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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 "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
46 struct 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
85 static 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
95 static 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
104 static 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;
142 fail:
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 */
156 static 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);
187 csum_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);
221 out:
222 bio_put(bio);
223 }
224
225 /*
226 * Clear the writeback bits on all of the file
227 * pages for a compressed write
228 */
229 static 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 */
266 static 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);
312 out:
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 */
325 int 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
438 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 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 }
543 next:
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 */
561 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 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 int faili = 0;
581 u32 *sums;
582
583 tree = &BTRFS_I(inode)->io_tree;
584 em_tree = &BTRFS_I(inode)->extent_tree;
585
586 /* we need the actual starting offset of this extent in the file */
587 read_lock(&em_tree->lock);
588 em = lookup_extent_mapping(em_tree,
589 page_offset(bio->bi_io_vec->bv_page),
590 PAGE_CACHE_SIZE);
591 read_unlock(&em_tree->lock);
592 if (!em)
593 return -EIO;
594
595 compressed_len = em->block_len;
596 cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS);
597 if (!cb)
598 goto out;
599
600 atomic_set(&cb->pending_bios, 0);
601 cb->errors = 0;
602 cb->inode = inode;
603 cb->mirror_num = mirror_num;
604 sums = &cb->sums;
605
606 cb->start = em->orig_start;
607 em_len = em->len;
608 em_start = em->start;
609
610 free_extent_map(em);
611 em = NULL;
612
613 cb->len = uncompressed_len;
614 cb->compressed_len = compressed_len;
615 cb->compress_type = extent_compress_type(bio_flags);
616 cb->orig_bio = bio;
617
618 nr_pages = (compressed_len + PAGE_CACHE_SIZE - 1) /
619 PAGE_CACHE_SIZE;
620 cb->compressed_pages = kzalloc(sizeof(struct page *) * nr_pages,
621 GFP_NOFS);
622 if (!cb->compressed_pages)
623 goto fail1;
624
625 bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
626
627 for (pg_index = 0; pg_index < nr_pages; pg_index++) {
628 cb->compressed_pages[pg_index] = alloc_page(GFP_NOFS |
629 __GFP_HIGHMEM);
630 if (!cb->compressed_pages[pg_index]) {
631 faili = pg_index - 1;
632 ret = -ENOMEM;
633 goto fail2;
634 }
635 }
636 faili = nr_pages - 1;
637 cb->nr_pages = nr_pages;
638
639 add_ra_bio_pages(inode, em_start + em_len, cb);
640
641 /* include any pages we added in add_ra-bio_pages */
642 uncompressed_len = bio->bi_vcnt * PAGE_CACHE_SIZE;
643 cb->len = uncompressed_len;
644
645 comp_bio = compressed_bio_alloc(bdev, cur_disk_byte, GFP_NOFS);
646 if (!comp_bio)
647 goto fail2;
648 comp_bio->bi_private = cb;
649 comp_bio->bi_end_io = end_compressed_bio_read;
650 atomic_inc(&cb->pending_bios);
651
652 for (pg_index = 0; pg_index < nr_pages; pg_index++) {
653 page = cb->compressed_pages[pg_index];
654 page->mapping = inode->i_mapping;
655 page->index = em_start >> PAGE_CACHE_SHIFT;
656
657 if (comp_bio->bi_size)
658 ret = tree->ops->merge_bio_hook(page, 0,
659 PAGE_CACHE_SIZE,
660 comp_bio, 0);
661 else
662 ret = 0;
663
664 page->mapping = NULL;
665 if (ret || bio_add_page(comp_bio, page, PAGE_CACHE_SIZE, 0) <
666 PAGE_CACHE_SIZE) {
667 bio_get(comp_bio);
668
669 ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0);
670 BUG_ON(ret); /* -ENOMEM */
671
672 /*
673 * inc the count before we submit the bio so
674 * we know the end IO handler won't happen before
675 * we inc the count. Otherwise, the cb might get
676 * freed before we're done setting it up
677 */
678 atomic_inc(&cb->pending_bios);
679
680 if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
681 ret = btrfs_lookup_bio_sums(root, inode,
682 comp_bio, sums);
683 BUG_ON(ret); /* -ENOMEM */
684 }
685 sums += (comp_bio->bi_size + root->sectorsize - 1) /
686 root->sectorsize;
687
688 ret = btrfs_map_bio(root, READ, comp_bio,
689 mirror_num, 0);
690 if (ret)
691 bio_endio(comp_bio, ret);
692
693 bio_put(comp_bio);
694
695 comp_bio = compressed_bio_alloc(bdev, cur_disk_byte,
696 GFP_NOFS);
697 BUG_ON(!comp_bio);
698 comp_bio->bi_private = cb;
699 comp_bio->bi_end_io = end_compressed_bio_read;
700
701 bio_add_page(comp_bio, page, PAGE_CACHE_SIZE, 0);
702 }
703 cur_disk_byte += PAGE_CACHE_SIZE;
704 }
705 bio_get(comp_bio);
706
707 ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0);
708 BUG_ON(ret); /* -ENOMEM */
709
710 if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
711 ret = btrfs_lookup_bio_sums(root, inode, comp_bio, sums);
712 BUG_ON(ret); /* -ENOMEM */
713 }
714
715 ret = btrfs_map_bio(root, READ, comp_bio, mirror_num, 0);
716 if (ret)
717 bio_endio(comp_bio, ret);
718
719 bio_put(comp_bio);
720 return 0;
721
722 fail2:
723 while (faili >= 0) {
724 __free_page(cb->compressed_pages[faili]);
725 faili--;
726 }
727
728 kfree(cb->compressed_pages);
729 fail1:
730 kfree(cb);
731 out:
732 free_extent_map(em);
733 return ret;
734 }
735
736 static struct list_head comp_idle_workspace[BTRFS_COMPRESS_TYPES];
737 static spinlock_t comp_workspace_lock[BTRFS_COMPRESS_TYPES];
738 static int comp_num_workspace[BTRFS_COMPRESS_TYPES];
739 static atomic_t comp_alloc_workspace[BTRFS_COMPRESS_TYPES];
740 static wait_queue_head_t comp_workspace_wait[BTRFS_COMPRESS_TYPES];
741
742 struct btrfs_compress_op *btrfs_compress_op[] = {
743 &btrfs_zlib_compress,
744 &btrfs_lzo_compress,
745 };
746
747 void __init btrfs_init_compress(void)
748 {
749 int i;
750
751 for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
752 INIT_LIST_HEAD(&comp_idle_workspace[i]);
753 spin_lock_init(&comp_workspace_lock[i]);
754 atomic_set(&comp_alloc_workspace[i], 0);
755 init_waitqueue_head(&comp_workspace_wait[i]);
756 }
757 }
758
759 /*
760 * this finds an available workspace or allocates a new one
761 * ERR_PTR is returned if things go bad.
762 */
763 static struct list_head *find_workspace(int type)
764 {
765 struct list_head *workspace;
766 int cpus = num_online_cpus();
767 int idx = type - 1;
768
769 struct list_head *idle_workspace = &comp_idle_workspace[idx];
770 spinlock_t *workspace_lock = &comp_workspace_lock[idx];
771 atomic_t *alloc_workspace = &comp_alloc_workspace[idx];
772 wait_queue_head_t *workspace_wait = &comp_workspace_wait[idx];
773 int *num_workspace = &comp_num_workspace[idx];
774 again:
775 spin_lock(workspace_lock);
776 if (!list_empty(idle_workspace)) {
777 workspace = idle_workspace->next;
778 list_del(workspace);
779 (*num_workspace)--;
780 spin_unlock(workspace_lock);
781 return workspace;
782
783 }
784 if (atomic_read(alloc_workspace) > cpus) {
785 DEFINE_WAIT(wait);
786
787 spin_unlock(workspace_lock);
788 prepare_to_wait(workspace_wait, &wait, TASK_UNINTERRUPTIBLE);
789 if (atomic_read(alloc_workspace) > cpus && !*num_workspace)
790 schedule();
791 finish_wait(workspace_wait, &wait);
792 goto again;
793 }
794 atomic_inc(alloc_workspace);
795 spin_unlock(workspace_lock);
796
797 workspace = btrfs_compress_op[idx]->alloc_workspace();
798 if (IS_ERR(workspace)) {
799 atomic_dec(alloc_workspace);
800 wake_up(workspace_wait);
801 }
802 return workspace;
803 }
804
805 /*
806 * put a workspace struct back on the list or free it if we have enough
807 * idle ones sitting around
808 */
809 static void free_workspace(int type, struct list_head *workspace)
810 {
811 int idx = type - 1;
812 struct list_head *idle_workspace = &comp_idle_workspace[idx];
813 spinlock_t *workspace_lock = &comp_workspace_lock[idx];
814 atomic_t *alloc_workspace = &comp_alloc_workspace[idx];
815 wait_queue_head_t *workspace_wait = &comp_workspace_wait[idx];
816 int *num_workspace = &comp_num_workspace[idx];
817
818 spin_lock(workspace_lock);
819 if (*num_workspace < num_online_cpus()) {
820 list_add_tail(workspace, idle_workspace);
821 (*num_workspace)++;
822 spin_unlock(workspace_lock);
823 goto wake;
824 }
825 spin_unlock(workspace_lock);
826
827 btrfs_compress_op[idx]->free_workspace(workspace);
828 atomic_dec(alloc_workspace);
829 wake:
830 smp_mb();
831 if (waitqueue_active(workspace_wait))
832 wake_up(workspace_wait);
833 }
834
835 /*
836 * cleanup function for module exit
837 */
838 static void free_workspaces(void)
839 {
840 struct list_head *workspace;
841 int i;
842
843 for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
844 while (!list_empty(&comp_idle_workspace[i])) {
845 workspace = comp_idle_workspace[i].next;
846 list_del(workspace);
847 btrfs_compress_op[i]->free_workspace(workspace);
848 atomic_dec(&comp_alloc_workspace[i]);
849 }
850 }
851 }
852
853 /*
854 * given an address space and start/len, compress the bytes.
855 *
856 * pages are allocated to hold the compressed result and stored
857 * in 'pages'
858 *
859 * out_pages is used to return the number of pages allocated. There
860 * may be pages allocated even if we return an error
861 *
862 * total_in is used to return the number of bytes actually read. It
863 * may be smaller then len if we had to exit early because we
864 * ran out of room in the pages array or because we cross the
865 * max_out threshold.
866 *
867 * total_out is used to return the total number of compressed bytes
868 *
869 * max_out tells us the max number of bytes that we're allowed to
870 * stuff into pages
871 */
872 int btrfs_compress_pages(int type, struct address_space *mapping,
873 u64 start, unsigned long len,
874 struct page **pages,
875 unsigned long nr_dest_pages,
876 unsigned long *out_pages,
877 unsigned long *total_in,
878 unsigned long *total_out,
879 unsigned long max_out)
880 {
881 struct list_head *workspace;
882 int ret;
883
884 workspace = find_workspace(type);
885 if (IS_ERR(workspace))
886 return -1;
887
888 ret = btrfs_compress_op[type-1]->compress_pages(workspace, mapping,
889 start, len, pages,
890 nr_dest_pages, out_pages,
891 total_in, total_out,
892 max_out);
893 free_workspace(type, workspace);
894 return ret;
895 }
896
897 /*
898 * pages_in is an array of pages with compressed data.
899 *
900 * disk_start is the starting logical offset of this array in the file
901 *
902 * bvec is a bio_vec of pages from the file that we want to decompress into
903 *
904 * vcnt is the count of pages in the biovec
905 *
906 * srclen is the number of bytes in pages_in
907 *
908 * The basic idea is that we have a bio that was created by readpages.
909 * The pages in the bio are for the uncompressed data, and they may not
910 * be contiguous. They all correspond to the range of bytes covered by
911 * the compressed extent.
912 */
913 int btrfs_decompress_biovec(int type, struct page **pages_in, u64 disk_start,
914 struct bio_vec *bvec, int vcnt, size_t srclen)
915 {
916 struct list_head *workspace;
917 int ret;
918
919 workspace = find_workspace(type);
920 if (IS_ERR(workspace))
921 return -ENOMEM;
922
923 ret = btrfs_compress_op[type-1]->decompress_biovec(workspace, pages_in,
924 disk_start,
925 bvec, vcnt, srclen);
926 free_workspace(type, workspace);
927 return ret;
928 }
929
930 /*
931 * a less complex decompression routine. Our compressed data fits in a
932 * single page, and we want to read a single page out of it.
933 * start_byte tells us the offset into the compressed data we're interested in
934 */
935 int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
936 unsigned long start_byte, size_t srclen, size_t destlen)
937 {
938 struct list_head *workspace;
939 int ret;
940
941 workspace = find_workspace(type);
942 if (IS_ERR(workspace))
943 return -ENOMEM;
944
945 ret = btrfs_compress_op[type-1]->decompress(workspace, data_in,
946 dest_page, start_byte,
947 srclen, destlen);
948
949 free_workspace(type, workspace);
950 return ret;
951 }
952
953 void btrfs_exit_compress(void)
954 {
955 free_workspaces();
956 }
957
958 /*
959 * Copy uncompressed data from working buffer to pages.
960 *
961 * buf_start is the byte offset we're of the start of our workspace buffer.
962 *
963 * total_out is the last byte of the buffer
964 */
965 int btrfs_decompress_buf2page(char *buf, unsigned long buf_start,
966 unsigned long total_out, u64 disk_start,
967 struct bio_vec *bvec, int vcnt,
968 unsigned long *pg_index,
969 unsigned long *pg_offset)
970 {
971 unsigned long buf_offset;
972 unsigned long current_buf_start;
973 unsigned long start_byte;
974 unsigned long working_bytes = total_out - buf_start;
975 unsigned long bytes;
976 char *kaddr;
977 struct page *page_out = bvec[*pg_index].bv_page;
978
979 /*
980 * start byte is the first byte of the page we're currently
981 * copying into relative to the start of the compressed data.
982 */
983 start_byte = page_offset(page_out) - disk_start;
984
985 /* we haven't yet hit data corresponding to this page */
986 if (total_out <= start_byte)
987 return 1;
988
989 /*
990 * the start of the data we care about is offset into
991 * the middle of our working buffer
992 */
993 if (total_out > start_byte && buf_start < start_byte) {
994 buf_offset = start_byte - buf_start;
995 working_bytes -= buf_offset;
996 } else {
997 buf_offset = 0;
998 }
999 current_buf_start = buf_start;
1000
1001 /* copy bytes from the working buffer into the pages */
1002 while (working_bytes > 0) {
1003 bytes = min(PAGE_CACHE_SIZE - *pg_offset,
1004 PAGE_CACHE_SIZE - buf_offset);
1005 bytes = min(bytes, working_bytes);
1006 kaddr = kmap_atomic(page_out);
1007 memcpy(kaddr + *pg_offset, buf + buf_offset, bytes);
1008 kunmap_atomic(kaddr);
1009 flush_dcache_page(page_out);
1010
1011 *pg_offset += bytes;
1012 buf_offset += bytes;
1013 working_bytes -= bytes;
1014 current_buf_start += bytes;
1015
1016 /* check if we need to pick another page */
1017 if (*pg_offset == PAGE_CACHE_SIZE) {
1018 (*pg_index)++;
1019 if (*pg_index >= vcnt)
1020 return 0;
1021
1022 page_out = bvec[*pg_index].bv_page;
1023 *pg_offset = 0;
1024 start_byte = page_offset(page_out) - disk_start;
1025
1026 /*
1027 * make sure our new page is covered by this
1028 * working buffer
1029 */
1030 if (total_out <= start_byte)
1031 return 1;
1032
1033 /*
1034 * the next page in the biovec might not be adjacent
1035 * to the last page, but it might still be found
1036 * inside this working buffer. bump our offset pointer
1037 */
1038 if (total_out > start_byte &&
1039 current_buf_start < start_byte) {
1040 buf_offset = start_byte - buf_start;
1041 working_bytes = total_out - start_byte;
1042 current_buf_start = buf_start + buf_offset;
1043 }
1044 }
1045 }
1046
1047 return 1;
1048 }