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[platform/adaptation/renesas_rcar/renesas_kernel.git] / fs / btrfs / compression.c
1 /*
2  * Copyright (C) 2008 Oracle.  All rights reserved.
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public
6  * License v2 as published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful,
9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
11  * General Public License for more details.
12  *
13  * You should have received a copy of the GNU General Public
14  * License along with this program; if not, write to the
15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16  * Boston, MA 021110-1307, USA.
17  */
18
19 #include <linux/kernel.h>
20 #include <linux/bio.h>
21 #include <linux/buffer_head.h>
22 #include <linux/file.h>
23 #include <linux/fs.h>
24 #include <linux/pagemap.h>
25 #include <linux/highmem.h>
26 #include <linux/time.h>
27 #include <linux/init.h>
28 #include <linux/string.h>
29 #include <linux/backing-dev.h>
30 #include <linux/mpage.h>
31 #include <linux/swap.h>
32 #include <linux/writeback.h>
33 #include <linux/bit_spinlock.h>
34 #include <linux/slab.h>
35 #include "ctree.h"
36 #include "disk-io.h"
37 #include "transaction.h"
38 #include "btrfs_inode.h"
39 #include "volumes.h"
40 #include "ordered-data.h"
41 #include "compression.h"
42 #include "extent_io.h"
43 #include "extent_map.h"
44
45 struct compressed_bio {
46         /* number of bios pending for this compressed extent */
47         atomic_t pending_bios;
48
49         /* the pages with the compressed data on them */
50         struct page **compressed_pages;
51
52         /* inode that owns this data */
53         struct inode *inode;
54
55         /* starting offset in the inode for our pages */
56         u64 start;
57
58         /* number of bytes in the inode we're working on */
59         unsigned long len;
60
61         /* number of bytes on disk */
62         unsigned long compressed_len;
63
64         /* the compression algorithm for this bio */
65         int compress_type;
66
67         /* number of compressed pages in the array */
68         unsigned long nr_pages;
69
70         /* IO errors */
71         int errors;
72         int mirror_num;
73
74         /* for reads, this is the bio we are copying the data into */
75         struct bio *orig_bio;
76
77         /*
78          * the start of a variable length array of checksums only
79          * used by reads
80          */
81         u32 sums;
82 };
83
84 static int btrfs_decompress_biovec(int type, struct page **pages_in,
85                                    u64 disk_start, struct bio_vec *bvec,
86                                    int vcnt, size_t srclen);
87
88 static inline int compressed_bio_size(struct btrfs_root *root,
89                                       unsigned long disk_size)
90 {
91         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
92
93         return sizeof(struct compressed_bio) +
94                 ((disk_size + root->sectorsize - 1) / root->sectorsize) *
95                 csum_size;
96 }
97
98 static struct bio *compressed_bio_alloc(struct block_device *bdev,
99                                         u64 first_byte, gfp_t gfp_flags)
100 {
101         int nr_vecs;
102
103         nr_vecs = bio_get_nr_vecs(bdev);
104         return btrfs_bio_alloc(bdev, first_byte >> 9, nr_vecs, gfp_flags);
105 }
106
107 static int check_compressed_csum(struct inode *inode,
108                                  struct compressed_bio *cb,
109                                  u64 disk_start)
110 {
111         int ret;
112         struct page *page;
113         unsigned long i;
114         char *kaddr;
115         u32 csum;
116         u32 *cb_sum = &cb->sums;
117
118         if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)
119                 return 0;
120
121         for (i = 0; i < cb->nr_pages; i++) {
122                 page = cb->compressed_pages[i];
123                 csum = ~(u32)0;
124
125                 kaddr = kmap_atomic(page);
126                 csum = btrfs_csum_data(kaddr, csum, PAGE_CACHE_SIZE);
127                 btrfs_csum_final(csum, (char *)&csum);
128                 kunmap_atomic(kaddr);
129
130                 if (csum != *cb_sum) {
131                         btrfs_info(BTRFS_I(inode)->root->fs_info,
132                            "csum failed ino %llu extent %llu csum %u wanted %u mirror %d",
133                            btrfs_ino(inode), disk_start, csum, *cb_sum,
134                            cb->mirror_num);
135                         ret = -EIO;
136                         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,
175                                     (u64)bio->bi_iter.bi_sector << 9);
176         if (ret)
177                 goto csum_failed;
178
179         /* ok, we're the last bio for this extent, lets start
180          * the decompression.
181          */
182         ret = btrfs_decompress_biovec(cb->compress_type,
183                                       cb->compressed_pages,
184                                       cb->start,
185                                       cb->orig_bio->bi_io_vec,
186                                       cb->orig_bio->bi_vcnt,
187                                       cb->compressed_len);
188 csum_failed:
189         if (ret)
190                 cb->errors = 1;
191
192         /* release the compressed pages */
193         index = 0;
194         for (index = 0; index < cb->nr_pages; index++) {
195                 page = cb->compressed_pages[index];
196                 page->mapping = NULL;
197                 page_cache_release(page);
198         }
199
200         /* do io completion on the original bio */
201         if (cb->errors) {
202                 bio_io_error(cb->orig_bio);
203         } else {
204                 int i;
205                 struct bio_vec *bvec;
206
207                 /*
208                  * we have verified the checksum already, set page
209                  * checked so the end_io handlers know about it
210                  */
211                 bio_for_each_segment_all(bvec, cb->orig_bio, i)
212                         SetPageChecked(bvec->bv_page);
213
214                 bio_endio(cb->orig_bio, 0);
215         }
216
217         /* finally free the cb struct */
218         kfree(cb->compressed_pages);
219         kfree(cb);
220 out:
221         bio_put(bio);
222 }
223
224 /*
225  * Clear the writeback bits on all of the file
226  * pages for a compressed write
227  */
228 static noinline void 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 }
256
257 /*
258  * do the cleanup once all the compressed pages hit the disk.
259  * This will clear writeback on the file pages and free the compressed
260  * pages.
261  *
262  * This also calls the writeback end hooks for the file pages so that
263  * metadata and checksums can be updated in the file.
264  */
265 static void end_compressed_bio_write(struct bio *bio, int err)
266 {
267         struct extent_io_tree *tree;
268         struct compressed_bio *cb = bio->bi_private;
269         struct inode *inode;
270         struct page *page;
271         unsigned long index;
272
273         if (err)
274                 cb->errors = 1;
275
276         /* if there are more bios still pending for this compressed
277          * extent, just exit
278          */
279         if (!atomic_dec_and_test(&cb->pending_bios))
280                 goto out;
281
282         /* ok, we're the last bio for this extent, step one is to
283          * call back into the FS and do all the end_io operations
284          */
285         inode = cb->inode;
286         tree = &BTRFS_I(inode)->io_tree;
287         cb->compressed_pages[0]->mapping = cb->inode->i_mapping;
288         tree->ops->writepage_end_io_hook(cb->compressed_pages[0],
289                                          cb->start,
290                                          cb->start + cb->len - 1,
291                                          NULL, 1);
292         cb->compressed_pages[0]->mapping = NULL;
293
294         end_compressed_writeback(inode, cb->start, cb->len);
295         /* note, our inode could be gone now */
296
297         /*
298          * release the compressed pages, these came from alloc_page and
299          * are not attached to the inode at all
300          */
301         index = 0;
302         for (index = 0; index < cb->nr_pages; index++) {
303                 page = cb->compressed_pages[index];
304                 page->mapping = NULL;
305                 page_cache_release(page);
306         }
307
308         /* finally free the cb struct */
309         kfree(cb->compressed_pages);
310         kfree(cb);
311 out:
312         bio_put(bio);
313 }
314
315 /*
316  * worker function to build and submit bios for previously compressed pages.
317  * The corresponding pages in the inode should be marked for writeback
318  * and the compressed pages should have a reference on them for dropping
319  * when the IO is complete.
320  *
321  * This also checksums the file bytes and gets things ready for
322  * the end io hooks.
323  */
324 int btrfs_submit_compressed_write(struct inode *inode, u64 start,
325                                  unsigned long len, u64 disk_start,
326                                  unsigned long compressed_len,
327                                  struct page **compressed_pages,
328                                  unsigned long nr_pages)
329 {
330         struct bio *bio = NULL;
331         struct btrfs_root *root = BTRFS_I(inode)->root;
332         struct compressed_bio *cb;
333         unsigned long bytes_left;
334         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
335         int pg_index = 0;
336         struct page *page;
337         u64 first_byte = disk_start;
338         struct block_device *bdev;
339         int ret;
340         int skip_sum = BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM;
341
342         WARN_ON(start & ((u64)PAGE_CACHE_SIZE - 1));
343         cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS);
344         if (!cb)
345                 return -ENOMEM;
346         atomic_set(&cb->pending_bios, 0);
347         cb->errors = 0;
348         cb->inode = inode;
349         cb->start = start;
350         cb->len = len;
351         cb->mirror_num = 0;
352         cb->compressed_pages = compressed_pages;
353         cb->compressed_len = compressed_len;
354         cb->orig_bio = NULL;
355         cb->nr_pages = nr_pages;
356
357         bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
358
359         bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
360         if (!bio) {
361                 kfree(cb);
362                 return -ENOMEM;
363         }
364         bio->bi_private = cb;
365         bio->bi_end_io = end_compressed_bio_write;
366         atomic_inc(&cb->pending_bios);
367
368         /* create and submit bios for the compressed pages */
369         bytes_left = compressed_len;
370         for (pg_index = 0; pg_index < cb->nr_pages; pg_index++) {
371                 page = compressed_pages[pg_index];
372                 page->mapping = inode->i_mapping;
373                 if (bio->bi_iter.bi_size)
374                         ret = io_tree->ops->merge_bio_hook(WRITE, page, 0,
375                                                            PAGE_CACHE_SIZE,
376                                                            bio, 0);
377                 else
378                         ret = 0;
379
380                 page->mapping = NULL;
381                 if (ret || bio_add_page(bio, page, PAGE_CACHE_SIZE, 0) <
382                     PAGE_CACHE_SIZE) {
383                         bio_get(bio);
384
385                         /*
386                          * inc the count before we submit the bio so
387                          * we know the end IO handler won't happen before
388                          * we inc the count.  Otherwise, the cb might get
389                          * freed before we're done setting it up
390                          */
391                         atomic_inc(&cb->pending_bios);
392                         ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0);
393                         BUG_ON(ret); /* -ENOMEM */
394
395                         if (!skip_sum) {
396                                 ret = btrfs_csum_one_bio(root, inode, bio,
397                                                          start, 1);
398                                 BUG_ON(ret); /* -ENOMEM */
399                         }
400
401                         ret = btrfs_map_bio(root, WRITE, bio, 0, 1);
402                         BUG_ON(ret); /* -ENOMEM */
403
404                         bio_put(bio);
405
406                         bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
407                         BUG_ON(!bio);
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                         btrfs_info(BTRFS_I(inode)->root->fs_info,
414                                         "bytes left %lu compress len %lu nr %lu",
415                                bytes_left, cb->compressed_len, cb->nr_pages);
416                 }
417                 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_iter.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_iter.bi_sector points to the compressed extent on disk
555  * bio->bi_io_vec points to all of the inode pages
556  * bio->bi_vcnt is a count of pages
557  *
558  * After the compressed pages are read, we copy the bytes into the
559  * bio we were passed and then call the bio end_io calls
560  */
561 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_iter.bi_sector << 9;
576         u64 em_len;
577         u64 em_start;
578         struct extent_map *em;
579         int ret = -ENOMEM;
580         int faili = 0;
581         u32 *sums;
582
583         tree = &BTRFS_I(inode)->io_tree;
584         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         /* In the parent-locked case, we only locked the range we are
640          * interested in.  In all other cases, we can opportunistically
641          * cache decompressed data that goes beyond the requested range. */
642         if (!(bio_flags & EXTENT_BIO_PARENT_LOCKED))
643                 add_ra_bio_pages(inode, em_start + em_len, cb);
644
645         /* include any pages we added in add_ra-bio_pages */
646         uncompressed_len = bio->bi_vcnt * PAGE_CACHE_SIZE;
647         cb->len = uncompressed_len;
648
649         comp_bio = compressed_bio_alloc(bdev, cur_disk_byte, GFP_NOFS);
650         if (!comp_bio)
651                 goto fail2;
652         comp_bio->bi_private = cb;
653         comp_bio->bi_end_io = end_compressed_bio_read;
654         atomic_inc(&cb->pending_bios);
655
656         for (pg_index = 0; pg_index < nr_pages; pg_index++) {
657                 page = cb->compressed_pages[pg_index];
658                 page->mapping = inode->i_mapping;
659                 page->index = em_start >> PAGE_CACHE_SHIFT;
660
661                 if (comp_bio->bi_iter.bi_size)
662                         ret = tree->ops->merge_bio_hook(READ, page, 0,
663                                                         PAGE_CACHE_SIZE,
664                                                         comp_bio, 0);
665                 else
666                         ret = 0;
667
668                 page->mapping = NULL;
669                 if (ret || bio_add_page(comp_bio, page, PAGE_CACHE_SIZE, 0) <
670                     PAGE_CACHE_SIZE) {
671                         bio_get(comp_bio);
672
673                         ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0);
674                         BUG_ON(ret); /* -ENOMEM */
675
676                         /*
677                          * inc the count before we submit the bio so
678                          * we know the end IO handler won't happen before
679                          * we inc the count.  Otherwise, the cb might get
680                          * freed before we're done setting it up
681                          */
682                         atomic_inc(&cb->pending_bios);
683
684                         if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
685                                 ret = btrfs_lookup_bio_sums(root, inode,
686                                                         comp_bio, sums);
687                                 BUG_ON(ret); /* -ENOMEM */
688                         }
689                         sums += (comp_bio->bi_iter.bi_size +
690                                  root->sectorsize - 1) / root->sectorsize;
691
692                         ret = btrfs_map_bio(root, READ, comp_bio,
693                                             mirror_num, 0);
694                         if (ret)
695                                 bio_endio(comp_bio, ret);
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_CACHE_SIZE, 0);
706                 }
707                 cur_disk_byte += PAGE_CACHE_SIZE;
708         }
709         bio_get(comp_bio);
710
711         ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0);
712         BUG_ON(ret); /* -ENOMEM */
713
714         if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
715                 ret = btrfs_lookup_bio_sums(root, inode, comp_bio, sums);
716                 BUG_ON(ret); /* -ENOMEM */
717         }
718
719         ret = btrfs_map_bio(root, READ, comp_bio, mirror_num, 0);
720         if (ret)
721                 bio_endio(comp_bio, ret);
722
723         bio_put(comp_bio);
724         return 0;
725
726 fail2:
727         while (faili >= 0) {
728                 __free_page(cb->compressed_pages[faili]);
729                 faili--;
730         }
731
732         kfree(cb->compressed_pages);
733 fail1:
734         kfree(cb);
735 out:
736         free_extent_map(em);
737         return ret;
738 }
739
740 static struct list_head comp_idle_workspace[BTRFS_COMPRESS_TYPES];
741 static spinlock_t comp_workspace_lock[BTRFS_COMPRESS_TYPES];
742 static int comp_num_workspace[BTRFS_COMPRESS_TYPES];
743 static atomic_t comp_alloc_workspace[BTRFS_COMPRESS_TYPES];
744 static wait_queue_head_t comp_workspace_wait[BTRFS_COMPRESS_TYPES];
745
746 static struct btrfs_compress_op *btrfs_compress_op[] = {
747         &btrfs_zlib_compress,
748         &btrfs_lzo_compress,
749 };
750
751 void __init btrfs_init_compress(void)
752 {
753         int i;
754
755         for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
756                 INIT_LIST_HEAD(&comp_idle_workspace[i]);
757                 spin_lock_init(&comp_workspace_lock[i]);
758                 atomic_set(&comp_alloc_workspace[i], 0);
759                 init_waitqueue_head(&comp_workspace_wait[i]);
760         }
761 }
762
763 /*
764  * this finds an available workspace or allocates a new one
765  * ERR_PTR is returned if things go bad.
766  */
767 static struct list_head *find_workspace(int type)
768 {
769         struct list_head *workspace;
770         int cpus = num_online_cpus();
771         int idx = type - 1;
772
773         struct list_head *idle_workspace        = &comp_idle_workspace[idx];
774         spinlock_t *workspace_lock              = &comp_workspace_lock[idx];
775         atomic_t *alloc_workspace               = &comp_alloc_workspace[idx];
776         wait_queue_head_t *workspace_wait       = &comp_workspace_wait[idx];
777         int *num_workspace                      = &comp_num_workspace[idx];
778 again:
779         spin_lock(workspace_lock);
780         if (!list_empty(idle_workspace)) {
781                 workspace = idle_workspace->next;
782                 list_del(workspace);
783                 (*num_workspace)--;
784                 spin_unlock(workspace_lock);
785                 return workspace;
786
787         }
788         if (atomic_read(alloc_workspace) > cpus) {
789                 DEFINE_WAIT(wait);
790
791                 spin_unlock(workspace_lock);
792                 prepare_to_wait(workspace_wait, &wait, TASK_UNINTERRUPTIBLE);
793                 if (atomic_read(alloc_workspace) > cpus && !*num_workspace)
794                         schedule();
795                 finish_wait(workspace_wait, &wait);
796                 goto again;
797         }
798         atomic_inc(alloc_workspace);
799         spin_unlock(workspace_lock);
800
801         workspace = btrfs_compress_op[idx]->alloc_workspace();
802         if (IS_ERR(workspace)) {
803                 atomic_dec(alloc_workspace);
804                 wake_up(workspace_wait);
805         }
806         return workspace;
807 }
808
809 /*
810  * put a workspace struct back on the list or free it if we have enough
811  * idle ones sitting around
812  */
813 static void free_workspace(int type, struct list_head *workspace)
814 {
815         int idx = type - 1;
816         struct list_head *idle_workspace        = &comp_idle_workspace[idx];
817         spinlock_t *workspace_lock              = &comp_workspace_lock[idx];
818         atomic_t *alloc_workspace               = &comp_alloc_workspace[idx];
819         wait_queue_head_t *workspace_wait       = &comp_workspace_wait[idx];
820         int *num_workspace                      = &comp_num_workspace[idx];
821
822         spin_lock(workspace_lock);
823         if (*num_workspace < num_online_cpus()) {
824                 list_add_tail(workspace, idle_workspace);
825                 (*num_workspace)++;
826                 spin_unlock(workspace_lock);
827                 goto wake;
828         }
829         spin_unlock(workspace_lock);
830
831         btrfs_compress_op[idx]->free_workspace(workspace);
832         atomic_dec(alloc_workspace);
833 wake:
834         smp_mb();
835         if (waitqueue_active(workspace_wait))
836                 wake_up(workspace_wait);
837 }
838
839 /*
840  * cleanup function for module exit
841  */
842 static void free_workspaces(void)
843 {
844         struct list_head *workspace;
845         int i;
846
847         for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
848                 while (!list_empty(&comp_idle_workspace[i])) {
849                         workspace = comp_idle_workspace[i].next;
850                         list_del(workspace);
851                         btrfs_compress_op[i]->free_workspace(workspace);
852                         atomic_dec(&comp_alloc_workspace[i]);
853                 }
854         }
855 }
856
857 /*
858  * given an address space and start/len, compress the bytes.
859  *
860  * pages are allocated to hold the compressed result and stored
861  * in 'pages'
862  *
863  * out_pages is used to return the number of pages allocated.  There
864  * may be pages allocated even if we return an error
865  *
866  * total_in is used to return the number of bytes actually read.  It
867  * may be smaller then len if we had to exit early because we
868  * ran out of room in the pages array or because we cross the
869  * max_out threshold.
870  *
871  * total_out is used to return the total number of compressed bytes
872  *
873  * max_out tells us the max number of bytes that we're allowed to
874  * stuff into pages
875  */
876 int btrfs_compress_pages(int type, struct address_space *mapping,
877                          u64 start, unsigned long len,
878                          struct page **pages,
879                          unsigned long nr_dest_pages,
880                          unsigned long *out_pages,
881                          unsigned long *total_in,
882                          unsigned long *total_out,
883                          unsigned long max_out)
884 {
885         struct list_head *workspace;
886         int ret;
887
888         workspace = find_workspace(type);
889         if (IS_ERR(workspace))
890                 return -1;
891
892         ret = btrfs_compress_op[type-1]->compress_pages(workspace, mapping,
893                                                       start, len, pages,
894                                                       nr_dest_pages, out_pages,
895                                                       total_in, total_out,
896                                                       max_out);
897         free_workspace(type, workspace);
898         return ret;
899 }
900
901 /*
902  * pages_in is an array of pages with compressed data.
903  *
904  * disk_start is the starting logical offset of this array in the file
905  *
906  * bvec is a bio_vec of pages from the file that we want to decompress into
907  *
908  * vcnt is the count of pages in the biovec
909  *
910  * srclen is the number of bytes in pages_in
911  *
912  * The basic idea is that we have a bio that was created by readpages.
913  * The pages in the bio are for the uncompressed data, and they may not
914  * be contiguous.  They all correspond to the range of bytes covered by
915  * the compressed extent.
916  */
917 static int btrfs_decompress_biovec(int type, struct page **pages_in,
918                                    u64 disk_start, struct bio_vec *bvec,
919                                    int vcnt, size_t srclen)
920 {
921         struct list_head *workspace;
922         int ret;
923
924         workspace = find_workspace(type);
925         if (IS_ERR(workspace))
926                 return -ENOMEM;
927
928         ret = btrfs_compress_op[type-1]->decompress_biovec(workspace, pages_in,
929                                                          disk_start,
930                                                          bvec, vcnt, srclen);
931         free_workspace(type, workspace);
932         return ret;
933 }
934
935 /*
936  * a less complex decompression routine.  Our compressed data fits in a
937  * single page, and we want to read a single page out of it.
938  * start_byte tells us the offset into the compressed data we're interested in
939  */
940 int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
941                      unsigned long start_byte, size_t srclen, size_t destlen)
942 {
943         struct list_head *workspace;
944         int ret;
945
946         workspace = find_workspace(type);
947         if (IS_ERR(workspace))
948                 return -ENOMEM;
949
950         ret = btrfs_compress_op[type-1]->decompress(workspace, data_in,
951                                                   dest_page, start_byte,
952                                                   srclen, destlen);
953
954         free_workspace(type, workspace);
955         return ret;
956 }
957
958 void btrfs_exit_compress(void)
959 {
960         free_workspaces();
961 }
962
963 /*
964  * Copy uncompressed data from working buffer to pages.
965  *
966  * buf_start is the byte offset we're of the start of our workspace buffer.
967  *
968  * total_out is the last byte of the buffer
969  */
970 int btrfs_decompress_buf2page(char *buf, unsigned long buf_start,
971                               unsigned long total_out, u64 disk_start,
972                               struct bio_vec *bvec, int vcnt,
973                               unsigned long *pg_index,
974                               unsigned long *pg_offset)
975 {
976         unsigned long buf_offset;
977         unsigned long current_buf_start;
978         unsigned long start_byte;
979         unsigned long working_bytes = total_out - buf_start;
980         unsigned long bytes;
981         char *kaddr;
982         struct page *page_out = bvec[*pg_index].bv_page;
983
984         /*
985          * start byte is the first byte of the page we're currently
986          * copying into relative to the start of the compressed data.
987          */
988         start_byte = page_offset(page_out) - disk_start;
989
990         /* we haven't yet hit data corresponding to this page */
991         if (total_out <= start_byte)
992                 return 1;
993
994         /*
995          * the start of the data we care about is offset into
996          * the middle of our working buffer
997          */
998         if (total_out > start_byte && buf_start < start_byte) {
999                 buf_offset = start_byte - buf_start;
1000                 working_bytes -= buf_offset;
1001         } else {
1002                 buf_offset = 0;
1003         }
1004         current_buf_start = buf_start;
1005
1006         /* copy bytes from the working buffer into the pages */
1007         while (working_bytes > 0) {
1008                 bytes = min(PAGE_CACHE_SIZE - *pg_offset,
1009                             PAGE_CACHE_SIZE - buf_offset);
1010                 bytes = min(bytes, working_bytes);
1011                 kaddr = kmap_atomic(page_out);
1012                 memcpy(kaddr + *pg_offset, buf + buf_offset, bytes);
1013                 if (*pg_index == (vcnt - 1) && *pg_offset == 0)
1014                         memset(kaddr + bytes, 0, PAGE_CACHE_SIZE - bytes);
1015                 kunmap_atomic(kaddr);
1016                 flush_dcache_page(page_out);
1017
1018                 *pg_offset += bytes;
1019                 buf_offset += bytes;
1020                 working_bytes -= bytes;
1021                 current_buf_start += bytes;
1022
1023                 /* check if we need to pick another page */
1024                 if (*pg_offset == PAGE_CACHE_SIZE) {
1025                         (*pg_index)++;
1026                         if (*pg_index >= vcnt)
1027                                 return 0;
1028
1029                         page_out = bvec[*pg_index].bv_page;
1030                         *pg_offset = 0;
1031                         start_byte = page_offset(page_out) - disk_start;
1032
1033                         /*
1034                          * make sure our new page is covered by this
1035                          * working buffer
1036                          */
1037                         if (total_out <= start_byte)
1038                                 return 1;
1039
1040                         /*
1041                          * the next page in the biovec might not be adjacent
1042                          * to the last page, but it might still be found
1043                          * inside this working buffer. bump our offset pointer
1044                          */
1045                         if (total_out > start_byte &&
1046                             current_buf_start < start_byte) {
1047                                 buf_offset = start_byte - buf_start;
1048                                 working_bytes = total_out - start_byte;
1049                                 current_buf_start = buf_start + buf_offset;
1050                         }
1051                 }
1052         }
1053
1054         return 1;
1055 }