2 * Copyright (C) 2008 Oracle. All rights reserved.
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.
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.
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.
19 #include <linux/kernel.h>
20 #include <linux/bio.h>
21 #include <linux/buffer_head.h>
22 #include <linux/file.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>
37 #include "transaction.h"
38 #include "btrfs_inode.h"
40 #include "ordered-data.h"
41 #include "compression.h"
42 #include "extent_io.h"
43 #include "extent_map.h"
45 struct compressed_bio
{
46 /* number of bios pending for this compressed extent */
47 atomic_t pending_bios
;
49 /* the pages with the compressed data on them */
50 struct page
**compressed_pages
;
52 /* inode that owns this data */
55 /* starting offset in the inode for our pages */
58 /* number of bytes in the inode we're working on */
61 /* number of bytes on disk */
62 unsigned long compressed_len
;
64 /* the compression algorithm for this bio */
67 /* number of compressed pages in the array */
68 unsigned long nr_pages
;
74 /* for reads, this is the bio we are copying the data into */
78 * the start of a variable length array of checksums only
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
);
88 static inline int compressed_bio_size(struct btrfs_root
*root
,
89 unsigned long disk_size
)
91 u16 csum_size
= btrfs_super_csum_size(root
->fs_info
->super_copy
);
93 return sizeof(struct compressed_bio
) +
94 (DIV_ROUND_UP(disk_size
, root
->sectorsize
)) * csum_size
;
97 static struct bio
*compressed_bio_alloc(struct block_device
*bdev
,
98 u64 first_byte
, gfp_t gfp_flags
)
102 nr_vecs
= bio_get_nr_vecs(bdev
);
103 return btrfs_bio_alloc(bdev
, first_byte
>> 9, nr_vecs
, gfp_flags
);
106 static int check_compressed_csum(struct inode
*inode
,
107 struct compressed_bio
*cb
,
115 u32
*cb_sum
= &cb
->sums
;
117 if (BTRFS_I(inode
)->flags
& BTRFS_INODE_NODATASUM
)
120 for (i
= 0; i
< cb
->nr_pages
; i
++) {
121 page
= cb
->compressed_pages
[i
];
124 kaddr
= kmap_atomic(page
);
125 csum
= btrfs_csum_data(kaddr
, csum
, PAGE_CACHE_SIZE
);
126 btrfs_csum_final(csum
, (char *)&csum
);
127 kunmap_atomic(kaddr
);
129 if (csum
!= *cb_sum
) {
130 btrfs_info(BTRFS_I(inode
)->root
->fs_info
,
131 "csum failed ino %llu extent %llu csum %u wanted %u mirror %d",
132 btrfs_ino(inode
), disk_start
, csum
, *cb_sum
,
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).
149 * This allows the checksumming and other IO error handling routines
152 * The compressed pages are freed here, and it must be run
155 static void end_compressed_bio_read(struct bio
*bio
, int err
)
157 struct compressed_bio
*cb
= bio
->bi_private
;
166 /* if there are more bios still pending for this compressed
169 if (!atomic_dec_and_test(&cb
->pending_bios
))
173 ret
= check_compressed_csum(inode
, cb
,
174 (u64
)bio
->bi_iter
.bi_sector
<< 9);
178 /* ok, we're the last bio for this extent, lets start
181 ret
= btrfs_decompress_biovec(cb
->compress_type
,
182 cb
->compressed_pages
,
184 cb
->orig_bio
->bi_io_vec
,
185 cb
->orig_bio
->bi_vcnt
,
191 /* release the compressed pages */
193 for (index
= 0; index
< cb
->nr_pages
; index
++) {
194 page
= cb
->compressed_pages
[index
];
195 page
->mapping
= NULL
;
196 page_cache_release(page
);
199 /* do io completion on the original bio */
201 bio_io_error(cb
->orig_bio
);
204 struct bio_vec
*bvec
;
207 * we have verified the checksum already, set page
208 * checked so the end_io handlers know about it
210 bio_for_each_segment_all(bvec
, cb
->orig_bio
, i
)
211 SetPageChecked(bvec
->bv_page
);
213 bio_endio(cb
->orig_bio
, 0);
216 /* finally free the cb struct */
217 kfree(cb
->compressed_pages
);
224 * Clear the writeback bits on all of the file
225 * pages for a compressed write
227 static noinline
void end_compressed_writeback(struct inode
*inode
, u64 start
,
228 unsigned long ram_size
)
230 unsigned long index
= start
>> PAGE_CACHE_SHIFT
;
231 unsigned long end_index
= (start
+ ram_size
- 1) >> PAGE_CACHE_SHIFT
;
232 struct page
*pages
[16];
233 unsigned long nr_pages
= end_index
- index
+ 1;
237 while (nr_pages
> 0) {
238 ret
= find_get_pages_contig(inode
->i_mapping
, index
,
240 nr_pages
, ARRAY_SIZE(pages
)), pages
);
246 for (i
= 0; i
< ret
; i
++) {
247 end_page_writeback(pages
[i
]);
248 page_cache_release(pages
[i
]);
253 /* the inode may be gone now */
257 * do the cleanup once all the compressed pages hit the disk.
258 * This will clear writeback on the file pages and free the compressed
261 * This also calls the writeback end hooks for the file pages so that
262 * metadata and checksums can be updated in the file.
264 static void end_compressed_bio_write(struct bio
*bio
, int err
)
266 struct extent_io_tree
*tree
;
267 struct compressed_bio
*cb
= bio
->bi_private
;
275 /* if there are more bios still pending for this compressed
278 if (!atomic_dec_and_test(&cb
->pending_bios
))
281 /* ok, we're the last bio for this extent, step one is to
282 * call back into the FS and do all the end_io operations
285 tree
= &BTRFS_I(inode
)->io_tree
;
286 cb
->compressed_pages
[0]->mapping
= cb
->inode
->i_mapping
;
287 tree
->ops
->writepage_end_io_hook(cb
->compressed_pages
[0],
289 cb
->start
+ cb
->len
- 1,
291 cb
->compressed_pages
[0]->mapping
= NULL
;
293 end_compressed_writeback(inode
, cb
->start
, cb
->len
);
294 /* note, our inode could be gone now */
297 * release the compressed pages, these came from alloc_page and
298 * are not attached to the inode at all
301 for (index
= 0; index
< cb
->nr_pages
; index
++) {
302 page
= cb
->compressed_pages
[index
];
303 page
->mapping
= NULL
;
304 page_cache_release(page
);
307 /* finally free the cb struct */
308 kfree(cb
->compressed_pages
);
315 * worker function to build and submit bios for previously compressed pages.
316 * The corresponding pages in the inode should be marked for writeback
317 * and the compressed pages should have a reference on them for dropping
318 * when the IO is complete.
320 * This also checksums the file bytes and gets things ready for
323 int btrfs_submit_compressed_write(struct inode
*inode
, u64 start
,
324 unsigned long len
, u64 disk_start
,
325 unsigned long compressed_len
,
326 struct page
**compressed_pages
,
327 unsigned long nr_pages
)
329 struct bio
*bio
= NULL
;
330 struct btrfs_root
*root
= BTRFS_I(inode
)->root
;
331 struct compressed_bio
*cb
;
332 unsigned long bytes_left
;
333 struct extent_io_tree
*io_tree
= &BTRFS_I(inode
)->io_tree
;
336 u64 first_byte
= disk_start
;
337 struct block_device
*bdev
;
339 int skip_sum
= BTRFS_I(inode
)->flags
& BTRFS_INODE_NODATASUM
;
341 WARN_ON(start
& ((u64
)PAGE_CACHE_SIZE
- 1));
342 cb
= kmalloc(compressed_bio_size(root
, compressed_len
), GFP_NOFS
);
345 atomic_set(&cb
->pending_bios
, 0);
351 cb
->compressed_pages
= compressed_pages
;
352 cb
->compressed_len
= compressed_len
;
354 cb
->nr_pages
= nr_pages
;
356 bdev
= BTRFS_I(inode
)->root
->fs_info
->fs_devices
->latest_bdev
;
358 bio
= compressed_bio_alloc(bdev
, first_byte
, GFP_NOFS
);
363 bio
->bi_private
= cb
;
364 bio
->bi_end_io
= end_compressed_bio_write
;
365 atomic_inc(&cb
->pending_bios
);
367 /* create and submit bios for the compressed pages */
368 bytes_left
= compressed_len
;
369 for (pg_index
= 0; pg_index
< cb
->nr_pages
; pg_index
++) {
370 page
= compressed_pages
[pg_index
];
371 page
->mapping
= inode
->i_mapping
;
372 if (bio
->bi_iter
.bi_size
)
373 ret
= io_tree
->ops
->merge_bio_hook(WRITE
, page
, 0,
379 page
->mapping
= NULL
;
380 if (ret
|| bio_add_page(bio
, page
, PAGE_CACHE_SIZE
, 0) <
385 * inc the count before we submit the bio so
386 * we know the end IO handler won't happen before
387 * we inc the count. Otherwise, the cb might get
388 * freed before we're done setting it up
390 atomic_inc(&cb
->pending_bios
);
391 ret
= btrfs_bio_wq_end_io(root
->fs_info
, bio
,
392 BTRFS_WQ_ENDIO_DATA
);
393 BUG_ON(ret
); /* -ENOMEM */
396 ret
= btrfs_csum_one_bio(root
, inode
, bio
,
398 BUG_ON(ret
); /* -ENOMEM */
401 ret
= btrfs_map_bio(root
, WRITE
, bio
, 0, 1);
402 BUG_ON(ret
); /* -ENOMEM */
406 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);
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
);
417 bytes_left
-= PAGE_CACHE_SIZE
;
418 first_byte
+= PAGE_CACHE_SIZE
;
423 ret
= btrfs_bio_wq_end_io(root
->fs_info
, bio
, BTRFS_WQ_ENDIO_DATA
);
424 BUG_ON(ret
); /* -ENOMEM */
427 ret
= btrfs_csum_one_bio(root
, inode
, bio
, start
, 1);
428 BUG_ON(ret
); /* -ENOMEM */
431 ret
= btrfs_map_bio(root
, WRITE
, bio
, 0, 1);
432 BUG_ON(ret
); /* -ENOMEM */
438 static noinline
int add_ra_bio_pages(struct inode
*inode
,
440 struct compressed_bio
*cb
)
442 unsigned long end_index
;
443 unsigned long pg_index
;
445 u64 isize
= i_size_read(inode
);
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
;
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
;
464 end_index
= (i_size_read(inode
) - 1) >> PAGE_CACHE_SHIFT
;
466 while (last_offset
< compressed_end
) {
467 pg_index
= last_offset
>> PAGE_CACHE_SHIFT
;
469 if (pg_index
> end_index
)
473 page
= radix_tree_lookup(&mapping
->page_tree
, pg_index
);
475 if (page
&& !radix_tree_exceptional_entry(page
)) {
482 page
= __page_cache_alloc(mapping_gfp_mask(mapping
) &
487 if (add_to_page_cache_lru(page
, mapping
, pg_index
,
489 page_cache_release(page
);
493 end
= last_offset
+ PAGE_CACHE_SIZE
- 1;
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.
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
,
504 read_unlock(&em_tree
->lock
);
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
) {
510 unlock_extent(tree
, last_offset
, end
);
512 page_cache_release(page
);
517 if (page
->index
== end_index
) {
519 size_t zero_offset
= isize
& (PAGE_CACHE_SIZE
- 1);
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
);
531 ret
= bio_add_page(cb
->orig_bio
, page
,
534 if (ret
== PAGE_CACHE_SIZE
) {
536 page_cache_release(page
);
538 unlock_extent(tree
, last_offset
, end
);
540 page_cache_release(page
);
544 last_offset
+= PAGE_CACHE_SIZE
;
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.
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
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
561 int btrfs_submit_compressed_read(struct inode
*inode
, struct bio
*bio
,
562 int mirror_num
, unsigned long bio_flags
)
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
;
573 struct block_device
*bdev
;
574 struct bio
*comp_bio
;
575 u64 cur_disk_byte
= (u64
)bio
->bi_iter
.bi_sector
<< 9;
578 struct extent_map
*em
;
583 tree
= &BTRFS_I(inode
)->io_tree
;
584 em_tree
= &BTRFS_I(inode
)->extent_tree
;
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
),
591 read_unlock(&em_tree
->lock
);
595 compressed_len
= em
->block_len
;
596 cb
= kmalloc(compressed_bio_size(root
, compressed_len
), GFP_NOFS
);
600 atomic_set(&cb
->pending_bios
, 0);
603 cb
->mirror_num
= mirror_num
;
606 cb
->start
= em
->orig_start
;
608 em_start
= em
->start
;
613 cb
->len
= uncompressed_len
;
614 cb
->compressed_len
= compressed_len
;
615 cb
->compress_type
= extent_compress_type(bio_flags
);
618 nr_pages
= DIV_ROUND_UP(compressed_len
, PAGE_CACHE_SIZE
);
619 cb
->compressed_pages
= kzalloc(sizeof(struct page
*) * nr_pages
,
621 if (!cb
->compressed_pages
)
624 bdev
= BTRFS_I(inode
)->root
->fs_info
->fs_devices
->latest_bdev
;
626 for (pg_index
= 0; pg_index
< nr_pages
; pg_index
++) {
627 cb
->compressed_pages
[pg_index
] = alloc_page(GFP_NOFS
|
629 if (!cb
->compressed_pages
[pg_index
]) {
630 faili
= pg_index
- 1;
635 faili
= nr_pages
- 1;
636 cb
->nr_pages
= nr_pages
;
638 /* In the parent-locked case, we only locked the range we are
639 * interested in. In all other cases, we can opportunistically
640 * cache decompressed data that goes beyond the requested range. */
641 if (!(bio_flags
& EXTENT_BIO_PARENT_LOCKED
))
642 add_ra_bio_pages(inode
, em_start
+ em_len
, cb
);
644 /* include any pages we added in add_ra-bio_pages */
645 uncompressed_len
= bio
->bi_vcnt
* PAGE_CACHE_SIZE
;
646 cb
->len
= uncompressed_len
;
648 comp_bio
= compressed_bio_alloc(bdev
, cur_disk_byte
, GFP_NOFS
);
651 comp_bio
->bi_private
= cb
;
652 comp_bio
->bi_end_io
= end_compressed_bio_read
;
653 atomic_inc(&cb
->pending_bios
);
655 for (pg_index
= 0; pg_index
< nr_pages
; pg_index
++) {
656 page
= cb
->compressed_pages
[pg_index
];
657 page
->mapping
= inode
->i_mapping
;
658 page
->index
= em_start
>> PAGE_CACHE_SHIFT
;
660 if (comp_bio
->bi_iter
.bi_size
)
661 ret
= tree
->ops
->merge_bio_hook(READ
, page
, 0,
667 page
->mapping
= NULL
;
668 if (ret
|| bio_add_page(comp_bio
, page
, PAGE_CACHE_SIZE
, 0) <
672 ret
= btrfs_bio_wq_end_io(root
->fs_info
, comp_bio
,
673 BTRFS_WQ_ENDIO_DATA
);
674 BUG_ON(ret
); /* -ENOMEM */
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
682 atomic_inc(&cb
->pending_bios
);
684 if (!(BTRFS_I(inode
)->flags
& BTRFS_INODE_NODATASUM
)) {
685 ret
= btrfs_lookup_bio_sums(root
, inode
,
687 BUG_ON(ret
); /* -ENOMEM */
689 sums
+= DIV_ROUND_UP(comp_bio
->bi_iter
.bi_size
,
692 ret
= btrfs_map_bio(root
, READ
, comp_bio
,
695 bio_endio(comp_bio
, ret
);
699 comp_bio
= compressed_bio_alloc(bdev
, cur_disk_byte
,
702 comp_bio
->bi_private
= cb
;
703 comp_bio
->bi_end_io
= end_compressed_bio_read
;
705 bio_add_page(comp_bio
, page
, PAGE_CACHE_SIZE
, 0);
707 cur_disk_byte
+= PAGE_CACHE_SIZE
;
711 ret
= btrfs_bio_wq_end_io(root
->fs_info
, comp_bio
,
712 BTRFS_WQ_ENDIO_DATA
);
713 BUG_ON(ret
); /* -ENOMEM */
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 */
720 ret
= btrfs_map_bio(root
, READ
, comp_bio
, mirror_num
, 0);
722 bio_endio(comp_bio
, ret
);
729 __free_page(cb
->compressed_pages
[faili
]);
733 kfree(cb
->compressed_pages
);
741 static struct list_head comp_idle_workspace
[BTRFS_COMPRESS_TYPES
];
742 static spinlock_t comp_workspace_lock
[BTRFS_COMPRESS_TYPES
];
743 static int comp_num_workspace
[BTRFS_COMPRESS_TYPES
];
744 static atomic_t comp_alloc_workspace
[BTRFS_COMPRESS_TYPES
];
745 static wait_queue_head_t comp_workspace_wait
[BTRFS_COMPRESS_TYPES
];
747 static struct btrfs_compress_op
*btrfs_compress_op
[] = {
748 &btrfs_zlib_compress
,
752 void __init
btrfs_init_compress(void)
756 for (i
= 0; i
< BTRFS_COMPRESS_TYPES
; i
++) {
757 INIT_LIST_HEAD(&comp_idle_workspace
[i
]);
758 spin_lock_init(&comp_workspace_lock
[i
]);
759 atomic_set(&comp_alloc_workspace
[i
], 0);
760 init_waitqueue_head(&comp_workspace_wait
[i
]);
765 * this finds an available workspace or allocates a new one
766 * ERR_PTR is returned if things go bad.
768 static struct list_head
*find_workspace(int type
)
770 struct list_head
*workspace
;
771 int cpus
= num_online_cpus();
774 struct list_head
*idle_workspace
= &comp_idle_workspace
[idx
];
775 spinlock_t
*workspace_lock
= &comp_workspace_lock
[idx
];
776 atomic_t
*alloc_workspace
= &comp_alloc_workspace
[idx
];
777 wait_queue_head_t
*workspace_wait
= &comp_workspace_wait
[idx
];
778 int *num_workspace
= &comp_num_workspace
[idx
];
780 spin_lock(workspace_lock
);
781 if (!list_empty(idle_workspace
)) {
782 workspace
= idle_workspace
->next
;
785 spin_unlock(workspace_lock
);
789 if (atomic_read(alloc_workspace
) > cpus
) {
792 spin_unlock(workspace_lock
);
793 prepare_to_wait(workspace_wait
, &wait
, TASK_UNINTERRUPTIBLE
);
794 if (atomic_read(alloc_workspace
) > cpus
&& !*num_workspace
)
796 finish_wait(workspace_wait
, &wait
);
799 atomic_inc(alloc_workspace
);
800 spin_unlock(workspace_lock
);
802 workspace
= btrfs_compress_op
[idx
]->alloc_workspace();
803 if (IS_ERR(workspace
)) {
804 atomic_dec(alloc_workspace
);
805 wake_up(workspace_wait
);
811 * put a workspace struct back on the list or free it if we have enough
812 * idle ones sitting around
814 static void free_workspace(int type
, struct list_head
*workspace
)
817 struct list_head
*idle_workspace
= &comp_idle_workspace
[idx
];
818 spinlock_t
*workspace_lock
= &comp_workspace_lock
[idx
];
819 atomic_t
*alloc_workspace
= &comp_alloc_workspace
[idx
];
820 wait_queue_head_t
*workspace_wait
= &comp_workspace_wait
[idx
];
821 int *num_workspace
= &comp_num_workspace
[idx
];
823 spin_lock(workspace_lock
);
824 if (*num_workspace
< num_online_cpus()) {
825 list_add(workspace
, idle_workspace
);
827 spin_unlock(workspace_lock
);
830 spin_unlock(workspace_lock
);
832 btrfs_compress_op
[idx
]->free_workspace(workspace
);
833 atomic_dec(alloc_workspace
);
836 if (waitqueue_active(workspace_wait
))
837 wake_up(workspace_wait
);
841 * cleanup function for module exit
843 static void free_workspaces(void)
845 struct list_head
*workspace
;
848 for (i
= 0; i
< BTRFS_COMPRESS_TYPES
; i
++) {
849 while (!list_empty(&comp_idle_workspace
[i
])) {
850 workspace
= comp_idle_workspace
[i
].next
;
852 btrfs_compress_op
[i
]->free_workspace(workspace
);
853 atomic_dec(&comp_alloc_workspace
[i
]);
859 * given an address space and start/len, compress the bytes.
861 * pages are allocated to hold the compressed result and stored
864 * out_pages is used to return the number of pages allocated. There
865 * may be pages allocated even if we return an error
867 * total_in is used to return the number of bytes actually read. It
868 * may be smaller then len if we had to exit early because we
869 * ran out of room in the pages array or because we cross the
872 * total_out is used to return the total number of compressed bytes
874 * max_out tells us the max number of bytes that we're allowed to
877 int btrfs_compress_pages(int type
, struct address_space
*mapping
,
878 u64 start
, unsigned long len
,
880 unsigned long nr_dest_pages
,
881 unsigned long *out_pages
,
882 unsigned long *total_in
,
883 unsigned long *total_out
,
884 unsigned long max_out
)
886 struct list_head
*workspace
;
889 workspace
= find_workspace(type
);
890 if (IS_ERR(workspace
))
891 return PTR_ERR(workspace
);
893 ret
= btrfs_compress_op
[type
-1]->compress_pages(workspace
, mapping
,
895 nr_dest_pages
, out_pages
,
898 free_workspace(type
, workspace
);
903 * pages_in is an array of pages with compressed data.
905 * disk_start is the starting logical offset of this array in the file
907 * bvec is a bio_vec of pages from the file that we want to decompress into
909 * vcnt is the count of pages in the biovec
911 * srclen is the number of bytes in pages_in
913 * The basic idea is that we have a bio that was created by readpages.
914 * The pages in the bio are for the uncompressed data, and they may not
915 * be contiguous. They all correspond to the range of bytes covered by
916 * the compressed extent.
918 static int btrfs_decompress_biovec(int type
, struct page
**pages_in
,
919 u64 disk_start
, struct bio_vec
*bvec
,
920 int vcnt
, size_t srclen
)
922 struct list_head
*workspace
;
925 workspace
= find_workspace(type
);
926 if (IS_ERR(workspace
))
927 return PTR_ERR(workspace
);
929 ret
= btrfs_compress_op
[type
-1]->decompress_biovec(workspace
, pages_in
,
932 free_workspace(type
, workspace
);
937 * a less complex decompression routine. Our compressed data fits in a
938 * single page, and we want to read a single page out of it.
939 * start_byte tells us the offset into the compressed data we're interested in
941 int btrfs_decompress(int type
, unsigned char *data_in
, struct page
*dest_page
,
942 unsigned long start_byte
, size_t srclen
, size_t destlen
)
944 struct list_head
*workspace
;
947 workspace
= find_workspace(type
);
948 if (IS_ERR(workspace
))
949 return PTR_ERR(workspace
);
951 ret
= btrfs_compress_op
[type
-1]->decompress(workspace
, data_in
,
952 dest_page
, start_byte
,
955 free_workspace(type
, workspace
);
959 void btrfs_exit_compress(void)
965 * Copy uncompressed data from working buffer to pages.
967 * buf_start is the byte offset we're of the start of our workspace buffer.
969 * total_out is the last byte of the buffer
971 int btrfs_decompress_buf2page(char *buf
, unsigned long buf_start
,
972 unsigned long total_out
, u64 disk_start
,
973 struct bio_vec
*bvec
, int vcnt
,
974 unsigned long *pg_index
,
975 unsigned long *pg_offset
)
977 unsigned long buf_offset
;
978 unsigned long current_buf_start
;
979 unsigned long start_byte
;
980 unsigned long working_bytes
= total_out
- buf_start
;
983 struct page
*page_out
= bvec
[*pg_index
].bv_page
;
986 * start byte is the first byte of the page we're currently
987 * copying into relative to the start of the compressed data.
989 start_byte
= page_offset(page_out
) - disk_start
;
991 /* we haven't yet hit data corresponding to this page */
992 if (total_out
<= start_byte
)
996 * the start of the data we care about is offset into
997 * the middle of our working buffer
999 if (total_out
> start_byte
&& buf_start
< start_byte
) {
1000 buf_offset
= start_byte
- buf_start
;
1001 working_bytes
-= buf_offset
;
1005 current_buf_start
= buf_start
;
1007 /* copy bytes from the working buffer into the pages */
1008 while (working_bytes
> 0) {
1009 bytes
= min(PAGE_CACHE_SIZE
- *pg_offset
,
1010 PAGE_CACHE_SIZE
- buf_offset
);
1011 bytes
= min(bytes
, working_bytes
);
1012 kaddr
= kmap_atomic(page_out
);
1013 memcpy(kaddr
+ *pg_offset
, buf
+ buf_offset
, bytes
);
1014 kunmap_atomic(kaddr
);
1015 flush_dcache_page(page_out
);
1017 *pg_offset
+= bytes
;
1018 buf_offset
+= bytes
;
1019 working_bytes
-= bytes
;
1020 current_buf_start
+= bytes
;
1022 /* check if we need to pick another page */
1023 if (*pg_offset
== PAGE_CACHE_SIZE
) {
1025 if (*pg_index
>= vcnt
)
1028 page_out
= bvec
[*pg_index
].bv_page
;
1030 start_byte
= page_offset(page_out
) - disk_start
;
1033 * make sure our new page is covered by this
1036 if (total_out
<= start_byte
)
1040 * the next page in the biovec might not be adjacent
1041 * to the last page, but it might still be found
1042 * inside this working buffer. bump our offset pointer
1044 if (total_out
> start_byte
&&
1045 current_buf_start
< start_byte
) {
1046 buf_offset
= start_byte
- buf_start
;
1047 working_bytes
= total_out
- start_byte
;
1048 current_buf_start
= buf_start
+ buf_offset
;
1057 * When uncompressing data, we need to make sure and zero any parts of
1058 * the biovec that were not filled in by the decompression code. pg_index
1059 * and pg_offset indicate the last page and the last offset of that page
1060 * that have been filled in. This will zero everything remaining in the
1063 void btrfs_clear_biovec_end(struct bio_vec
*bvec
, int vcnt
,
1064 unsigned long pg_index
,
1065 unsigned long pg_offset
)
1067 while (pg_index
< vcnt
) {
1068 struct page
*page
= bvec
[pg_index
].bv_page
;
1069 unsigned long off
= bvec
[pg_index
].bv_offset
;
1070 unsigned long len
= bvec
[pg_index
].bv_len
;
1072 if (pg_offset
< off
)
1074 if (pg_offset
< off
+ len
) {
1075 unsigned long bytes
= off
+ len
- pg_offset
;
1078 kaddr
= kmap_atomic(page
);
1079 memset(kaddr
+ pg_offset
, 0, bytes
);
1080 kunmap_atomic(kaddr
);