static struct {
753 struct list_head idle_ws;
754 spinlock_t ws_lock;
755 /* Number of free workspaces */
756 int free_ws;
757 /* Total number of allocated workspaces */
758 atomic_t total_ws;
759 /* Waiters for a free workspace */
760 wait_queue_head_t ws_wait;
761} btrfs_comp_ws[BTRFS_COMPRESS_TYPES];
762
763static const struct btrfs_compress_op * const btrfs_compress_op[] = {
764 &btrfs_zlib_compress,
765 &btrfs_lzo_compress,
766};
767
768void __init btrfs_init_compress(void)
769{
770 int i;
771
772 for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
773 struct list_head *workspace;
774
775 INIT_LIST_HEAD(&btrfs_comp_ws[i].idle_ws);
776 spin_lock_init(&btrfs_comp_ws[i].ws_lock);
777 atomic_set(&btrfs_comp_ws[i].total_ws, 0);
778 init_waitqueue_head(&btrfs_comp_ws[i].ws_wait);
779
780 /*
781 * Preallocate one workspace for each compression type so
782 * we can guarantee forward progress in the worst case
783 */
784 workspace = btrfs_compress_op[i]->alloc_workspace();
785 if (IS_ERR(workspace)) {
786 pr_warn("BTRFS: cannot preallocate compression workspace, will try later\n");
787 } else {
788 atomic_set(&btrfs_comp_ws[i].total_ws, 1);
789 btrfs_comp_ws[i].free_ws = 1;
790 list_add(workspace, &btrfs_comp_ws[i].idle_ws);
791 }
792 }
793}
794
795/*
796 * This finds an available workspace or allocates a new one.
797 * If it's not possible to allocate a new one, waits until there's one.
798 * Preallocation makes a forward progress guarantees and we do not return
799 * errors.
800 */
801static struct list_head *find_workspace(int type)
802{
803 struct list_head *workspace;
804 int cpus = num_online_cpus();
805 int idx = type - 1;
806
807 struct list_head *idle_ws = &btrfs_comp_ws[idx].idle_ws;
808 spinlock_t *ws_lock = &btrfs_comp_ws[idx].ws_lock;
809 atomic_t *total_ws = &btrfs_comp_ws[idx].total_ws;
810 wait_queue_head_t *ws_wait = &btrfs_comp_ws[idx].ws_wait;
811 int *free_ws = &btrfs_comp_ws[idx].free_ws;
812again:
813 spin_lock(ws_lock);
814 if (!list_empty(idle_ws)) {
815 workspace = idle_ws->next;
816 list_del(workspace);
817 (*free_ws)--;
818 spin_unlock(ws_lock);
819 return workspace;
820
821 }
822 if (atomic_read(total_ws) > cpus) {
823 DEFINE_WAIT(wait);
824
825 spin_unlock(ws_lock);
826 prepare_to_wait(ws_wait, &wait, TASK_UNINTERRUPTIBLE);
827 if (atomic_read(total_ws) > cpus && !*free_ws)
828 schedule();
829 finish_wait(ws_wait, &wait);
830 goto again;
831 }
832 atomic_inc(total_ws);
833 spin_unlock(ws_lock);
834
835 workspace = btrfs_compress_op[idx]->alloc_workspace();
836 if (IS_ERR(workspace)) {
837 atomic_dec(total_ws);
838 wake_up(ws_wait);
839
840 /*
841 * Do not return the error but go back to waiting. There's a
842 * workspace preallocated for each type and the compression
843 * time is bounded so we get to a workspace eventually. This
844 * makes our caller's life easier.
845 *
846 * To prevent silent and low-probability deadlocks (when the
847 * initial preallocation fails), check if there are any
848 * workspaces at all.
849 */
850 if (atomic_read(total_ws) == 0) {
851 static DEFINE_RATELIMIT_STATE(_rs,
852 /* once per minute */ 60 * HZ,
853 /* no burst */ 1);
854
855 if (__ratelimit(&_rs)) {
856 pr_warn("BTRFS: no compression workspaces, low memory, retrying\n");
857 }
858 }
859 goto again;
860 }
861 return workspace;
862}
863
864/*
865 * put a workspace struct back on the list or free it if we have enough
866 * idle ones sitting around
867 */
868static void free_workspace(int type, struct list_head *workspace)
869{
870 int idx = type - 1;
871 struct list_head *idle_ws = &btrfs_comp_ws[idx].idle_ws;
872 spinlock_t *ws_lock = &btrfs_comp_ws[idx].ws_lock;
873 atomic_t *total_ws = &btrfs_comp_ws[idx].total_ws;
874 wait_queue_head_t *ws_wait = &btrfs_comp_ws[idx].ws_wait;
875 int *free_ws = &btrfs_comp_ws[idx].free_ws;
876
877 spin_lock(ws_lock);
878 if (*free_ws < num_online_cpus()) {
879 list_add(workspace, idle_ws);
880 (*free_ws)++;
881 spin_unlock(ws_lock);
882 goto wake;
883 }
884 spin_unlock(ws_lock);
885
886 btrfs_compress_op[idx]->free_workspace(workspace);
887 atomic_dec(total_ws);
888wake:
889 /*
890 * Make sure counter is updated before we wake up waiters.
891 */
892 smp_mb();
893 if (waitqueue_active(ws_wait))
894 wake_up(ws_wait);
895}
896
897/*
898 * cleanup function for module exit
899 */
900static void free_workspaces(void)
901{
902 struct list_head *workspace;
903 int i;
904
905 for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
906 while (!list_empty(&btrfs_comp_ws[i].idle_ws)) {
907 workspace = btrfs_comp_ws[i].idle_ws.next;
908 list_del(workspace);
909 btrfs_compress_op[i]->free_workspace(workspace);
910 atomic_dec(&btrfs_comp_ws[i].total_ws);
911 }
912 }
913}
914
915/*
916 * given an address space and start/len, compress the bytes.
917 *
918 * pages are allocated to hold the compressed result and stored
919 * in 'pages'
920 *
921 * out_pages is used to return the number of pages allocated. There
922 * may be pages allocated even if we return an error
923 *
924 * total_in is used to return the number of bytes actually read. It
925 * may be smaller then len if we had to exit early because we
926 * ran out of room in the pages array or because we cross the
927 * max_out threshold.
928 *
929 * total_out is used to return the total number of compressed bytes
930 *
931 * max_out tells us the max number of bytes that we're allowed to
932 * stuff into pages
933 */
934int btrfs_compress_pages(int type, struct address_space *mapping,
935 u64 start, unsigned long len,
936 struct page **pages,
937 unsigned long nr_dest_pages,
938 unsigned long *out_pages,
939 unsigned long *total_in,
940 unsigned long *total_out,
941 unsigned long max_out)
942{
943 struct list_head *workspace;
944 int ret;
945
946 workspace = find_workspace(type);
947
948 ret = btrfs_compress_op[type-1]->compress_pages(workspace, mapping,
949 start, len, pages,
950 nr_dest_pages, out_pages,
951 total_in, total_out,
952 max_out);
953 free_workspace(type, workspace);
954 return ret;
955}
956
957/*
958 * pages_in is an array of pages with compressed data.
959 *
960 * disk_start is the starting logical offset of this array in the file
961 *
962 * orig_bio contains the pages from the file that we want to decompress into
963 *
964 * srclen is the number of bytes in pages_in
965 *
966 * The basic idea is that we have a bio that was created by readpages.
967 * The pages in the bio are for the uncompressed data, and they may not
968 * be contiguous. They all correspond to the range of bytes covered by
969 * the compressed extent.
970 */
971static int btrfs_decompress_bio(int type, struct page **pages_in,
972 u64 disk_start, struct bio *orig_bio,
973 size_t srclen)
974{
975 struct list_head *workspace;
976 int ret;
977
978 workspace = find_workspace(type);
979
980 ret = btrfs_compress_op[type-1]->decompress_bio(workspace, pages_in,
981 disk_start, orig_bio,
982 srclen);
983 free_workspace(type, workspace);
984 return ret;
985}
986
987/*
988 * a less complex decompression routine. Our compressed data fits in a
989 * single page, and we want to read a single page out of it.
990 * start_byte tells us the offset into the compressed data we're interested in
991 */
992int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
993 unsigned long start_byte, size_t srclen, size_t destlen)
994{
995 struct list_head *workspace;
996 int ret;
997
998 workspace = find_workspace(type);
999
1000 ret = btrfs_compress_op[type-1]->decompress(workspace, data_in,
1001 dest_page, start_byte,
1002 srclen, destlen);
1003
1004 free_workspace(type, workspace);
1005 return ret;
1006}
1007
1008void btrfs_exit_compress(void)
1009{
1010 free_workspaces();
1011}
1012
1013/*
1014 * Copy uncompressed data from working buffer to pages.
1015 *
1016 * buf_start is the byte offset we're of the start of our workspace buffer.
1017 *
1018 * total_out is the last byte of the buffer
1019 */
1020int btrfs_decompress_buf2page(char *buf, unsigned long buf_start,
1021 unsigned long total_out, u64 disk_start,
1022 struct bio *bio)
1023{
1024 unsigned long buf_offset;
1025 unsigned long current_buf_start;
1026 unsigned long start_byte;
1027 unsigned long prev_start_byte;
1028 unsigned long working_bytes = total_out - buf_start;
1029 unsigned long bytes;
1030 char *kaddr;
1031 struct bio_vec bvec = bio_iter_iovec(bio, bio->bi_iter);
1032
1033 /*
1034 * start byte is the first byte of the page we're currently
1035 * copying into relative to the start of the compressed data.
1036 */
1037 start_byte = page_offset(bvec.bv_page) - disk_start;
1038
1039 /* we haven't yet hit data corresponding to this page */
1040 if (total_out <= start_byte)
1041 return 1;
1042
1043 /*
1044 * the start of the data we care about is offset into
1045 * the middle of our working buffer
1046 */
1047 if (total_out > start_byte && buf_start < start_byte) {
1048 buf_offset = start_byte - buf_start;
1049 working_bytes -= buf_offset;
1050 } else {
1051 buf_offset = 0;
1052 }
1053 current_buf_start = buf_start;
1054
1055 /* copy bytes from the working buffer into the pages */
1056 while (working_bytes > 0) {
1057 bytes = min_t(unsigned long, bvec.bv_len,
1058 PAGE_SIZE - buf_offset);
1059 bytes = min(bytes, working_bytes);
1060
1061 kaddr = kmap_atomic(bvec.bv_page);
1062 memcpy(kaddr + bvec.bv_offset, buf + buf_offset, bytes);
1063 kunmap_atomic(kaddr);
1064 flush_dcache_page(bvec.bv_page);
1065
1066 buf_offset += bytes;
1067 working_bytes -= bytes;
1068 current_buf_start += bytes;
1069
1070 /* check if we need to pick another page */
1071 bio_advance(bio, bytes);
1072 if (!bio->bi_iter.bi_size)
1073 return 0;
1074 bvec = bio_iter_iovec(bio, bio->bi_iter);
1075 prev_start_byte = start_byte;
1076 start_byte = page_offset(bvec.bv_page) - disk_start;
1077
1078 /*
1079 * We need to make sure we're only adjusting
1080 * our offset into compression working buffer when
1081 * we're switching pages. Otherwise we can incorrectly
1082 * keep copying when we were actually done.
1083 */
1084 if (start_byte != prev_start_byte) {
1085 /*
1086 * make sure our new page is covered by this
1087 * working buffer
1088 */
1089 if (total_out <= start_byte)
1090 return 1;
1091
1092 /*
1093 * the next page in the biovec might not be adjacent
1094 * to the last page, but it might still be found
1095 * inside this working buffer. bump our offset pointer
1096 */
1097 if (total_out > start_byte &&
1098 current_buf_start < start_byte) {
1099 buf_offset = start_byte - buf_start;
1100 working_bytes = total_out - start_byte;
1101 current_buf_start = buf_start + buf_offset;
1102 }
1103 }
1104 }
1105
1106 return 1;
1107}