Line data Source code
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 :
45 : struct 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 :
84 : static int btrfs_decompress_biovec(int type, struct page **pages_in,
85 : u64 disk_start, struct bio_vec *bvec,
86 : int vcnt, size_t srclen);
87 :
88 : static inline int compressed_bio_size(struct btrfs_root *root,
89 : unsigned long disk_size)
90 : {
91 195 : u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
92 :
93 195 : return sizeof(struct compressed_bio) +
94 195 : ((disk_size + root->sectorsize - 1) / root->sectorsize) *
95 : csum_size;
96 : }
97 :
98 195 : static struct bio *compressed_bio_alloc(struct block_device *bdev,
99 : u64 first_byte, gfp_t gfp_flags)
100 : {
101 : int nr_vecs;
102 :
103 195 : nr_vecs = bio_get_nr_vecs(bdev);
104 195 : return btrfs_bio_alloc(bdev, first_byte >> 9, nr_vecs, gfp_flags);
105 : }
106 :
107 42 : static int check_compressed_csum(struct inode *inode,
108 : struct compressed_bio *cb,
109 : u64 disk_start)
110 : {
111 : int ret;
112 : struct page *page;
113 : unsigned long i;
114 : char *kaddr;
115 : u32 csum;
116 42 : u32 *cb_sum = &cb->sums;
117 :
118 42 : if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)
119 : return 0;
120 :
121 42 : for (i = 0; i < cb->nr_pages; i++) {
122 42 : page = cb->compressed_pages[i];
123 42 : csum = ~(u32)0;
124 :
125 : kaddr = kmap_atomic(page);
126 42 : csum = btrfs_csum_data(kaddr, csum, PAGE_CACHE_SIZE);
127 42 : btrfs_csum_final(csum, (char *)&csum);
128 : kunmap_atomic(kaddr);
129 :
130 42 : if (csum != *cb_sum) {
131 0 : btrfs_info(BTRFS_I(inode)->root->fs_info,
132 : "csum failed ino %llu extent %llu csum %u wanted %u mirror %d",
133 : btrfs_ino(inode), disk_start, csum, *cb_sum,
134 : cb->mirror_num);
135 : ret = -EIO;
136 0 : goto fail;
137 : }
138 42 : cb_sum++;
139 :
140 : }
141 : ret = 0;
142 : fail:
143 42 : return ret;
144 : }
145 :
146 : /* when we finish reading compressed pages from the disk, we
147 : * decompress them and then run the bio end_io routines on the
148 : * decompressed pages (in the inode address space).
149 : *
150 : * This allows the checksumming and other IO error handling routines
151 : * to work normally
152 : *
153 : * The compressed pages are freed here, and it must be run
154 : * in process context
155 : */
156 42 : static void end_compressed_bio_read(struct bio *bio, int err)
157 : {
158 42 : struct compressed_bio *cb = bio->bi_private;
159 : struct inode *inode;
160 : struct page *page;
161 : unsigned long index;
162 : int ret;
163 :
164 42 : if (err)
165 0 : cb->errors = 1;
166 :
167 : /* if there are more bios still pending for this compressed
168 : * extent, just exit
169 : */
170 84 : if (!atomic_dec_and_test(&cb->pending_bios))
171 : goto out;
172 :
173 42 : inode = cb->inode;
174 42 : ret = check_compressed_csum(inode, cb,
175 42 : (u64)bio->bi_iter.bi_sector << 9);
176 42 : if (ret)
177 : goto csum_failed;
178 :
179 : /* ok, we're the last bio for this extent, lets start
180 : * the decompression.
181 : */
182 84 : ret = btrfs_decompress_biovec(cb->compress_type,
183 : cb->compressed_pages,
184 : cb->start,
185 : cb->orig_bio->bi_io_vec,
186 42 : cb->orig_bio->bi_vcnt,
187 : cb->compressed_len);
188 : csum_failed:
189 42 : if (ret)
190 0 : cb->errors = 1;
191 :
192 : /* release the compressed pages */
193 : index = 0;
194 42 : for (index = 0; index < cb->nr_pages; index++) {
195 42 : page = cb->compressed_pages[index];
196 42 : page->mapping = NULL;
197 42 : page_cache_release(page);
198 : }
199 :
200 : /* do io completion on the original bio */
201 42 : if (cb->errors) {
202 0 : bio_io_error(cb->orig_bio);
203 : } else {
204 : int i;
205 : struct bio_vec *bvec;
206 :
207 : /*
208 : * we have verified the checksum already, set page
209 : * checked so the end_io handlers know about it
210 : */
211 374 : bio_for_each_segment_all(bvec, cb->orig_bio, i)
212 332 : SetPageChecked(bvec->bv_page);
213 :
214 42 : bio_endio(cb->orig_bio, 0);
215 : }
216 :
217 : /* finally free the cb struct */
218 42 : kfree(cb->compressed_pages);
219 42 : kfree(cb);
220 : out:
221 42 : bio_put(bio);
222 42 : }
223 :
224 : /*
225 : * Clear the writeback bits on all of the file
226 : * pages for a compressed write
227 : */
228 153 : static noinline void end_compressed_writeback(struct inode *inode, u64 start,
229 : unsigned long ram_size)
230 : {
231 153 : unsigned long index = start >> PAGE_CACHE_SHIFT;
232 153 : unsigned long end_index = (start + ram_size - 1) >> PAGE_CACHE_SHIFT;
233 : struct page *pages[16];
234 153 : unsigned long nr_pages = end_index - index + 1;
235 : int i;
236 : int ret;
237 :
238 392 : while (nr_pages > 0) {
239 239 : ret = find_get_pages_contig(inode->i_mapping, index,
240 239 : min_t(unsigned long,
241 : nr_pages, ARRAY_SIZE(pages)), pages);
242 238 : if (ret == 0) {
243 0 : nr_pages -= 1;
244 0 : index += 1;
245 0 : continue;
246 : }
247 2942 : for (i = 0; i < ret; i++) {
248 2941 : end_page_writeback(pages[i]);
249 2940 : page_cache_release(pages[i]);
250 : }
251 239 : nr_pages -= ret;
252 239 : index += ret;
253 : }
254 : /* the inode may be gone now */
255 153 : }
256 :
257 : /*
258 : * do the cleanup once all the compressed pages hit the disk.
259 : * This will clear writeback on the file pages and free the compressed
260 : * pages.
261 : *
262 : * This also calls the writeback end hooks for the file pages so that
263 : * metadata and checksums can be updated in the file.
264 : */
265 153 : static void end_compressed_bio_write(struct bio *bio, int err)
266 : {
267 : struct extent_io_tree *tree;
268 153 : struct compressed_bio *cb = bio->bi_private;
269 : struct inode *inode;
270 : struct page *page;
271 : unsigned long index;
272 :
273 153 : if (err)
274 0 : cb->errors = 1;
275 :
276 : /* if there are more bios still pending for this compressed
277 : * extent, just exit
278 : */
279 306 : 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 : */
285 153 : inode = cb->inode;
286 : tree = &BTRFS_I(inode)->io_tree;
287 153 : cb->compressed_pages[0]->mapping = cb->inode->i_mapping;
288 306 : tree->ops->writepage_end_io_hook(cb->compressed_pages[0],
289 : cb->start,
290 153 : cb->start + cb->len - 1,
291 : NULL, 1);
292 153 : cb->compressed_pages[0]->mapping = NULL;
293 :
294 153 : end_compressed_writeback(inode, cb->start, cb->len);
295 : /* note, our inode could be gone now */
296 :
297 : /*
298 : * release the compressed pages, these came from alloc_page and
299 : * are not attached to the inode at all
300 : */
301 : index = 0;
302 306 : for (index = 0; index < cb->nr_pages; index++) {
303 153 : page = cb->compressed_pages[index];
304 153 : page->mapping = NULL;
305 153 : page_cache_release(page);
306 : }
307 :
308 : /* finally free the cb struct */
309 153 : kfree(cb->compressed_pages);
310 152 : kfree(cb);
311 : out:
312 152 : bio_put(bio);
313 153 : }
314 :
315 : /*
316 : * worker function to build and submit bios for previously compressed pages.
317 : * The corresponding pages in the inode should be marked for writeback
318 : * and the compressed pages should have a reference on them for dropping
319 : * when the IO is complete.
320 : *
321 : * This also checksums the file bytes and gets things ready for
322 : * the end io hooks.
323 : */
324 153 : int btrfs_submit_compressed_write(struct inode *inode, u64 start,
325 : unsigned long len, u64 disk_start,
326 : unsigned long compressed_len,
327 : struct page **compressed_pages,
328 : unsigned long nr_pages)
329 : {
330 : struct bio *bio = NULL;
331 306 : struct btrfs_root *root = BTRFS_I(inode)->root;
332 : struct compressed_bio *cb;
333 : unsigned long bytes_left;
334 : struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
335 : int pg_index = 0;
336 : struct page *page;
337 : u64 first_byte = disk_start;
338 : struct block_device *bdev;
339 : int ret;
340 153 : int skip_sum = BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM;
341 :
342 153 : WARN_ON(start & ((u64)PAGE_CACHE_SIZE - 1));
343 153 : cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS);
344 153 : if (!cb)
345 : return -ENOMEM;
346 : atomic_set(&cb->pending_bios, 0);
347 153 : cb->errors = 0;
348 153 : cb->inode = inode;
349 153 : cb->start = start;
350 153 : cb->len = len;
351 153 : cb->mirror_num = 0;
352 153 : cb->compressed_pages = compressed_pages;
353 153 : cb->compressed_len = compressed_len;
354 153 : cb->orig_bio = NULL;
355 153 : cb->nr_pages = nr_pages;
356 :
357 153 : bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
358 :
359 153 : bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
360 153 : if (!bio) {
361 0 : kfree(cb);
362 0 : return -ENOMEM;
363 : }
364 153 : bio->bi_private = cb;
365 153 : bio->bi_end_io = end_compressed_bio_write;
366 153 : atomic_inc(&cb->pending_bios);
367 :
368 : /* create and submit bios for the compressed pages */
369 : bytes_left = compressed_len;
370 306 : for (pg_index = 0; pg_index < cb->nr_pages; pg_index++) {
371 153 : page = compressed_pages[pg_index];
372 153 : page->mapping = inode->i_mapping;
373 153 : if (bio->bi_iter.bi_size)
374 0 : ret = io_tree->ops->merge_bio_hook(WRITE, page, 0,
375 : PAGE_CACHE_SIZE,
376 : bio, 0);
377 : else
378 : ret = 0;
379 :
380 153 : page->mapping = NULL;
381 153 : if (ret || bio_add_page(bio, page, PAGE_CACHE_SIZE, 0) <
382 : PAGE_CACHE_SIZE) {
383 0 : bio_get(bio);
384 :
385 : /*
386 : * inc the count before we submit the bio so
387 : * we know the end IO handler won't happen before
388 : * we inc the count. Otherwise, the cb might get
389 : * freed before we're done setting it up
390 : */
391 : atomic_inc(&cb->pending_bios);
392 0 : ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0);
393 0 : BUG_ON(ret); /* -ENOMEM */
394 :
395 0 : if (!skip_sum) {
396 0 : ret = btrfs_csum_one_bio(root, inode, bio,
397 : start, 1);
398 0 : BUG_ON(ret); /* -ENOMEM */
399 : }
400 :
401 0 : ret = btrfs_map_bio(root, WRITE, bio, 0, 1);
402 0 : BUG_ON(ret); /* -ENOMEM */
403 :
404 0 : bio_put(bio);
405 :
406 0 : bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
407 0 : BUG_ON(!bio);
408 0 : bio->bi_private = cb;
409 0 : bio->bi_end_io = end_compressed_bio_write;
410 0 : bio_add_page(bio, page, PAGE_CACHE_SIZE, 0);
411 : }
412 153 : if (bytes_left < PAGE_CACHE_SIZE) {
413 0 : btrfs_info(BTRFS_I(inode)->root->fs_info,
414 : "bytes left %lu compress len %lu nr %lu",
415 : bytes_left, cb->compressed_len, cb->nr_pages);
416 : }
417 153 : bytes_left -= PAGE_CACHE_SIZE;
418 153 : first_byte += PAGE_CACHE_SIZE;
419 153 : cond_resched();
420 : }
421 153 : bio_get(bio);
422 :
423 153 : ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0);
424 153 : BUG_ON(ret); /* -ENOMEM */
425 :
426 153 : if (!skip_sum) {
427 153 : ret = btrfs_csum_one_bio(root, inode, bio, start, 1);
428 153 : BUG_ON(ret); /* -ENOMEM */
429 : }
430 :
431 153 : ret = btrfs_map_bio(root, WRITE, bio, 0, 1);
432 153 : BUG_ON(ret); /* -ENOMEM */
433 :
434 153 : bio_put(bio);
435 153 : return 0;
436 : }
437 :
438 42 : static noinline int add_ra_bio_pages(struct inode *inode,
439 : u64 compressed_end,
440 : struct compressed_bio *cb)
441 : {
442 : unsigned long end_index;
443 : unsigned long pg_index;
444 : u64 last_offset;
445 42 : u64 isize = i_size_read(inode);
446 : int ret;
447 42 : struct page *page;
448 : unsigned long nr_pages = 0;
449 0 : struct extent_map *em;
450 42 : struct address_space *mapping = inode->i_mapping;
451 : struct extent_map_tree *em_tree;
452 : struct extent_io_tree *tree;
453 : u64 end;
454 : int misses = 0;
455 :
456 42 : page = cb->orig_bio->bi_io_vec[cb->orig_bio->bi_vcnt - 1].bv_page;
457 42 : last_offset = (page_offset(page) + PAGE_CACHE_SIZE);
458 42 : em_tree = &BTRFS_I(inode)->extent_tree;
459 42 : tree = &BTRFS_I(inode)->io_tree;
460 :
461 42 : if (isize == 0)
462 : return 0;
463 :
464 42 : end_index = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;
465 :
466 42 : while (last_offset < compressed_end) {
467 0 : pg_index = last_offset >> PAGE_CACHE_SHIFT;
468 :
469 0 : if (pg_index > end_index)
470 : break;
471 :
472 : rcu_read_lock();
473 0 : page = radix_tree_lookup(&mapping->page_tree, pg_index);
474 : rcu_read_unlock();
475 0 : if (page && !radix_tree_exceptional_entry(page)) {
476 0 : misses++;
477 0 : if (misses > 4)
478 : break;
479 : goto next;
480 : }
481 :
482 0 : page = __page_cache_alloc(mapping_gfp_mask(mapping) &
483 : ~__GFP_FS);
484 0 : if (!page)
485 : break;
486 :
487 0 : if (add_to_page_cache_lru(page, mapping, pg_index,
488 : GFP_NOFS)) {
489 0 : page_cache_release(page);
490 : goto next;
491 : }
492 :
493 0 : end = last_offset + PAGE_CACHE_SIZE - 1;
494 : /*
495 : * at this point, we have a locked page in the page cache
496 : * for these bytes in the file. But, we have to make
497 : * sure they map to this compressed extent on disk.
498 : */
499 0 : set_page_extent_mapped(page);
500 0 : lock_extent(tree, last_offset, end);
501 0 : read_lock(&em_tree->lock);
502 0 : em = lookup_extent_mapping(em_tree, last_offset,
503 : PAGE_CACHE_SIZE);
504 : read_unlock(&em_tree->lock);
505 :
506 0 : if (!em || last_offset < em->start ||
507 0 : (last_offset + PAGE_CACHE_SIZE > extent_map_end(em)) ||
508 0 : (em->block_start >> 9) != cb->orig_bio->bi_iter.bi_sector) {
509 0 : free_extent_map(em);
510 0 : unlock_extent(tree, last_offset, end);
511 0 : unlock_page(page);
512 0 : page_cache_release(page);
513 : break;
514 : }
515 0 : free_extent_map(em);
516 :
517 0 : if (page->index == end_index) {
518 : char *userpage;
519 0 : size_t zero_offset = isize & (PAGE_CACHE_SIZE - 1);
520 :
521 0 : if (zero_offset) {
522 : int zeros;
523 0 : zeros = PAGE_CACHE_SIZE - zero_offset;
524 : userpage = kmap_atomic(page);
525 0 : memset(userpage + zero_offset, 0, zeros);
526 : flush_dcache_page(page);
527 : kunmap_atomic(userpage);
528 : }
529 : }
530 :
531 0 : ret = bio_add_page(cb->orig_bio, page,
532 : PAGE_CACHE_SIZE, 0);
533 :
534 0 : if (ret == PAGE_CACHE_SIZE) {
535 : nr_pages++;
536 0 : page_cache_release(page);
537 : } else {
538 0 : unlock_extent(tree, last_offset, end);
539 0 : unlock_page(page);
540 0 : page_cache_release(page);
541 : break;
542 : }
543 : next:
544 0 : last_offset += PAGE_CACHE_SIZE;
545 : }
546 : return 0;
547 : }
548 :
549 : /*
550 : * for a compressed read, the bio we get passed has all the inode pages
551 : * in it. We don't actually do IO on those pages but allocate new ones
552 : * to hold the compressed pages on disk.
553 : *
554 : * bio->bi_iter.bi_sector points to the compressed extent on disk
555 : * bio->bi_io_vec points to all of the inode pages
556 : * bio->bi_vcnt is a count of pages
557 : *
558 : * After the compressed pages are read, we copy the bytes into the
559 : * bio we were passed and then call the bio end_io calls
560 : */
561 42 : int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
562 : int mirror_num, unsigned long bio_flags)
563 : {
564 : struct extent_io_tree *tree;
565 : struct extent_map_tree *em_tree;
566 : struct compressed_bio *cb;
567 84 : struct btrfs_root *root = BTRFS_I(inode)->root;
568 42 : unsigned long uncompressed_len = bio->bi_vcnt * PAGE_CACHE_SIZE;
569 : unsigned long compressed_len;
570 : unsigned long nr_pages;
571 : unsigned long pg_index;
572 : struct page *page;
573 : struct block_device *bdev;
574 : struct bio *comp_bio;
575 42 : u64 cur_disk_byte = (u64)bio->bi_iter.bi_sector << 9;
576 : u64 em_len;
577 : u64 em_start;
578 : struct extent_map *em;
579 : int ret = -ENOMEM;
580 : int faili = 0;
581 : u32 *sums;
582 :
583 : tree = &BTRFS_I(inode)->io_tree;
584 42 : em_tree = &BTRFS_I(inode)->extent_tree;
585 :
586 : /* we need the actual starting offset of this extent in the file */
587 42 : read_lock(&em_tree->lock);
588 42 : em = lookup_extent_mapping(em_tree,
589 42 : page_offset(bio->bi_io_vec->bv_page),
590 : PAGE_CACHE_SIZE);
591 : read_unlock(&em_tree->lock);
592 42 : if (!em)
593 : return -EIO;
594 :
595 42 : compressed_len = em->block_len;
596 42 : cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS);
597 42 : if (!cb)
598 : goto out;
599 :
600 : atomic_set(&cb->pending_bios, 0);
601 42 : cb->errors = 0;
602 42 : cb->inode = inode;
603 42 : cb->mirror_num = mirror_num;
604 42 : sums = &cb->sums;
605 :
606 42 : cb->start = em->orig_start;
607 42 : em_len = em->len;
608 42 : em_start = em->start;
609 :
610 42 : free_extent_map(em);
611 : em = NULL;
612 :
613 42 : cb->len = uncompressed_len;
614 42 : cb->compressed_len = compressed_len;
615 42 : cb->compress_type = extent_compress_type(bio_flags);
616 42 : cb->orig_bio = bio;
617 :
618 42 : nr_pages = (compressed_len + PAGE_CACHE_SIZE - 1) /
619 : PAGE_CACHE_SIZE;
620 42 : cb->compressed_pages = kzalloc(sizeof(struct page *) * nr_pages,
621 : GFP_NOFS);
622 42 : if (!cb->compressed_pages)
623 : goto fail1;
624 :
625 42 : bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
626 :
627 84 : for (pg_index = 0; pg_index < nr_pages; pg_index++) {
628 84 : cb->compressed_pages[pg_index] = alloc_page(GFP_NOFS |
629 : __GFP_HIGHMEM);
630 42 : if (!cb->compressed_pages[pg_index]) {
631 0 : faili = pg_index - 1;
632 : ret = -ENOMEM;
633 0 : goto fail2;
634 : }
635 : }
636 42 : faili = nr_pages - 1;
637 42 : cb->nr_pages = nr_pages;
638 :
639 : /* In the parent-locked case, we only locked the range we are
640 : * interested in. In all other cases, we can opportunistically
641 : * cache decompressed data that goes beyond the requested range. */
642 42 : if (!(bio_flags & EXTENT_BIO_PARENT_LOCKED))
643 42 : add_ra_bio_pages(inode, em_start + em_len, cb);
644 :
645 : /* include any pages we added in add_ra-bio_pages */
646 42 : uncompressed_len = bio->bi_vcnt * PAGE_CACHE_SIZE;
647 42 : cb->len = uncompressed_len;
648 :
649 42 : comp_bio = compressed_bio_alloc(bdev, cur_disk_byte, GFP_NOFS);
650 42 : if (!comp_bio)
651 : goto fail2;
652 42 : comp_bio->bi_private = cb;
653 42 : comp_bio->bi_end_io = end_compressed_bio_read;
654 42 : atomic_inc(&cb->pending_bios);
655 :
656 84 : for (pg_index = 0; pg_index < nr_pages; pg_index++) {
657 42 : page = cb->compressed_pages[pg_index];
658 42 : page->mapping = inode->i_mapping;
659 42 : page->index = em_start >> PAGE_CACHE_SHIFT;
660 :
661 42 : if (comp_bio->bi_iter.bi_size)
662 0 : ret = tree->ops->merge_bio_hook(READ, page, 0,
663 : PAGE_CACHE_SIZE,
664 : comp_bio, 0);
665 : else
666 : ret = 0;
667 :
668 42 : page->mapping = NULL;
669 42 : if (ret || bio_add_page(comp_bio, page, PAGE_CACHE_SIZE, 0) <
670 : PAGE_CACHE_SIZE) {
671 0 : bio_get(comp_bio);
672 :
673 0 : ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0);
674 0 : BUG_ON(ret); /* -ENOMEM */
675 :
676 : /*
677 : * inc the count before we submit the bio so
678 : * we know the end IO handler won't happen before
679 : * we inc the count. Otherwise, the cb might get
680 : * freed before we're done setting it up
681 : */
682 : atomic_inc(&cb->pending_bios);
683 :
684 0 : if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
685 0 : ret = btrfs_lookup_bio_sums(root, inode,
686 : comp_bio, sums);
687 0 : BUG_ON(ret); /* -ENOMEM */
688 : }
689 0 : sums += (comp_bio->bi_iter.bi_size +
690 0 : root->sectorsize - 1) / root->sectorsize;
691 :
692 0 : ret = btrfs_map_bio(root, READ, comp_bio,
693 : mirror_num, 0);
694 0 : if (ret)
695 0 : bio_endio(comp_bio, ret);
696 :
697 0 : bio_put(comp_bio);
698 :
699 0 : comp_bio = compressed_bio_alloc(bdev, cur_disk_byte,
700 : GFP_NOFS);
701 0 : BUG_ON(!comp_bio);
702 0 : comp_bio->bi_private = cb;
703 0 : comp_bio->bi_end_io = end_compressed_bio_read;
704 :
705 0 : bio_add_page(comp_bio, page, PAGE_CACHE_SIZE, 0);
706 : }
707 42 : cur_disk_byte += PAGE_CACHE_SIZE;
708 : }
709 42 : bio_get(comp_bio);
710 :
711 42 : ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0);
712 42 : BUG_ON(ret); /* -ENOMEM */
713 :
714 42 : if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
715 42 : ret = btrfs_lookup_bio_sums(root, inode, comp_bio, sums);
716 42 : BUG_ON(ret); /* -ENOMEM */
717 : }
718 :
719 42 : ret = btrfs_map_bio(root, READ, comp_bio, mirror_num, 0);
720 42 : if (ret)
721 0 : bio_endio(comp_bio, ret);
722 :
723 42 : bio_put(comp_bio);
724 42 : return 0;
725 :
726 : fail2:
727 0 : while (faili >= 0) {
728 0 : __free_page(cb->compressed_pages[faili]);
729 0 : faili--;
730 : }
731 :
732 0 : kfree(cb->compressed_pages);
733 : fail1:
734 0 : kfree(cb);
735 : out:
736 0 : free_extent_map(em);
737 0 : return ret;
738 : }
739 :
740 : static struct list_head comp_idle_workspace[BTRFS_COMPRESS_TYPES];
741 : static spinlock_t comp_workspace_lock[BTRFS_COMPRESS_TYPES];
742 : static int comp_num_workspace[BTRFS_COMPRESS_TYPES];
743 : static atomic_t comp_alloc_workspace[BTRFS_COMPRESS_TYPES];
744 : static wait_queue_head_t comp_workspace_wait[BTRFS_COMPRESS_TYPES];
745 :
746 : static struct btrfs_compress_op *btrfs_compress_op[] = {
747 : &btrfs_zlib_compress,
748 : &btrfs_lzo_compress,
749 : };
750 :
751 0 : void __init btrfs_init_compress(void)
752 : {
753 : int i;
754 :
755 0 : for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
756 0 : INIT_LIST_HEAD(&comp_idle_workspace[i]);
757 0 : spin_lock_init(&comp_workspace_lock[i]);
758 0 : atomic_set(&comp_alloc_workspace[i], 0);
759 0 : init_waitqueue_head(&comp_workspace_wait[i]);
760 : }
761 0 : }
762 :
763 : /*
764 : * this finds an available workspace or allocates a new one
765 : * ERR_PTR is returned if things go bad.
766 : */
767 197 : static struct list_head *find_workspace(int type)
768 : {
769 : struct list_head *workspace;
770 197 : int cpus = num_online_cpus();
771 197 : int idx = type - 1;
772 :
773 197 : struct list_head *idle_workspace = &comp_idle_workspace[idx];
774 197 : spinlock_t *workspace_lock = &comp_workspace_lock[idx];
775 197 : atomic_t *alloc_workspace = &comp_alloc_workspace[idx];
776 197 : wait_queue_head_t *workspace_wait = &comp_workspace_wait[idx];
777 : int *num_workspace = &comp_num_workspace[idx];
778 : again:
779 : spin_lock(workspace_lock);
780 197 : if (!list_empty(idle_workspace)) {
781 : workspace = idle_workspace->next;
782 196 : list_del(workspace);
783 196 : (*num_workspace)--;
784 : spin_unlock(workspace_lock);
785 196 : return workspace;
786 :
787 : }
788 1 : if (atomic_read(alloc_workspace) > cpus) {
789 0 : DEFINE_WAIT(wait);
790 :
791 : spin_unlock(workspace_lock);
792 0 : prepare_to_wait(workspace_wait, &wait, TASK_UNINTERRUPTIBLE);
793 0 : if (atomic_read(alloc_workspace) > cpus && !*num_workspace)
794 0 : schedule();
795 0 : finish_wait(workspace_wait, &wait);
796 : goto again;
797 : }
798 : atomic_inc(alloc_workspace);
799 : spin_unlock(workspace_lock);
800 :
801 1 : workspace = btrfs_compress_op[idx]->alloc_workspace();
802 1 : if (IS_ERR(workspace)) {
803 : atomic_dec(alloc_workspace);
804 0 : wake_up(workspace_wait);
805 : }
806 1 : return workspace;
807 : }
808 :
809 : /*
810 : * put a workspace struct back on the list or free it if we have enough
811 : * idle ones sitting around
812 : */
813 197 : static void free_workspace(int type, struct list_head *workspace)
814 : {
815 197 : int idx = type - 1;
816 197 : struct list_head *idle_workspace = &comp_idle_workspace[idx];
817 197 : spinlock_t *workspace_lock = &comp_workspace_lock[idx];
818 197 : atomic_t *alloc_workspace = &comp_alloc_workspace[idx];
819 197 : wait_queue_head_t *workspace_wait = &comp_workspace_wait[idx];
820 : int *num_workspace = &comp_num_workspace[idx];
821 :
822 : spin_lock(workspace_lock);
823 394 : if (*num_workspace < num_online_cpus()) {
824 : list_add(workspace, idle_workspace);
825 197 : (*num_workspace)++;
826 : spin_unlock(workspace_lock);
827 : goto wake;
828 : }
829 : spin_unlock(workspace_lock);
830 :
831 0 : btrfs_compress_op[idx]->free_workspace(workspace);
832 : atomic_dec(alloc_workspace);
833 : wake:
834 197 : smp_mb();
835 197 : if (waitqueue_active(workspace_wait))
836 0 : wake_up(workspace_wait);
837 197 : }
838 :
839 : /*
840 : * cleanup function for module exit
841 : */
842 0 : static void free_workspaces(void)
843 : {
844 : struct list_head *workspace;
845 : int i;
846 :
847 0 : for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
848 0 : while (!list_empty(&comp_idle_workspace[i])) {
849 0 : workspace = comp_idle_workspace[i].next;
850 0 : list_del(workspace);
851 0 : btrfs_compress_op[i]->free_workspace(workspace);
852 0 : atomic_dec(&comp_alloc_workspace[i]);
853 : }
854 : }
855 0 : }
856 :
857 : /*
858 : * given an address space and start/len, compress the bytes.
859 : *
860 : * pages are allocated to hold the compressed result and stored
861 : * in 'pages'
862 : *
863 : * out_pages is used to return the number of pages allocated. There
864 : * may be pages allocated even if we return an error
865 : *
866 : * total_in is used to return the number of bytes actually read. It
867 : * may be smaller then len if we had to exit early because we
868 : * ran out of room in the pages array or because we cross the
869 : * max_out threshold.
870 : *
871 : * total_out is used to return the total number of compressed bytes
872 : *
873 : * max_out tells us the max number of bytes that we're allowed to
874 : * stuff into pages
875 : */
876 155 : int btrfs_compress_pages(int type, struct address_space *mapping,
877 : u64 start, unsigned long len,
878 : struct page **pages,
879 : unsigned long nr_dest_pages,
880 : unsigned long *out_pages,
881 : unsigned long *total_in,
882 : unsigned long *total_out,
883 : unsigned long max_out)
884 : {
885 : struct list_head *workspace;
886 : int ret;
887 :
888 155 : workspace = find_workspace(type);
889 155 : if (IS_ERR(workspace))
890 0 : return PTR_ERR(workspace);
891 :
892 155 : ret = btrfs_compress_op[type-1]->compress_pages(workspace, mapping,
893 : start, len, pages,
894 : nr_dest_pages, out_pages,
895 : total_in, total_out,
896 : max_out);
897 155 : free_workspace(type, workspace);
898 155 : return ret;
899 : }
900 :
901 : /*
902 : * pages_in is an array of pages with compressed data.
903 : *
904 : * disk_start is the starting logical offset of this array in the file
905 : *
906 : * bvec is a bio_vec of pages from the file that we want to decompress into
907 : *
908 : * vcnt is the count of pages in the biovec
909 : *
910 : * srclen is the number of bytes in pages_in
911 : *
912 : * The basic idea is that we have a bio that was created by readpages.
913 : * The pages in the bio are for the uncompressed data, and they may not
914 : * be contiguous. They all correspond to the range of bytes covered by
915 : * the compressed extent.
916 : */
917 42 : static int btrfs_decompress_biovec(int type, struct page **pages_in,
918 : u64 disk_start, struct bio_vec *bvec,
919 : int vcnt, size_t srclen)
920 : {
921 : struct list_head *workspace;
922 : int ret;
923 :
924 42 : workspace = find_workspace(type);
925 42 : if (IS_ERR(workspace))
926 0 : return PTR_ERR(workspace);
927 :
928 42 : ret = btrfs_compress_op[type-1]->decompress_biovec(workspace, pages_in,
929 : disk_start,
930 : bvec, vcnt, srclen);
931 42 : free_workspace(type, workspace);
932 42 : return ret;
933 : }
934 :
935 : /*
936 : * a less complex decompression routine. Our compressed data fits in a
937 : * single page, and we want to read a single page out of it.
938 : * start_byte tells us the offset into the compressed data we're interested in
939 : */
940 0 : int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
941 : unsigned long start_byte, size_t srclen, size_t destlen)
942 : {
943 : struct list_head *workspace;
944 : int ret;
945 :
946 0 : workspace = find_workspace(type);
947 0 : if (IS_ERR(workspace))
948 0 : return PTR_ERR(workspace);
949 :
950 0 : ret = btrfs_compress_op[type-1]->decompress(workspace, data_in,
951 : dest_page, start_byte,
952 : srclen, destlen);
953 :
954 0 : free_workspace(type, workspace);
955 0 : return ret;
956 : }
957 :
958 0 : void btrfs_exit_compress(void)
959 : {
960 0 : free_workspaces();
961 0 : }
962 :
963 : /*
964 : * Copy uncompressed data from working buffer to pages.
965 : *
966 : * buf_start is the byte offset we're of the start of our workspace buffer.
967 : *
968 : * total_out is the last byte of the buffer
969 : */
970 364 : int btrfs_decompress_buf2page(char *buf, unsigned long buf_start,
971 : unsigned long total_out, u64 disk_start,
972 : struct bio_vec *bvec, int vcnt,
973 : unsigned long *pg_index,
974 : unsigned long *pg_offset)
975 : {
976 : unsigned long buf_offset;
977 : unsigned long current_buf_start;
978 : unsigned long start_byte;
979 364 : unsigned long working_bytes = total_out - buf_start;
980 : unsigned long bytes;
981 : char *kaddr;
982 654 : struct page *page_out = bvec[*pg_index].bv_page;
983 :
984 : /*
985 : * start byte is the first byte of the page we're currently
986 : * copying into relative to the start of the compressed data.
987 : */
988 364 : start_byte = page_offset(page_out) - disk_start;
989 :
990 : /* we haven't yet hit data corresponding to this page */
991 364 : if (total_out <= start_byte)
992 : return 1;
993 :
994 : /*
995 : * the start of the data we care about is offset into
996 : * the middle of our working buffer
997 : */
998 332 : if (total_out > start_byte && buf_start < start_byte) {
999 0 : buf_offset = start_byte - buf_start;
1000 0 : working_bytes -= buf_offset;
1001 : } else {
1002 : buf_offset = 0;
1003 : }
1004 : current_buf_start = buf_start;
1005 :
1006 : /* copy bytes from the working buffer into the pages */
1007 694 : while (working_bytes > 0) {
1008 332 : bytes = min(PAGE_CACHE_SIZE - *pg_offset,
1009 : PAGE_CACHE_SIZE - buf_offset);
1010 332 : bytes = min(bytes, working_bytes);
1011 : kaddr = kmap_atomic(page_out);
1012 332 : memcpy(kaddr + *pg_offset, buf + buf_offset, bytes);
1013 332 : if (*pg_index == (vcnt - 1) && *pg_offset == 0)
1014 42 : memset(kaddr + bytes, 0, PAGE_CACHE_SIZE - bytes);
1015 : kunmap_atomic(kaddr);
1016 : flush_dcache_page(page_out);
1017 :
1018 332 : *pg_offset += bytes;
1019 332 : buf_offset += bytes;
1020 332 : working_bytes -= bytes;
1021 332 : current_buf_start += bytes;
1022 :
1023 : /* check if we need to pick another page */
1024 332 : if (*pg_offset == PAGE_CACHE_SIZE) {
1025 302 : (*pg_index)++;
1026 302 : if (*pg_index >= vcnt)
1027 : return 0;
1028 :
1029 290 : page_out = bvec[*pg_index].bv_page;
1030 290 : *pg_offset = 0;
1031 290 : start_byte = page_offset(page_out) - disk_start;
1032 :
1033 : /*
1034 : * make sure our new page is covered by this
1035 : * working buffer
1036 : */
1037 290 : if (total_out <= start_byte)
1038 : return 1;
1039 :
1040 : /*
1041 : * the next page in the biovec might not be adjacent
1042 : * to the last page, but it might still be found
1043 : * inside this working buffer. bump our offset pointer
1044 : */
1045 0 : if (total_out > start_byte &&
1046 0 : current_buf_start < start_byte) {
1047 0 : buf_offset = start_byte - buf_start;
1048 0 : working_bytes = total_out - start_byte;
1049 : current_buf_start = buf_start + buf_offset;
1050 : }
1051 : }
1052 : }
1053 :
1054 : return 1;
1055 : }
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