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>
35 #include <linux/sched/mm.h>
38 #include "transaction.h"
39 #include "btrfs_inode.h"
41 #include "ordered-data.h"
42 #include "compression.h"
43 #include "extent_io.h"
44 #include "extent_map.h"
46 static int btrfs_decompress_bio(struct compressed_bio
*cb
);
48 static inline int compressed_bio_size(struct btrfs_fs_info
*fs_info
,
49 unsigned long disk_size
)
51 u16 csum_size
= btrfs_super_csum_size(fs_info
->super_copy
);
53 return sizeof(struct compressed_bio
) +
54 (DIV_ROUND_UP(disk_size
, fs_info
->sectorsize
)) * csum_size
;
57 static int check_compressed_csum(struct btrfs_inode
*inode
,
58 struct compressed_bio
*cb
,
66 u32
*cb_sum
= &cb
->sums
;
68 if (inode
->flags
& BTRFS_INODE_NODATASUM
)
71 for (i
= 0; i
< cb
->nr_pages
; i
++) {
72 page
= cb
->compressed_pages
[i
];
75 kaddr
= kmap_atomic(page
);
76 csum
= btrfs_csum_data(kaddr
, csum
, PAGE_SIZE
);
77 btrfs_csum_final(csum
, (u8
*)&csum
);
80 if (csum
!= *cb_sum
) {
81 btrfs_print_data_csum_error(inode
, disk_start
, csum
,
82 *cb_sum
, cb
->mirror_num
);
94 /* when we finish reading compressed pages from the disk, we
95 * decompress them and then run the bio end_io routines on the
96 * decompressed pages (in the inode address space).
98 * This allows the checksumming and other IO error handling routines
101 * The compressed pages are freed here, and it must be run
104 static void end_compressed_bio_read(struct bio
*bio
)
106 struct compressed_bio
*cb
= bio
->bi_private
;
110 unsigned int mirror
= btrfs_io_bio(bio
)->mirror_num
;
116 /* if there are more bios still pending for this compressed
119 if (!refcount_dec_and_test(&cb
->pending_bios
))
123 * Record the correct mirror_num in cb->orig_bio so that
124 * read-repair can work properly.
126 ASSERT(btrfs_io_bio(cb
->orig_bio
));
127 btrfs_io_bio(cb
->orig_bio
)->mirror_num
= mirror
;
128 cb
->mirror_num
= mirror
;
131 * Some IO in this cb have failed, just skip checksum as there
132 * is no way it could be correct.
138 ret
= check_compressed_csum(BTRFS_I(inode
), cb
,
139 (u64
)bio
->bi_iter
.bi_sector
<< 9);
143 /* ok, we're the last bio for this extent, lets start
146 ret
= btrfs_decompress_bio(cb
);
152 /* release the compressed pages */
154 for (index
= 0; index
< cb
->nr_pages
; index
++) {
155 page
= cb
->compressed_pages
[index
];
156 page
->mapping
= NULL
;
160 /* do io completion on the original bio */
162 bio_io_error(cb
->orig_bio
);
165 struct bio_vec
*bvec
;
168 * we have verified the checksum already, set page
169 * checked so the end_io handlers know about it
171 ASSERT(!bio_flagged(bio
, BIO_CLONED
));
172 bio_for_each_segment_all(bvec
, cb
->orig_bio
, i
)
173 SetPageChecked(bvec
->bv_page
);
175 bio_endio(cb
->orig_bio
);
178 /* finally free the cb struct */
179 kfree(cb
->compressed_pages
);
186 * Clear the writeback bits on all of the file
187 * pages for a compressed write
189 static noinline
void end_compressed_writeback(struct inode
*inode
,
190 const struct compressed_bio
*cb
)
192 unsigned long index
= cb
->start
>> PAGE_SHIFT
;
193 unsigned long end_index
= (cb
->start
+ cb
->len
- 1) >> PAGE_SHIFT
;
194 struct page
*pages
[16];
195 unsigned long nr_pages
= end_index
- index
+ 1;
200 mapping_set_error(inode
->i_mapping
, -EIO
);
202 while (nr_pages
> 0) {
203 ret
= find_get_pages_contig(inode
->i_mapping
, index
,
205 nr_pages
, ARRAY_SIZE(pages
)), pages
);
211 for (i
= 0; i
< ret
; i
++) {
213 SetPageError(pages
[i
]);
214 end_page_writeback(pages
[i
]);
220 /* the inode may be gone now */
224 * do the cleanup once all the compressed pages hit the disk.
225 * This will clear writeback on the file pages and free the compressed
228 * This also calls the writeback end hooks for the file pages so that
229 * metadata and checksums can be updated in the file.
231 static void end_compressed_bio_write(struct bio
*bio
)
233 struct extent_io_tree
*tree
;
234 struct compressed_bio
*cb
= bio
->bi_private
;
242 /* if there are more bios still pending for this compressed
245 if (!refcount_dec_and_test(&cb
->pending_bios
))
248 /* ok, we're the last bio for this extent, step one is to
249 * call back into the FS and do all the end_io operations
252 tree
= &BTRFS_I(inode
)->io_tree
;
253 cb
->compressed_pages
[0]->mapping
= cb
->inode
->i_mapping
;
254 tree
->ops
->writepage_end_io_hook(cb
->compressed_pages
[0],
256 cb
->start
+ cb
->len
- 1,
258 bio
->bi_status
? 0 : 1);
259 cb
->compressed_pages
[0]->mapping
= NULL
;
261 end_compressed_writeback(inode
, cb
);
262 /* note, our inode could be gone now */
265 * release the compressed pages, these came from alloc_page and
266 * are not attached to the inode at all
269 for (index
= 0; index
< cb
->nr_pages
; index
++) {
270 page
= cb
->compressed_pages
[index
];
271 page
->mapping
= NULL
;
275 /* finally free the cb struct */
276 kfree(cb
->compressed_pages
);
283 * worker function to build and submit bios for previously compressed pages.
284 * The corresponding pages in the inode should be marked for writeback
285 * and the compressed pages should have a reference on them for dropping
286 * when the IO is complete.
288 * This also checksums the file bytes and gets things ready for
291 blk_status_t
btrfs_submit_compressed_write(struct inode
*inode
, u64 start
,
292 unsigned long len
, u64 disk_start
,
293 unsigned long compressed_len
,
294 struct page
**compressed_pages
,
295 unsigned long nr_pages
)
297 struct btrfs_fs_info
*fs_info
= btrfs_sb(inode
->i_sb
);
298 struct bio
*bio
= NULL
;
299 struct compressed_bio
*cb
;
300 unsigned long bytes_left
;
301 struct extent_io_tree
*io_tree
= &BTRFS_I(inode
)->io_tree
;
304 u64 first_byte
= disk_start
;
305 struct block_device
*bdev
;
307 int skip_sum
= BTRFS_I(inode
)->flags
& BTRFS_INODE_NODATASUM
;
309 WARN_ON(start
& ((u64
)PAGE_SIZE
- 1));
310 cb
= kmalloc(compressed_bio_size(fs_info
, compressed_len
), GFP_NOFS
);
312 return BLK_STS_RESOURCE
;
313 refcount_set(&cb
->pending_bios
, 0);
319 cb
->compressed_pages
= compressed_pages
;
320 cb
->compressed_len
= compressed_len
;
322 cb
->nr_pages
= nr_pages
;
324 bdev
= fs_info
->fs_devices
->latest_bdev
;
326 bio
= btrfs_bio_alloc(bdev
, first_byte
);
327 bio_set_op_attrs(bio
, REQ_OP_WRITE
, 0);
328 bio
->bi_private
= cb
;
329 bio
->bi_end_io
= end_compressed_bio_write
;
330 refcount_set(&cb
->pending_bios
, 1);
332 /* create and submit bios for the compressed pages */
333 bytes_left
= compressed_len
;
334 for (pg_index
= 0; pg_index
< cb
->nr_pages
; pg_index
++) {
337 page
= compressed_pages
[pg_index
];
338 page
->mapping
= inode
->i_mapping
;
339 if (bio
->bi_iter
.bi_size
)
340 submit
= io_tree
->ops
->merge_bio_hook(page
, 0,
344 page
->mapping
= NULL
;
345 if (submit
|| bio_add_page(bio
, page
, PAGE_SIZE
, 0) <
350 * inc the count before we submit the bio so
351 * we know the end IO handler won't happen before
352 * we inc the count. Otherwise, the cb might get
353 * freed before we're done setting it up
355 refcount_inc(&cb
->pending_bios
);
356 ret
= btrfs_bio_wq_end_io(fs_info
, bio
,
357 BTRFS_WQ_ENDIO_DATA
);
358 BUG_ON(ret
); /* -ENOMEM */
361 ret
= btrfs_csum_one_bio(inode
, bio
, start
, 1);
362 BUG_ON(ret
); /* -ENOMEM */
365 ret
= btrfs_map_bio(fs_info
, bio
, 0, 1);
367 bio
->bi_status
= ret
;
373 bio
= btrfs_bio_alloc(bdev
, first_byte
);
374 bio_set_op_attrs(bio
, REQ_OP_WRITE
, 0);
375 bio
->bi_private
= cb
;
376 bio
->bi_end_io
= end_compressed_bio_write
;
377 bio_add_page(bio
, page
, PAGE_SIZE
, 0);
379 if (bytes_left
< PAGE_SIZE
) {
381 "bytes left %lu compress len %lu nr %lu",
382 bytes_left
, cb
->compressed_len
, cb
->nr_pages
);
384 bytes_left
-= PAGE_SIZE
;
385 first_byte
+= PAGE_SIZE
;
390 ret
= btrfs_bio_wq_end_io(fs_info
, bio
, BTRFS_WQ_ENDIO_DATA
);
391 BUG_ON(ret
); /* -ENOMEM */
394 ret
= btrfs_csum_one_bio(inode
, bio
, start
, 1);
395 BUG_ON(ret
); /* -ENOMEM */
398 ret
= btrfs_map_bio(fs_info
, bio
, 0, 1);
400 bio
->bi_status
= ret
;
408 static u64
bio_end_offset(struct bio
*bio
)
410 struct bio_vec
*last
= &bio
->bi_io_vec
[bio
->bi_vcnt
- 1];
412 return page_offset(last
->bv_page
) + last
->bv_len
+ last
->bv_offset
;
415 static noinline
int add_ra_bio_pages(struct inode
*inode
,
417 struct compressed_bio
*cb
)
419 unsigned long end_index
;
420 unsigned long pg_index
;
422 u64 isize
= i_size_read(inode
);
425 unsigned long nr_pages
= 0;
426 struct extent_map
*em
;
427 struct address_space
*mapping
= inode
->i_mapping
;
428 struct extent_map_tree
*em_tree
;
429 struct extent_io_tree
*tree
;
433 last_offset
= bio_end_offset(cb
->orig_bio
);
434 em_tree
= &BTRFS_I(inode
)->extent_tree
;
435 tree
= &BTRFS_I(inode
)->io_tree
;
440 end_index
= (i_size_read(inode
) - 1) >> PAGE_SHIFT
;
442 while (last_offset
< compressed_end
) {
443 pg_index
= last_offset
>> PAGE_SHIFT
;
445 if (pg_index
> end_index
)
449 page
= radix_tree_lookup(&mapping
->page_tree
, pg_index
);
451 if (page
&& !radix_tree_exceptional_entry(page
)) {
458 page
= __page_cache_alloc(mapping_gfp_constraint(mapping
,
463 if (add_to_page_cache_lru(page
, mapping
, pg_index
, GFP_NOFS
)) {
468 end
= last_offset
+ PAGE_SIZE
- 1;
470 * at this point, we have a locked page in the page cache
471 * for these bytes in the file. But, we have to make
472 * sure they map to this compressed extent on disk.
474 set_page_extent_mapped(page
);
475 lock_extent(tree
, last_offset
, end
);
476 read_lock(&em_tree
->lock
);
477 em
= lookup_extent_mapping(em_tree
, last_offset
,
479 read_unlock(&em_tree
->lock
);
481 if (!em
|| last_offset
< em
->start
||
482 (last_offset
+ PAGE_SIZE
> extent_map_end(em
)) ||
483 (em
->block_start
>> 9) != cb
->orig_bio
->bi_iter
.bi_sector
) {
485 unlock_extent(tree
, last_offset
, end
);
492 if (page
->index
== end_index
) {
494 size_t zero_offset
= isize
& (PAGE_SIZE
- 1);
498 zeros
= PAGE_SIZE
- zero_offset
;
499 userpage
= kmap_atomic(page
);
500 memset(userpage
+ zero_offset
, 0, zeros
);
501 flush_dcache_page(page
);
502 kunmap_atomic(userpage
);
506 ret
= bio_add_page(cb
->orig_bio
, page
,
509 if (ret
== PAGE_SIZE
) {
513 unlock_extent(tree
, last_offset
, end
);
519 last_offset
+= PAGE_SIZE
;
525 * for a compressed read, the bio we get passed has all the inode pages
526 * in it. We don't actually do IO on those pages but allocate new ones
527 * to hold the compressed pages on disk.
529 * bio->bi_iter.bi_sector points to the compressed extent on disk
530 * bio->bi_io_vec points to all of the inode pages
532 * After the compressed pages are read, we copy the bytes into the
533 * bio we were passed and then call the bio end_io calls
535 blk_status_t
btrfs_submit_compressed_read(struct inode
*inode
, struct bio
*bio
,
536 int mirror_num
, unsigned long bio_flags
)
538 struct btrfs_fs_info
*fs_info
= btrfs_sb(inode
->i_sb
);
539 struct extent_io_tree
*tree
;
540 struct extent_map_tree
*em_tree
;
541 struct compressed_bio
*cb
;
542 unsigned long compressed_len
;
543 unsigned long nr_pages
;
544 unsigned long pg_index
;
546 struct block_device
*bdev
;
547 struct bio
*comp_bio
;
548 u64 cur_disk_byte
= (u64
)bio
->bi_iter
.bi_sector
<< 9;
551 struct extent_map
*em
;
552 blk_status_t ret
= BLK_STS_RESOURCE
;
556 tree
= &BTRFS_I(inode
)->io_tree
;
557 em_tree
= &BTRFS_I(inode
)->extent_tree
;
559 /* we need the actual starting offset of this extent in the file */
560 read_lock(&em_tree
->lock
);
561 em
= lookup_extent_mapping(em_tree
,
562 page_offset(bio
->bi_io_vec
->bv_page
),
564 read_unlock(&em_tree
->lock
);
566 return BLK_STS_IOERR
;
568 compressed_len
= em
->block_len
;
569 cb
= kmalloc(compressed_bio_size(fs_info
, compressed_len
), GFP_NOFS
);
573 refcount_set(&cb
->pending_bios
, 0);
576 cb
->mirror_num
= mirror_num
;
579 cb
->start
= em
->orig_start
;
581 em_start
= em
->start
;
586 cb
->len
= bio
->bi_iter
.bi_size
;
587 cb
->compressed_len
= compressed_len
;
588 cb
->compress_type
= extent_compress_type(bio_flags
);
591 nr_pages
= DIV_ROUND_UP(compressed_len
, PAGE_SIZE
);
592 cb
->compressed_pages
= kcalloc(nr_pages
, sizeof(struct page
*),
594 if (!cb
->compressed_pages
)
597 bdev
= fs_info
->fs_devices
->latest_bdev
;
599 for (pg_index
= 0; pg_index
< nr_pages
; pg_index
++) {
600 cb
->compressed_pages
[pg_index
] = alloc_page(GFP_NOFS
|
602 if (!cb
->compressed_pages
[pg_index
]) {
603 faili
= pg_index
- 1;
604 ret
= BLK_STS_RESOURCE
;
608 faili
= nr_pages
- 1;
609 cb
->nr_pages
= nr_pages
;
611 add_ra_bio_pages(inode
, em_start
+ em_len
, cb
);
613 /* include any pages we added in add_ra-bio_pages */
614 cb
->len
= bio
->bi_iter
.bi_size
;
616 comp_bio
= btrfs_bio_alloc(bdev
, cur_disk_byte
);
617 bio_set_op_attrs (comp_bio
, REQ_OP_READ
, 0);
618 comp_bio
->bi_private
= cb
;
619 comp_bio
->bi_end_io
= end_compressed_bio_read
;
620 refcount_set(&cb
->pending_bios
, 1);
622 for (pg_index
= 0; pg_index
< nr_pages
; pg_index
++) {
625 page
= cb
->compressed_pages
[pg_index
];
626 page
->mapping
= inode
->i_mapping
;
627 page
->index
= em_start
>> PAGE_SHIFT
;
629 if (comp_bio
->bi_iter
.bi_size
)
630 submit
= tree
->ops
->merge_bio_hook(page
, 0,
634 page
->mapping
= NULL
;
635 if (submit
|| bio_add_page(comp_bio
, page
, PAGE_SIZE
, 0) <
639 ret
= btrfs_bio_wq_end_io(fs_info
, comp_bio
,
640 BTRFS_WQ_ENDIO_DATA
);
641 BUG_ON(ret
); /* -ENOMEM */
644 * inc the count before we submit the bio so
645 * we know the end IO handler won't happen before
646 * we inc the count. Otherwise, the cb might get
647 * freed before we're done setting it up
649 refcount_inc(&cb
->pending_bios
);
651 if (!(BTRFS_I(inode
)->flags
& BTRFS_INODE_NODATASUM
)) {
652 ret
= btrfs_lookup_bio_sums(inode
, comp_bio
,
654 BUG_ON(ret
); /* -ENOMEM */
656 sums
+= DIV_ROUND_UP(comp_bio
->bi_iter
.bi_size
,
657 fs_info
->sectorsize
);
659 ret
= btrfs_map_bio(fs_info
, comp_bio
, mirror_num
, 0);
661 comp_bio
->bi_status
= ret
;
667 comp_bio
= btrfs_bio_alloc(bdev
, cur_disk_byte
);
668 bio_set_op_attrs(comp_bio
, REQ_OP_READ
, 0);
669 comp_bio
->bi_private
= cb
;
670 comp_bio
->bi_end_io
= end_compressed_bio_read
;
672 bio_add_page(comp_bio
, page
, PAGE_SIZE
, 0);
674 cur_disk_byte
+= PAGE_SIZE
;
678 ret
= btrfs_bio_wq_end_io(fs_info
, comp_bio
, BTRFS_WQ_ENDIO_DATA
);
679 BUG_ON(ret
); /* -ENOMEM */
681 if (!(BTRFS_I(inode
)->flags
& BTRFS_INODE_NODATASUM
)) {
682 ret
= btrfs_lookup_bio_sums(inode
, comp_bio
, sums
);
683 BUG_ON(ret
); /* -ENOMEM */
686 ret
= btrfs_map_bio(fs_info
, comp_bio
, mirror_num
, 0);
688 comp_bio
->bi_status
= ret
;
697 __free_page(cb
->compressed_pages
[faili
]);
701 kfree(cb
->compressed_pages
);
710 struct list_head idle_ws
;
712 /* Number of free workspaces */
714 /* Total number of allocated workspaces */
716 /* Waiters for a free workspace */
717 wait_queue_head_t ws_wait
;
718 } btrfs_comp_ws
[BTRFS_COMPRESS_TYPES
];
720 static const struct btrfs_compress_op
* const btrfs_compress_op
[] = {
721 &btrfs_zlib_compress
,
723 &btrfs_zstd_compress
,
726 void __init
btrfs_init_compress(void)
730 for (i
= 0; i
< BTRFS_COMPRESS_TYPES
; i
++) {
731 struct list_head
*workspace
;
733 INIT_LIST_HEAD(&btrfs_comp_ws
[i
].idle_ws
);
734 spin_lock_init(&btrfs_comp_ws
[i
].ws_lock
);
735 atomic_set(&btrfs_comp_ws
[i
].total_ws
, 0);
736 init_waitqueue_head(&btrfs_comp_ws
[i
].ws_wait
);
739 * Preallocate one workspace for each compression type so
740 * we can guarantee forward progress in the worst case
742 workspace
= btrfs_compress_op
[i
]->alloc_workspace();
743 if (IS_ERR(workspace
)) {
744 pr_warn("BTRFS: cannot preallocate compression workspace, will try later\n");
746 atomic_set(&btrfs_comp_ws
[i
].total_ws
, 1);
747 btrfs_comp_ws
[i
].free_ws
= 1;
748 list_add(workspace
, &btrfs_comp_ws
[i
].idle_ws
);
754 * This finds an available workspace or allocates a new one.
755 * If it's not possible to allocate a new one, waits until there's one.
756 * Preallocation makes a forward progress guarantees and we do not return
759 static struct list_head
*find_workspace(int type
)
761 struct list_head
*workspace
;
762 int cpus
= num_online_cpus();
766 struct list_head
*idle_ws
= &btrfs_comp_ws
[idx
].idle_ws
;
767 spinlock_t
*ws_lock
= &btrfs_comp_ws
[idx
].ws_lock
;
768 atomic_t
*total_ws
= &btrfs_comp_ws
[idx
].total_ws
;
769 wait_queue_head_t
*ws_wait
= &btrfs_comp_ws
[idx
].ws_wait
;
770 int *free_ws
= &btrfs_comp_ws
[idx
].free_ws
;
773 if (!list_empty(idle_ws
)) {
774 workspace
= idle_ws
->next
;
777 spin_unlock(ws_lock
);
781 if (atomic_read(total_ws
) > cpus
) {
784 spin_unlock(ws_lock
);
785 prepare_to_wait(ws_wait
, &wait
, TASK_UNINTERRUPTIBLE
);
786 if (atomic_read(total_ws
) > cpus
&& !*free_ws
)
788 finish_wait(ws_wait
, &wait
);
791 atomic_inc(total_ws
);
792 spin_unlock(ws_lock
);
795 * Allocation helpers call vmalloc that can't use GFP_NOFS, so we have
796 * to turn it off here because we might get called from the restricted
797 * context of btrfs_compress_bio/btrfs_compress_pages
799 nofs_flag
= memalloc_nofs_save();
800 workspace
= btrfs_compress_op
[idx
]->alloc_workspace();
801 memalloc_nofs_restore(nofs_flag
);
803 if (IS_ERR(workspace
)) {
804 atomic_dec(total_ws
);
808 * Do not return the error but go back to waiting. There's a
809 * workspace preallocated for each type and the compression
810 * time is bounded so we get to a workspace eventually. This
811 * makes our caller's life easier.
813 * To prevent silent and low-probability deadlocks (when the
814 * initial preallocation fails), check if there are any
817 if (atomic_read(total_ws
) == 0) {
818 static DEFINE_RATELIMIT_STATE(_rs
,
819 /* once per minute */ 60 * HZ
,
822 if (__ratelimit(&_rs
)) {
823 pr_warn("BTRFS: no compression workspaces, low memory, retrying\n");
832 * put a workspace struct back on the list or free it if we have enough
833 * idle ones sitting around
835 static void free_workspace(int type
, struct list_head
*workspace
)
838 struct list_head
*idle_ws
= &btrfs_comp_ws
[idx
].idle_ws
;
839 spinlock_t
*ws_lock
= &btrfs_comp_ws
[idx
].ws_lock
;
840 atomic_t
*total_ws
= &btrfs_comp_ws
[idx
].total_ws
;
841 wait_queue_head_t
*ws_wait
= &btrfs_comp_ws
[idx
].ws_wait
;
842 int *free_ws
= &btrfs_comp_ws
[idx
].free_ws
;
845 if (*free_ws
<= num_online_cpus()) {
846 list_add(workspace
, idle_ws
);
848 spin_unlock(ws_lock
);
851 spin_unlock(ws_lock
);
853 btrfs_compress_op
[idx
]->free_workspace(workspace
);
854 atomic_dec(total_ws
);
857 * Make sure counter is updated before we wake up waiters.
860 if (waitqueue_active(ws_wait
))
865 * cleanup function for module exit
867 static void free_workspaces(void)
869 struct list_head
*workspace
;
872 for (i
= 0; i
< BTRFS_COMPRESS_TYPES
; i
++) {
873 while (!list_empty(&btrfs_comp_ws
[i
].idle_ws
)) {
874 workspace
= btrfs_comp_ws
[i
].idle_ws
.next
;
876 btrfs_compress_op
[i
]->free_workspace(workspace
);
877 atomic_dec(&btrfs_comp_ws
[i
].total_ws
);
883 * Given an address space and start and length, compress the bytes into @pages
884 * that are allocated on demand.
886 * @out_pages is an in/out parameter, holds maximum number of pages to allocate
887 * and returns number of actually allocated pages
889 * @total_in is used to return the number of bytes actually read. It
890 * may be smaller than the input length if we had to exit early because we
891 * ran out of room in the pages array or because we cross the
894 * @total_out is an in/out parameter, must be set to the input length and will
895 * be also used to return the total number of compressed bytes
897 * @max_out tells us the max number of bytes that we're allowed to
900 int btrfs_compress_pages(int type
, struct address_space
*mapping
,
901 u64 start
, struct page
**pages
,
902 unsigned long *out_pages
,
903 unsigned long *total_in
,
904 unsigned long *total_out
)
906 struct list_head
*workspace
;
909 workspace
= find_workspace(type
);
911 ret
= btrfs_compress_op
[type
-1]->compress_pages(workspace
, mapping
,
914 total_in
, total_out
);
915 free_workspace(type
, workspace
);
920 * pages_in is an array of pages with compressed data.
922 * disk_start is the starting logical offset of this array in the file
924 * orig_bio contains the pages from the file that we want to decompress into
926 * srclen is the number of bytes in pages_in
928 * The basic idea is that we have a bio that was created by readpages.
929 * The pages in the bio are for the uncompressed data, and they may not
930 * be contiguous. They all correspond to the range of bytes covered by
931 * the compressed extent.
933 static int btrfs_decompress_bio(struct compressed_bio
*cb
)
935 struct list_head
*workspace
;
937 int type
= cb
->compress_type
;
939 workspace
= find_workspace(type
);
940 ret
= btrfs_compress_op
[type
- 1]->decompress_bio(workspace
, cb
);
941 free_workspace(type
, workspace
);
947 * a less complex decompression routine. Our compressed data fits in a
948 * single page, and we want to read a single page out of it.
949 * start_byte tells us the offset into the compressed data we're interested in
951 int btrfs_decompress(int type
, unsigned char *data_in
, struct page
*dest_page
,
952 unsigned long start_byte
, size_t srclen
, size_t destlen
)
954 struct list_head
*workspace
;
957 workspace
= find_workspace(type
);
959 ret
= btrfs_compress_op
[type
-1]->decompress(workspace
, data_in
,
960 dest_page
, start_byte
,
963 free_workspace(type
, workspace
);
967 void btrfs_exit_compress(void)
973 * Copy uncompressed data from working buffer to pages.
975 * buf_start is the byte offset we're of the start of our workspace buffer.
977 * total_out is the last byte of the buffer
979 int btrfs_decompress_buf2page(const char *buf
, unsigned long buf_start
,
980 unsigned long total_out
, u64 disk_start
,
983 unsigned long buf_offset
;
984 unsigned long current_buf_start
;
985 unsigned long start_byte
;
986 unsigned long prev_start_byte
;
987 unsigned long working_bytes
= total_out
- buf_start
;
990 struct bio_vec bvec
= bio_iter_iovec(bio
, bio
->bi_iter
);
993 * start byte is the first byte of the page we're currently
994 * copying into relative to the start of the compressed data.
996 start_byte
= page_offset(bvec
.bv_page
) - disk_start
;
998 /* we haven't yet hit data corresponding to this page */
999 if (total_out
<= start_byte
)
1003 * the start of the data we care about is offset into
1004 * the middle of our working buffer
1006 if (total_out
> start_byte
&& buf_start
< start_byte
) {
1007 buf_offset
= start_byte
- buf_start
;
1008 working_bytes
-= buf_offset
;
1012 current_buf_start
= buf_start
;
1014 /* copy bytes from the working buffer into the pages */
1015 while (working_bytes
> 0) {
1016 bytes
= min_t(unsigned long, bvec
.bv_len
,
1017 PAGE_SIZE
- buf_offset
);
1018 bytes
= min(bytes
, working_bytes
);
1020 kaddr
= kmap_atomic(bvec
.bv_page
);
1021 memcpy(kaddr
+ bvec
.bv_offset
, buf
+ buf_offset
, bytes
);
1022 kunmap_atomic(kaddr
);
1023 flush_dcache_page(bvec
.bv_page
);
1025 buf_offset
+= bytes
;
1026 working_bytes
-= bytes
;
1027 current_buf_start
+= bytes
;
1029 /* check if we need to pick another page */
1030 bio_advance(bio
, bytes
);
1031 if (!bio
->bi_iter
.bi_size
)
1033 bvec
= bio_iter_iovec(bio
, bio
->bi_iter
);
1034 prev_start_byte
= start_byte
;
1035 start_byte
= page_offset(bvec
.bv_page
) - disk_start
;
1038 * We need to make sure we're only adjusting
1039 * our offset into compression working buffer when
1040 * we're switching pages. Otherwise we can incorrectly
1041 * keep copying when we were actually done.
1043 if (start_byte
!= prev_start_byte
) {
1045 * make sure our new page is covered by this
1048 if (total_out
<= start_byte
)
1052 * the next page in the biovec might not be adjacent
1053 * to the last page, but it might still be found
1054 * inside this working buffer. bump our offset pointer
1056 if (total_out
> start_byte
&&
1057 current_buf_start
< start_byte
) {
1058 buf_offset
= start_byte
- buf_start
;
1059 working_bytes
= total_out
- start_byte
;
1060 current_buf_start
= buf_start
+ buf_offset
;
1069 * Compression heuristic.
1071 * For now is's a naive and optimistic 'return true', we'll extend the logic to
1072 * quickly (compared to direct compression) detect data characteristics
1073 * (compressible/uncompressible) to avoid wasting CPU time on uncompressible
1076 * The following types of analysis can be performed:
1077 * - detect mostly zero data
1078 * - detect data with low "byte set" size (text, etc)
1079 * - detect data with low/high "core byte" set
1081 * Return non-zero if the compression should be done, 0 otherwise.
1083 int btrfs_compress_heuristic(struct inode
*inode
, u64 start
, u64 end
)
1085 u64 index
= start
>> PAGE_SHIFT
;
1086 u64 end_index
= end
>> PAGE_SHIFT
;
1090 while (index
<= end_index
) {
1091 page
= find_get_page(inode
->i_mapping
, index
);