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