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c8b97818 CM |
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> | |
c8b97818 CM |
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> | |
5a0e3ad6 | 34 | #include <linux/slab.h> |
fe308533 | 35 | #include <linux/sched/mm.h> |
19562430 | 36 | #include <linux/log2.h> |
c8b97818 CM |
37 | #include "ctree.h" |
38 | #include "disk-io.h" | |
39 | #include "transaction.h" | |
40 | #include "btrfs_inode.h" | |
41 | #include "volumes.h" | |
42 | #include "ordered-data.h" | |
c8b97818 CM |
43 | #include "compression.h" |
44 | #include "extent_io.h" | |
45 | #include "extent_map.h" | |
46 | ||
e128f9c3 DS |
47 | static const char* const btrfs_compress_types[] = { "", "zlib", "lzo", "zstd" }; |
48 | ||
49 | const char* btrfs_compress_type2str(enum btrfs_compression_type type) | |
50 | { | |
51 | switch (type) { | |
52 | case BTRFS_COMPRESS_ZLIB: | |
53 | case BTRFS_COMPRESS_LZO: | |
54 | case BTRFS_COMPRESS_ZSTD: | |
55 | case BTRFS_COMPRESS_NONE: | |
56 | return btrfs_compress_types[type]; | |
57 | } | |
58 | ||
59 | return NULL; | |
60 | } | |
61 | ||
8140dc30 | 62 | static int btrfs_decompress_bio(struct compressed_bio *cb); |
48a3b636 | 63 | |
2ff7e61e | 64 | static inline int compressed_bio_size(struct btrfs_fs_info *fs_info, |
d20f7043 CM |
65 | unsigned long disk_size) |
66 | { | |
0b246afa | 67 | u16 csum_size = btrfs_super_csum_size(fs_info->super_copy); |
6c41761f | 68 | |
d20f7043 | 69 | return sizeof(struct compressed_bio) + |
0b246afa | 70 | (DIV_ROUND_UP(disk_size, fs_info->sectorsize)) * csum_size; |
d20f7043 CM |
71 | } |
72 | ||
f898ac6a | 73 | static int check_compressed_csum(struct btrfs_inode *inode, |
d20f7043 CM |
74 | struct compressed_bio *cb, |
75 | u64 disk_start) | |
76 | { | |
77 | int ret; | |
d20f7043 CM |
78 | struct page *page; |
79 | unsigned long i; | |
80 | char *kaddr; | |
81 | u32 csum; | |
82 | u32 *cb_sum = &cb->sums; | |
83 | ||
f898ac6a | 84 | if (inode->flags & BTRFS_INODE_NODATASUM) |
d20f7043 CM |
85 | return 0; |
86 | ||
87 | for (i = 0; i < cb->nr_pages; i++) { | |
88 | page = cb->compressed_pages[i]; | |
89 | csum = ~(u32)0; | |
90 | ||
7ac687d9 | 91 | kaddr = kmap_atomic(page); |
09cbfeaf | 92 | csum = btrfs_csum_data(kaddr, csum, PAGE_SIZE); |
0b5e3daf | 93 | btrfs_csum_final(csum, (u8 *)&csum); |
7ac687d9 | 94 | kunmap_atomic(kaddr); |
d20f7043 CM |
95 | |
96 | if (csum != *cb_sum) { | |
f898ac6a | 97 | btrfs_print_data_csum_error(inode, disk_start, csum, |
0970a22e | 98 | *cb_sum, cb->mirror_num); |
d20f7043 CM |
99 | ret = -EIO; |
100 | goto fail; | |
101 | } | |
102 | cb_sum++; | |
103 | ||
104 | } | |
105 | ret = 0; | |
106 | fail: | |
107 | return ret; | |
108 | } | |
109 | ||
c8b97818 CM |
110 | /* when we finish reading compressed pages from the disk, we |
111 | * decompress them and then run the bio end_io routines on the | |
112 | * decompressed pages (in the inode address space). | |
113 | * | |
114 | * This allows the checksumming and other IO error handling routines | |
115 | * to work normally | |
116 | * | |
117 | * The compressed pages are freed here, and it must be run | |
118 | * in process context | |
119 | */ | |
4246a0b6 | 120 | static void end_compressed_bio_read(struct bio *bio) |
c8b97818 | 121 | { |
c8b97818 CM |
122 | struct compressed_bio *cb = bio->bi_private; |
123 | struct inode *inode; | |
124 | struct page *page; | |
125 | unsigned long index; | |
cf1167d5 | 126 | unsigned int mirror = btrfs_io_bio(bio)->mirror_num; |
e6311f24 | 127 | int ret = 0; |
c8b97818 | 128 | |
4e4cbee9 | 129 | if (bio->bi_status) |
c8b97818 CM |
130 | cb->errors = 1; |
131 | ||
132 | /* if there are more bios still pending for this compressed | |
133 | * extent, just exit | |
134 | */ | |
a50299ae | 135 | if (!refcount_dec_and_test(&cb->pending_bios)) |
c8b97818 CM |
136 | goto out; |
137 | ||
cf1167d5 LB |
138 | /* |
139 | * Record the correct mirror_num in cb->orig_bio so that | |
140 | * read-repair can work properly. | |
141 | */ | |
142 | ASSERT(btrfs_io_bio(cb->orig_bio)); | |
143 | btrfs_io_bio(cb->orig_bio)->mirror_num = mirror; | |
144 | cb->mirror_num = mirror; | |
145 | ||
e6311f24 LB |
146 | /* |
147 | * Some IO in this cb have failed, just skip checksum as there | |
148 | * is no way it could be correct. | |
149 | */ | |
150 | if (cb->errors == 1) | |
151 | goto csum_failed; | |
152 | ||
d20f7043 | 153 | inode = cb->inode; |
f898ac6a | 154 | ret = check_compressed_csum(BTRFS_I(inode), cb, |
4f024f37 | 155 | (u64)bio->bi_iter.bi_sector << 9); |
d20f7043 CM |
156 | if (ret) |
157 | goto csum_failed; | |
158 | ||
c8b97818 CM |
159 | /* ok, we're the last bio for this extent, lets start |
160 | * the decompression. | |
161 | */ | |
8140dc30 AJ |
162 | ret = btrfs_decompress_bio(cb); |
163 | ||
d20f7043 | 164 | csum_failed: |
c8b97818 CM |
165 | if (ret) |
166 | cb->errors = 1; | |
167 | ||
168 | /* release the compressed pages */ | |
169 | index = 0; | |
170 | for (index = 0; index < cb->nr_pages; index++) { | |
171 | page = cb->compressed_pages[index]; | |
172 | page->mapping = NULL; | |
09cbfeaf | 173 | put_page(page); |
c8b97818 CM |
174 | } |
175 | ||
176 | /* do io completion on the original bio */ | |
771ed689 | 177 | if (cb->errors) { |
c8b97818 | 178 | bio_io_error(cb->orig_bio); |
d20f7043 | 179 | } else { |
2c30c71b KO |
180 | int i; |
181 | struct bio_vec *bvec; | |
d20f7043 CM |
182 | |
183 | /* | |
184 | * we have verified the checksum already, set page | |
185 | * checked so the end_io handlers know about it | |
186 | */ | |
c09abff8 | 187 | ASSERT(!bio_flagged(bio, BIO_CLONED)); |
2c30c71b | 188 | bio_for_each_segment_all(bvec, cb->orig_bio, i) |
d20f7043 | 189 | SetPageChecked(bvec->bv_page); |
2c30c71b | 190 | |
4246a0b6 | 191 | bio_endio(cb->orig_bio); |
d20f7043 | 192 | } |
c8b97818 CM |
193 | |
194 | /* finally free the cb struct */ | |
195 | kfree(cb->compressed_pages); | |
196 | kfree(cb); | |
197 | out: | |
198 | bio_put(bio); | |
199 | } | |
200 | ||
201 | /* | |
202 | * Clear the writeback bits on all of the file | |
203 | * pages for a compressed write | |
204 | */ | |
7bdcefc1 FM |
205 | static noinline void end_compressed_writeback(struct inode *inode, |
206 | const struct compressed_bio *cb) | |
c8b97818 | 207 | { |
09cbfeaf KS |
208 | unsigned long index = cb->start >> PAGE_SHIFT; |
209 | unsigned long end_index = (cb->start + cb->len - 1) >> PAGE_SHIFT; | |
c8b97818 CM |
210 | struct page *pages[16]; |
211 | unsigned long nr_pages = end_index - index + 1; | |
212 | int i; | |
213 | int ret; | |
214 | ||
7bdcefc1 FM |
215 | if (cb->errors) |
216 | mapping_set_error(inode->i_mapping, -EIO); | |
217 | ||
d397712b | 218 | while (nr_pages > 0) { |
c8b97818 | 219 | ret = find_get_pages_contig(inode->i_mapping, index, |
5b050f04 CM |
220 | min_t(unsigned long, |
221 | nr_pages, ARRAY_SIZE(pages)), pages); | |
c8b97818 CM |
222 | if (ret == 0) { |
223 | nr_pages -= 1; | |
224 | index += 1; | |
225 | continue; | |
226 | } | |
227 | for (i = 0; i < ret; i++) { | |
7bdcefc1 FM |
228 | if (cb->errors) |
229 | SetPageError(pages[i]); | |
c8b97818 | 230 | end_page_writeback(pages[i]); |
09cbfeaf | 231 | put_page(pages[i]); |
c8b97818 CM |
232 | } |
233 | nr_pages -= ret; | |
234 | index += ret; | |
235 | } | |
236 | /* the inode may be gone now */ | |
c8b97818 CM |
237 | } |
238 | ||
239 | /* | |
240 | * do the cleanup once all the compressed pages hit the disk. | |
241 | * This will clear writeback on the file pages and free the compressed | |
242 | * pages. | |
243 | * | |
244 | * This also calls the writeback end hooks for the file pages so that | |
245 | * metadata and checksums can be updated in the file. | |
246 | */ | |
4246a0b6 | 247 | static void end_compressed_bio_write(struct bio *bio) |
c8b97818 CM |
248 | { |
249 | struct extent_io_tree *tree; | |
250 | struct compressed_bio *cb = bio->bi_private; | |
251 | struct inode *inode; | |
252 | struct page *page; | |
253 | unsigned long index; | |
254 | ||
4e4cbee9 | 255 | if (bio->bi_status) |
c8b97818 CM |
256 | cb->errors = 1; |
257 | ||
258 | /* if there are more bios still pending for this compressed | |
259 | * extent, just exit | |
260 | */ | |
a50299ae | 261 | if (!refcount_dec_and_test(&cb->pending_bios)) |
c8b97818 CM |
262 | goto out; |
263 | ||
264 | /* ok, we're the last bio for this extent, step one is to | |
265 | * call back into the FS and do all the end_io operations | |
266 | */ | |
267 | inode = cb->inode; | |
268 | tree = &BTRFS_I(inode)->io_tree; | |
70b99e69 | 269 | cb->compressed_pages[0]->mapping = cb->inode->i_mapping; |
c8b97818 CM |
270 | tree->ops->writepage_end_io_hook(cb->compressed_pages[0], |
271 | cb->start, | |
272 | cb->start + cb->len - 1, | |
7bdcefc1 | 273 | NULL, |
2dbe0c77 AJ |
274 | bio->bi_status ? |
275 | BLK_STS_OK : BLK_STS_NOTSUPP); | |
70b99e69 | 276 | cb->compressed_pages[0]->mapping = NULL; |
c8b97818 | 277 | |
7bdcefc1 | 278 | end_compressed_writeback(inode, cb); |
c8b97818 CM |
279 | /* note, our inode could be gone now */ |
280 | ||
281 | /* | |
282 | * release the compressed pages, these came from alloc_page and | |
283 | * are not attached to the inode at all | |
284 | */ | |
285 | index = 0; | |
286 | for (index = 0; index < cb->nr_pages; index++) { | |
287 | page = cb->compressed_pages[index]; | |
288 | page->mapping = NULL; | |
09cbfeaf | 289 | put_page(page); |
c8b97818 CM |
290 | } |
291 | ||
292 | /* finally free the cb struct */ | |
293 | kfree(cb->compressed_pages); | |
294 | kfree(cb); | |
295 | out: | |
296 | bio_put(bio); | |
297 | } | |
298 | ||
299 | /* | |
300 | * worker function to build and submit bios for previously compressed pages. | |
301 | * The corresponding pages in the inode should be marked for writeback | |
302 | * and the compressed pages should have a reference on them for dropping | |
303 | * when the IO is complete. | |
304 | * | |
305 | * This also checksums the file bytes and gets things ready for | |
306 | * the end io hooks. | |
307 | */ | |
4e4cbee9 | 308 | blk_status_t btrfs_submit_compressed_write(struct inode *inode, u64 start, |
c8b97818 CM |
309 | unsigned long len, u64 disk_start, |
310 | unsigned long compressed_len, | |
311 | struct page **compressed_pages, | |
f82b7359 LB |
312 | unsigned long nr_pages, |
313 | unsigned int write_flags) | |
c8b97818 | 314 | { |
0b246afa | 315 | struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); |
c8b97818 | 316 | struct bio *bio = NULL; |
c8b97818 CM |
317 | struct compressed_bio *cb; |
318 | unsigned long bytes_left; | |
319 | struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree; | |
306e16ce | 320 | int pg_index = 0; |
c8b97818 CM |
321 | struct page *page; |
322 | u64 first_byte = disk_start; | |
323 | struct block_device *bdev; | |
4e4cbee9 | 324 | blk_status_t ret; |
e55179b3 | 325 | int skip_sum = BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM; |
c8b97818 | 326 | |
09cbfeaf | 327 | WARN_ON(start & ((u64)PAGE_SIZE - 1)); |
2ff7e61e | 328 | cb = kmalloc(compressed_bio_size(fs_info, compressed_len), GFP_NOFS); |
dac97e51 | 329 | if (!cb) |
4e4cbee9 | 330 | return BLK_STS_RESOURCE; |
a50299ae | 331 | refcount_set(&cb->pending_bios, 0); |
c8b97818 CM |
332 | cb->errors = 0; |
333 | cb->inode = inode; | |
334 | cb->start = start; | |
335 | cb->len = len; | |
d20f7043 | 336 | cb->mirror_num = 0; |
c8b97818 CM |
337 | cb->compressed_pages = compressed_pages; |
338 | cb->compressed_len = compressed_len; | |
339 | cb->orig_bio = NULL; | |
340 | cb->nr_pages = nr_pages; | |
341 | ||
0b246afa | 342 | bdev = fs_info->fs_devices->latest_bdev; |
c8b97818 | 343 | |
c821e7f3 | 344 | bio = btrfs_bio_alloc(bdev, first_byte); |
f82b7359 | 345 | bio->bi_opf = REQ_OP_WRITE | write_flags; |
c8b97818 CM |
346 | bio->bi_private = cb; |
347 | bio->bi_end_io = end_compressed_bio_write; | |
a50299ae | 348 | refcount_set(&cb->pending_bios, 1); |
c8b97818 CM |
349 | |
350 | /* create and submit bios for the compressed pages */ | |
351 | bytes_left = compressed_len; | |
306e16ce | 352 | for (pg_index = 0; pg_index < cb->nr_pages; pg_index++) { |
4e4cbee9 CH |
353 | int submit = 0; |
354 | ||
306e16ce | 355 | page = compressed_pages[pg_index]; |
c8b97818 | 356 | page->mapping = inode->i_mapping; |
4f024f37 | 357 | if (bio->bi_iter.bi_size) |
4e4cbee9 | 358 | submit = io_tree->ops->merge_bio_hook(page, 0, |
09cbfeaf | 359 | PAGE_SIZE, |
c8b97818 | 360 | bio, 0); |
c8b97818 | 361 | |
70b99e69 | 362 | page->mapping = NULL; |
4e4cbee9 | 363 | if (submit || bio_add_page(bio, page, PAGE_SIZE, 0) < |
09cbfeaf | 364 | PAGE_SIZE) { |
af09abfe CM |
365 | /* |
366 | * inc the count before we submit the bio so | |
367 | * we know the end IO handler won't happen before | |
368 | * we inc the count. Otherwise, the cb might get | |
369 | * freed before we're done setting it up | |
370 | */ | |
a50299ae | 371 | refcount_inc(&cb->pending_bios); |
0b246afa JM |
372 | ret = btrfs_bio_wq_end_io(fs_info, bio, |
373 | BTRFS_WQ_ENDIO_DATA); | |
79787eaa | 374 | BUG_ON(ret); /* -ENOMEM */ |
c8b97818 | 375 | |
e55179b3 | 376 | if (!skip_sum) { |
2ff7e61e | 377 | ret = btrfs_csum_one_bio(inode, bio, start, 1); |
79787eaa | 378 | BUG_ON(ret); /* -ENOMEM */ |
e55179b3 | 379 | } |
d20f7043 | 380 | |
2ff7e61e | 381 | ret = btrfs_map_bio(fs_info, bio, 0, 1); |
f5daf2c7 | 382 | if (ret) { |
4e4cbee9 | 383 | bio->bi_status = ret; |
f5daf2c7 LB |
384 | bio_endio(bio); |
385 | } | |
c8b97818 | 386 | |
c821e7f3 | 387 | bio = btrfs_bio_alloc(bdev, first_byte); |
f82b7359 | 388 | bio->bi_opf = REQ_OP_WRITE | write_flags; |
c8b97818 CM |
389 | bio->bi_private = cb; |
390 | bio->bi_end_io = end_compressed_bio_write; | |
09cbfeaf | 391 | bio_add_page(bio, page, PAGE_SIZE, 0); |
c8b97818 | 392 | } |
09cbfeaf | 393 | if (bytes_left < PAGE_SIZE) { |
0b246afa | 394 | btrfs_info(fs_info, |
efe120a0 | 395 | "bytes left %lu compress len %lu nr %lu", |
cfbc246e CM |
396 | bytes_left, cb->compressed_len, cb->nr_pages); |
397 | } | |
09cbfeaf KS |
398 | bytes_left -= PAGE_SIZE; |
399 | first_byte += PAGE_SIZE; | |
771ed689 | 400 | cond_resched(); |
c8b97818 | 401 | } |
c8b97818 | 402 | |
0b246afa | 403 | ret = btrfs_bio_wq_end_io(fs_info, bio, BTRFS_WQ_ENDIO_DATA); |
79787eaa | 404 | BUG_ON(ret); /* -ENOMEM */ |
c8b97818 | 405 | |
e55179b3 | 406 | if (!skip_sum) { |
2ff7e61e | 407 | ret = btrfs_csum_one_bio(inode, bio, start, 1); |
79787eaa | 408 | BUG_ON(ret); /* -ENOMEM */ |
e55179b3 | 409 | } |
d20f7043 | 410 | |
2ff7e61e | 411 | ret = btrfs_map_bio(fs_info, bio, 0, 1); |
f5daf2c7 | 412 | if (ret) { |
4e4cbee9 | 413 | bio->bi_status = ret; |
f5daf2c7 LB |
414 | bio_endio(bio); |
415 | } | |
c8b97818 | 416 | |
c8b97818 CM |
417 | return 0; |
418 | } | |
419 | ||
2a4d0c90 CH |
420 | static u64 bio_end_offset(struct bio *bio) |
421 | { | |
c45a8f2d | 422 | struct bio_vec *last = bio_last_bvec_all(bio); |
2a4d0c90 CH |
423 | |
424 | return page_offset(last->bv_page) + last->bv_len + last->bv_offset; | |
425 | } | |
426 | ||
771ed689 CM |
427 | static noinline int add_ra_bio_pages(struct inode *inode, |
428 | u64 compressed_end, | |
429 | struct compressed_bio *cb) | |
430 | { | |
431 | unsigned long end_index; | |
306e16ce | 432 | unsigned long pg_index; |
771ed689 CM |
433 | u64 last_offset; |
434 | u64 isize = i_size_read(inode); | |
435 | int ret; | |
436 | struct page *page; | |
437 | unsigned long nr_pages = 0; | |
438 | struct extent_map *em; | |
439 | struct address_space *mapping = inode->i_mapping; | |
771ed689 CM |
440 | struct extent_map_tree *em_tree; |
441 | struct extent_io_tree *tree; | |
442 | u64 end; | |
443 | int misses = 0; | |
444 | ||
2a4d0c90 | 445 | last_offset = bio_end_offset(cb->orig_bio); |
771ed689 CM |
446 | em_tree = &BTRFS_I(inode)->extent_tree; |
447 | tree = &BTRFS_I(inode)->io_tree; | |
448 | ||
449 | if (isize == 0) | |
450 | return 0; | |
451 | ||
09cbfeaf | 452 | end_index = (i_size_read(inode) - 1) >> PAGE_SHIFT; |
771ed689 | 453 | |
d397712b | 454 | while (last_offset < compressed_end) { |
09cbfeaf | 455 | pg_index = last_offset >> PAGE_SHIFT; |
771ed689 | 456 | |
306e16ce | 457 | if (pg_index > end_index) |
771ed689 CM |
458 | break; |
459 | ||
460 | rcu_read_lock(); | |
306e16ce | 461 | page = radix_tree_lookup(&mapping->page_tree, pg_index); |
771ed689 | 462 | rcu_read_unlock(); |
0cd6144a | 463 | if (page && !radix_tree_exceptional_entry(page)) { |
771ed689 CM |
464 | misses++; |
465 | if (misses > 4) | |
466 | break; | |
467 | goto next; | |
468 | } | |
469 | ||
c62d2555 MH |
470 | page = __page_cache_alloc(mapping_gfp_constraint(mapping, |
471 | ~__GFP_FS)); | |
771ed689 CM |
472 | if (!page) |
473 | break; | |
474 | ||
c62d2555 | 475 | if (add_to_page_cache_lru(page, mapping, pg_index, GFP_NOFS)) { |
09cbfeaf | 476 | put_page(page); |
771ed689 CM |
477 | goto next; |
478 | } | |
479 | ||
09cbfeaf | 480 | end = last_offset + PAGE_SIZE - 1; |
771ed689 CM |
481 | /* |
482 | * at this point, we have a locked page in the page cache | |
483 | * for these bytes in the file. But, we have to make | |
484 | * sure they map to this compressed extent on disk. | |
485 | */ | |
486 | set_page_extent_mapped(page); | |
d0082371 | 487 | lock_extent(tree, last_offset, end); |
890871be | 488 | read_lock(&em_tree->lock); |
771ed689 | 489 | em = lookup_extent_mapping(em_tree, last_offset, |
09cbfeaf | 490 | PAGE_SIZE); |
890871be | 491 | read_unlock(&em_tree->lock); |
771ed689 CM |
492 | |
493 | if (!em || last_offset < em->start || | |
09cbfeaf | 494 | (last_offset + PAGE_SIZE > extent_map_end(em)) || |
4f024f37 | 495 | (em->block_start >> 9) != cb->orig_bio->bi_iter.bi_sector) { |
771ed689 | 496 | free_extent_map(em); |
d0082371 | 497 | unlock_extent(tree, last_offset, end); |
771ed689 | 498 | unlock_page(page); |
09cbfeaf | 499 | put_page(page); |
771ed689 CM |
500 | break; |
501 | } | |
502 | free_extent_map(em); | |
503 | ||
504 | if (page->index == end_index) { | |
505 | char *userpage; | |
09cbfeaf | 506 | size_t zero_offset = isize & (PAGE_SIZE - 1); |
771ed689 CM |
507 | |
508 | if (zero_offset) { | |
509 | int zeros; | |
09cbfeaf | 510 | zeros = PAGE_SIZE - zero_offset; |
7ac687d9 | 511 | userpage = kmap_atomic(page); |
771ed689 CM |
512 | memset(userpage + zero_offset, 0, zeros); |
513 | flush_dcache_page(page); | |
7ac687d9 | 514 | kunmap_atomic(userpage); |
771ed689 CM |
515 | } |
516 | } | |
517 | ||
518 | ret = bio_add_page(cb->orig_bio, page, | |
09cbfeaf | 519 | PAGE_SIZE, 0); |
771ed689 | 520 | |
09cbfeaf | 521 | if (ret == PAGE_SIZE) { |
771ed689 | 522 | nr_pages++; |
09cbfeaf | 523 | put_page(page); |
771ed689 | 524 | } else { |
d0082371 | 525 | unlock_extent(tree, last_offset, end); |
771ed689 | 526 | unlock_page(page); |
09cbfeaf | 527 | put_page(page); |
771ed689 CM |
528 | break; |
529 | } | |
530 | next: | |
09cbfeaf | 531 | last_offset += PAGE_SIZE; |
771ed689 | 532 | } |
771ed689 CM |
533 | return 0; |
534 | } | |
535 | ||
c8b97818 CM |
536 | /* |
537 | * for a compressed read, the bio we get passed has all the inode pages | |
538 | * in it. We don't actually do IO on those pages but allocate new ones | |
539 | * to hold the compressed pages on disk. | |
540 | * | |
4f024f37 | 541 | * bio->bi_iter.bi_sector points to the compressed extent on disk |
c8b97818 | 542 | * bio->bi_io_vec points to all of the inode pages |
c8b97818 CM |
543 | * |
544 | * After the compressed pages are read, we copy the bytes into the | |
545 | * bio we were passed and then call the bio end_io calls | |
546 | */ | |
4e4cbee9 | 547 | blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio, |
c8b97818 CM |
548 | int mirror_num, unsigned long bio_flags) |
549 | { | |
0b246afa | 550 | struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); |
c8b97818 CM |
551 | struct extent_io_tree *tree; |
552 | struct extent_map_tree *em_tree; | |
553 | struct compressed_bio *cb; | |
c8b97818 CM |
554 | unsigned long compressed_len; |
555 | unsigned long nr_pages; | |
306e16ce | 556 | unsigned long pg_index; |
c8b97818 CM |
557 | struct page *page; |
558 | struct block_device *bdev; | |
559 | struct bio *comp_bio; | |
4f024f37 | 560 | u64 cur_disk_byte = (u64)bio->bi_iter.bi_sector << 9; |
e04ca626 CM |
561 | u64 em_len; |
562 | u64 em_start; | |
c8b97818 | 563 | struct extent_map *em; |
4e4cbee9 | 564 | blk_status_t ret = BLK_STS_RESOURCE; |
15e3004a | 565 | int faili = 0; |
d20f7043 | 566 | u32 *sums; |
c8b97818 CM |
567 | |
568 | tree = &BTRFS_I(inode)->io_tree; | |
569 | em_tree = &BTRFS_I(inode)->extent_tree; | |
570 | ||
571 | /* we need the actual starting offset of this extent in the file */ | |
890871be | 572 | read_lock(&em_tree->lock); |
c8b97818 | 573 | em = lookup_extent_mapping(em_tree, |
263663cd | 574 | page_offset(bio_first_page_all(bio)), |
09cbfeaf | 575 | PAGE_SIZE); |
890871be | 576 | read_unlock(&em_tree->lock); |
285190d9 | 577 | if (!em) |
4e4cbee9 | 578 | return BLK_STS_IOERR; |
c8b97818 | 579 | |
d20f7043 | 580 | compressed_len = em->block_len; |
2ff7e61e | 581 | cb = kmalloc(compressed_bio_size(fs_info, compressed_len), GFP_NOFS); |
6b82ce8d | 582 | if (!cb) |
583 | goto out; | |
584 | ||
a50299ae | 585 | refcount_set(&cb->pending_bios, 0); |
c8b97818 CM |
586 | cb->errors = 0; |
587 | cb->inode = inode; | |
d20f7043 CM |
588 | cb->mirror_num = mirror_num; |
589 | sums = &cb->sums; | |
c8b97818 | 590 | |
ff5b7ee3 | 591 | cb->start = em->orig_start; |
e04ca626 CM |
592 | em_len = em->len; |
593 | em_start = em->start; | |
d20f7043 | 594 | |
c8b97818 | 595 | free_extent_map(em); |
e04ca626 | 596 | em = NULL; |
c8b97818 | 597 | |
81381053 | 598 | cb->len = bio->bi_iter.bi_size; |
c8b97818 | 599 | cb->compressed_len = compressed_len; |
261507a0 | 600 | cb->compress_type = extent_compress_type(bio_flags); |
c8b97818 CM |
601 | cb->orig_bio = bio; |
602 | ||
09cbfeaf | 603 | nr_pages = DIV_ROUND_UP(compressed_len, PAGE_SIZE); |
31e818fe | 604 | cb->compressed_pages = kcalloc(nr_pages, sizeof(struct page *), |
c8b97818 | 605 | GFP_NOFS); |
6b82ce8d | 606 | if (!cb->compressed_pages) |
607 | goto fail1; | |
608 | ||
0b246afa | 609 | bdev = fs_info->fs_devices->latest_bdev; |
c8b97818 | 610 | |
306e16ce DS |
611 | for (pg_index = 0; pg_index < nr_pages; pg_index++) { |
612 | cb->compressed_pages[pg_index] = alloc_page(GFP_NOFS | | |
c8b97818 | 613 | __GFP_HIGHMEM); |
15e3004a JB |
614 | if (!cb->compressed_pages[pg_index]) { |
615 | faili = pg_index - 1; | |
0e9350de | 616 | ret = BLK_STS_RESOURCE; |
6b82ce8d | 617 | goto fail2; |
15e3004a | 618 | } |
c8b97818 | 619 | } |
15e3004a | 620 | faili = nr_pages - 1; |
c8b97818 CM |
621 | cb->nr_pages = nr_pages; |
622 | ||
7f042a83 | 623 | add_ra_bio_pages(inode, em_start + em_len, cb); |
771ed689 | 624 | |
771ed689 | 625 | /* include any pages we added in add_ra-bio_pages */ |
81381053 | 626 | cb->len = bio->bi_iter.bi_size; |
771ed689 | 627 | |
c821e7f3 | 628 | comp_bio = btrfs_bio_alloc(bdev, cur_disk_byte); |
37226b21 | 629 | bio_set_op_attrs (comp_bio, REQ_OP_READ, 0); |
c8b97818 CM |
630 | comp_bio->bi_private = cb; |
631 | comp_bio->bi_end_io = end_compressed_bio_read; | |
a50299ae | 632 | refcount_set(&cb->pending_bios, 1); |
c8b97818 | 633 | |
306e16ce | 634 | for (pg_index = 0; pg_index < nr_pages; pg_index++) { |
4e4cbee9 CH |
635 | int submit = 0; |
636 | ||
306e16ce | 637 | page = cb->compressed_pages[pg_index]; |
c8b97818 | 638 | page->mapping = inode->i_mapping; |
09cbfeaf | 639 | page->index = em_start >> PAGE_SHIFT; |
d20f7043 | 640 | |
4f024f37 | 641 | if (comp_bio->bi_iter.bi_size) |
4e4cbee9 | 642 | submit = tree->ops->merge_bio_hook(page, 0, |
09cbfeaf | 643 | PAGE_SIZE, |
c8b97818 | 644 | comp_bio, 0); |
c8b97818 | 645 | |
70b99e69 | 646 | page->mapping = NULL; |
4e4cbee9 | 647 | if (submit || bio_add_page(comp_bio, page, PAGE_SIZE, 0) < |
09cbfeaf | 648 | PAGE_SIZE) { |
0b246afa JM |
649 | ret = btrfs_bio_wq_end_io(fs_info, comp_bio, |
650 | BTRFS_WQ_ENDIO_DATA); | |
79787eaa | 651 | BUG_ON(ret); /* -ENOMEM */ |
c8b97818 | 652 | |
af09abfe CM |
653 | /* |
654 | * inc the count before we submit the bio so | |
655 | * we know the end IO handler won't happen before | |
656 | * we inc the count. Otherwise, the cb might get | |
657 | * freed before we're done setting it up | |
658 | */ | |
a50299ae | 659 | refcount_inc(&cb->pending_bios); |
af09abfe | 660 | |
6cbff00f | 661 | if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) { |
2ff7e61e JM |
662 | ret = btrfs_lookup_bio_sums(inode, comp_bio, |
663 | sums); | |
79787eaa | 664 | BUG_ON(ret); /* -ENOMEM */ |
d20f7043 | 665 | } |
ed6078f7 | 666 | sums += DIV_ROUND_UP(comp_bio->bi_iter.bi_size, |
0b246afa | 667 | fs_info->sectorsize); |
d20f7043 | 668 | |
2ff7e61e | 669 | ret = btrfs_map_bio(fs_info, comp_bio, mirror_num, 0); |
4246a0b6 | 670 | if (ret) { |
4e4cbee9 | 671 | comp_bio->bi_status = ret; |
4246a0b6 CH |
672 | bio_endio(comp_bio); |
673 | } | |
c8b97818 | 674 | |
c821e7f3 | 675 | comp_bio = btrfs_bio_alloc(bdev, cur_disk_byte); |
37226b21 | 676 | bio_set_op_attrs(comp_bio, REQ_OP_READ, 0); |
771ed689 CM |
677 | comp_bio->bi_private = cb; |
678 | comp_bio->bi_end_io = end_compressed_bio_read; | |
679 | ||
09cbfeaf | 680 | bio_add_page(comp_bio, page, PAGE_SIZE, 0); |
c8b97818 | 681 | } |
09cbfeaf | 682 | cur_disk_byte += PAGE_SIZE; |
c8b97818 | 683 | } |
c8b97818 | 684 | |
0b246afa | 685 | ret = btrfs_bio_wq_end_io(fs_info, comp_bio, BTRFS_WQ_ENDIO_DATA); |
79787eaa | 686 | BUG_ON(ret); /* -ENOMEM */ |
c8b97818 | 687 | |
c2db1073 | 688 | if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) { |
2ff7e61e | 689 | ret = btrfs_lookup_bio_sums(inode, comp_bio, sums); |
79787eaa | 690 | BUG_ON(ret); /* -ENOMEM */ |
c2db1073 | 691 | } |
d20f7043 | 692 | |
2ff7e61e | 693 | ret = btrfs_map_bio(fs_info, comp_bio, mirror_num, 0); |
4246a0b6 | 694 | if (ret) { |
4e4cbee9 | 695 | comp_bio->bi_status = ret; |
4246a0b6 CH |
696 | bio_endio(comp_bio); |
697 | } | |
c8b97818 | 698 | |
c8b97818 | 699 | return 0; |
6b82ce8d | 700 | |
701 | fail2: | |
15e3004a JB |
702 | while (faili >= 0) { |
703 | __free_page(cb->compressed_pages[faili]); | |
704 | faili--; | |
705 | } | |
6b82ce8d | 706 | |
707 | kfree(cb->compressed_pages); | |
708 | fail1: | |
709 | kfree(cb); | |
710 | out: | |
711 | free_extent_map(em); | |
712 | return ret; | |
c8b97818 | 713 | } |
261507a0 | 714 | |
17b5a6c1 TT |
715 | /* |
716 | * Heuristic uses systematic sampling to collect data from the input data | |
717 | * range, the logic can be tuned by the following constants: | |
718 | * | |
719 | * @SAMPLING_READ_SIZE - how many bytes will be copied from for each sample | |
720 | * @SAMPLING_INTERVAL - range from which the sampled data can be collected | |
721 | */ | |
722 | #define SAMPLING_READ_SIZE (16) | |
723 | #define SAMPLING_INTERVAL (256) | |
724 | ||
725 | /* | |
726 | * For statistical analysis of the input data we consider bytes that form a | |
727 | * Galois Field of 256 objects. Each object has an attribute count, ie. how | |
728 | * many times the object appeared in the sample. | |
729 | */ | |
730 | #define BUCKET_SIZE (256) | |
731 | ||
732 | /* | |
733 | * The size of the sample is based on a statistical sampling rule of thumb. | |
734 | * The common way is to perform sampling tests as long as the number of | |
735 | * elements in each cell is at least 5. | |
736 | * | |
737 | * Instead of 5, we choose 32 to obtain more accurate results. | |
738 | * If the data contain the maximum number of symbols, which is 256, we obtain a | |
739 | * sample size bound by 8192. | |
740 | * | |
741 | * For a sample of at most 8KB of data per data range: 16 consecutive bytes | |
742 | * from up to 512 locations. | |
743 | */ | |
744 | #define MAX_SAMPLE_SIZE (BTRFS_MAX_UNCOMPRESSED * \ | |
745 | SAMPLING_READ_SIZE / SAMPLING_INTERVAL) | |
746 | ||
747 | struct bucket_item { | |
748 | u32 count; | |
749 | }; | |
4e439a0b TT |
750 | |
751 | struct heuristic_ws { | |
17b5a6c1 TT |
752 | /* Partial copy of input data */ |
753 | u8 *sample; | |
a440d48c | 754 | u32 sample_size; |
17b5a6c1 TT |
755 | /* Buckets store counters for each byte value */ |
756 | struct bucket_item *bucket; | |
440c840c TT |
757 | /* Sorting buffer */ |
758 | struct bucket_item *bucket_b; | |
4e439a0b TT |
759 | struct list_head list; |
760 | }; | |
761 | ||
762 | static void free_heuristic_ws(struct list_head *ws) | |
763 | { | |
764 | struct heuristic_ws *workspace; | |
765 | ||
766 | workspace = list_entry(ws, struct heuristic_ws, list); | |
767 | ||
17b5a6c1 TT |
768 | kvfree(workspace->sample); |
769 | kfree(workspace->bucket); | |
440c840c | 770 | kfree(workspace->bucket_b); |
4e439a0b TT |
771 | kfree(workspace); |
772 | } | |
773 | ||
774 | static struct list_head *alloc_heuristic_ws(void) | |
775 | { | |
776 | struct heuristic_ws *ws; | |
777 | ||
778 | ws = kzalloc(sizeof(*ws), GFP_KERNEL); | |
779 | if (!ws) | |
780 | return ERR_PTR(-ENOMEM); | |
781 | ||
17b5a6c1 TT |
782 | ws->sample = kvmalloc(MAX_SAMPLE_SIZE, GFP_KERNEL); |
783 | if (!ws->sample) | |
784 | goto fail; | |
785 | ||
786 | ws->bucket = kcalloc(BUCKET_SIZE, sizeof(*ws->bucket), GFP_KERNEL); | |
787 | if (!ws->bucket) | |
788 | goto fail; | |
4e439a0b | 789 | |
440c840c TT |
790 | ws->bucket_b = kcalloc(BUCKET_SIZE, sizeof(*ws->bucket_b), GFP_KERNEL); |
791 | if (!ws->bucket_b) | |
792 | goto fail; | |
793 | ||
17b5a6c1 | 794 | INIT_LIST_HEAD(&ws->list); |
4e439a0b | 795 | return &ws->list; |
17b5a6c1 TT |
796 | fail: |
797 | free_heuristic_ws(&ws->list); | |
798 | return ERR_PTR(-ENOMEM); | |
4e439a0b TT |
799 | } |
800 | ||
801 | struct workspaces_list { | |
d9187649 BL |
802 | struct list_head idle_ws; |
803 | spinlock_t ws_lock; | |
6ac10a6a DS |
804 | /* Number of free workspaces */ |
805 | int free_ws; | |
806 | /* Total number of allocated workspaces */ | |
807 | atomic_t total_ws; | |
808 | /* Waiters for a free workspace */ | |
d9187649 | 809 | wait_queue_head_t ws_wait; |
4e439a0b TT |
810 | }; |
811 | ||
812 | static struct workspaces_list btrfs_comp_ws[BTRFS_COMPRESS_TYPES]; | |
813 | ||
814 | static struct workspaces_list btrfs_heuristic_ws; | |
261507a0 | 815 | |
e8c9f186 | 816 | static const struct btrfs_compress_op * const btrfs_compress_op[] = { |
261507a0 | 817 | &btrfs_zlib_compress, |
a6fa6fae | 818 | &btrfs_lzo_compress, |
5c1aab1d | 819 | &btrfs_zstd_compress, |
261507a0 LZ |
820 | }; |
821 | ||
143bede5 | 822 | void __init btrfs_init_compress(void) |
261507a0 | 823 | { |
4e439a0b | 824 | struct list_head *workspace; |
261507a0 LZ |
825 | int i; |
826 | ||
4e439a0b TT |
827 | INIT_LIST_HEAD(&btrfs_heuristic_ws.idle_ws); |
828 | spin_lock_init(&btrfs_heuristic_ws.ws_lock); | |
829 | atomic_set(&btrfs_heuristic_ws.total_ws, 0); | |
830 | init_waitqueue_head(&btrfs_heuristic_ws.ws_wait); | |
f77dd0d6 | 831 | |
4e439a0b TT |
832 | workspace = alloc_heuristic_ws(); |
833 | if (IS_ERR(workspace)) { | |
834 | pr_warn( | |
835 | "BTRFS: cannot preallocate heuristic workspace, will try later\n"); | |
836 | } else { | |
837 | atomic_set(&btrfs_heuristic_ws.total_ws, 1); | |
838 | btrfs_heuristic_ws.free_ws = 1; | |
839 | list_add(workspace, &btrfs_heuristic_ws.idle_ws); | |
840 | } | |
841 | ||
842 | for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) { | |
d9187649 BL |
843 | INIT_LIST_HEAD(&btrfs_comp_ws[i].idle_ws); |
844 | spin_lock_init(&btrfs_comp_ws[i].ws_lock); | |
6ac10a6a | 845 | atomic_set(&btrfs_comp_ws[i].total_ws, 0); |
d9187649 | 846 | init_waitqueue_head(&btrfs_comp_ws[i].ws_wait); |
f77dd0d6 DS |
847 | |
848 | /* | |
849 | * Preallocate one workspace for each compression type so | |
850 | * we can guarantee forward progress in the worst case | |
851 | */ | |
852 | workspace = btrfs_compress_op[i]->alloc_workspace(); | |
853 | if (IS_ERR(workspace)) { | |
62e85577 | 854 | pr_warn("BTRFS: cannot preallocate compression workspace, will try later\n"); |
f77dd0d6 DS |
855 | } else { |
856 | atomic_set(&btrfs_comp_ws[i].total_ws, 1); | |
857 | btrfs_comp_ws[i].free_ws = 1; | |
858 | list_add(workspace, &btrfs_comp_ws[i].idle_ws); | |
859 | } | |
261507a0 | 860 | } |
261507a0 LZ |
861 | } |
862 | ||
863 | /* | |
e721e49d DS |
864 | * This finds an available workspace or allocates a new one. |
865 | * If it's not possible to allocate a new one, waits until there's one. | |
866 | * Preallocation makes a forward progress guarantees and we do not return | |
867 | * errors. | |
261507a0 | 868 | */ |
4e439a0b | 869 | static struct list_head *__find_workspace(int type, bool heuristic) |
261507a0 LZ |
870 | { |
871 | struct list_head *workspace; | |
872 | int cpus = num_online_cpus(); | |
873 | int idx = type - 1; | |
fe308533 | 874 | unsigned nofs_flag; |
4e439a0b TT |
875 | struct list_head *idle_ws; |
876 | spinlock_t *ws_lock; | |
877 | atomic_t *total_ws; | |
878 | wait_queue_head_t *ws_wait; | |
879 | int *free_ws; | |
880 | ||
881 | if (heuristic) { | |
882 | idle_ws = &btrfs_heuristic_ws.idle_ws; | |
883 | ws_lock = &btrfs_heuristic_ws.ws_lock; | |
884 | total_ws = &btrfs_heuristic_ws.total_ws; | |
885 | ws_wait = &btrfs_heuristic_ws.ws_wait; | |
886 | free_ws = &btrfs_heuristic_ws.free_ws; | |
887 | } else { | |
888 | idle_ws = &btrfs_comp_ws[idx].idle_ws; | |
889 | ws_lock = &btrfs_comp_ws[idx].ws_lock; | |
890 | total_ws = &btrfs_comp_ws[idx].total_ws; | |
891 | ws_wait = &btrfs_comp_ws[idx].ws_wait; | |
892 | free_ws = &btrfs_comp_ws[idx].free_ws; | |
893 | } | |
261507a0 | 894 | |
261507a0 | 895 | again: |
d9187649 BL |
896 | spin_lock(ws_lock); |
897 | if (!list_empty(idle_ws)) { | |
898 | workspace = idle_ws->next; | |
261507a0 | 899 | list_del(workspace); |
6ac10a6a | 900 | (*free_ws)--; |
d9187649 | 901 | spin_unlock(ws_lock); |
261507a0 LZ |
902 | return workspace; |
903 | ||
904 | } | |
6ac10a6a | 905 | if (atomic_read(total_ws) > cpus) { |
261507a0 LZ |
906 | DEFINE_WAIT(wait); |
907 | ||
d9187649 BL |
908 | spin_unlock(ws_lock); |
909 | prepare_to_wait(ws_wait, &wait, TASK_UNINTERRUPTIBLE); | |
6ac10a6a | 910 | if (atomic_read(total_ws) > cpus && !*free_ws) |
261507a0 | 911 | schedule(); |
d9187649 | 912 | finish_wait(ws_wait, &wait); |
261507a0 LZ |
913 | goto again; |
914 | } | |
6ac10a6a | 915 | atomic_inc(total_ws); |
d9187649 | 916 | spin_unlock(ws_lock); |
261507a0 | 917 | |
fe308533 DS |
918 | /* |
919 | * Allocation helpers call vmalloc that can't use GFP_NOFS, so we have | |
920 | * to turn it off here because we might get called from the restricted | |
921 | * context of btrfs_compress_bio/btrfs_compress_pages | |
922 | */ | |
923 | nofs_flag = memalloc_nofs_save(); | |
4e439a0b TT |
924 | if (heuristic) |
925 | workspace = alloc_heuristic_ws(); | |
926 | else | |
927 | workspace = btrfs_compress_op[idx]->alloc_workspace(); | |
fe308533 DS |
928 | memalloc_nofs_restore(nofs_flag); |
929 | ||
261507a0 | 930 | if (IS_ERR(workspace)) { |
6ac10a6a | 931 | atomic_dec(total_ws); |
d9187649 | 932 | wake_up(ws_wait); |
e721e49d DS |
933 | |
934 | /* | |
935 | * Do not return the error but go back to waiting. There's a | |
936 | * workspace preallocated for each type and the compression | |
937 | * time is bounded so we get to a workspace eventually. This | |
938 | * makes our caller's life easier. | |
52356716 DS |
939 | * |
940 | * To prevent silent and low-probability deadlocks (when the | |
941 | * initial preallocation fails), check if there are any | |
942 | * workspaces at all. | |
e721e49d | 943 | */ |
52356716 DS |
944 | if (atomic_read(total_ws) == 0) { |
945 | static DEFINE_RATELIMIT_STATE(_rs, | |
946 | /* once per minute */ 60 * HZ, | |
947 | /* no burst */ 1); | |
948 | ||
949 | if (__ratelimit(&_rs)) { | |
ab8d0fc4 | 950 | pr_warn("BTRFS: no compression workspaces, low memory, retrying\n"); |
52356716 DS |
951 | } |
952 | } | |
e721e49d | 953 | goto again; |
261507a0 LZ |
954 | } |
955 | return workspace; | |
956 | } | |
957 | ||
4e439a0b TT |
958 | static struct list_head *find_workspace(int type) |
959 | { | |
960 | return __find_workspace(type, false); | |
961 | } | |
962 | ||
261507a0 LZ |
963 | /* |
964 | * put a workspace struct back on the list or free it if we have enough | |
965 | * idle ones sitting around | |
966 | */ | |
4e439a0b TT |
967 | static void __free_workspace(int type, struct list_head *workspace, |
968 | bool heuristic) | |
261507a0 LZ |
969 | { |
970 | int idx = type - 1; | |
4e439a0b TT |
971 | struct list_head *idle_ws; |
972 | spinlock_t *ws_lock; | |
973 | atomic_t *total_ws; | |
974 | wait_queue_head_t *ws_wait; | |
975 | int *free_ws; | |
976 | ||
977 | if (heuristic) { | |
978 | idle_ws = &btrfs_heuristic_ws.idle_ws; | |
979 | ws_lock = &btrfs_heuristic_ws.ws_lock; | |
980 | total_ws = &btrfs_heuristic_ws.total_ws; | |
981 | ws_wait = &btrfs_heuristic_ws.ws_wait; | |
982 | free_ws = &btrfs_heuristic_ws.free_ws; | |
983 | } else { | |
984 | idle_ws = &btrfs_comp_ws[idx].idle_ws; | |
985 | ws_lock = &btrfs_comp_ws[idx].ws_lock; | |
986 | total_ws = &btrfs_comp_ws[idx].total_ws; | |
987 | ws_wait = &btrfs_comp_ws[idx].ws_wait; | |
988 | free_ws = &btrfs_comp_ws[idx].free_ws; | |
989 | } | |
d9187649 BL |
990 | |
991 | spin_lock(ws_lock); | |
26b28dce | 992 | if (*free_ws <= num_online_cpus()) { |
d9187649 | 993 | list_add(workspace, idle_ws); |
6ac10a6a | 994 | (*free_ws)++; |
d9187649 | 995 | spin_unlock(ws_lock); |
261507a0 LZ |
996 | goto wake; |
997 | } | |
d9187649 | 998 | spin_unlock(ws_lock); |
261507a0 | 999 | |
4e439a0b TT |
1000 | if (heuristic) |
1001 | free_heuristic_ws(workspace); | |
1002 | else | |
1003 | btrfs_compress_op[idx]->free_workspace(workspace); | |
6ac10a6a | 1004 | atomic_dec(total_ws); |
261507a0 | 1005 | wake: |
a83342aa DS |
1006 | /* |
1007 | * Make sure counter is updated before we wake up waiters. | |
1008 | */ | |
66657b31 | 1009 | smp_mb(); |
d9187649 BL |
1010 | if (waitqueue_active(ws_wait)) |
1011 | wake_up(ws_wait); | |
261507a0 LZ |
1012 | } |
1013 | ||
4e439a0b TT |
1014 | static void free_workspace(int type, struct list_head *ws) |
1015 | { | |
1016 | return __free_workspace(type, ws, false); | |
1017 | } | |
1018 | ||
261507a0 LZ |
1019 | /* |
1020 | * cleanup function for module exit | |
1021 | */ | |
1022 | static void free_workspaces(void) | |
1023 | { | |
1024 | struct list_head *workspace; | |
1025 | int i; | |
1026 | ||
4e439a0b TT |
1027 | while (!list_empty(&btrfs_heuristic_ws.idle_ws)) { |
1028 | workspace = btrfs_heuristic_ws.idle_ws.next; | |
1029 | list_del(workspace); | |
1030 | free_heuristic_ws(workspace); | |
1031 | atomic_dec(&btrfs_heuristic_ws.total_ws); | |
1032 | } | |
1033 | ||
261507a0 | 1034 | for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) { |
d9187649 BL |
1035 | while (!list_empty(&btrfs_comp_ws[i].idle_ws)) { |
1036 | workspace = btrfs_comp_ws[i].idle_ws.next; | |
261507a0 LZ |
1037 | list_del(workspace); |
1038 | btrfs_compress_op[i]->free_workspace(workspace); | |
6ac10a6a | 1039 | atomic_dec(&btrfs_comp_ws[i].total_ws); |
261507a0 LZ |
1040 | } |
1041 | } | |
1042 | } | |
1043 | ||
1044 | /* | |
38c31464 DS |
1045 | * Given an address space and start and length, compress the bytes into @pages |
1046 | * that are allocated on demand. | |
261507a0 | 1047 | * |
f51d2b59 DS |
1048 | * @type_level is encoded algorithm and level, where level 0 means whatever |
1049 | * default the algorithm chooses and is opaque here; | |
1050 | * - compression algo are 0-3 | |
1051 | * - the level are bits 4-7 | |
1052 | * | |
4d3a800e DS |
1053 | * @out_pages is an in/out parameter, holds maximum number of pages to allocate |
1054 | * and returns number of actually allocated pages | |
261507a0 | 1055 | * |
38c31464 DS |
1056 | * @total_in is used to return the number of bytes actually read. It |
1057 | * may be smaller than the input length if we had to exit early because we | |
261507a0 LZ |
1058 | * ran out of room in the pages array or because we cross the |
1059 | * max_out threshold. | |
1060 | * | |
38c31464 DS |
1061 | * @total_out is an in/out parameter, must be set to the input length and will |
1062 | * be also used to return the total number of compressed bytes | |
261507a0 | 1063 | * |
38c31464 | 1064 | * @max_out tells us the max number of bytes that we're allowed to |
261507a0 LZ |
1065 | * stuff into pages |
1066 | */ | |
f51d2b59 | 1067 | int btrfs_compress_pages(unsigned int type_level, struct address_space *mapping, |
38c31464 | 1068 | u64 start, struct page **pages, |
261507a0 LZ |
1069 | unsigned long *out_pages, |
1070 | unsigned long *total_in, | |
e5d74902 | 1071 | unsigned long *total_out) |
261507a0 LZ |
1072 | { |
1073 | struct list_head *workspace; | |
1074 | int ret; | |
f51d2b59 | 1075 | int type = type_level & 0xF; |
261507a0 LZ |
1076 | |
1077 | workspace = find_workspace(type); | |
261507a0 | 1078 | |
f51d2b59 | 1079 | btrfs_compress_op[type - 1]->set_level(workspace, type_level); |
261507a0 | 1080 | ret = btrfs_compress_op[type-1]->compress_pages(workspace, mapping, |
38c31464 | 1081 | start, pages, |
4d3a800e | 1082 | out_pages, |
e5d74902 | 1083 | total_in, total_out); |
261507a0 LZ |
1084 | free_workspace(type, workspace); |
1085 | return ret; | |
1086 | } | |
1087 | ||
1088 | /* | |
1089 | * pages_in is an array of pages with compressed data. | |
1090 | * | |
1091 | * disk_start is the starting logical offset of this array in the file | |
1092 | * | |
974b1adc | 1093 | * orig_bio contains the pages from the file that we want to decompress into |
261507a0 LZ |
1094 | * |
1095 | * srclen is the number of bytes in pages_in | |
1096 | * | |
1097 | * The basic idea is that we have a bio that was created by readpages. | |
1098 | * The pages in the bio are for the uncompressed data, and they may not | |
1099 | * be contiguous. They all correspond to the range of bytes covered by | |
1100 | * the compressed extent. | |
1101 | */ | |
8140dc30 | 1102 | static int btrfs_decompress_bio(struct compressed_bio *cb) |
261507a0 LZ |
1103 | { |
1104 | struct list_head *workspace; | |
1105 | int ret; | |
8140dc30 | 1106 | int type = cb->compress_type; |
261507a0 LZ |
1107 | |
1108 | workspace = find_workspace(type); | |
e1ddce71 | 1109 | ret = btrfs_compress_op[type - 1]->decompress_bio(workspace, cb); |
261507a0 | 1110 | free_workspace(type, workspace); |
e1ddce71 | 1111 | |
261507a0 LZ |
1112 | return ret; |
1113 | } | |
1114 | ||
1115 | /* | |
1116 | * a less complex decompression routine. Our compressed data fits in a | |
1117 | * single page, and we want to read a single page out of it. | |
1118 | * start_byte tells us the offset into the compressed data we're interested in | |
1119 | */ | |
1120 | int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page, | |
1121 | unsigned long start_byte, size_t srclen, size_t destlen) | |
1122 | { | |
1123 | struct list_head *workspace; | |
1124 | int ret; | |
1125 | ||
1126 | workspace = find_workspace(type); | |
261507a0 LZ |
1127 | |
1128 | ret = btrfs_compress_op[type-1]->decompress(workspace, data_in, | |
1129 | dest_page, start_byte, | |
1130 | srclen, destlen); | |
1131 | ||
1132 | free_workspace(type, workspace); | |
1133 | return ret; | |
1134 | } | |
1135 | ||
8e4eef7a | 1136 | void btrfs_exit_compress(void) |
261507a0 LZ |
1137 | { |
1138 | free_workspaces(); | |
1139 | } | |
3a39c18d LZ |
1140 | |
1141 | /* | |
1142 | * Copy uncompressed data from working buffer to pages. | |
1143 | * | |
1144 | * buf_start is the byte offset we're of the start of our workspace buffer. | |
1145 | * | |
1146 | * total_out is the last byte of the buffer | |
1147 | */ | |
14a3357b | 1148 | int btrfs_decompress_buf2page(const char *buf, unsigned long buf_start, |
3a39c18d | 1149 | unsigned long total_out, u64 disk_start, |
974b1adc | 1150 | struct bio *bio) |
3a39c18d LZ |
1151 | { |
1152 | unsigned long buf_offset; | |
1153 | unsigned long current_buf_start; | |
1154 | unsigned long start_byte; | |
6e78b3f7 | 1155 | unsigned long prev_start_byte; |
3a39c18d LZ |
1156 | unsigned long working_bytes = total_out - buf_start; |
1157 | unsigned long bytes; | |
1158 | char *kaddr; | |
974b1adc | 1159 | struct bio_vec bvec = bio_iter_iovec(bio, bio->bi_iter); |
3a39c18d LZ |
1160 | |
1161 | /* | |
1162 | * start byte is the first byte of the page we're currently | |
1163 | * copying into relative to the start of the compressed data. | |
1164 | */ | |
974b1adc | 1165 | start_byte = page_offset(bvec.bv_page) - disk_start; |
3a39c18d LZ |
1166 | |
1167 | /* we haven't yet hit data corresponding to this page */ | |
1168 | if (total_out <= start_byte) | |
1169 | return 1; | |
1170 | ||
1171 | /* | |
1172 | * the start of the data we care about is offset into | |
1173 | * the middle of our working buffer | |
1174 | */ | |
1175 | if (total_out > start_byte && buf_start < start_byte) { | |
1176 | buf_offset = start_byte - buf_start; | |
1177 | working_bytes -= buf_offset; | |
1178 | } else { | |
1179 | buf_offset = 0; | |
1180 | } | |
1181 | current_buf_start = buf_start; | |
1182 | ||
1183 | /* copy bytes from the working buffer into the pages */ | |
1184 | while (working_bytes > 0) { | |
974b1adc CH |
1185 | bytes = min_t(unsigned long, bvec.bv_len, |
1186 | PAGE_SIZE - buf_offset); | |
3a39c18d | 1187 | bytes = min(bytes, working_bytes); |
974b1adc CH |
1188 | |
1189 | kaddr = kmap_atomic(bvec.bv_page); | |
1190 | memcpy(kaddr + bvec.bv_offset, buf + buf_offset, bytes); | |
7ac687d9 | 1191 | kunmap_atomic(kaddr); |
974b1adc | 1192 | flush_dcache_page(bvec.bv_page); |
3a39c18d | 1193 | |
3a39c18d LZ |
1194 | buf_offset += bytes; |
1195 | working_bytes -= bytes; | |
1196 | current_buf_start += bytes; | |
1197 | ||
1198 | /* check if we need to pick another page */ | |
974b1adc CH |
1199 | bio_advance(bio, bytes); |
1200 | if (!bio->bi_iter.bi_size) | |
1201 | return 0; | |
1202 | bvec = bio_iter_iovec(bio, bio->bi_iter); | |
6e78b3f7 | 1203 | prev_start_byte = start_byte; |
974b1adc | 1204 | start_byte = page_offset(bvec.bv_page) - disk_start; |
3a39c18d | 1205 | |
974b1adc | 1206 | /* |
6e78b3f7 OS |
1207 | * We need to make sure we're only adjusting |
1208 | * our offset into compression working buffer when | |
1209 | * we're switching pages. Otherwise we can incorrectly | |
1210 | * keep copying when we were actually done. | |
974b1adc | 1211 | */ |
6e78b3f7 OS |
1212 | if (start_byte != prev_start_byte) { |
1213 | /* | |
1214 | * make sure our new page is covered by this | |
1215 | * working buffer | |
1216 | */ | |
1217 | if (total_out <= start_byte) | |
1218 | return 1; | |
3a39c18d | 1219 | |
6e78b3f7 OS |
1220 | /* |
1221 | * the next page in the biovec might not be adjacent | |
1222 | * to the last page, but it might still be found | |
1223 | * inside this working buffer. bump our offset pointer | |
1224 | */ | |
1225 | if (total_out > start_byte && | |
1226 | current_buf_start < start_byte) { | |
1227 | buf_offset = start_byte - buf_start; | |
1228 | working_bytes = total_out - start_byte; | |
1229 | current_buf_start = buf_start + buf_offset; | |
1230 | } | |
3a39c18d LZ |
1231 | } |
1232 | } | |
1233 | ||
1234 | return 1; | |
1235 | } | |
c2fcdcdf | 1236 | |
19562430 TT |
1237 | /* |
1238 | * Shannon Entropy calculation | |
1239 | * | |
1240 | * Pure byte distribution analysis fails to determine compressiability of data. | |
1241 | * Try calculating entropy to estimate the average minimum number of bits | |
1242 | * needed to encode the sampled data. | |
1243 | * | |
1244 | * For convenience, return the percentage of needed bits, instead of amount of | |
1245 | * bits directly. | |
1246 | * | |
1247 | * @ENTROPY_LVL_ACEPTABLE - below that threshold, sample has low byte entropy | |
1248 | * and can be compressible with high probability | |
1249 | * | |
1250 | * @ENTROPY_LVL_HIGH - data are not compressible with high probability | |
1251 | * | |
1252 | * Use of ilog2() decreases precision, we lower the LVL to 5 to compensate. | |
1253 | */ | |
1254 | #define ENTROPY_LVL_ACEPTABLE (65) | |
1255 | #define ENTROPY_LVL_HIGH (80) | |
1256 | ||
1257 | /* | |
1258 | * For increasead precision in shannon_entropy calculation, | |
1259 | * let's do pow(n, M) to save more digits after comma: | |
1260 | * | |
1261 | * - maximum int bit length is 64 | |
1262 | * - ilog2(MAX_SAMPLE_SIZE) -> 13 | |
1263 | * - 13 * 4 = 52 < 64 -> M = 4 | |
1264 | * | |
1265 | * So use pow(n, 4). | |
1266 | */ | |
1267 | static inline u32 ilog2_w(u64 n) | |
1268 | { | |
1269 | return ilog2(n * n * n * n); | |
1270 | } | |
1271 | ||
1272 | static u32 shannon_entropy(struct heuristic_ws *ws) | |
1273 | { | |
1274 | const u32 entropy_max = 8 * ilog2_w(2); | |
1275 | u32 entropy_sum = 0; | |
1276 | u32 p, p_base, sz_base; | |
1277 | u32 i; | |
1278 | ||
1279 | sz_base = ilog2_w(ws->sample_size); | |
1280 | for (i = 0; i < BUCKET_SIZE && ws->bucket[i].count > 0; i++) { | |
1281 | p = ws->bucket[i].count; | |
1282 | p_base = ilog2_w(p); | |
1283 | entropy_sum += p * (sz_base - p_base); | |
1284 | } | |
1285 | ||
1286 | entropy_sum /= ws->sample_size; | |
1287 | return entropy_sum * 100 / entropy_max; | |
1288 | } | |
1289 | ||
440c840c TT |
1290 | #define RADIX_BASE 4U |
1291 | #define COUNTERS_SIZE (1U << RADIX_BASE) | |
1292 | ||
1293 | static u8 get4bits(u64 num, int shift) { | |
1294 | u8 low4bits; | |
1295 | ||
1296 | num >>= shift; | |
1297 | /* Reverse order */ | |
1298 | low4bits = (COUNTERS_SIZE - 1) - (num % COUNTERS_SIZE); | |
1299 | return low4bits; | |
1300 | } | |
1301 | ||
440c840c TT |
1302 | /* |
1303 | * Use 4 bits as radix base | |
1304 | * Use 16 u32 counters for calculating new possition in buf array | |
1305 | * | |
1306 | * @array - array that will be sorted | |
1307 | * @array_buf - buffer array to store sorting results | |
1308 | * must be equal in size to @array | |
1309 | * @num - array size | |
440c840c | 1310 | */ |
23ae8c63 | 1311 | static void radix_sort(struct bucket_item *array, struct bucket_item *array_buf, |
36243c91 | 1312 | int num) |
858177d3 | 1313 | { |
440c840c TT |
1314 | u64 max_num; |
1315 | u64 buf_num; | |
1316 | u32 counters[COUNTERS_SIZE]; | |
1317 | u32 new_addr; | |
1318 | u32 addr; | |
1319 | int bitlen; | |
1320 | int shift; | |
1321 | int i; | |
858177d3 | 1322 | |
440c840c TT |
1323 | /* |
1324 | * Try avoid useless loop iterations for small numbers stored in big | |
1325 | * counters. Example: 48 33 4 ... in 64bit array | |
1326 | */ | |
23ae8c63 | 1327 | max_num = array[0].count; |
440c840c | 1328 | for (i = 1; i < num; i++) { |
23ae8c63 | 1329 | buf_num = array[i].count; |
440c840c TT |
1330 | if (buf_num > max_num) |
1331 | max_num = buf_num; | |
1332 | } | |
1333 | ||
1334 | buf_num = ilog2(max_num); | |
1335 | bitlen = ALIGN(buf_num, RADIX_BASE * 2); | |
1336 | ||
1337 | shift = 0; | |
1338 | while (shift < bitlen) { | |
1339 | memset(counters, 0, sizeof(counters)); | |
1340 | ||
1341 | for (i = 0; i < num; i++) { | |
23ae8c63 | 1342 | buf_num = array[i].count; |
440c840c TT |
1343 | addr = get4bits(buf_num, shift); |
1344 | counters[addr]++; | |
1345 | } | |
1346 | ||
1347 | for (i = 1; i < COUNTERS_SIZE; i++) | |
1348 | counters[i] += counters[i - 1]; | |
1349 | ||
1350 | for (i = num - 1; i >= 0; i--) { | |
23ae8c63 | 1351 | buf_num = array[i].count; |
440c840c TT |
1352 | addr = get4bits(buf_num, shift); |
1353 | counters[addr]--; | |
1354 | new_addr = counters[addr]; | |
7add17be | 1355 | array_buf[new_addr] = array[i]; |
440c840c TT |
1356 | } |
1357 | ||
1358 | shift += RADIX_BASE; | |
1359 | ||
1360 | /* | |
1361 | * Normal radix expects to move data from a temporary array, to | |
1362 | * the main one. But that requires some CPU time. Avoid that | |
1363 | * by doing another sort iteration to original array instead of | |
1364 | * memcpy() | |
1365 | */ | |
1366 | memset(counters, 0, sizeof(counters)); | |
1367 | ||
1368 | for (i = 0; i < num; i ++) { | |
23ae8c63 | 1369 | buf_num = array_buf[i].count; |
440c840c TT |
1370 | addr = get4bits(buf_num, shift); |
1371 | counters[addr]++; | |
1372 | } | |
1373 | ||
1374 | for (i = 1; i < COUNTERS_SIZE; i++) | |
1375 | counters[i] += counters[i - 1]; | |
1376 | ||
1377 | for (i = num - 1; i >= 0; i--) { | |
23ae8c63 | 1378 | buf_num = array_buf[i].count; |
440c840c TT |
1379 | addr = get4bits(buf_num, shift); |
1380 | counters[addr]--; | |
1381 | new_addr = counters[addr]; | |
7add17be | 1382 | array[new_addr] = array_buf[i]; |
440c840c TT |
1383 | } |
1384 | ||
1385 | shift += RADIX_BASE; | |
1386 | } | |
858177d3 TT |
1387 | } |
1388 | ||
1389 | /* | |
1390 | * Size of the core byte set - how many bytes cover 90% of the sample | |
1391 | * | |
1392 | * There are several types of structured binary data that use nearly all byte | |
1393 | * values. The distribution can be uniform and counts in all buckets will be | |
1394 | * nearly the same (eg. encrypted data). Unlikely to be compressible. | |
1395 | * | |
1396 | * Other possibility is normal (Gaussian) distribution, where the data could | |
1397 | * be potentially compressible, but we have to take a few more steps to decide | |
1398 | * how much. | |
1399 | * | |
1400 | * @BYTE_CORE_SET_LOW - main part of byte values repeated frequently, | |
1401 | * compression algo can easy fix that | |
1402 | * @BYTE_CORE_SET_HIGH - data have uniform distribution and with high | |
1403 | * probability is not compressible | |
1404 | */ | |
1405 | #define BYTE_CORE_SET_LOW (64) | |
1406 | #define BYTE_CORE_SET_HIGH (200) | |
1407 | ||
1408 | static int byte_core_set_size(struct heuristic_ws *ws) | |
1409 | { | |
1410 | u32 i; | |
1411 | u32 coreset_sum = 0; | |
1412 | const u32 core_set_threshold = ws->sample_size * 90 / 100; | |
1413 | struct bucket_item *bucket = ws->bucket; | |
1414 | ||
1415 | /* Sort in reverse order */ | |
36243c91 | 1416 | radix_sort(ws->bucket, ws->bucket_b, BUCKET_SIZE); |
858177d3 TT |
1417 | |
1418 | for (i = 0; i < BYTE_CORE_SET_LOW; i++) | |
1419 | coreset_sum += bucket[i].count; | |
1420 | ||
1421 | if (coreset_sum > core_set_threshold) | |
1422 | return i; | |
1423 | ||
1424 | for (; i < BYTE_CORE_SET_HIGH && bucket[i].count > 0; i++) { | |
1425 | coreset_sum += bucket[i].count; | |
1426 | if (coreset_sum > core_set_threshold) | |
1427 | break; | |
1428 | } | |
1429 | ||
1430 | return i; | |
1431 | } | |
1432 | ||
a288e92c TT |
1433 | /* |
1434 | * Count byte values in buckets. | |
1435 | * This heuristic can detect textual data (configs, xml, json, html, etc). | |
1436 | * Because in most text-like data byte set is restricted to limited number of | |
1437 | * possible characters, and that restriction in most cases makes data easy to | |
1438 | * compress. | |
1439 | * | |
1440 | * @BYTE_SET_THRESHOLD - consider all data within this byte set size: | |
1441 | * less - compressible | |
1442 | * more - need additional analysis | |
1443 | */ | |
1444 | #define BYTE_SET_THRESHOLD (64) | |
1445 | ||
1446 | static u32 byte_set_size(const struct heuristic_ws *ws) | |
1447 | { | |
1448 | u32 i; | |
1449 | u32 byte_set_size = 0; | |
1450 | ||
1451 | for (i = 0; i < BYTE_SET_THRESHOLD; i++) { | |
1452 | if (ws->bucket[i].count > 0) | |
1453 | byte_set_size++; | |
1454 | } | |
1455 | ||
1456 | /* | |
1457 | * Continue collecting count of byte values in buckets. If the byte | |
1458 | * set size is bigger then the threshold, it's pointless to continue, | |
1459 | * the detection technique would fail for this type of data. | |
1460 | */ | |
1461 | for (; i < BUCKET_SIZE; i++) { | |
1462 | if (ws->bucket[i].count > 0) { | |
1463 | byte_set_size++; | |
1464 | if (byte_set_size > BYTE_SET_THRESHOLD) | |
1465 | return byte_set_size; | |
1466 | } | |
1467 | } | |
1468 | ||
1469 | return byte_set_size; | |
1470 | } | |
1471 | ||
1fe4f6fa TT |
1472 | static bool sample_repeated_patterns(struct heuristic_ws *ws) |
1473 | { | |
1474 | const u32 half_of_sample = ws->sample_size / 2; | |
1475 | const u8 *data = ws->sample; | |
1476 | ||
1477 | return memcmp(&data[0], &data[half_of_sample], half_of_sample) == 0; | |
1478 | } | |
1479 | ||
a440d48c TT |
1480 | static void heuristic_collect_sample(struct inode *inode, u64 start, u64 end, |
1481 | struct heuristic_ws *ws) | |
1482 | { | |
1483 | struct page *page; | |
1484 | u64 index, index_end; | |
1485 | u32 i, curr_sample_pos; | |
1486 | u8 *in_data; | |
1487 | ||
1488 | /* | |
1489 | * Compression handles the input data by chunks of 128KiB | |
1490 | * (defined by BTRFS_MAX_UNCOMPRESSED) | |
1491 | * | |
1492 | * We do the same for the heuristic and loop over the whole range. | |
1493 | * | |
1494 | * MAX_SAMPLE_SIZE - calculated under assumption that heuristic will | |
1495 | * process no more than BTRFS_MAX_UNCOMPRESSED at a time. | |
1496 | */ | |
1497 | if (end - start > BTRFS_MAX_UNCOMPRESSED) | |
1498 | end = start + BTRFS_MAX_UNCOMPRESSED; | |
1499 | ||
1500 | index = start >> PAGE_SHIFT; | |
1501 | index_end = end >> PAGE_SHIFT; | |
1502 | ||
1503 | /* Don't miss unaligned end */ | |
1504 | if (!IS_ALIGNED(end, PAGE_SIZE)) | |
1505 | index_end++; | |
1506 | ||
1507 | curr_sample_pos = 0; | |
1508 | while (index < index_end) { | |
1509 | page = find_get_page(inode->i_mapping, index); | |
1510 | in_data = kmap(page); | |
1511 | /* Handle case where the start is not aligned to PAGE_SIZE */ | |
1512 | i = start % PAGE_SIZE; | |
1513 | while (i < PAGE_SIZE - SAMPLING_READ_SIZE) { | |
1514 | /* Don't sample any garbage from the last page */ | |
1515 | if (start > end - SAMPLING_READ_SIZE) | |
1516 | break; | |
1517 | memcpy(&ws->sample[curr_sample_pos], &in_data[i], | |
1518 | SAMPLING_READ_SIZE); | |
1519 | i += SAMPLING_INTERVAL; | |
1520 | start += SAMPLING_INTERVAL; | |
1521 | curr_sample_pos += SAMPLING_READ_SIZE; | |
1522 | } | |
1523 | kunmap(page); | |
1524 | put_page(page); | |
1525 | ||
1526 | index++; | |
1527 | } | |
1528 | ||
1529 | ws->sample_size = curr_sample_pos; | |
1530 | } | |
1531 | ||
c2fcdcdf TT |
1532 | /* |
1533 | * Compression heuristic. | |
1534 | * | |
1535 | * For now is's a naive and optimistic 'return true', we'll extend the logic to | |
1536 | * quickly (compared to direct compression) detect data characteristics | |
1537 | * (compressible/uncompressible) to avoid wasting CPU time on uncompressible | |
1538 | * data. | |
1539 | * | |
1540 | * The following types of analysis can be performed: | |
1541 | * - detect mostly zero data | |
1542 | * - detect data with low "byte set" size (text, etc) | |
1543 | * - detect data with low/high "core byte" set | |
1544 | * | |
1545 | * Return non-zero if the compression should be done, 0 otherwise. | |
1546 | */ | |
1547 | int btrfs_compress_heuristic(struct inode *inode, u64 start, u64 end) | |
1548 | { | |
4e439a0b TT |
1549 | struct list_head *ws_list = __find_workspace(0, true); |
1550 | struct heuristic_ws *ws; | |
a440d48c TT |
1551 | u32 i; |
1552 | u8 byte; | |
19562430 | 1553 | int ret = 0; |
c2fcdcdf | 1554 | |
4e439a0b TT |
1555 | ws = list_entry(ws_list, struct heuristic_ws, list); |
1556 | ||
a440d48c TT |
1557 | heuristic_collect_sample(inode, start, end, ws); |
1558 | ||
1fe4f6fa TT |
1559 | if (sample_repeated_patterns(ws)) { |
1560 | ret = 1; | |
1561 | goto out; | |
1562 | } | |
1563 | ||
a440d48c TT |
1564 | memset(ws->bucket, 0, sizeof(*ws->bucket)*BUCKET_SIZE); |
1565 | ||
1566 | for (i = 0; i < ws->sample_size; i++) { | |
1567 | byte = ws->sample[i]; | |
1568 | ws->bucket[byte].count++; | |
c2fcdcdf TT |
1569 | } |
1570 | ||
a288e92c TT |
1571 | i = byte_set_size(ws); |
1572 | if (i < BYTE_SET_THRESHOLD) { | |
1573 | ret = 2; | |
1574 | goto out; | |
1575 | } | |
1576 | ||
858177d3 TT |
1577 | i = byte_core_set_size(ws); |
1578 | if (i <= BYTE_CORE_SET_LOW) { | |
1579 | ret = 3; | |
1580 | goto out; | |
1581 | } | |
1582 | ||
1583 | if (i >= BYTE_CORE_SET_HIGH) { | |
1584 | ret = 0; | |
1585 | goto out; | |
1586 | } | |
1587 | ||
19562430 TT |
1588 | i = shannon_entropy(ws); |
1589 | if (i <= ENTROPY_LVL_ACEPTABLE) { | |
1590 | ret = 4; | |
1591 | goto out; | |
1592 | } | |
1593 | ||
1594 | /* | |
1595 | * For the levels below ENTROPY_LVL_HIGH, additional analysis would be | |
1596 | * needed to give green light to compression. | |
1597 | * | |
1598 | * For now just assume that compression at that level is not worth the | |
1599 | * resources because: | |
1600 | * | |
1601 | * 1. it is possible to defrag the data later | |
1602 | * | |
1603 | * 2. the data would turn out to be hardly compressible, eg. 150 byte | |
1604 | * values, every bucket has counter at level ~54. The heuristic would | |
1605 | * be confused. This can happen when data have some internal repeated | |
1606 | * patterns like "abbacbbc...". This can be detected by analyzing | |
1607 | * pairs of bytes, which is too costly. | |
1608 | */ | |
1609 | if (i < ENTROPY_LVL_HIGH) { | |
1610 | ret = 5; | |
1611 | goto out; | |
1612 | } else { | |
1613 | ret = 0; | |
1614 | goto out; | |
1615 | } | |
1616 | ||
1fe4f6fa | 1617 | out: |
4e439a0b | 1618 | __free_workspace(0, ws_list, true); |
c2fcdcdf TT |
1619 | return ret; |
1620 | } | |
f51d2b59 DS |
1621 | |
1622 | unsigned int btrfs_compress_str2level(const char *str) | |
1623 | { | |
1624 | if (strncmp(str, "zlib", 4) != 0) | |
1625 | return 0; | |
1626 | ||
fa4d885a AB |
1627 | /* Accepted form: zlib:1 up to zlib:9 and nothing left after the number */ |
1628 | if (str[4] == ':' && '1' <= str[5] && str[5] <= '9' && str[6] == 0) | |
1629 | return str[5] - '0'; | |
f51d2b59 | 1630 | |
eae8d825 | 1631 | return BTRFS_ZLIB_DEFAULT_LEVEL; |
f51d2b59 | 1632 | } |