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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
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 return sizeof(struct compressed_bio) +
90 ((disk_size + root->sectorsize - 1) / root->sectorsize) *
91 csum_size;
92}
93
94static struct bio *compressed_bio_alloc(struct block_device *bdev,
95 u64 first_byte, gfp_t gfp_flags)
96{
97 int nr_vecs;
98
99 nr_vecs = bio_get_nr_vecs(bdev);
100 return btrfs_bio_alloc(bdev, first_byte >> 9, nr_vecs, 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 btrfs_root *root = BTRFS_I(inode)->root;
109 struct page *page;
110 unsigned long i;
111 char *kaddr;
112 u32 csum;
113 u32 *cb_sum = &cb->sums;
114
115 if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)
116 return 0;
117
118 for (i = 0; i < cb->nr_pages; i++) {
119 page = cb->compressed_pages[i];
120 csum = ~(u32)0;
121
122 kaddr = kmap_atomic(page, KM_USER0);
123 csum = btrfs_csum_data(root, kaddr, csum, PAGE_CACHE_SIZE);
124 btrfs_csum_final(csum, (char *)&csum);
125 kunmap_atomic(kaddr, KM_USER0);
126
127 if (csum != *cb_sum) {
128 printk(KERN_INFO "btrfs csum failed ino %llu "
129 "extent %llu csum %u "
130 "wanted %u mirror %d\n",
131 (unsigned long long)btrfs_ino(inode),
132 (unsigned long long)disk_start,
133 csum, *cb_sum, cb->mirror_num);
134 ret = -EIO;
135 goto fail;
136 }
137 cb_sum++;
138
139 }
140 ret = 0;
141fail:
142 return ret;
143}
144
145/* when we finish reading compressed pages from the disk, we
146 * decompress them and then run the bio end_io routines on the
147 * decompressed pages (in the inode address space).
148 *
149 * This allows the checksumming and other IO error handling routines
150 * to work normally
151 *
152 * The compressed pages are freed here, and it must be run
153 * in process context
154 */
155static void end_compressed_bio_read(struct bio *bio, int err)
156{
157 struct compressed_bio *cb = bio->bi_private;
158 struct inode *inode;
159 struct page *page;
160 unsigned long index;
161 int ret;
162
163 if (err)
164 cb->errors = 1;
165
166 /* if there are more bios still pending for this compressed
167 * extent, just exit
168 */
169 if (!atomic_dec_and_test(&cb->pending_bios))
170 goto out;
171
172 inode = cb->inode;
173 ret = check_compressed_csum(inode, cb, (u64)bio->bi_sector << 9);
174 if (ret)
175 goto csum_failed;
176
177 /* ok, we're the last bio for this extent, lets start
178 * the decompression.
179 */
180 ret = btrfs_decompress_biovec(cb->compress_type,
181 cb->compressed_pages,
182 cb->start,
183 cb->orig_bio->bi_io_vec,
184 cb->orig_bio->bi_vcnt,
185 cb->compressed_len);
186csum_failed:
187 if (ret)
188 cb->errors = 1;
189
190 /* release the compressed pages */
191 index = 0;
192 for (index = 0; index < cb->nr_pages; index++) {
193 page = cb->compressed_pages[index];
194 page->mapping = NULL;
195 page_cache_release(page);
196 }
197
198 /* do io completion on the original bio */
199 if (cb->errors) {
200 bio_io_error(cb->orig_bio);
201 } else {
202 int bio_index = 0;
203 struct bio_vec *bvec = cb->orig_bio->bi_io_vec;
204
205 /*
206 * we have verified the checksum already, set page
207 * checked so the end_io handlers know about it
208 */
209 while (bio_index < cb->orig_bio->bi_vcnt) {
210 SetPageChecked(bvec->bv_page);
211 bvec++;
212 bio_index++;
213 }
214 bio_endio(cb->orig_bio, 0);
215 }
216
217 /* finally free the cb struct */
218 kfree(cb->compressed_pages);
219 kfree(cb);
220out:
221 bio_put(bio);
222}
223
224/*
225 * Clear the writeback bits on all of the file
226 * pages for a compressed write
227 */
228static noinline int end_compressed_writeback(struct inode *inode, u64 start,
229 unsigned long ram_size)
230{
231 unsigned long index = start >> PAGE_CACHE_SHIFT;
232 unsigned long end_index = (start + ram_size - 1) >> PAGE_CACHE_SHIFT;
233 struct page *pages[16];
234 unsigned long nr_pages = end_index - index + 1;
235 int i;
236 int ret;
237
238 while (nr_pages > 0) {
239 ret = find_get_pages_contig(inode->i_mapping, index,
240 min_t(unsigned long,
241 nr_pages, ARRAY_SIZE(pages)), pages);
242 if (ret == 0) {
243 nr_pages -= 1;
244 index += 1;
245 continue;
246 }
247 for (i = 0; i < ret; i++) {
248 end_page_writeback(pages[i]);
249 page_cache_release(pages[i]);
250 }
251 nr_pages -= ret;
252 index += ret;
253 }
254 /* the inode may be gone now */
255 return 0;
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);
395
396 if (!skip_sum) {
397 ret = btrfs_csum_one_bio(root, inode, bio,
398 start, 1);
399 BUG_ON(ret);
400 }
401
402 ret = btrfs_map_bio(root, WRITE, bio, 0, 1);
403 BUG_ON(ret);
404
405 bio_put(bio);
406
407 bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
408 bio->bi_private = cb;
409 bio->bi_end_io = end_compressed_bio_write;
410 bio_add_page(bio, page, PAGE_CACHE_SIZE, 0);
411 }
412 if (bytes_left < PAGE_CACHE_SIZE) {
413 printk("bytes left %lu compress len %lu nr %lu\n",
414 bytes_left, cb->compressed_len, cb->nr_pages);
415 }
416 bytes_left -= PAGE_CACHE_SIZE;
417 first_byte += PAGE_CACHE_SIZE;
418 cond_resched();
419 }
420 bio_get(bio);
421
422 ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0);
423 BUG_ON(ret);
424
425 if (!skip_sum) {
426 ret = btrfs_csum_one_bio(root, inode, bio, start, 1);
427 BUG_ON(ret);
428 }
429
430 ret = btrfs_map_bio(root, WRITE, bio, 0, 1);
431 BUG_ON(ret);
432
433 bio_put(bio);
434 return 0;
435}
436
437static noinline int add_ra_bio_pages(struct inode *inode,
438 u64 compressed_end,
439 struct compressed_bio *cb)
440{
441 unsigned long end_index;
442 unsigned long pg_index;
443 u64 last_offset;
444 u64 isize = i_size_read(inode);
445 int ret;
446 struct page *page;
447 unsigned long nr_pages = 0;
448 struct extent_map *em;
449 struct address_space *mapping = inode->i_mapping;
450 struct extent_map_tree *em_tree;
451 struct extent_io_tree *tree;
452 u64 end;
453 int misses = 0;
454
455 page = cb->orig_bio->bi_io_vec[cb->orig_bio->bi_vcnt - 1].bv_page;
456 last_offset = (page_offset(page) + PAGE_CACHE_SIZE);
457 em_tree = &BTRFS_I(inode)->extent_tree;
458 tree = &BTRFS_I(inode)->io_tree;
459
460 if (isize == 0)
461 return 0;
462
463 end_index = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;
464
465 while (last_offset < compressed_end) {
466 pg_index = last_offset >> PAGE_CACHE_SHIFT;
467
468 if (pg_index > end_index)
469 break;
470
471 rcu_read_lock();
472 page = radix_tree_lookup(&mapping->page_tree, pg_index);
473 rcu_read_unlock();
474 if (page) {
475 misses++;
476 if (misses > 4)
477 break;
478 goto next;
479 }
480
481 page = __page_cache_alloc(mapping_gfp_mask(mapping) &
482 ~__GFP_FS);
483 if (!page)
484 break;
485
486 if (add_to_page_cache_lru(page, mapping, pg_index,
487 GFP_NOFS)) {
488 page_cache_release(page);
489 goto next;
490 }
491
492 end = last_offset + PAGE_CACHE_SIZE - 1;
493 /*
494 * at this point, we have a locked page in the page cache
495 * for these bytes in the file. But, we have to make
496 * sure they map to this compressed extent on disk.
497 */
498 set_page_extent_mapped(page);
499 lock_extent(tree, last_offset, end, GFP_NOFS);
500 read_lock(&em_tree->lock);
501 em = lookup_extent_mapping(em_tree, last_offset,
502 PAGE_CACHE_SIZE);
503 read_unlock(&em_tree->lock);
504
505 if (!em || last_offset < em->start ||
506 (last_offset + PAGE_CACHE_SIZE > extent_map_end(em)) ||
507 (em->block_start >> 9) != cb->orig_bio->bi_sector) {
508 free_extent_map(em);
509 unlock_extent(tree, last_offset, end, GFP_NOFS);
510 unlock_page(page);
511 page_cache_release(page);
512 break;
513 }
514 free_extent_map(em);
515
516 if (page->index == end_index) {
517 char *userpage;
518 size_t zero_offset = isize & (PAGE_CACHE_SIZE - 1);
519
520 if (zero_offset) {
521 int zeros;
522 zeros = PAGE_CACHE_SIZE - zero_offset;
523 userpage = kmap_atomic(page, KM_USER0);
524 memset(userpage + zero_offset, 0, zeros);
525 flush_dcache_page(page);
526 kunmap_atomic(userpage, KM_USER0);
527 }
528 }
529
530 ret = bio_add_page(cb->orig_bio, page,
531 PAGE_CACHE_SIZE, 0);
532
533 if (ret == PAGE_CACHE_SIZE) {
534 nr_pages++;
535 page_cache_release(page);
536 } else {
537 unlock_extent(tree, last_offset, end, GFP_NOFS);
538 unlock_page(page);
539 page_cache_release(page);
540 break;
541 }
542next:
543 last_offset += PAGE_CACHE_SIZE;
544 }
545 return 0;
546}
547
548/*
549 * for a compressed read, the bio we get passed has all the inode pages
550 * in it. We don't actually do IO on those pages but allocate new ones
551 * to hold the compressed pages on disk.
552 *
553 * bio->bi_sector points to the compressed extent on disk
554 * bio->bi_io_vec points to all of the inode pages
555 * bio->bi_vcnt is a count of pages
556 *
557 * After the compressed pages are read, we copy the bytes into the
558 * bio we were passed and then call the bio end_io calls
559 */
560int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
561 int mirror_num, unsigned long bio_flags)
562{
563 struct extent_io_tree *tree;
564 struct extent_map_tree *em_tree;
565 struct compressed_bio *cb;
566 struct btrfs_root *root = BTRFS_I(inode)->root;
567 unsigned long uncompressed_len = bio->bi_vcnt * PAGE_CACHE_SIZE;
568 unsigned long compressed_len;
569 unsigned long nr_pages;
570 unsigned long pg_index;
571 struct page *page;
572 struct block_device *bdev;
573 struct bio *comp_bio;
574 u64 cur_disk_byte = (u64)bio->bi_sector << 9;
575 u64 em_len;
576 u64 em_start;
577 struct extent_map *em;
578 int ret = -ENOMEM;
579 u32 *sums;
580
581 tree = &BTRFS_I(inode)->io_tree;
582 em_tree = &BTRFS_I(inode)->extent_tree;
583
584 /* we need the actual starting offset of this extent in the file */
585 read_lock(&em_tree->lock);
586 em = lookup_extent_mapping(em_tree,
587 page_offset(bio->bi_io_vec->bv_page),
588 PAGE_CACHE_SIZE);
589 read_unlock(&em_tree->lock);
590
591 compressed_len = em->block_len;
592 cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS);
593 if (!cb)
594 goto out;
595
596 atomic_set(&cb->pending_bios, 0);
597 cb->errors = 0;
598 cb->inode = inode;
599 cb->mirror_num = mirror_num;
600 sums = &cb->sums;
601
602 cb->start = em->orig_start;
603 em_len = em->len;
604 em_start = em->start;
605
606 free_extent_map(em);
607 em = NULL;
608
609 cb->len = uncompressed_len;
610 cb->compressed_len = compressed_len;
611 cb->compress_type = extent_compress_type(bio_flags);
612 cb->orig_bio = bio;
613
614 nr_pages = (compressed_len + PAGE_CACHE_SIZE - 1) /
615 PAGE_CACHE_SIZE;
616 cb->compressed_pages = kzalloc(sizeof(struct page *) * nr_pages,
617 GFP_NOFS);
618 if (!cb->compressed_pages)
619 goto fail1;
620
621 bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
622
623 for (pg_index = 0; pg_index < nr_pages; pg_index++) {
624 cb->compressed_pages[pg_index] = alloc_page(GFP_NOFS |
625 __GFP_HIGHMEM);
626 if (!cb->compressed_pages[pg_index])
627 goto fail2;
628 }
629 cb->nr_pages = nr_pages;
630
631 add_ra_bio_pages(inode, em_start + em_len, cb);
632
633 /* include any pages we added in add_ra-bio_pages */
634 uncompressed_len = bio->bi_vcnt * PAGE_CACHE_SIZE;
635 cb->len = uncompressed_len;
636
637 comp_bio = compressed_bio_alloc(bdev, cur_disk_byte, GFP_NOFS);
638 if (!comp_bio)
639 goto fail2;
640 comp_bio->bi_private = cb;
641 comp_bio->bi_end_io = end_compressed_bio_read;
642 atomic_inc(&cb->pending_bios);
643
644 for (pg_index = 0; pg_index < nr_pages; pg_index++) {
645 page = cb->compressed_pages[pg_index];
646 page->mapping = inode->i_mapping;
647 page->index = em_start >> PAGE_CACHE_SHIFT;
648
649 if (comp_bio->bi_size)
650 ret = tree->ops->merge_bio_hook(page, 0,
651 PAGE_CACHE_SIZE,
652 comp_bio, 0);
653 else
654 ret = 0;
655
656 page->mapping = NULL;
657 if (ret || bio_add_page(comp_bio, page, PAGE_CACHE_SIZE, 0) <
658 PAGE_CACHE_SIZE) {
659 bio_get(comp_bio);
660
661 ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0);
662 BUG_ON(ret);
663
664 /*
665 * inc the count before we submit the bio so
666 * we know the end IO handler won't happen before
667 * we inc the count. Otherwise, the cb might get
668 * freed before we're done setting it up
669 */
670 atomic_inc(&cb->pending_bios);
671
672 if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
673 ret = btrfs_lookup_bio_sums(root, inode,
674 comp_bio, sums);
675 BUG_ON(ret);
676 }
677 sums += (comp_bio->bi_size + root->sectorsize - 1) /
678 root->sectorsize;
679
680 ret = btrfs_map_bio(root, READ, comp_bio,
681 mirror_num, 0);
682 BUG_ON(ret);
683
684 bio_put(comp_bio);
685
686 comp_bio = compressed_bio_alloc(bdev, cur_disk_byte,
687 GFP_NOFS);
688 comp_bio->bi_private = cb;
689 comp_bio->bi_end_io = end_compressed_bio_read;
690
691 bio_add_page(comp_bio, page, PAGE_CACHE_SIZE, 0);
692 }
693 cur_disk_byte += PAGE_CACHE_SIZE;
694 }
695 bio_get(comp_bio);
696
697 ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0);
698 BUG_ON(ret);
699
700 if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
701 ret = btrfs_lookup_bio_sums(root, inode, comp_bio, sums);
702 BUG_ON(ret);
703 }
704
705 ret = btrfs_map_bio(root, READ, comp_bio, mirror_num, 0);
706 BUG_ON(ret);
707
708 bio_put(comp_bio);
709 return 0;
710
711fail2:
712 for (pg_index = 0; pg_index < nr_pages; pg_index++)
713 free_page((unsigned long)cb->compressed_pages[pg_index]);
714
715 kfree(cb->compressed_pages);
716fail1:
717 kfree(cb);
718out:
719 free_extent_map(em);
720 return ret;
721}
722
723static struct list_head comp_idle_workspace[BTRFS_COMPRESS_TYPES];
724static spinlock_t comp_workspace_lock[BTRFS_COMPRESS_TYPES];
725static int comp_num_workspace[BTRFS_COMPRESS_TYPES];
726static atomic_t comp_alloc_workspace[BTRFS_COMPRESS_TYPES];
727static wait_queue_head_t comp_workspace_wait[BTRFS_COMPRESS_TYPES];
728
729struct btrfs_compress_op *btrfs_compress_op[] = {
730 &btrfs_zlib_compress,
731 &btrfs_lzo_compress,
732};
733
734int __init btrfs_init_compress(void)
735{
736 int i;
737
738 for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
739 INIT_LIST_HEAD(&comp_idle_workspace[i]);
740 spin_lock_init(&comp_workspace_lock[i]);
741 atomic_set(&comp_alloc_workspace[i], 0);
742 init_waitqueue_head(&comp_workspace_wait[i]);
743 }
744 return 0;
745}
746
747/*
748 * this finds an available workspace or allocates a new one
749 * ERR_PTR is returned if things go bad.
750 */
751static struct list_head *find_workspace(int type)
752{
753 struct list_head *workspace;
754 int cpus = num_online_cpus();
755 int idx = type - 1;
756
757 struct list_head *idle_workspace = &comp_idle_workspace[idx];
758 spinlock_t *workspace_lock = &comp_workspace_lock[idx];
759 atomic_t *alloc_workspace = &comp_alloc_workspace[idx];
760 wait_queue_head_t *workspace_wait = &comp_workspace_wait[idx];
761 int *num_workspace = &comp_num_workspace[idx];
762again:
763 spin_lock(workspace_lock);
764 if (!list_empty(idle_workspace)) {
765 workspace = idle_workspace->next;
766 list_del(workspace);
767 (*num_workspace)--;
768 spin_unlock(workspace_lock);
769 return workspace;
770
771 }
772 if (atomic_read(alloc_workspace) > cpus) {
773 DEFINE_WAIT(wait);
774
775 spin_unlock(workspace_lock);
776 prepare_to_wait(workspace_wait, &wait, TASK_UNINTERRUPTIBLE);
777 if (atomic_read(alloc_workspace) > cpus && !*num_workspace)
778 schedule();
779 finish_wait(workspace_wait, &wait);
780 goto again;
781 }
782 atomic_inc(alloc_workspace);
783 spin_unlock(workspace_lock);
784
785 workspace = btrfs_compress_op[idx]->alloc_workspace();
786 if (IS_ERR(workspace)) {
787 atomic_dec(alloc_workspace);
788 wake_up(workspace_wait);
789 }
790 return workspace;
791}
792
793/*
794 * put a workspace struct back on the list or free it if we have enough
795 * idle ones sitting around
796 */
797static void free_workspace(int type, struct list_head *workspace)
798{
799 int idx = type - 1;
800 struct list_head *idle_workspace = &comp_idle_workspace[idx];
801 spinlock_t *workspace_lock = &comp_workspace_lock[idx];
802 atomic_t *alloc_workspace = &comp_alloc_workspace[idx];
803 wait_queue_head_t *workspace_wait = &comp_workspace_wait[idx];
804 int *num_workspace = &comp_num_workspace[idx];
805
806 spin_lock(workspace_lock);
807 if (*num_workspace < num_online_cpus()) {
808 list_add_tail(workspace, idle_workspace);
809 (*num_workspace)++;
810 spin_unlock(workspace_lock);
811 goto wake;
812 }
813 spin_unlock(workspace_lock);
814
815 btrfs_compress_op[idx]->free_workspace(workspace);
816 atomic_dec(alloc_workspace);
817wake:
818 if (waitqueue_active(workspace_wait))
819 wake_up(workspace_wait);
820}
821
822/*
823 * cleanup function for module exit
824 */
825static void free_workspaces(void)
826{
827 struct list_head *workspace;
828 int i;
829
830 for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
831 while (!list_empty(&comp_idle_workspace[i])) {
832 workspace = comp_idle_workspace[i].next;
833 list_del(workspace);
834 btrfs_compress_op[i]->free_workspace(workspace);
835 atomic_dec(&comp_alloc_workspace[i]);
836 }
837 }
838}
839
840/*
841 * given an address space and start/len, compress the bytes.
842 *
843 * pages are allocated to hold the compressed result and stored
844 * in 'pages'
845 *
846 * out_pages is used to return the number of pages allocated. There
847 * may be pages allocated even if we return an error
848 *
849 * total_in is used to return the number of bytes actually read. It
850 * may be smaller then len if we had to exit early because we
851 * ran out of room in the pages array or because we cross the
852 * max_out threshold.
853 *
854 * total_out is used to return the total number of compressed bytes
855 *
856 * max_out tells us the max number of bytes that we're allowed to
857 * stuff into pages
858 */
859int btrfs_compress_pages(int type, struct address_space *mapping,
860 u64 start, unsigned long len,
861 struct page **pages,
862 unsigned long nr_dest_pages,
863 unsigned long *out_pages,
864 unsigned long *total_in,
865 unsigned long *total_out,
866 unsigned long max_out)
867{
868 struct list_head *workspace;
869 int ret;
870
871 workspace = find_workspace(type);
872 if (IS_ERR(workspace))
873 return -1;
874
875 ret = btrfs_compress_op[type-1]->compress_pages(workspace, mapping,
876 start, len, pages,
877 nr_dest_pages, out_pages,
878 total_in, total_out,
879 max_out);
880 free_workspace(type, workspace);
881 return ret;
882}
883
884/*
885 * pages_in is an array of pages with compressed data.
886 *
887 * disk_start is the starting logical offset of this array in the file
888 *
889 * bvec is a bio_vec of pages from the file that we want to decompress into
890 *
891 * vcnt is the count of pages in the biovec
892 *
893 * srclen is the number of bytes in pages_in
894 *
895 * The basic idea is that we have a bio that was created by readpages.
896 * The pages in the bio are for the uncompressed data, and they may not
897 * be contiguous. They all correspond to the range of bytes covered by
898 * the compressed extent.
899 */
900int btrfs_decompress_biovec(int type, struct page **pages_in, u64 disk_start,
901 struct bio_vec *bvec, int vcnt, size_t srclen)
902{
903 struct list_head *workspace;
904 int ret;
905
906 workspace = find_workspace(type);
907 if (IS_ERR(workspace))
908 return -ENOMEM;
909
910 ret = btrfs_compress_op[type-1]->decompress_biovec(workspace, pages_in,
911 disk_start,
912 bvec, vcnt, srclen);
913 free_workspace(type, workspace);
914 return ret;
915}
916
917/*
918 * a less complex decompression routine. Our compressed data fits in a
919 * single page, and we want to read a single page out of it.
920 * start_byte tells us the offset into the compressed data we're interested in
921 */
922int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
923 unsigned long start_byte, size_t srclen, size_t destlen)
924{
925 struct list_head *workspace;
926 int ret;
927
928 workspace = find_workspace(type);
929 if (IS_ERR(workspace))
930 return -ENOMEM;
931
932 ret = btrfs_compress_op[type-1]->decompress(workspace, data_in,
933 dest_page, start_byte,
934 srclen, destlen);
935
936 free_workspace(type, workspace);
937 return ret;
938}
939
940void btrfs_exit_compress(void)
941{
942 free_workspaces();
943}
944
945/*
946 * Copy uncompressed data from working buffer to pages.
947 *
948 * buf_start is the byte offset we're of the start of our workspace buffer.
949 *
950 * total_out is the last byte of the buffer
951 */
952int btrfs_decompress_buf2page(char *buf, unsigned long buf_start,
953 unsigned long total_out, u64 disk_start,
954 struct bio_vec *bvec, int vcnt,
955 unsigned long *pg_index,
956 unsigned long *pg_offset)
957{
958 unsigned long buf_offset;
959 unsigned long current_buf_start;
960 unsigned long start_byte;
961 unsigned long working_bytes = total_out - buf_start;
962 unsigned long bytes;
963 char *kaddr;
964 struct page *page_out = bvec[*pg_index].bv_page;
965
966 /*
967 * start byte is the first byte of the page we're currently
968 * copying into relative to the start of the compressed data.
969 */
970 start_byte = page_offset(page_out) - disk_start;
971
972 /* we haven't yet hit data corresponding to this page */
973 if (total_out <= start_byte)
974 return 1;
975
976 /*
977 * the start of the data we care about is offset into
978 * the middle of our working buffer
979 */
980 if (total_out > start_byte && buf_start < start_byte) {
981 buf_offset = start_byte - buf_start;
982 working_bytes -= buf_offset;
983 } else {
984 buf_offset = 0;
985 }
986 current_buf_start = buf_start;
987
988 /* copy bytes from the working buffer into the pages */
989 while (working_bytes > 0) {
990 bytes = min(PAGE_CACHE_SIZE - *pg_offset,
991 PAGE_CACHE_SIZE - buf_offset);
992 bytes = min(bytes, working_bytes);
993 kaddr = kmap_atomic(page_out, KM_USER0);
994 memcpy(kaddr + *pg_offset, buf + buf_offset, bytes);
995 kunmap_atomic(kaddr, KM_USER0);
996 flush_dcache_page(page_out);
997
998 *pg_offset += bytes;
999 buf_offset += bytes;
1000 working_bytes -= bytes;
1001 current_buf_start += bytes;
1002
1003 /* check if we need to pick another page */
1004 if (*pg_offset == PAGE_CACHE_SIZE) {
1005 (*pg_index)++;
1006 if (*pg_index >= vcnt)
1007 return 0;
1008
1009 page_out = bvec[*pg_index].bv_page;
1010 *pg_offset = 0;
1011 start_byte = page_offset(page_out) - disk_start;
1012
1013 /*
1014 * make sure our new page is covered by this
1015 * working buffer
1016 */
1017 if (total_out <= start_byte)
1018 return 1;
1019
1020 /*
1021 * the next page in the biovec might not be adjacent
1022 * to the last page, but it might still be found
1023 * inside this working buffer. bump our offset pointer
1024 */
1025 if (total_out > start_byte &&
1026 current_buf_start < start_byte) {
1027 buf_offset = start_byte - buf_start;
1028 working_bytes = total_out - start_byte;
1029 current_buf_start = buf_start + buf_offset;
1030 }
1031 }
1032 }
1033
1034 return 1;
1035}
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_biovec(int type, struct page **pages_in,
85 u64 disk_start, struct bio_vec *bvec,
86 int vcnt, size_t srclen);
87
88static inline int compressed_bio_size(struct btrfs_root *root,
89 unsigned long disk_size)
90{
91 u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
92
93 return sizeof(struct compressed_bio) +
94 (DIV_ROUND_UP(disk_size, root->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, (char *)&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_biovec(cb->compress_type,
179 cb->compressed_pages,
180 cb->start,
181 cb->orig_bio->bi_io_vec,
182 cb->orig_bio->bi_vcnt,
183 cb->compressed_len);
184csum_failed:
185 if (ret)
186 cb->errors = 1;
187
188 /* release the compressed pages */
189 index = 0;
190 for (index = 0; index < cb->nr_pages; index++) {
191 page = cb->compressed_pages[index];
192 page->mapping = NULL;
193 put_page(page);
194 }
195
196 /* do io completion on the original bio */
197 if (cb->errors) {
198 bio_io_error(cb->orig_bio);
199 } else {
200 int i;
201 struct bio_vec *bvec;
202
203 /*
204 * we have verified the checksum already, set page
205 * checked so the end_io handlers know about it
206 */
207 bio_for_each_segment_all(bvec, cb->orig_bio, i)
208 SetPageChecked(bvec->bv_page);
209
210 bio_endio(cb->orig_bio);
211 }
212
213 /* finally free the cb struct */
214 kfree(cb->compressed_pages);
215 kfree(cb);
216out:
217 bio_put(bio);
218}
219
220/*
221 * Clear the writeback bits on all of the file
222 * pages for a compressed write
223 */
224static noinline void end_compressed_writeback(struct inode *inode,
225 const struct compressed_bio *cb)
226{
227 unsigned long index = cb->start >> PAGE_SHIFT;
228 unsigned long end_index = (cb->start + cb->len - 1) >> PAGE_SHIFT;
229 struct page *pages[16];
230 unsigned long nr_pages = end_index - index + 1;
231 int i;
232 int ret;
233
234 if (cb->errors)
235 mapping_set_error(inode->i_mapping, -EIO);
236
237 while (nr_pages > 0) {
238 ret = find_get_pages_contig(inode->i_mapping, index,
239 min_t(unsigned long,
240 nr_pages, ARRAY_SIZE(pages)), pages);
241 if (ret == 0) {
242 nr_pages -= 1;
243 index += 1;
244 continue;
245 }
246 for (i = 0; i < ret; i++) {
247 if (cb->errors)
248 SetPageError(pages[i]);
249 end_page_writeback(pages[i]);
250 put_page(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)
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 (bio->bi_error)
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,
293 bio->bi_error ? 0 : 1);
294 cb->compressed_pages[0]->mapping = NULL;
295
296 end_compressed_writeback(inode, cb);
297 /* note, our inode could be gone now */
298
299 /*
300 * release the compressed pages, these came from alloc_page and
301 * are not attached to the inode at all
302 */
303 index = 0;
304 for (index = 0; index < cb->nr_pages; index++) {
305 page = cb->compressed_pages[index];
306 page->mapping = NULL;
307 put_page(page);
308 }
309
310 /* finally free the cb struct */
311 kfree(cb->compressed_pages);
312 kfree(cb);
313out:
314 bio_put(bio);
315}
316
317/*
318 * worker function to build and submit bios for previously compressed pages.
319 * The corresponding pages in the inode should be marked for writeback
320 * and the compressed pages should have a reference on them for dropping
321 * when the IO is complete.
322 *
323 * This also checksums the file bytes and gets things ready for
324 * the end io hooks.
325 */
326int btrfs_submit_compressed_write(struct inode *inode, u64 start,
327 unsigned long len, u64 disk_start,
328 unsigned long compressed_len,
329 struct page **compressed_pages,
330 unsigned long nr_pages)
331{
332 struct bio *bio = NULL;
333 struct btrfs_root *root = BTRFS_I(inode)->root;
334 struct compressed_bio *cb;
335 unsigned long bytes_left;
336 struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
337 int pg_index = 0;
338 struct page *page;
339 u64 first_byte = disk_start;
340 struct block_device *bdev;
341 int ret;
342 int skip_sum = BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM;
343
344 WARN_ON(start & ((u64)PAGE_SIZE - 1));
345 cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS);
346 if (!cb)
347 return -ENOMEM;
348 atomic_set(&cb->pending_bios, 0);
349 cb->errors = 0;
350 cb->inode = inode;
351 cb->start = start;
352 cb->len = len;
353 cb->mirror_num = 0;
354 cb->compressed_pages = compressed_pages;
355 cb->compressed_len = compressed_len;
356 cb->orig_bio = NULL;
357 cb->nr_pages = nr_pages;
358
359 bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
360
361 bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
362 if (!bio) {
363 kfree(cb);
364 return -ENOMEM;
365 }
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(WRITE, 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(root->fs_info, bio,
395 BTRFS_WQ_ENDIO_DATA);
396 BUG_ON(ret); /* -ENOMEM */
397
398 if (!skip_sum) {
399 ret = btrfs_csum_one_bio(root, inode, bio,
400 start, 1);
401 BUG_ON(ret); /* -ENOMEM */
402 }
403
404 ret = btrfs_map_bio(root, WRITE, bio, 0, 1);
405 BUG_ON(ret); /* -ENOMEM */
406
407 bio_put(bio);
408
409 bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
410 BUG_ON(!bio);
411 bio->bi_private = cb;
412 bio->bi_end_io = end_compressed_bio_write;
413 bio_add_page(bio, page, PAGE_SIZE, 0);
414 }
415 if (bytes_left < PAGE_SIZE) {
416 btrfs_info(BTRFS_I(inode)->root->fs_info,
417 "bytes left %lu compress len %lu nr %lu",
418 bytes_left, cb->compressed_len, cb->nr_pages);
419 }
420 bytes_left -= PAGE_SIZE;
421 first_byte += PAGE_SIZE;
422 cond_resched();
423 }
424 bio_get(bio);
425
426 ret = btrfs_bio_wq_end_io(root->fs_info, bio, BTRFS_WQ_ENDIO_DATA);
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
441static 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_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_SHIFT;
468
469 while (last_offset < compressed_end) {
470 pg_index = last_offset >> PAGE_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 && !radix_tree_exceptional_entry(page)) {
479 misses++;
480 if (misses > 4)
481 break;
482 goto next;
483 }
484
485 page = __page_cache_alloc(mapping_gfp_constraint(mapping,
486 ~__GFP_FS));
487 if (!page)
488 break;
489
490 if (add_to_page_cache_lru(page, mapping, pg_index, GFP_NOFS)) {
491 put_page(page);
492 goto next;
493 }
494
495 end = last_offset + PAGE_SIZE - 1;
496 /*
497 * at this point, we have a locked page in the page cache
498 * for these bytes in the file. But, we have to make
499 * sure they map to this compressed extent on disk.
500 */
501 set_page_extent_mapped(page);
502 lock_extent(tree, last_offset, end);
503 read_lock(&em_tree->lock);
504 em = lookup_extent_mapping(em_tree, last_offset,
505 PAGE_SIZE);
506 read_unlock(&em_tree->lock);
507
508 if (!em || last_offset < em->start ||
509 (last_offset + PAGE_SIZE > extent_map_end(em)) ||
510 (em->block_start >> 9) != cb->orig_bio->bi_iter.bi_sector) {
511 free_extent_map(em);
512 unlock_extent(tree, last_offset, end);
513 unlock_page(page);
514 put_page(page);
515 break;
516 }
517 free_extent_map(em);
518
519 if (page->index == end_index) {
520 char *userpage;
521 size_t zero_offset = isize & (PAGE_SIZE - 1);
522
523 if (zero_offset) {
524 int zeros;
525 zeros = PAGE_SIZE - zero_offset;
526 userpage = kmap_atomic(page);
527 memset(userpage + zero_offset, 0, zeros);
528 flush_dcache_page(page);
529 kunmap_atomic(userpage);
530 }
531 }
532
533 ret = bio_add_page(cb->orig_bio, page,
534 PAGE_SIZE, 0);
535
536 if (ret == PAGE_SIZE) {
537 nr_pages++;
538 put_page(page);
539 } else {
540 unlock_extent(tree, last_offset, end);
541 unlock_page(page);
542 put_page(page);
543 break;
544 }
545next:
546 last_offset += PAGE_SIZE;
547 }
548 return 0;
549}
550
551/*
552 * for a compressed read, the bio we get passed has all the inode pages
553 * in it. We don't actually do IO on those pages but allocate new ones
554 * to hold the compressed pages on disk.
555 *
556 * bio->bi_iter.bi_sector points to the compressed extent on disk
557 * bio->bi_io_vec points to all of the inode pages
558 * bio->bi_vcnt is a count of pages
559 *
560 * After the compressed pages are read, we copy the bytes into the
561 * bio we were passed and then call the bio end_io calls
562 */
563int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
564 int mirror_num, unsigned long bio_flags)
565{
566 struct extent_io_tree *tree;
567 struct extent_map_tree *em_tree;
568 struct compressed_bio *cb;
569 struct btrfs_root *root = BTRFS_I(inode)->root;
570 unsigned long uncompressed_len = bio->bi_vcnt * PAGE_SIZE;
571 unsigned long compressed_len;
572 unsigned long nr_pages;
573 unsigned long pg_index;
574 struct page *page;
575 struct block_device *bdev;
576 struct bio *comp_bio;
577 u64 cur_disk_byte = (u64)bio->bi_iter.bi_sector << 9;
578 u64 em_len;
579 u64 em_start;
580 struct extent_map *em;
581 int ret = -ENOMEM;
582 int faili = 0;
583 u32 *sums;
584
585 tree = &BTRFS_I(inode)->io_tree;
586 em_tree = &BTRFS_I(inode)->extent_tree;
587
588 /* we need the actual starting offset of this extent in the file */
589 read_lock(&em_tree->lock);
590 em = lookup_extent_mapping(em_tree,
591 page_offset(bio->bi_io_vec->bv_page),
592 PAGE_SIZE);
593 read_unlock(&em_tree->lock);
594 if (!em)
595 return -EIO;
596
597 compressed_len = em->block_len;
598 cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS);
599 if (!cb)
600 goto out;
601
602 atomic_set(&cb->pending_bios, 0);
603 cb->errors = 0;
604 cb->inode = inode;
605 cb->mirror_num = mirror_num;
606 sums = &cb->sums;
607
608 cb->start = em->orig_start;
609 em_len = em->len;
610 em_start = em->start;
611
612 free_extent_map(em);
613 em = NULL;
614
615 cb->len = uncompressed_len;
616 cb->compressed_len = compressed_len;
617 cb->compress_type = extent_compress_type(bio_flags);
618 cb->orig_bio = bio;
619
620 nr_pages = DIV_ROUND_UP(compressed_len, PAGE_SIZE);
621 cb->compressed_pages = kcalloc(nr_pages, sizeof(struct page *),
622 GFP_NOFS);
623 if (!cb->compressed_pages)
624 goto fail1;
625
626 bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
627
628 for (pg_index = 0; pg_index < nr_pages; pg_index++) {
629 cb->compressed_pages[pg_index] = alloc_page(GFP_NOFS |
630 __GFP_HIGHMEM);
631 if (!cb->compressed_pages[pg_index]) {
632 faili = pg_index - 1;
633 ret = -ENOMEM;
634 goto fail2;
635 }
636 }
637 faili = nr_pages - 1;
638 cb->nr_pages = nr_pages;
639
640 add_ra_bio_pages(inode, em_start + em_len, cb);
641
642 /* include any pages we added in add_ra-bio_pages */
643 uncompressed_len = bio->bi_vcnt * PAGE_SIZE;
644 cb->len = uncompressed_len;
645
646 comp_bio = compressed_bio_alloc(bdev, cur_disk_byte, GFP_NOFS);
647 if (!comp_bio)
648 goto fail2;
649 comp_bio->bi_private = cb;
650 comp_bio->bi_end_io = end_compressed_bio_read;
651 atomic_inc(&cb->pending_bios);
652
653 for (pg_index = 0; pg_index < nr_pages; pg_index++) {
654 page = cb->compressed_pages[pg_index];
655 page->mapping = inode->i_mapping;
656 page->index = em_start >> PAGE_SHIFT;
657
658 if (comp_bio->bi_iter.bi_size)
659 ret = tree->ops->merge_bio_hook(READ, page, 0,
660 PAGE_SIZE,
661 comp_bio, 0);
662 else
663 ret = 0;
664
665 page->mapping = NULL;
666 if (ret || bio_add_page(comp_bio, page, PAGE_SIZE, 0) <
667 PAGE_SIZE) {
668 bio_get(comp_bio);
669
670 ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio,
671 BTRFS_WQ_ENDIO_DATA);
672 BUG_ON(ret); /* -ENOMEM */
673
674 /*
675 * inc the count before we submit the bio so
676 * we know the end IO handler won't happen before
677 * we inc the count. Otherwise, the cb might get
678 * freed before we're done setting it up
679 */
680 atomic_inc(&cb->pending_bios);
681
682 if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
683 ret = btrfs_lookup_bio_sums(root, inode,
684 comp_bio, sums);
685 BUG_ON(ret); /* -ENOMEM */
686 }
687 sums += DIV_ROUND_UP(comp_bio->bi_iter.bi_size,
688 root->sectorsize);
689
690 ret = btrfs_map_bio(root, READ, comp_bio,
691 mirror_num, 0);
692 if (ret) {
693 bio->bi_error = ret;
694 bio_endio(comp_bio);
695 }
696
697 bio_put(comp_bio);
698
699 comp_bio = compressed_bio_alloc(bdev, cur_disk_byte,
700 GFP_NOFS);
701 BUG_ON(!comp_bio);
702 comp_bio->bi_private = cb;
703 comp_bio->bi_end_io = end_compressed_bio_read;
704
705 bio_add_page(comp_bio, page, PAGE_SIZE, 0);
706 }
707 cur_disk_byte += PAGE_SIZE;
708 }
709 bio_get(comp_bio);
710
711 ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio,
712 BTRFS_WQ_ENDIO_DATA);
713 BUG_ON(ret); /* -ENOMEM */
714
715 if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
716 ret = btrfs_lookup_bio_sums(root, inode, comp_bio, sums);
717 BUG_ON(ret); /* -ENOMEM */
718 }
719
720 ret = btrfs_map_bio(root, READ, comp_bio, mirror_num, 0);
721 if (ret) {
722 bio->bi_error = ret;
723 bio_endio(comp_bio);
724 }
725
726 bio_put(comp_bio);
727 return 0;
728
729fail2:
730 while (faili >= 0) {
731 __free_page(cb->compressed_pages[faili]);
732 faili--;
733 }
734
735 kfree(cb->compressed_pages);
736fail1:
737 kfree(cb);
738out:
739 free_extent_map(em);
740 return ret;
741}
742
743static struct {
744 struct list_head idle_ws;
745 spinlock_t ws_lock;
746 int num_ws;
747 atomic_t alloc_ws;
748 wait_queue_head_t ws_wait;
749} btrfs_comp_ws[BTRFS_COMPRESS_TYPES];
750
751static const struct btrfs_compress_op * const btrfs_compress_op[] = {
752 &btrfs_zlib_compress,
753 &btrfs_lzo_compress,
754};
755
756void __init btrfs_init_compress(void)
757{
758 int i;
759
760 for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
761 INIT_LIST_HEAD(&btrfs_comp_ws[i].idle_ws);
762 spin_lock_init(&btrfs_comp_ws[i].ws_lock);
763 atomic_set(&btrfs_comp_ws[i].alloc_ws, 0);
764 init_waitqueue_head(&btrfs_comp_ws[i].ws_wait);
765 }
766}
767
768/*
769 * this finds an available workspace or allocates a new one
770 * ERR_PTR is returned if things go bad.
771 */
772static struct list_head *find_workspace(int type)
773{
774 struct list_head *workspace;
775 int cpus = num_online_cpus();
776 int idx = type - 1;
777
778 struct list_head *idle_ws = &btrfs_comp_ws[idx].idle_ws;
779 spinlock_t *ws_lock = &btrfs_comp_ws[idx].ws_lock;
780 atomic_t *alloc_ws = &btrfs_comp_ws[idx].alloc_ws;
781 wait_queue_head_t *ws_wait = &btrfs_comp_ws[idx].ws_wait;
782 int *num_ws = &btrfs_comp_ws[idx].num_ws;
783again:
784 spin_lock(ws_lock);
785 if (!list_empty(idle_ws)) {
786 workspace = idle_ws->next;
787 list_del(workspace);
788 (*num_ws)--;
789 spin_unlock(ws_lock);
790 return workspace;
791
792 }
793 if (atomic_read(alloc_ws) > cpus) {
794 DEFINE_WAIT(wait);
795
796 spin_unlock(ws_lock);
797 prepare_to_wait(ws_wait, &wait, TASK_UNINTERRUPTIBLE);
798 if (atomic_read(alloc_ws) > cpus && !*num_ws)
799 schedule();
800 finish_wait(ws_wait, &wait);
801 goto again;
802 }
803 atomic_inc(alloc_ws);
804 spin_unlock(ws_lock);
805
806 workspace = btrfs_compress_op[idx]->alloc_workspace();
807 if (IS_ERR(workspace)) {
808 atomic_dec(alloc_ws);
809 wake_up(ws_wait);
810 }
811 return workspace;
812}
813
814/*
815 * put a workspace struct back on the list or free it if we have enough
816 * idle ones sitting around
817 */
818static void free_workspace(int type, struct list_head *workspace)
819{
820 int idx = type - 1;
821 struct list_head *idle_ws = &btrfs_comp_ws[idx].idle_ws;
822 spinlock_t *ws_lock = &btrfs_comp_ws[idx].ws_lock;
823 atomic_t *alloc_ws = &btrfs_comp_ws[idx].alloc_ws;
824 wait_queue_head_t *ws_wait = &btrfs_comp_ws[idx].ws_wait;
825 int *num_ws = &btrfs_comp_ws[idx].num_ws;
826
827 spin_lock(ws_lock);
828 if (*num_ws < num_online_cpus()) {
829 list_add(workspace, idle_ws);
830 (*num_ws)++;
831 spin_unlock(ws_lock);
832 goto wake;
833 }
834 spin_unlock(ws_lock);
835
836 btrfs_compress_op[idx]->free_workspace(workspace);
837 atomic_dec(alloc_ws);
838wake:
839 /*
840 * Make sure counter is updated before we wake up waiters.
841 */
842 smp_mb();
843 if (waitqueue_active(ws_wait))
844 wake_up(ws_wait);
845}
846
847/*
848 * cleanup function for module exit
849 */
850static void free_workspaces(void)
851{
852 struct list_head *workspace;
853 int i;
854
855 for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
856 while (!list_empty(&btrfs_comp_ws[i].idle_ws)) {
857 workspace = btrfs_comp_ws[i].idle_ws.next;
858 list_del(workspace);
859 btrfs_compress_op[i]->free_workspace(workspace);
860 atomic_dec(&btrfs_comp_ws[i].alloc_ws);
861 }
862 }
863}
864
865/*
866 * given an address space and start/len, compress the bytes.
867 *
868 * pages are allocated to hold the compressed result and stored
869 * in 'pages'
870 *
871 * out_pages is used to return the number of pages allocated. There
872 * may be pages allocated even if we return an error
873 *
874 * total_in is used to return the number of bytes actually read. It
875 * may be smaller then len if we had to exit early because we
876 * ran out of room in the pages array or because we cross the
877 * max_out threshold.
878 *
879 * total_out is used to return the total number of compressed bytes
880 *
881 * max_out tells us the max number of bytes that we're allowed to
882 * stuff into pages
883 */
884int btrfs_compress_pages(int type, struct address_space *mapping,
885 u64 start, unsigned long len,
886 struct page **pages,
887 unsigned long nr_dest_pages,
888 unsigned long *out_pages,
889 unsigned long *total_in,
890 unsigned long *total_out,
891 unsigned long max_out)
892{
893 struct list_head *workspace;
894 int ret;
895
896 workspace = find_workspace(type);
897 if (IS_ERR(workspace))
898 return PTR_ERR(workspace);
899
900 ret = btrfs_compress_op[type-1]->compress_pages(workspace, mapping,
901 start, len, pages,
902 nr_dest_pages, out_pages,
903 total_in, total_out,
904 max_out);
905 free_workspace(type, workspace);
906 return ret;
907}
908
909/*
910 * pages_in is an array of pages with compressed data.
911 *
912 * disk_start is the starting logical offset of this array in the file
913 *
914 * bvec is a bio_vec of pages from the file that we want to decompress into
915 *
916 * vcnt is the count of pages in the biovec
917 *
918 * srclen is the number of bytes in pages_in
919 *
920 * The basic idea is that we have a bio that was created by readpages.
921 * The pages in the bio are for the uncompressed data, and they may not
922 * be contiguous. They all correspond to the range of bytes covered by
923 * the compressed extent.
924 */
925static int btrfs_decompress_biovec(int type, struct page **pages_in,
926 u64 disk_start, struct bio_vec *bvec,
927 int vcnt, size_t srclen)
928{
929 struct list_head *workspace;
930 int ret;
931
932 workspace = find_workspace(type);
933 if (IS_ERR(workspace))
934 return PTR_ERR(workspace);
935
936 ret = btrfs_compress_op[type-1]->decompress_biovec(workspace, pages_in,
937 disk_start,
938 bvec, vcnt, srclen);
939 free_workspace(type, workspace);
940 return ret;
941}
942
943/*
944 * a less complex decompression routine. Our compressed data fits in a
945 * single page, and we want to read a single page out of it.
946 * start_byte tells us the offset into the compressed data we're interested in
947 */
948int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
949 unsigned long start_byte, size_t srclen, size_t destlen)
950{
951 struct list_head *workspace;
952 int ret;
953
954 workspace = find_workspace(type);
955 if (IS_ERR(workspace))
956 return PTR_ERR(workspace);
957
958 ret = btrfs_compress_op[type-1]->decompress(workspace, data_in,
959 dest_page, start_byte,
960 srclen, destlen);
961
962 free_workspace(type, workspace);
963 return ret;
964}
965
966void btrfs_exit_compress(void)
967{
968 free_workspaces();
969}
970
971/*
972 * Copy uncompressed data from working buffer to pages.
973 *
974 * buf_start is the byte offset we're of the start of our workspace buffer.
975 *
976 * total_out is the last byte of the buffer
977 */
978int btrfs_decompress_buf2page(char *buf, unsigned long buf_start,
979 unsigned long total_out, u64 disk_start,
980 struct bio_vec *bvec, int vcnt,
981 unsigned long *pg_index,
982 unsigned long *pg_offset)
983{
984 unsigned long buf_offset;
985 unsigned long current_buf_start;
986 unsigned long start_byte;
987 unsigned long working_bytes = total_out - buf_start;
988 unsigned long bytes;
989 char *kaddr;
990 struct page *page_out = bvec[*pg_index].bv_page;
991
992 /*
993 * start byte is the first byte of the page we're currently
994 * copying into relative to the start of the compressed data.
995 */
996 start_byte = page_offset(page_out) - disk_start;
997
998 /* we haven't yet hit data corresponding to this page */
999 if (total_out <= start_byte)
1000 return 1;
1001
1002 /*
1003 * the start of the data we care about is offset into
1004 * the middle of our working buffer
1005 */
1006 if (total_out > start_byte && buf_start < start_byte) {
1007 buf_offset = start_byte - buf_start;
1008 working_bytes -= buf_offset;
1009 } else {
1010 buf_offset = 0;
1011 }
1012 current_buf_start = buf_start;
1013
1014 /* copy bytes from the working buffer into the pages */
1015 while (working_bytes > 0) {
1016 bytes = min(PAGE_SIZE - *pg_offset,
1017 PAGE_SIZE - buf_offset);
1018 bytes = min(bytes, working_bytes);
1019 kaddr = kmap_atomic(page_out);
1020 memcpy(kaddr + *pg_offset, buf + buf_offset, bytes);
1021 kunmap_atomic(kaddr);
1022 flush_dcache_page(page_out);
1023
1024 *pg_offset += bytes;
1025 buf_offset += bytes;
1026 working_bytes -= bytes;
1027 current_buf_start += bytes;
1028
1029 /* check if we need to pick another page */
1030 if (*pg_offset == PAGE_SIZE) {
1031 (*pg_index)++;
1032 if (*pg_index >= vcnt)
1033 return 0;
1034
1035 page_out = bvec[*pg_index].bv_page;
1036 *pg_offset = 0;
1037 start_byte = page_offset(page_out) - disk_start;
1038
1039 /*
1040 * make sure our new page is covered by this
1041 * working buffer
1042 */
1043 if (total_out <= start_byte)
1044 return 1;
1045
1046 /*
1047 * the next page in the biovec might not be adjacent
1048 * to the last page, but it might still be found
1049 * inside this working buffer. bump our offset pointer
1050 */
1051 if (total_out > start_byte &&
1052 current_buf_start < start_byte) {
1053 buf_offset = start_byte - buf_start;
1054 working_bytes = total_out - start_byte;
1055 current_buf_start = buf_start + buf_offset;
1056 }
1057 }
1058 }
1059
1060 return 1;
1061}
1062
1063/*
1064 * When uncompressing data, we need to make sure and zero any parts of
1065 * the biovec that were not filled in by the decompression code. pg_index
1066 * and pg_offset indicate the last page and the last offset of that page
1067 * that have been filled in. This will zero everything remaining in the
1068 * biovec.
1069 */
1070void btrfs_clear_biovec_end(struct bio_vec *bvec, int vcnt,
1071 unsigned long pg_index,
1072 unsigned long pg_offset)
1073{
1074 while (pg_index < vcnt) {
1075 struct page *page = bvec[pg_index].bv_page;
1076 unsigned long off = bvec[pg_index].bv_offset;
1077 unsigned long len = bvec[pg_index].bv_len;
1078
1079 if (pg_offset < off)
1080 pg_offset = off;
1081 if (pg_offset < off + len) {
1082 unsigned long bytes = off + len - pg_offset;
1083 char *kaddr;
1084
1085 kaddr = kmap_atomic(page);
1086 memset(kaddr + pg_offset, 0, bytes);
1087 kunmap_atomic(kaddr);
1088 }
1089 pg_index++;
1090 pg_offset = 0;
1091 }
1092}