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1/*
2 * Copyright (C) 2008 Oracle. All rights reserved.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public
6 * License v2 as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public
14 * License along with this program; if not, write to the
15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16 * Boston, MA 021110-1307, USA.
17 */
18
19#include <linux/kernel.h>
20#include <linux/bio.h>
21#include <linux/buffer_head.h>
22#include <linux/file.h>
23#include <linux/fs.h>
24#include <linux/pagemap.h>
25#include <linux/highmem.h>
26#include <linux/time.h>
27#include <linux/init.h>
28#include <linux/string.h>
29#include <linux/backing-dev.h>
30#include <linux/mpage.h>
31#include <linux/swap.h>
32#include <linux/writeback.h>
33#include <linux/bit_spinlock.h>
34#include <linux/slab.h>
35#include "ctree.h"
36#include "disk-io.h"
37#include "transaction.h"
38#include "btrfs_inode.h"
39#include "volumes.h"
40#include "ordered-data.h"
41#include "compression.h"
42#include "extent_io.h"
43#include "extent_map.h"
44
45struct compressed_bio {
46 /* number of bios pending for this compressed extent */
47 atomic_t pending_bios;
48
49 /* the pages with the compressed data on them */
50 struct page **compressed_pages;
51
52 /* inode that owns this data */
53 struct inode *inode;
54
55 /* starting offset in the inode for our pages */
56 u64 start;
57
58 /* number of bytes in the inode we're working on */
59 unsigned long len;
60
61 /* number of bytes on disk */
62 unsigned long compressed_len;
63
64 /* the compression algorithm for this bio */
65 int compress_type;
66
67 /* number of compressed pages in the array */
68 unsigned long nr_pages;
69
70 /* IO errors */
71 int errors;
72 int mirror_num;
73
74 /* for reads, this is the bio we are copying the data into */
75 struct bio *orig_bio;
76
77 /*
78 * the start of a variable length array of checksums only
79 * used by reads
80 */
81 u32 sums;
82};
83
84static int btrfs_decompress_bio(int type, struct page **pages_in,
85 u64 disk_start, struct bio *orig_bio,
86 size_t srclen);
87
88static inline int compressed_bio_size(struct btrfs_fs_info *fs_info,
89 unsigned long disk_size)
90{
91 u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
92
93 return sizeof(struct compressed_bio) +
94 (DIV_ROUND_UP(disk_size, fs_info->sectorsize)) * csum_size;
95}
96
97static struct bio *compressed_bio_alloc(struct block_device *bdev,
98 u64 first_byte, gfp_t gfp_flags)
99{
100 return btrfs_bio_alloc(bdev, first_byte >> 9, BIO_MAX_PAGES, gfp_flags);
101}
102
103static int check_compressed_csum(struct inode *inode,
104 struct compressed_bio *cb,
105 u64 disk_start)
106{
107 int ret;
108 struct page *page;
109 unsigned long i;
110 char *kaddr;
111 u32 csum;
112 u32 *cb_sum = &cb->sums;
113
114 if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)
115 return 0;
116
117 for (i = 0; i < cb->nr_pages; i++) {
118 page = cb->compressed_pages[i];
119 csum = ~(u32)0;
120
121 kaddr = kmap_atomic(page);
122 csum = btrfs_csum_data(kaddr, csum, PAGE_SIZE);
123 btrfs_csum_final(csum, (u8 *)&csum);
124 kunmap_atomic(kaddr);
125
126 if (csum != *cb_sum) {
127 btrfs_info(BTRFS_I(inode)->root->fs_info,
128 "csum failed ino %llu extent %llu csum %u wanted %u mirror %d",
129 btrfs_ino(inode), disk_start, csum, *cb_sum,
130 cb->mirror_num);
131 ret = -EIO;
132 goto fail;
133 }
134 cb_sum++;
135
136 }
137 ret = 0;
138fail:
139 return ret;
140}
141
142/* when we finish reading compressed pages from the disk, we
143 * decompress them and then run the bio end_io routines on the
144 * decompressed pages (in the inode address space).
145 *
146 * This allows the checksumming and other IO error handling routines
147 * to work normally
148 *
149 * The compressed pages are freed here, and it must be run
150 * in process context
151 */
152static void end_compressed_bio_read(struct bio *bio)
153{
154 struct compressed_bio *cb = bio->bi_private;
155 struct inode *inode;
156 struct page *page;
157 unsigned long index;
158 int ret;
159
160 if (bio->bi_error)
161 cb->errors = 1;
162
163 /* if there are more bios still pending for this compressed
164 * extent, just exit
165 */
166 if (!atomic_dec_and_test(&cb->pending_bios))
167 goto out;
168
169 inode = cb->inode;
170 ret = check_compressed_csum(inode, cb,
171 (u64)bio->bi_iter.bi_sector << 9);
172 if (ret)
173 goto csum_failed;
174
175 /* ok, we're the last bio for this extent, lets start
176 * the decompression.
177 */
178 ret = btrfs_decompress_bio(cb->compress_type,
179 cb->compressed_pages,
180 cb->start,
181 cb->orig_bio,
182 cb->compressed_len);
183csum_failed:
184 if (ret)
185 cb->errors = 1;
186
187 /* release the compressed pages */
188 index = 0;
189 for (index = 0; index < cb->nr_pages; index++) {
190 page = cb->compressed_pages[index];
191 page->mapping = NULL;
192 put_page(page);
193 }
194
195 /* do io completion on the original bio */
196 if (cb->errors) {
197 bio_io_error(cb->orig_bio);
198 } else {
199 int i;
200 struct bio_vec *bvec;
201
202 /*
203 * we have verified the checksum already, set page
204 * checked so the end_io handlers know about it
205 */
206 bio_for_each_segment_all(bvec, cb->orig_bio, i)
207 SetPageChecked(bvec->bv_page);
208
209 bio_endio(cb->orig_bio);
210 }
211
212 /* finally free the cb struct */
213 kfree(cb->compressed_pages);
214 kfree(cb);
215out:
216 bio_put(bio);
217}
218
219/*
220 * Clear the writeback bits on all of the file
221 * pages for a compressed write
222 */
223static noinline void end_compressed_writeback(struct inode *inode,
224 const struct compressed_bio *cb)
225{
226 unsigned long index = cb->start >> PAGE_SHIFT;
227 unsigned long end_index = (cb->start + cb->len - 1) >> PAGE_SHIFT;
228 struct page *pages[16];
229 unsigned long nr_pages = end_index - index + 1;
230 int i;
231 int ret;
232
233 if (cb->errors)
234 mapping_set_error(inode->i_mapping, -EIO);
235
236 while (nr_pages > 0) {
237 ret = find_get_pages_contig(inode->i_mapping, index,
238 min_t(unsigned long,
239 nr_pages, ARRAY_SIZE(pages)), pages);
240 if (ret == 0) {
241 nr_pages -= 1;
242 index += 1;
243 continue;
244 }
245 for (i = 0; i < ret; i++) {
246 if (cb->errors)
247 SetPageError(pages[i]);
248 end_page_writeback(pages[i]);
249 put_page(pages[i]);
250 }
251 nr_pages -= ret;
252 index += ret;
253 }
254 /* the inode may be gone now */
255}
256
257/*
258 * do the cleanup once all the compressed pages hit the disk.
259 * This will clear writeback on the file pages and free the compressed
260 * pages.
261 *
262 * This also calls the writeback end hooks for the file pages so that
263 * metadata and checksums can be updated in the file.
264 */
265static void end_compressed_bio_write(struct bio *bio)
266{
267 struct extent_io_tree *tree;
268 struct compressed_bio *cb = bio->bi_private;
269 struct inode *inode;
270 struct page *page;
271 unsigned long index;
272
273 if (bio->bi_error)
274 cb->errors = 1;
275
276 /* if there are more bios still pending for this compressed
277 * extent, just exit
278 */
279 if (!atomic_dec_and_test(&cb->pending_bios))
280 goto out;
281
282 /* ok, we're the last bio for this extent, step one is to
283 * call back into the FS and do all the end_io operations
284 */
285 inode = cb->inode;
286 tree = &BTRFS_I(inode)->io_tree;
287 cb->compressed_pages[0]->mapping = cb->inode->i_mapping;
288 tree->ops->writepage_end_io_hook(cb->compressed_pages[0],
289 cb->start,
290 cb->start + cb->len - 1,
291 NULL,
292 bio->bi_error ? 0 : 1);
293 cb->compressed_pages[0]->mapping = NULL;
294
295 end_compressed_writeback(inode, cb);
296 /* note, our inode could be gone now */
297
298 /*
299 * release the compressed pages, these came from alloc_page and
300 * are not attached to the inode at all
301 */
302 index = 0;
303 for (index = 0; index < cb->nr_pages; index++) {
304 page = cb->compressed_pages[index];
305 page->mapping = NULL;
306 put_page(page);
307 }
308
309 /* finally free the cb struct */
310 kfree(cb->compressed_pages);
311 kfree(cb);
312out:
313 bio_put(bio);
314}
315
316/*
317 * worker function to build and submit bios for previously compressed pages.
318 * The corresponding pages in the inode should be marked for writeback
319 * and the compressed pages should have a reference on them for dropping
320 * when the IO is complete.
321 *
322 * This also checksums the file bytes and gets things ready for
323 * the end io hooks.
324 */
325int btrfs_submit_compressed_write(struct inode *inode, u64 start,
326 unsigned long len, u64 disk_start,
327 unsigned long compressed_len,
328 struct page **compressed_pages,
329 unsigned long nr_pages)
330{
331 struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
332 struct bio *bio = NULL;
333 struct compressed_bio *cb;
334 unsigned long bytes_left;
335 struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
336 int pg_index = 0;
337 struct page *page;
338 u64 first_byte = disk_start;
339 struct block_device *bdev;
340 int ret;
341 int skip_sum = BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM;
342
343 WARN_ON(start & ((u64)PAGE_SIZE - 1));
344 cb = kmalloc(compressed_bio_size(fs_info, compressed_len), GFP_NOFS);
345 if (!cb)
346 return -ENOMEM;
347 atomic_set(&cb->pending_bios, 0);
348 cb->errors = 0;
349 cb->inode = inode;
350 cb->start = start;
351 cb->len = len;
352 cb->mirror_num = 0;
353 cb->compressed_pages = compressed_pages;
354 cb->compressed_len = compressed_len;
355 cb->orig_bio = NULL;
356 cb->nr_pages = nr_pages;
357
358 bdev = fs_info->fs_devices->latest_bdev;
359
360 bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
361 if (!bio) {
362 kfree(cb);
363 return -ENOMEM;
364 }
365 bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
366 bio->bi_private = cb;
367 bio->bi_end_io = end_compressed_bio_write;
368 atomic_inc(&cb->pending_bios);
369
370 /* create and submit bios for the compressed pages */
371 bytes_left = compressed_len;
372 for (pg_index = 0; pg_index < cb->nr_pages; pg_index++) {
373 page = compressed_pages[pg_index];
374 page->mapping = inode->i_mapping;
375 if (bio->bi_iter.bi_size)
376 ret = io_tree->ops->merge_bio_hook(page, 0,
377 PAGE_SIZE,
378 bio, 0);
379 else
380 ret = 0;
381
382 page->mapping = NULL;
383 if (ret || bio_add_page(bio, page, PAGE_SIZE, 0) <
384 PAGE_SIZE) {
385 bio_get(bio);
386
387 /*
388 * inc the count before we submit the bio so
389 * we know the end IO handler won't happen before
390 * we inc the count. Otherwise, the cb might get
391 * freed before we're done setting it up
392 */
393 atomic_inc(&cb->pending_bios);
394 ret = btrfs_bio_wq_end_io(fs_info, bio,
395 BTRFS_WQ_ENDIO_DATA);
396 BUG_ON(ret); /* -ENOMEM */
397
398 if (!skip_sum) {
399 ret = btrfs_csum_one_bio(inode, bio, start, 1);
400 BUG_ON(ret); /* -ENOMEM */
401 }
402
403 ret = btrfs_map_bio(fs_info, bio, 0, 1);
404 if (ret) {
405 bio->bi_error = ret;
406 bio_endio(bio);
407 }
408
409 bio_put(bio);
410
411 bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
412 BUG_ON(!bio);
413 bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
414 bio->bi_private = cb;
415 bio->bi_end_io = end_compressed_bio_write;
416 bio_add_page(bio, page, PAGE_SIZE, 0);
417 }
418 if (bytes_left < PAGE_SIZE) {
419 btrfs_info(fs_info,
420 "bytes left %lu compress len %lu nr %lu",
421 bytes_left, cb->compressed_len, cb->nr_pages);
422 }
423 bytes_left -= PAGE_SIZE;
424 first_byte += PAGE_SIZE;
425 cond_resched();
426 }
427 bio_get(bio);
428
429 ret = btrfs_bio_wq_end_io(fs_info, bio, BTRFS_WQ_ENDIO_DATA);
430 BUG_ON(ret); /* -ENOMEM */
431
432 if (!skip_sum) {
433 ret = btrfs_csum_one_bio(inode, bio, start, 1);
434 BUG_ON(ret); /* -ENOMEM */
435 }
436
437 ret = btrfs_map_bio(fs_info, bio, 0, 1);
438 if (ret) {
439 bio->bi_error = ret;
440 bio_endio(bio);
441 }
442
443 bio_put(bio);
444 return 0;
445}
446
447static u64 bio_end_offset(struct bio *bio)
448{
449 struct bio_vec *last = &bio->bi_io_vec[bio->bi_vcnt - 1];
450
451 return page_offset(last->bv_page) + last->bv_len + last->bv_offset;
452}
453
454static noinline int add_ra_bio_pages(struct inode *inode,
455 u64 compressed_end,
456 struct compressed_bio *cb)
457{
458 unsigned long end_index;
459 unsigned long pg_index;
460 u64 last_offset;
461 u64 isize = i_size_read(inode);
462 int ret;
463 struct page *page;
464 unsigned long nr_pages = 0;
465 struct extent_map *em;
466 struct address_space *mapping = inode->i_mapping;
467 struct extent_map_tree *em_tree;
468 struct extent_io_tree *tree;
469 u64 end;
470 int misses = 0;
471
472 last_offset = bio_end_offset(cb->orig_bio);
473 em_tree = &BTRFS_I(inode)->extent_tree;
474 tree = &BTRFS_I(inode)->io_tree;
475
476 if (isize == 0)
477 return 0;
478
479 end_index = (i_size_read(inode) - 1) >> PAGE_SHIFT;
480
481 while (last_offset < compressed_end) {
482 pg_index = last_offset >> PAGE_SHIFT;
483
484 if (pg_index > end_index)
485 break;
486
487 rcu_read_lock();
488 page = radix_tree_lookup(&mapping->page_tree, pg_index);
489 rcu_read_unlock();
490 if (page && !radix_tree_exceptional_entry(page)) {
491 misses++;
492 if (misses > 4)
493 break;
494 goto next;
495 }
496
497 page = __page_cache_alloc(mapping_gfp_constraint(mapping,
498 ~__GFP_FS));
499 if (!page)
500 break;
501
502 if (add_to_page_cache_lru(page, mapping, pg_index, GFP_NOFS)) {
503 put_page(page);
504 goto next;
505 }
506
507 end = last_offset + PAGE_SIZE - 1;
508 /*
509 * at this point, we have a locked page in the page cache
510 * for these bytes in the file. But, we have to make
511 * sure they map to this compressed extent on disk.
512 */
513 set_page_extent_mapped(page);
514 lock_extent(tree, last_offset, end);
515 read_lock(&em_tree->lock);
516 em = lookup_extent_mapping(em_tree, last_offset,
517 PAGE_SIZE);
518 read_unlock(&em_tree->lock);
519
520 if (!em || last_offset < em->start ||
521 (last_offset + PAGE_SIZE > extent_map_end(em)) ||
522 (em->block_start >> 9) != cb->orig_bio->bi_iter.bi_sector) {
523 free_extent_map(em);
524 unlock_extent(tree, last_offset, end);
525 unlock_page(page);
526 put_page(page);
527 break;
528 }
529 free_extent_map(em);
530
531 if (page->index == end_index) {
532 char *userpage;
533 size_t zero_offset = isize & (PAGE_SIZE - 1);
534
535 if (zero_offset) {
536 int zeros;
537 zeros = PAGE_SIZE - zero_offset;
538 userpage = kmap_atomic(page);
539 memset(userpage + zero_offset, 0, zeros);
540 flush_dcache_page(page);
541 kunmap_atomic(userpage);
542 }
543 }
544
545 ret = bio_add_page(cb->orig_bio, page,
546 PAGE_SIZE, 0);
547
548 if (ret == PAGE_SIZE) {
549 nr_pages++;
550 put_page(page);
551 } else {
552 unlock_extent(tree, last_offset, end);
553 unlock_page(page);
554 put_page(page);
555 break;
556 }
557next:
558 last_offset += PAGE_SIZE;
559 }
560 return 0;
561}
562
563/*
564 * for a compressed read, the bio we get passed has all the inode pages
565 * in it. We don't actually do IO on those pages but allocate new ones
566 * to hold the compressed pages on disk.
567 *
568 * bio->bi_iter.bi_sector points to the compressed extent on disk
569 * bio->bi_io_vec points to all of the inode pages
570 *
571 * After the compressed pages are read, we copy the bytes into the
572 * bio we were passed and then call the bio end_io calls
573 */
574int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
575 int mirror_num, unsigned long bio_flags)
576{
577 struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
578 struct extent_io_tree *tree;
579 struct extent_map_tree *em_tree;
580 struct compressed_bio *cb;
581 unsigned long compressed_len;
582 unsigned long nr_pages;
583 unsigned long pg_index;
584 struct page *page;
585 struct block_device *bdev;
586 struct bio *comp_bio;
587 u64 cur_disk_byte = (u64)bio->bi_iter.bi_sector << 9;
588 u64 em_len;
589 u64 em_start;
590 struct extent_map *em;
591 int ret = -ENOMEM;
592 int faili = 0;
593 u32 *sums;
594
595 tree = &BTRFS_I(inode)->io_tree;
596 em_tree = &BTRFS_I(inode)->extent_tree;
597
598 /* we need the actual starting offset of this extent in the file */
599 read_lock(&em_tree->lock);
600 em = lookup_extent_mapping(em_tree,
601 page_offset(bio->bi_io_vec->bv_page),
602 PAGE_SIZE);
603 read_unlock(&em_tree->lock);
604 if (!em)
605 return -EIO;
606
607 compressed_len = em->block_len;
608 cb = kmalloc(compressed_bio_size(fs_info, compressed_len), GFP_NOFS);
609 if (!cb)
610 goto out;
611
612 atomic_set(&cb->pending_bios, 0);
613 cb->errors = 0;
614 cb->inode = inode;
615 cb->mirror_num = mirror_num;
616 sums = &cb->sums;
617
618 cb->start = em->orig_start;
619 em_len = em->len;
620 em_start = em->start;
621
622 free_extent_map(em);
623 em = NULL;
624
625 cb->len = bio->bi_iter.bi_size;
626 cb->compressed_len = compressed_len;
627 cb->compress_type = extent_compress_type(bio_flags);
628 cb->orig_bio = bio;
629
630 nr_pages = DIV_ROUND_UP(compressed_len, PAGE_SIZE);
631 cb->compressed_pages = kcalloc(nr_pages, sizeof(struct page *),
632 GFP_NOFS);
633 if (!cb->compressed_pages)
634 goto fail1;
635
636 bdev = fs_info->fs_devices->latest_bdev;
637
638 for (pg_index = 0; pg_index < nr_pages; pg_index++) {
639 cb->compressed_pages[pg_index] = alloc_page(GFP_NOFS |
640 __GFP_HIGHMEM);
641 if (!cb->compressed_pages[pg_index]) {
642 faili = pg_index - 1;
643 ret = -ENOMEM;
644 goto fail2;
645 }
646 }
647 faili = nr_pages - 1;
648 cb->nr_pages = nr_pages;
649
650 add_ra_bio_pages(inode, em_start + em_len, cb);
651
652 /* include any pages we added in add_ra-bio_pages */
653 cb->len = bio->bi_iter.bi_size;
654
655 comp_bio = compressed_bio_alloc(bdev, cur_disk_byte, GFP_NOFS);
656 if (!comp_bio)
657 goto fail2;
658 bio_set_op_attrs (comp_bio, REQ_OP_READ, 0);
659 comp_bio->bi_private = cb;
660 comp_bio->bi_end_io = end_compressed_bio_read;
661 atomic_inc(&cb->pending_bios);
662
663 for (pg_index = 0; pg_index < nr_pages; pg_index++) {
664 page = cb->compressed_pages[pg_index];
665 page->mapping = inode->i_mapping;
666 page->index = em_start >> PAGE_SHIFT;
667
668 if (comp_bio->bi_iter.bi_size)
669 ret = tree->ops->merge_bio_hook(page, 0,
670 PAGE_SIZE,
671 comp_bio, 0);
672 else
673 ret = 0;
674
675 page->mapping = NULL;
676 if (ret || bio_add_page(comp_bio, page, PAGE_SIZE, 0) <
677 PAGE_SIZE) {
678 bio_get(comp_bio);
679
680 ret = btrfs_bio_wq_end_io(fs_info, comp_bio,
681 BTRFS_WQ_ENDIO_DATA);
682 BUG_ON(ret); /* -ENOMEM */
683
684 /*
685 * inc the count before we submit the bio so
686 * we know the end IO handler won't happen before
687 * we inc the count. Otherwise, the cb might get
688 * freed before we're done setting it up
689 */
690 atomic_inc(&cb->pending_bios);
691
692 if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
693 ret = btrfs_lookup_bio_sums(inode, comp_bio,
694 sums);
695 BUG_ON(ret); /* -ENOMEM */
696 }
697 sums += DIV_ROUND_UP(comp_bio->bi_iter.bi_size,
698 fs_info->sectorsize);
699
700 ret = btrfs_map_bio(fs_info, comp_bio, mirror_num, 0);
701 if (ret) {
702 comp_bio->bi_error = ret;
703 bio_endio(comp_bio);
704 }
705
706 bio_put(comp_bio);
707
708 comp_bio = compressed_bio_alloc(bdev, cur_disk_byte,
709 GFP_NOFS);
710 BUG_ON(!comp_bio);
711 bio_set_op_attrs(comp_bio, REQ_OP_READ, 0);
712 comp_bio->bi_private = cb;
713 comp_bio->bi_end_io = end_compressed_bio_read;
714
715 bio_add_page(comp_bio, page, PAGE_SIZE, 0);
716 }
717 cur_disk_byte += PAGE_SIZE;
718 }
719 bio_get(comp_bio);
720
721 ret = btrfs_bio_wq_end_io(fs_info, comp_bio, BTRFS_WQ_ENDIO_DATA);
722 BUG_ON(ret); /* -ENOMEM */
723
724 if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
725 ret = btrfs_lookup_bio_sums(inode, comp_bio, sums);
726 BUG_ON(ret); /* -ENOMEM */
727 }
728
729 ret = btrfs_map_bio(fs_info, comp_bio, mirror_num, 0);
730 if (ret) {
731 comp_bio->bi_error = ret;
732 bio_endio(comp_bio);
733 }
734
735 bio_put(comp_bio);
736 return 0;
737
738fail2:
739 while (faili >= 0) {
740 __free_page(cb->compressed_pages[faili]);
741 faili--;
742 }
743
744 kfree(cb->compressed_pages);
745fail1:
746 kfree(cb);
747out:
748 free_extent_map(em);
749 return ret;
750}
751
752static struct {
753 struct list_head idle_ws;
754 spinlock_t ws_lock;
755 /* Number of free workspaces */
756 int free_ws;
757 /* Total number of allocated workspaces */
758 atomic_t total_ws;
759 /* Waiters for a free workspace */
760 wait_queue_head_t ws_wait;
761} btrfs_comp_ws[BTRFS_COMPRESS_TYPES];
762
763static const struct btrfs_compress_op * const btrfs_compress_op[] = {
764 &btrfs_zlib_compress,
765 &btrfs_lzo_compress,
766};
767
768void __init btrfs_init_compress(void)
769{
770 int i;
771
772 for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
773 struct list_head *workspace;
774
775 INIT_LIST_HEAD(&btrfs_comp_ws[i].idle_ws);
776 spin_lock_init(&btrfs_comp_ws[i].ws_lock);
777 atomic_set(&btrfs_comp_ws[i].total_ws, 0);
778 init_waitqueue_head(&btrfs_comp_ws[i].ws_wait);
779
780 /*
781 * Preallocate one workspace for each compression type so
782 * we can guarantee forward progress in the worst case
783 */
784 workspace = btrfs_compress_op[i]->alloc_workspace();
785 if (IS_ERR(workspace)) {
786 pr_warn("BTRFS: cannot preallocate compression workspace, will try later\n");
787 } else {
788 atomic_set(&btrfs_comp_ws[i].total_ws, 1);
789 btrfs_comp_ws[i].free_ws = 1;
790 list_add(workspace, &btrfs_comp_ws[i].idle_ws);
791 }
792 }
793}
794
795/*
796 * This finds an available workspace or allocates a new one.
797 * If it's not possible to allocate a new one, waits until there's one.
798 * Preallocation makes a forward progress guarantees and we do not return
799 * errors.
800 */
801static struct list_head *find_workspace(int type)
802{
803 struct list_head *workspace;
804 int cpus = num_online_cpus();
805 int idx = type - 1;
806
807 struct list_head *idle_ws = &btrfs_comp_ws[idx].idle_ws;
808 spinlock_t *ws_lock = &btrfs_comp_ws[idx].ws_lock;
809 atomic_t *total_ws = &btrfs_comp_ws[idx].total_ws;
810 wait_queue_head_t *ws_wait = &btrfs_comp_ws[idx].ws_wait;
811 int *free_ws = &btrfs_comp_ws[idx].free_ws;
812again:
813 spin_lock(ws_lock);
814 if (!list_empty(idle_ws)) {
815 workspace = idle_ws->next;
816 list_del(workspace);
817 (*free_ws)--;
818 spin_unlock(ws_lock);
819 return workspace;
820
821 }
822 if (atomic_read(total_ws) > cpus) {
823 DEFINE_WAIT(wait);
824
825 spin_unlock(ws_lock);
826 prepare_to_wait(ws_wait, &wait, TASK_UNINTERRUPTIBLE);
827 if (atomic_read(total_ws) > cpus && !*free_ws)
828 schedule();
829 finish_wait(ws_wait, &wait);
830 goto again;
831 }
832 atomic_inc(total_ws);
833 spin_unlock(ws_lock);
834
835 workspace = btrfs_compress_op[idx]->alloc_workspace();
836 if (IS_ERR(workspace)) {
837 atomic_dec(total_ws);
838 wake_up(ws_wait);
839
840 /*
841 * Do not return the error but go back to waiting. There's a
842 * workspace preallocated for each type and the compression
843 * time is bounded so we get to a workspace eventually. This
844 * makes our caller's life easier.
845 *
846 * To prevent silent and low-probability deadlocks (when the
847 * initial preallocation fails), check if there are any
848 * workspaces at all.
849 */
850 if (atomic_read(total_ws) == 0) {
851 static DEFINE_RATELIMIT_STATE(_rs,
852 /* once per minute */ 60 * HZ,
853 /* no burst */ 1);
854
855 if (__ratelimit(&_rs)) {
856 pr_warn("BTRFS: no compression workspaces, low memory, retrying\n");
857 }
858 }
859 goto again;
860 }
861 return workspace;
862}
863
864/*
865 * put a workspace struct back on the list or free it if we have enough
866 * idle ones sitting around
867 */
868static void free_workspace(int type, struct list_head *workspace)
869{
870 int idx = type - 1;
871 struct list_head *idle_ws = &btrfs_comp_ws[idx].idle_ws;
872 spinlock_t *ws_lock = &btrfs_comp_ws[idx].ws_lock;
873 atomic_t *total_ws = &btrfs_comp_ws[idx].total_ws;
874 wait_queue_head_t *ws_wait = &btrfs_comp_ws[idx].ws_wait;
875 int *free_ws = &btrfs_comp_ws[idx].free_ws;
876
877 spin_lock(ws_lock);
878 if (*free_ws < num_online_cpus()) {
879 list_add(workspace, idle_ws);
880 (*free_ws)++;
881 spin_unlock(ws_lock);
882 goto wake;
883 }
884 spin_unlock(ws_lock);
885
886 btrfs_compress_op[idx]->free_workspace(workspace);
887 atomic_dec(total_ws);
888wake:
889 /*
890 * Make sure counter is updated before we wake up waiters.
891 */
892 smp_mb();
893 if (waitqueue_active(ws_wait))
894 wake_up(ws_wait);
895}
896
897/*
898 * cleanup function for module exit
899 */
900static void free_workspaces(void)
901{
902 struct list_head *workspace;
903 int i;
904
905 for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
906 while (!list_empty(&btrfs_comp_ws[i].idle_ws)) {
907 workspace = btrfs_comp_ws[i].idle_ws.next;
908 list_del(workspace);
909 btrfs_compress_op[i]->free_workspace(workspace);
910 atomic_dec(&btrfs_comp_ws[i].total_ws);
911 }
912 }
913}
914
915/*
916 * given an address space and start/len, compress the bytes.
917 *
918 * pages are allocated to hold the compressed result and stored
919 * in 'pages'
920 *
921 * out_pages is used to return the number of pages allocated. There
922 * may be pages allocated even if we return an error
923 *
924 * total_in is used to return the number of bytes actually read. It
925 * may be smaller then len if we had to exit early because we
926 * ran out of room in the pages array or because we cross the
927 * max_out threshold.
928 *
929 * total_out is used to return the total number of compressed bytes
930 *
931 * max_out tells us the max number of bytes that we're allowed to
932 * stuff into pages
933 */
934int btrfs_compress_pages(int type, struct address_space *mapping,
935 u64 start, unsigned long len,
936 struct page **pages,
937 unsigned long nr_dest_pages,
938 unsigned long *out_pages,
939 unsigned long *total_in,
940 unsigned long *total_out,
941 unsigned long max_out)
942{
943 struct list_head *workspace;
944 int ret;
945
946 workspace = find_workspace(type);
947
948 ret = btrfs_compress_op[type-1]->compress_pages(workspace, mapping,
949 start, len, pages,
950 nr_dest_pages, out_pages,
951 total_in, total_out,
952 max_out);
953 free_workspace(type, workspace);
954 return ret;
955}
956
957/*
958 * pages_in is an array of pages with compressed data.
959 *
960 * disk_start is the starting logical offset of this array in the file
961 *
962 * orig_bio contains the pages from the file that we want to decompress into
963 *
964 * srclen is the number of bytes in pages_in
965 *
966 * The basic idea is that we have a bio that was created by readpages.
967 * The pages in the bio are for the uncompressed data, and they may not
968 * be contiguous. They all correspond to the range of bytes covered by
969 * the compressed extent.
970 */
971static int btrfs_decompress_bio(int type, struct page **pages_in,
972 u64 disk_start, struct bio *orig_bio,
973 size_t srclen)
974{
975 struct list_head *workspace;
976 int ret;
977
978 workspace = find_workspace(type);
979
980 ret = btrfs_compress_op[type-1]->decompress_bio(workspace, pages_in,
981 disk_start, orig_bio,
982 srclen);
983 free_workspace(type, workspace);
984 return ret;
985}
986
987/*
988 * a less complex decompression routine. Our compressed data fits in a
989 * single page, and we want to read a single page out of it.
990 * start_byte tells us the offset into the compressed data we're interested in
991 */
992int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
993 unsigned long start_byte, size_t srclen, size_t destlen)
994{
995 struct list_head *workspace;
996 int ret;
997
998 workspace = find_workspace(type);
999
1000 ret = btrfs_compress_op[type-1]->decompress(workspace, data_in,
1001 dest_page, start_byte,
1002 srclen, destlen);
1003
1004 free_workspace(type, workspace);
1005 return ret;
1006}
1007
1008void btrfs_exit_compress(void)
1009{
1010 free_workspaces();
1011}
1012
1013/*
1014 * Copy uncompressed data from working buffer to pages.
1015 *
1016 * buf_start is the byte offset we're of the start of our workspace buffer.
1017 *
1018 * total_out is the last byte of the buffer
1019 */
1020int btrfs_decompress_buf2page(char *buf, unsigned long buf_start,
1021 unsigned long total_out, u64 disk_start,
1022 struct bio *bio)
1023{
1024 unsigned long buf_offset;
1025 unsigned long current_buf_start;
1026 unsigned long start_byte;
1027 unsigned long prev_start_byte;
1028 unsigned long working_bytes = total_out - buf_start;
1029 unsigned long bytes;
1030 char *kaddr;
1031 struct bio_vec bvec = bio_iter_iovec(bio, bio->bi_iter);
1032
1033 /*
1034 * start byte is the first byte of the page we're currently
1035 * copying into relative to the start of the compressed data.
1036 */
1037 start_byte = page_offset(bvec.bv_page) - disk_start;
1038
1039 /* we haven't yet hit data corresponding to this page */
1040 if (total_out <= start_byte)
1041 return 1;
1042
1043 /*
1044 * the start of the data we care about is offset into
1045 * the middle of our working buffer
1046 */
1047 if (total_out > start_byte && buf_start < start_byte) {
1048 buf_offset = start_byte - buf_start;
1049 working_bytes -= buf_offset;
1050 } else {
1051 buf_offset = 0;
1052 }
1053 current_buf_start = buf_start;
1054
1055 /* copy bytes from the working buffer into the pages */
1056 while (working_bytes > 0) {
1057 bytes = min_t(unsigned long, bvec.bv_len,
1058 PAGE_SIZE - buf_offset);
1059 bytes = min(bytes, working_bytes);
1060
1061 kaddr = kmap_atomic(bvec.bv_page);
1062 memcpy(kaddr + bvec.bv_offset, buf + buf_offset, bytes);
1063 kunmap_atomic(kaddr);
1064 flush_dcache_page(bvec.bv_page);
1065
1066 buf_offset += bytes;
1067 working_bytes -= bytes;
1068 current_buf_start += bytes;
1069
1070 /* check if we need to pick another page */
1071 bio_advance(bio, bytes);
1072 if (!bio->bi_iter.bi_size)
1073 return 0;
1074 bvec = bio_iter_iovec(bio, bio->bi_iter);
1075 prev_start_byte = start_byte;
1076 start_byte = page_offset(bvec.bv_page) - disk_start;
1077
1078 /*
1079 * We need to make sure we're only adjusting
1080 * our offset into compression working buffer when
1081 * we're switching pages. Otherwise we can incorrectly
1082 * keep copying when we were actually done.
1083 */
1084 if (start_byte != prev_start_byte) {
1085 /*
1086 * make sure our new page is covered by this
1087 * working buffer
1088 */
1089 if (total_out <= start_byte)
1090 return 1;
1091
1092 /*
1093 * the next page in the biovec might not be adjacent
1094 * to the last page, but it might still be found
1095 * inside this working buffer. bump our offset pointer
1096 */
1097 if (total_out > start_byte &&
1098 current_buf_start < start_byte) {
1099 buf_offset = start_byte - buf_start;
1100 working_bytes = total_out - start_byte;
1101 current_buf_start = buf_start + buf_offset;
1102 }
1103 }
1104 }
1105
1106 return 1;
1107}
1/*
2 * Copyright (C) 2008 Oracle. All rights reserved.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public
6 * License v2 as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public
14 * License along with this program; if not, write to the
15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16 * Boston, MA 021110-1307, USA.
17 */
18
19#include <linux/kernel.h>
20#include <linux/bio.h>
21#include <linux/buffer_head.h>
22#include <linux/file.h>
23#include <linux/fs.h>
24#include <linux/pagemap.h>
25#include <linux/highmem.h>
26#include <linux/time.h>
27#include <linux/init.h>
28#include <linux/string.h>
29#include <linux/backing-dev.h>
30#include <linux/mpage.h>
31#include <linux/swap.h>
32#include <linux/writeback.h>
33#include <linux/bit_spinlock.h>
34#include <linux/slab.h>
35#include "compat.h"
36#include "ctree.h"
37#include "disk-io.h"
38#include "transaction.h"
39#include "btrfs_inode.h"
40#include "volumes.h"
41#include "ordered-data.h"
42#include "compression.h"
43#include "extent_io.h"
44#include "extent_map.h"
45
46struct compressed_bio {
47 /* number of bios pending for this compressed extent */
48 atomic_t pending_bios;
49
50 /* the pages with the compressed data on them */
51 struct page **compressed_pages;
52
53 /* inode that owns this data */
54 struct inode *inode;
55
56 /* starting offset in the inode for our pages */
57 u64 start;
58
59 /* number of bytes in the inode we're working on */
60 unsigned long len;
61
62 /* number of bytes on disk */
63 unsigned long compressed_len;
64
65 /* the compression algorithm for this bio */
66 int compress_type;
67
68 /* number of compressed pages in the array */
69 unsigned long nr_pages;
70
71 /* IO errors */
72 int errors;
73 int mirror_num;
74
75 /* for reads, this is the bio we are copying the data into */
76 struct bio *orig_bio;
77
78 /*
79 * the start of a variable length array of checksums only
80 * used by reads
81 */
82 u32 sums;
83};
84
85static inline int compressed_bio_size(struct btrfs_root *root,
86 unsigned long disk_size)
87{
88 u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
89
90 return sizeof(struct compressed_bio) +
91 ((disk_size + root->sectorsize - 1) / root->sectorsize) *
92 csum_size;
93}
94
95static struct bio *compressed_bio_alloc(struct block_device *bdev,
96 u64 first_byte, gfp_t gfp_flags)
97{
98 int nr_vecs;
99
100 nr_vecs = bio_get_nr_vecs(bdev);
101 return btrfs_bio_alloc(bdev, first_byte >> 9, nr_vecs, gfp_flags);
102}
103
104static int check_compressed_csum(struct inode *inode,
105 struct compressed_bio *cb,
106 u64 disk_start)
107{
108 int ret;
109 struct btrfs_root *root = BTRFS_I(inode)->root;
110 struct page *page;
111 unsigned long i;
112 char *kaddr;
113 u32 csum;
114 u32 *cb_sum = &cb->sums;
115
116 if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)
117 return 0;
118
119 for (i = 0; i < cb->nr_pages; i++) {
120 page = cb->compressed_pages[i];
121 csum = ~(u32)0;
122
123 kaddr = kmap_atomic(page);
124 csum = btrfs_csum_data(root, kaddr, csum, PAGE_CACHE_SIZE);
125 btrfs_csum_final(csum, (char *)&csum);
126 kunmap_atomic(kaddr);
127
128 if (csum != *cb_sum) {
129 printk(KERN_INFO "btrfs csum failed ino %llu "
130 "extent %llu csum %u "
131 "wanted %u mirror %d\n",
132 (unsigned long long)btrfs_ino(inode),
133 (unsigned long long)disk_start,
134 csum, *cb_sum, cb->mirror_num);
135 ret = -EIO;
136 goto fail;
137 }
138 cb_sum++;
139
140 }
141 ret = 0;
142fail:
143 return ret;
144}
145
146/* when we finish reading compressed pages from the disk, we
147 * decompress them and then run the bio end_io routines on the
148 * decompressed pages (in the inode address space).
149 *
150 * This allows the checksumming and other IO error handling routines
151 * to work normally
152 *
153 * The compressed pages are freed here, and it must be run
154 * in process context
155 */
156static void end_compressed_bio_read(struct bio *bio, int err)
157{
158 struct compressed_bio *cb = bio->bi_private;
159 struct inode *inode;
160 struct page *page;
161 unsigned long index;
162 int ret;
163
164 if (err)
165 cb->errors = 1;
166
167 /* if there are more bios still pending for this compressed
168 * extent, just exit
169 */
170 if (!atomic_dec_and_test(&cb->pending_bios))
171 goto out;
172
173 inode = cb->inode;
174 ret = check_compressed_csum(inode, cb, (u64)bio->bi_sector << 9);
175 if (ret)
176 goto csum_failed;
177
178 /* ok, we're the last bio for this extent, lets start
179 * the decompression.
180 */
181 ret = btrfs_decompress_biovec(cb->compress_type,
182 cb->compressed_pages,
183 cb->start,
184 cb->orig_bio->bi_io_vec,
185 cb->orig_bio->bi_vcnt,
186 cb->compressed_len);
187csum_failed:
188 if (ret)
189 cb->errors = 1;
190
191 /* release the compressed pages */
192 index = 0;
193 for (index = 0; index < cb->nr_pages; index++) {
194 page = cb->compressed_pages[index];
195 page->mapping = NULL;
196 page_cache_release(page);
197 }
198
199 /* do io completion on the original bio */
200 if (cb->errors) {
201 bio_io_error(cb->orig_bio);
202 } else {
203 int bio_index = 0;
204 struct bio_vec *bvec = cb->orig_bio->bi_io_vec;
205
206 /*
207 * we have verified the checksum already, set page
208 * checked so the end_io handlers know about it
209 */
210 while (bio_index < cb->orig_bio->bi_vcnt) {
211 SetPageChecked(bvec->bv_page);
212 bvec++;
213 bio_index++;
214 }
215 bio_endio(cb->orig_bio, 0);
216 }
217
218 /* finally free the cb struct */
219 kfree(cb->compressed_pages);
220 kfree(cb);
221out:
222 bio_put(bio);
223}
224
225/*
226 * Clear the writeback bits on all of the file
227 * pages for a compressed write
228 */
229static noinline void end_compressed_writeback(struct inode *inode, u64 start,
230 unsigned long ram_size)
231{
232 unsigned long index = start >> PAGE_CACHE_SHIFT;
233 unsigned long end_index = (start + ram_size - 1) >> PAGE_CACHE_SHIFT;
234 struct page *pages[16];
235 unsigned long nr_pages = end_index - index + 1;
236 int i;
237 int ret;
238
239 while (nr_pages > 0) {
240 ret = find_get_pages_contig(inode->i_mapping, index,
241 min_t(unsigned long,
242 nr_pages, ARRAY_SIZE(pages)), pages);
243 if (ret == 0) {
244 nr_pages -= 1;
245 index += 1;
246 continue;
247 }
248 for (i = 0; i < ret; i++) {
249 end_page_writeback(pages[i]);
250 page_cache_release(pages[i]);
251 }
252 nr_pages -= ret;
253 index += ret;
254 }
255 /* the inode may be gone now */
256}
257
258/*
259 * do the cleanup once all the compressed pages hit the disk.
260 * This will clear writeback on the file pages and free the compressed
261 * pages.
262 *
263 * This also calls the writeback end hooks for the file pages so that
264 * metadata and checksums can be updated in the file.
265 */
266static void end_compressed_bio_write(struct bio *bio, int err)
267{
268 struct extent_io_tree *tree;
269 struct compressed_bio *cb = bio->bi_private;
270 struct inode *inode;
271 struct page *page;
272 unsigned long index;
273
274 if (err)
275 cb->errors = 1;
276
277 /* if there are more bios still pending for this compressed
278 * extent, just exit
279 */
280 if (!atomic_dec_and_test(&cb->pending_bios))
281 goto out;
282
283 /* ok, we're the last bio for this extent, step one is to
284 * call back into the FS and do all the end_io operations
285 */
286 inode = cb->inode;
287 tree = &BTRFS_I(inode)->io_tree;
288 cb->compressed_pages[0]->mapping = cb->inode->i_mapping;
289 tree->ops->writepage_end_io_hook(cb->compressed_pages[0],
290 cb->start,
291 cb->start + cb->len - 1,
292 NULL, 1);
293 cb->compressed_pages[0]->mapping = NULL;
294
295 end_compressed_writeback(inode, cb->start, cb->len);
296 /* note, our inode could be gone now */
297
298 /*
299 * release the compressed pages, these came from alloc_page and
300 * are not attached to the inode at all
301 */
302 index = 0;
303 for (index = 0; index < cb->nr_pages; index++) {
304 page = cb->compressed_pages[index];
305 page->mapping = NULL;
306 page_cache_release(page);
307 }
308
309 /* finally free the cb struct */
310 kfree(cb->compressed_pages);
311 kfree(cb);
312out:
313 bio_put(bio);
314}
315
316/*
317 * worker function to build and submit bios for previously compressed pages.
318 * The corresponding pages in the inode should be marked for writeback
319 * and the compressed pages should have a reference on them for dropping
320 * when the IO is complete.
321 *
322 * This also checksums the file bytes and gets things ready for
323 * the end io hooks.
324 */
325int btrfs_submit_compressed_write(struct inode *inode, u64 start,
326 unsigned long len, u64 disk_start,
327 unsigned long compressed_len,
328 struct page **compressed_pages,
329 unsigned long nr_pages)
330{
331 struct bio *bio = NULL;
332 struct btrfs_root *root = BTRFS_I(inode)->root;
333 struct compressed_bio *cb;
334 unsigned long bytes_left;
335 struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
336 int pg_index = 0;
337 struct page *page;
338 u64 first_byte = disk_start;
339 struct block_device *bdev;
340 int ret;
341 int skip_sum = BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM;
342
343 WARN_ON(start & ((u64)PAGE_CACHE_SIZE - 1));
344 cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS);
345 if (!cb)
346 return -ENOMEM;
347 atomic_set(&cb->pending_bios, 0);
348 cb->errors = 0;
349 cb->inode = inode;
350 cb->start = start;
351 cb->len = len;
352 cb->mirror_num = 0;
353 cb->compressed_pages = compressed_pages;
354 cb->compressed_len = compressed_len;
355 cb->orig_bio = NULL;
356 cb->nr_pages = nr_pages;
357
358 bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
359
360 bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
361 if(!bio) {
362 kfree(cb);
363 return -ENOMEM;
364 }
365 bio->bi_private = cb;
366 bio->bi_end_io = end_compressed_bio_write;
367 atomic_inc(&cb->pending_bios);
368
369 /* create and submit bios for the compressed pages */
370 bytes_left = compressed_len;
371 for (pg_index = 0; pg_index < cb->nr_pages; pg_index++) {
372 page = compressed_pages[pg_index];
373 page->mapping = inode->i_mapping;
374 if (bio->bi_size)
375 ret = io_tree->ops->merge_bio_hook(page, 0,
376 PAGE_CACHE_SIZE,
377 bio, 0);
378 else
379 ret = 0;
380
381 page->mapping = NULL;
382 if (ret || bio_add_page(bio, page, PAGE_CACHE_SIZE, 0) <
383 PAGE_CACHE_SIZE) {
384 bio_get(bio);
385
386 /*
387 * inc the count before we submit the bio so
388 * we know the end IO handler won't happen before
389 * we inc the count. Otherwise, the cb might get
390 * freed before we're done setting it up
391 */
392 atomic_inc(&cb->pending_bios);
393 ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0);
394 BUG_ON(ret); /* -ENOMEM */
395
396 if (!skip_sum) {
397 ret = btrfs_csum_one_bio(root, inode, bio,
398 start, 1);
399 BUG_ON(ret); /* -ENOMEM */
400 }
401
402 ret = btrfs_map_bio(root, WRITE, bio, 0, 1);
403 BUG_ON(ret); /* -ENOMEM */
404
405 bio_put(bio);
406
407 bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
408 BUG_ON(!bio);
409 bio->bi_private = cb;
410 bio->bi_end_io = end_compressed_bio_write;
411 bio_add_page(bio, page, PAGE_CACHE_SIZE, 0);
412 }
413 if (bytes_left < PAGE_CACHE_SIZE) {
414 printk("bytes left %lu compress len %lu nr %lu\n",
415 bytes_left, cb->compressed_len, cb->nr_pages);
416 }
417 bytes_left -= PAGE_CACHE_SIZE;
418 first_byte += PAGE_CACHE_SIZE;
419 cond_resched();
420 }
421 bio_get(bio);
422
423 ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0);
424 BUG_ON(ret); /* -ENOMEM */
425
426 if (!skip_sum) {
427 ret = btrfs_csum_one_bio(root, inode, bio, start, 1);
428 BUG_ON(ret); /* -ENOMEM */
429 }
430
431 ret = btrfs_map_bio(root, WRITE, bio, 0, 1);
432 BUG_ON(ret); /* -ENOMEM */
433
434 bio_put(bio);
435 return 0;
436}
437
438static noinline int add_ra_bio_pages(struct inode *inode,
439 u64 compressed_end,
440 struct compressed_bio *cb)
441{
442 unsigned long end_index;
443 unsigned long pg_index;
444 u64 last_offset;
445 u64 isize = i_size_read(inode);
446 int ret;
447 struct page *page;
448 unsigned long nr_pages = 0;
449 struct extent_map *em;
450 struct address_space *mapping = inode->i_mapping;
451 struct extent_map_tree *em_tree;
452 struct extent_io_tree *tree;
453 u64 end;
454 int misses = 0;
455
456 page = cb->orig_bio->bi_io_vec[cb->orig_bio->bi_vcnt - 1].bv_page;
457 last_offset = (page_offset(page) + PAGE_CACHE_SIZE);
458 em_tree = &BTRFS_I(inode)->extent_tree;
459 tree = &BTRFS_I(inode)->io_tree;
460
461 if (isize == 0)
462 return 0;
463
464 end_index = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;
465
466 while (last_offset < compressed_end) {
467 pg_index = last_offset >> PAGE_CACHE_SHIFT;
468
469 if (pg_index > end_index)
470 break;
471
472 rcu_read_lock();
473 page = radix_tree_lookup(&mapping->page_tree, pg_index);
474 rcu_read_unlock();
475 if (page) {
476 misses++;
477 if (misses > 4)
478 break;
479 goto next;
480 }
481
482 page = __page_cache_alloc(mapping_gfp_mask(mapping) &
483 ~__GFP_FS);
484 if (!page)
485 break;
486
487 if (add_to_page_cache_lru(page, mapping, pg_index,
488 GFP_NOFS)) {
489 page_cache_release(page);
490 goto next;
491 }
492
493 end = last_offset + PAGE_CACHE_SIZE - 1;
494 /*
495 * at this point, we have a locked page in the page cache
496 * for these bytes in the file. But, we have to make
497 * sure they map to this compressed extent on disk.
498 */
499 set_page_extent_mapped(page);
500 lock_extent(tree, last_offset, end);
501 read_lock(&em_tree->lock);
502 em = lookup_extent_mapping(em_tree, last_offset,
503 PAGE_CACHE_SIZE);
504 read_unlock(&em_tree->lock);
505
506 if (!em || last_offset < em->start ||
507 (last_offset + PAGE_CACHE_SIZE > extent_map_end(em)) ||
508 (em->block_start >> 9) != cb->orig_bio->bi_sector) {
509 free_extent_map(em);
510 unlock_extent(tree, last_offset, end);
511 unlock_page(page);
512 page_cache_release(page);
513 break;
514 }
515 free_extent_map(em);
516
517 if (page->index == end_index) {
518 char *userpage;
519 size_t zero_offset = isize & (PAGE_CACHE_SIZE - 1);
520
521 if (zero_offset) {
522 int zeros;
523 zeros = PAGE_CACHE_SIZE - zero_offset;
524 userpage = kmap_atomic(page);
525 memset(userpage + zero_offset, 0, zeros);
526 flush_dcache_page(page);
527 kunmap_atomic(userpage);
528 }
529 }
530
531 ret = bio_add_page(cb->orig_bio, page,
532 PAGE_CACHE_SIZE, 0);
533
534 if (ret == PAGE_CACHE_SIZE) {
535 nr_pages++;
536 page_cache_release(page);
537 } else {
538 unlock_extent(tree, last_offset, end);
539 unlock_page(page);
540 page_cache_release(page);
541 break;
542 }
543next:
544 last_offset += PAGE_CACHE_SIZE;
545 }
546 return 0;
547}
548
549/*
550 * for a compressed read, the bio we get passed has all the inode pages
551 * in it. We don't actually do IO on those pages but allocate new ones
552 * to hold the compressed pages on disk.
553 *
554 * bio->bi_sector points to the compressed extent on disk
555 * bio->bi_io_vec points to all of the inode pages
556 * bio->bi_vcnt is a count of pages
557 *
558 * After the compressed pages are read, we copy the bytes into the
559 * bio we were passed and then call the bio end_io calls
560 */
561int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
562 int mirror_num, unsigned long bio_flags)
563{
564 struct extent_io_tree *tree;
565 struct extent_map_tree *em_tree;
566 struct compressed_bio *cb;
567 struct btrfs_root *root = BTRFS_I(inode)->root;
568 unsigned long uncompressed_len = bio->bi_vcnt * PAGE_CACHE_SIZE;
569 unsigned long compressed_len;
570 unsigned long nr_pages;
571 unsigned long pg_index;
572 struct page *page;
573 struct block_device *bdev;
574 struct bio *comp_bio;
575 u64 cur_disk_byte = (u64)bio->bi_sector << 9;
576 u64 em_len;
577 u64 em_start;
578 struct extent_map *em;
579 int ret = -ENOMEM;
580 u32 *sums;
581
582 tree = &BTRFS_I(inode)->io_tree;
583 em_tree = &BTRFS_I(inode)->extent_tree;
584
585 /* we need the actual starting offset of this extent in the file */
586 read_lock(&em_tree->lock);
587 em = lookup_extent_mapping(em_tree,
588 page_offset(bio->bi_io_vec->bv_page),
589 PAGE_CACHE_SIZE);
590 read_unlock(&em_tree->lock);
591 if (!em)
592 return -EIO;
593
594 compressed_len = em->block_len;
595 cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS);
596 if (!cb)
597 goto out;
598
599 atomic_set(&cb->pending_bios, 0);
600 cb->errors = 0;
601 cb->inode = inode;
602 cb->mirror_num = mirror_num;
603 sums = &cb->sums;
604
605 cb->start = em->orig_start;
606 em_len = em->len;
607 em_start = em->start;
608
609 free_extent_map(em);
610 em = NULL;
611
612 cb->len = uncompressed_len;
613 cb->compressed_len = compressed_len;
614 cb->compress_type = extent_compress_type(bio_flags);
615 cb->orig_bio = bio;
616
617 nr_pages = (compressed_len + PAGE_CACHE_SIZE - 1) /
618 PAGE_CACHE_SIZE;
619 cb->compressed_pages = kzalloc(sizeof(struct page *) * nr_pages,
620 GFP_NOFS);
621 if (!cb->compressed_pages)
622 goto fail1;
623
624 bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
625
626 for (pg_index = 0; pg_index < nr_pages; pg_index++) {
627 cb->compressed_pages[pg_index] = alloc_page(GFP_NOFS |
628 __GFP_HIGHMEM);
629 if (!cb->compressed_pages[pg_index])
630 goto fail2;
631 }
632 cb->nr_pages = nr_pages;
633
634 add_ra_bio_pages(inode, em_start + em_len, cb);
635
636 /* include any pages we added in add_ra-bio_pages */
637 uncompressed_len = bio->bi_vcnt * PAGE_CACHE_SIZE;
638 cb->len = uncompressed_len;
639
640 comp_bio = compressed_bio_alloc(bdev, cur_disk_byte, GFP_NOFS);
641 if (!comp_bio)
642 goto fail2;
643 comp_bio->bi_private = cb;
644 comp_bio->bi_end_io = end_compressed_bio_read;
645 atomic_inc(&cb->pending_bios);
646
647 for (pg_index = 0; pg_index < nr_pages; pg_index++) {
648 page = cb->compressed_pages[pg_index];
649 page->mapping = inode->i_mapping;
650 page->index = em_start >> PAGE_CACHE_SHIFT;
651
652 if (comp_bio->bi_size)
653 ret = tree->ops->merge_bio_hook(page, 0,
654 PAGE_CACHE_SIZE,
655 comp_bio, 0);
656 else
657 ret = 0;
658
659 page->mapping = NULL;
660 if (ret || bio_add_page(comp_bio, page, PAGE_CACHE_SIZE, 0) <
661 PAGE_CACHE_SIZE) {
662 bio_get(comp_bio);
663
664 ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0);
665 BUG_ON(ret); /* -ENOMEM */
666
667 /*
668 * inc the count before we submit the bio so
669 * we know the end IO handler won't happen before
670 * we inc the count. Otherwise, the cb might get
671 * freed before we're done setting it up
672 */
673 atomic_inc(&cb->pending_bios);
674
675 if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
676 ret = btrfs_lookup_bio_sums(root, inode,
677 comp_bio, sums);
678 BUG_ON(ret); /* -ENOMEM */
679 }
680 sums += (comp_bio->bi_size + root->sectorsize - 1) /
681 root->sectorsize;
682
683 ret = btrfs_map_bio(root, READ, comp_bio,
684 mirror_num, 0);
685 BUG_ON(ret); /* -ENOMEM */
686
687 bio_put(comp_bio);
688
689 comp_bio = compressed_bio_alloc(bdev, cur_disk_byte,
690 GFP_NOFS);
691 BUG_ON(!comp_bio);
692 comp_bio->bi_private = cb;
693 comp_bio->bi_end_io = end_compressed_bio_read;
694
695 bio_add_page(comp_bio, page, PAGE_CACHE_SIZE, 0);
696 }
697 cur_disk_byte += PAGE_CACHE_SIZE;
698 }
699 bio_get(comp_bio);
700
701 ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0);
702 BUG_ON(ret); /* -ENOMEM */
703
704 if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
705 ret = btrfs_lookup_bio_sums(root, inode, comp_bio, sums);
706 BUG_ON(ret); /* -ENOMEM */
707 }
708
709 ret = btrfs_map_bio(root, READ, comp_bio, mirror_num, 0);
710 BUG_ON(ret); /* -ENOMEM */
711
712 bio_put(comp_bio);
713 return 0;
714
715fail2:
716 for (pg_index = 0; pg_index < nr_pages; pg_index++)
717 free_page((unsigned long)cb->compressed_pages[pg_index]);
718
719 kfree(cb->compressed_pages);
720fail1:
721 kfree(cb);
722out:
723 free_extent_map(em);
724 return ret;
725}
726
727static struct list_head comp_idle_workspace[BTRFS_COMPRESS_TYPES];
728static spinlock_t comp_workspace_lock[BTRFS_COMPRESS_TYPES];
729static int comp_num_workspace[BTRFS_COMPRESS_TYPES];
730static atomic_t comp_alloc_workspace[BTRFS_COMPRESS_TYPES];
731static wait_queue_head_t comp_workspace_wait[BTRFS_COMPRESS_TYPES];
732
733struct btrfs_compress_op *btrfs_compress_op[] = {
734 &btrfs_zlib_compress,
735 &btrfs_lzo_compress,
736};
737
738void __init btrfs_init_compress(void)
739{
740 int i;
741
742 for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
743 INIT_LIST_HEAD(&comp_idle_workspace[i]);
744 spin_lock_init(&comp_workspace_lock[i]);
745 atomic_set(&comp_alloc_workspace[i], 0);
746 init_waitqueue_head(&comp_workspace_wait[i]);
747 }
748}
749
750/*
751 * this finds an available workspace or allocates a new one
752 * ERR_PTR is returned if things go bad.
753 */
754static struct list_head *find_workspace(int type)
755{
756 struct list_head *workspace;
757 int cpus = num_online_cpus();
758 int idx = type - 1;
759
760 struct list_head *idle_workspace = &comp_idle_workspace[idx];
761 spinlock_t *workspace_lock = &comp_workspace_lock[idx];
762 atomic_t *alloc_workspace = &comp_alloc_workspace[idx];
763 wait_queue_head_t *workspace_wait = &comp_workspace_wait[idx];
764 int *num_workspace = &comp_num_workspace[idx];
765again:
766 spin_lock(workspace_lock);
767 if (!list_empty(idle_workspace)) {
768 workspace = idle_workspace->next;
769 list_del(workspace);
770 (*num_workspace)--;
771 spin_unlock(workspace_lock);
772 return workspace;
773
774 }
775 if (atomic_read(alloc_workspace) > cpus) {
776 DEFINE_WAIT(wait);
777
778 spin_unlock(workspace_lock);
779 prepare_to_wait(workspace_wait, &wait, TASK_UNINTERRUPTIBLE);
780 if (atomic_read(alloc_workspace) > cpus && !*num_workspace)
781 schedule();
782 finish_wait(workspace_wait, &wait);
783 goto again;
784 }
785 atomic_inc(alloc_workspace);
786 spin_unlock(workspace_lock);
787
788 workspace = btrfs_compress_op[idx]->alloc_workspace();
789 if (IS_ERR(workspace)) {
790 atomic_dec(alloc_workspace);
791 wake_up(workspace_wait);
792 }
793 return workspace;
794}
795
796/*
797 * put a workspace struct back on the list or free it if we have enough
798 * idle ones sitting around
799 */
800static void free_workspace(int type, struct list_head *workspace)
801{
802 int idx = type - 1;
803 struct list_head *idle_workspace = &comp_idle_workspace[idx];
804 spinlock_t *workspace_lock = &comp_workspace_lock[idx];
805 atomic_t *alloc_workspace = &comp_alloc_workspace[idx];
806 wait_queue_head_t *workspace_wait = &comp_workspace_wait[idx];
807 int *num_workspace = &comp_num_workspace[idx];
808
809 spin_lock(workspace_lock);
810 if (*num_workspace < num_online_cpus()) {
811 list_add_tail(workspace, idle_workspace);
812 (*num_workspace)++;
813 spin_unlock(workspace_lock);
814 goto wake;
815 }
816 spin_unlock(workspace_lock);
817
818 btrfs_compress_op[idx]->free_workspace(workspace);
819 atomic_dec(alloc_workspace);
820wake:
821 if (waitqueue_active(workspace_wait))
822 wake_up(workspace_wait);
823}
824
825/*
826 * cleanup function for module exit
827 */
828static void free_workspaces(void)
829{
830 struct list_head *workspace;
831 int i;
832
833 for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
834 while (!list_empty(&comp_idle_workspace[i])) {
835 workspace = comp_idle_workspace[i].next;
836 list_del(workspace);
837 btrfs_compress_op[i]->free_workspace(workspace);
838 atomic_dec(&comp_alloc_workspace[i]);
839 }
840 }
841}
842
843/*
844 * given an address space and start/len, compress the bytes.
845 *
846 * pages are allocated to hold the compressed result and stored
847 * in 'pages'
848 *
849 * out_pages is used to return the number of pages allocated. There
850 * may be pages allocated even if we return an error
851 *
852 * total_in is used to return the number of bytes actually read. It
853 * may be smaller then len if we had to exit early because we
854 * ran out of room in the pages array or because we cross the
855 * max_out threshold.
856 *
857 * total_out is used to return the total number of compressed bytes
858 *
859 * max_out tells us the max number of bytes that we're allowed to
860 * stuff into pages
861 */
862int btrfs_compress_pages(int type, struct address_space *mapping,
863 u64 start, unsigned long len,
864 struct page **pages,
865 unsigned long nr_dest_pages,
866 unsigned long *out_pages,
867 unsigned long *total_in,
868 unsigned long *total_out,
869 unsigned long max_out)
870{
871 struct list_head *workspace;
872 int ret;
873
874 workspace = find_workspace(type);
875 if (IS_ERR(workspace))
876 return -1;
877
878 ret = btrfs_compress_op[type-1]->compress_pages(workspace, mapping,
879 start, len, pages,
880 nr_dest_pages, out_pages,
881 total_in, total_out,
882 max_out);
883 free_workspace(type, workspace);
884 return ret;
885}
886
887/*
888 * pages_in is an array of pages with compressed data.
889 *
890 * disk_start is the starting logical offset of this array in the file
891 *
892 * bvec is a bio_vec of pages from the file that we want to decompress into
893 *
894 * vcnt is the count of pages in the biovec
895 *
896 * srclen is the number of bytes in pages_in
897 *
898 * The basic idea is that we have a bio that was created by readpages.
899 * The pages in the bio are for the uncompressed data, and they may not
900 * be contiguous. They all correspond to the range of bytes covered by
901 * the compressed extent.
902 */
903int btrfs_decompress_biovec(int type, struct page **pages_in, u64 disk_start,
904 struct bio_vec *bvec, int vcnt, size_t srclen)
905{
906 struct list_head *workspace;
907 int ret;
908
909 workspace = find_workspace(type);
910 if (IS_ERR(workspace))
911 return -ENOMEM;
912
913 ret = btrfs_compress_op[type-1]->decompress_biovec(workspace, pages_in,
914 disk_start,
915 bvec, vcnt, srclen);
916 free_workspace(type, workspace);
917 return ret;
918}
919
920/*
921 * a less complex decompression routine. Our compressed data fits in a
922 * single page, and we want to read a single page out of it.
923 * start_byte tells us the offset into the compressed data we're interested in
924 */
925int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
926 unsigned long start_byte, size_t srclen, size_t destlen)
927{
928 struct list_head *workspace;
929 int ret;
930
931 workspace = find_workspace(type);
932 if (IS_ERR(workspace))
933 return -ENOMEM;
934
935 ret = btrfs_compress_op[type-1]->decompress(workspace, data_in,
936 dest_page, start_byte,
937 srclen, destlen);
938
939 free_workspace(type, workspace);
940 return ret;
941}
942
943void btrfs_exit_compress(void)
944{
945 free_workspaces();
946}
947
948/*
949 * Copy uncompressed data from working buffer to pages.
950 *
951 * buf_start is the byte offset we're of the start of our workspace buffer.
952 *
953 * total_out is the last byte of the buffer
954 */
955int btrfs_decompress_buf2page(char *buf, unsigned long buf_start,
956 unsigned long total_out, u64 disk_start,
957 struct bio_vec *bvec, int vcnt,
958 unsigned long *pg_index,
959 unsigned long *pg_offset)
960{
961 unsigned long buf_offset;
962 unsigned long current_buf_start;
963 unsigned long start_byte;
964 unsigned long working_bytes = total_out - buf_start;
965 unsigned long bytes;
966 char *kaddr;
967 struct page *page_out = bvec[*pg_index].bv_page;
968
969 /*
970 * start byte is the first byte of the page we're currently
971 * copying into relative to the start of the compressed data.
972 */
973 start_byte = page_offset(page_out) - disk_start;
974
975 /* we haven't yet hit data corresponding to this page */
976 if (total_out <= start_byte)
977 return 1;
978
979 /*
980 * the start of the data we care about is offset into
981 * the middle of our working buffer
982 */
983 if (total_out > start_byte && buf_start < start_byte) {
984 buf_offset = start_byte - buf_start;
985 working_bytes -= buf_offset;
986 } else {
987 buf_offset = 0;
988 }
989 current_buf_start = buf_start;
990
991 /* copy bytes from the working buffer into the pages */
992 while (working_bytes > 0) {
993 bytes = min(PAGE_CACHE_SIZE - *pg_offset,
994 PAGE_CACHE_SIZE - buf_offset);
995 bytes = min(bytes, working_bytes);
996 kaddr = kmap_atomic(page_out);
997 memcpy(kaddr + *pg_offset, buf + buf_offset, bytes);
998 kunmap_atomic(kaddr);
999 flush_dcache_page(page_out);
1000
1001 *pg_offset += bytes;
1002 buf_offset += bytes;
1003 working_bytes -= bytes;
1004 current_buf_start += bytes;
1005
1006 /* check if we need to pick another page */
1007 if (*pg_offset == PAGE_CACHE_SIZE) {
1008 (*pg_index)++;
1009 if (*pg_index >= vcnt)
1010 return 0;
1011
1012 page_out = bvec[*pg_index].bv_page;
1013 *pg_offset = 0;
1014 start_byte = page_offset(page_out) - disk_start;
1015
1016 /*
1017 * make sure our new page is covered by this
1018 * working buffer
1019 */
1020 if (total_out <= start_byte)
1021 return 1;
1022
1023 /*
1024 * the next page in the biovec might not be adjacent
1025 * to the last page, but it might still be found
1026 * inside this working buffer. bump our offset pointer
1027 */
1028 if (total_out > start_byte &&
1029 current_buf_start < start_byte) {
1030 buf_offset = start_byte - buf_start;
1031 working_bytes = total_out - start_byte;
1032 current_buf_start = buf_start + buf_offset;
1033 }
1034 }
1035 }
1036
1037 return 1;
1038}