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 ((disk_size + root->sectorsize - 1) / root->sectorsize) *
98 static struct bio *compressed_bio_alloc(struct block_device *bdev,
99 u64 first_byte, gfp_t gfp_flags)
103 nr_vecs = bio_get_nr_vecs(bdev);
104 return btrfs_bio_alloc(bdev, first_byte >> 9, nr_vecs, gfp_flags);
107 static int check_compressed_csum(struct inode *inode,
108 struct compressed_bio *cb,
116 u32 *cb_sum = &cb->sums;
118 if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)
121 for (i = 0; i < cb->nr_pages; i++) {
122 page = cb->compressed_pages[i];
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);
130 if (csum != *cb_sum) {
131 printk(KERN_INFO "btrfs csum failed ino %llu "
132 "extent %llu csum %u "
133 "wanted %u mirror %d\n",
134 btrfs_ino(inode), disk_start, csum, *cb_sum,
147 /* when we finish reading compressed pages from the disk, we
148 * decompress them and then run the bio end_io routines on the
149 * decompressed pages (in the inode address space).
151 * This allows the checksumming and other IO error handling routines
154 * The compressed pages are freed here, and it must be run
157 static void end_compressed_bio_read(struct bio *bio, int err)
159 struct compressed_bio *cb = bio->bi_private;
168 /* if there are more bios still pending for this compressed
171 if (!atomic_dec_and_test(&cb->pending_bios))
175 ret = check_compressed_csum(inode, cb, (u64)bio->bi_sector << 9);
179 /* ok, we're the last bio for this extent, lets start
182 ret = btrfs_decompress_biovec(cb->compress_type,
183 cb->compressed_pages,
185 cb->orig_bio->bi_io_vec,
186 cb->orig_bio->bi_vcnt,
192 /* release the compressed pages */
194 for (index = 0; index < cb->nr_pages; index++) {
195 page = cb->compressed_pages[index];
196 page->mapping = NULL;
197 page_cache_release(page);
200 /* do io completion on the original bio */
202 bio_io_error(cb->orig_bio);
205 struct bio_vec *bvec = cb->orig_bio->bi_io_vec;
208 * we have verified the checksum already, set page
209 * checked so the end_io handlers know about it
211 while (bio_index < cb->orig_bio->bi_vcnt) {
212 SetPageChecked(bvec->bv_page);
216 bio_endio(cb->orig_bio, 0);
219 /* finally free the cb struct */
220 kfree(cb->compressed_pages);
227 * Clear the writeback bits on all of the file
228 * pages for a compressed write
230 static noinline void end_compressed_writeback(struct inode *inode, u64 start,
231 unsigned long ram_size)
233 unsigned long index = start >> PAGE_CACHE_SHIFT;
234 unsigned long end_index = (start + ram_size - 1) >> PAGE_CACHE_SHIFT;
235 struct page *pages[16];
236 unsigned long nr_pages = end_index - index + 1;
240 while (nr_pages > 0) {
241 ret = find_get_pages_contig(inode->i_mapping, index,
243 nr_pages, ARRAY_SIZE(pages)), pages);
249 for (i = 0; i < ret; i++) {
250 end_page_writeback(pages[i]);
251 page_cache_release(pages[i]);
256 /* the inode may be gone now */
260 * do the cleanup once all the compressed pages hit the disk.
261 * This will clear writeback on the file pages and free the compressed
264 * This also calls the writeback end hooks for the file pages so that
265 * metadata and checksums can be updated in the file.
267 static void end_compressed_bio_write(struct bio *bio, int err)
269 struct extent_io_tree *tree;
270 struct compressed_bio *cb = bio->bi_private;
278 /* if there are more bios still pending for this compressed
281 if (!atomic_dec_and_test(&cb->pending_bios))
284 /* ok, we're the last bio for this extent, step one is to
285 * call back into the FS and do all the end_io operations
288 tree = &BTRFS_I(inode)->io_tree;
289 cb->compressed_pages[0]->mapping = cb->inode->i_mapping;
290 tree->ops->writepage_end_io_hook(cb->compressed_pages[0],
292 cb->start + cb->len - 1,
294 cb->compressed_pages[0]->mapping = NULL;
296 end_compressed_writeback(inode, cb->start, cb->len);
297 /* note, our inode could be gone now */
300 * release the compressed pages, these came from alloc_page and
301 * are not attached to the inode at all
304 for (index = 0; index < cb->nr_pages; index++) {
305 page = cb->compressed_pages[index];
306 page->mapping = NULL;
307 page_cache_release(page);
310 /* finally free the cb struct */
311 kfree(cb->compressed_pages);
318 * worker function to build and submit bios for previously compressed pages.
319 * The corresponding pages in the inode should be marked for writeback
320 * and the compressed pages should have a reference on them for dropping
321 * when the IO is complete.
323 * This also checksums the file bytes and gets things ready for
326 int btrfs_submit_compressed_write(struct inode *inode, u64 start,
327 unsigned long len, u64 disk_start,
328 unsigned long compressed_len,
329 struct page **compressed_pages,
330 unsigned long nr_pages)
332 struct bio *bio = NULL;
333 struct btrfs_root *root = BTRFS_I(inode)->root;
334 struct compressed_bio *cb;
335 unsigned long bytes_left;
336 struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
339 u64 first_byte = disk_start;
340 struct block_device *bdev;
342 int skip_sum = BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM;
344 WARN_ON(start & ((u64)PAGE_CACHE_SIZE - 1));
345 cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS);
348 atomic_set(&cb->pending_bios, 0);
354 cb->compressed_pages = compressed_pages;
355 cb->compressed_len = compressed_len;
357 cb->nr_pages = nr_pages;
359 bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
361 bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
366 bio->bi_private = cb;
367 bio->bi_end_io = end_compressed_bio_write;
368 atomic_inc(&cb->pending_bios);
370 /* create and submit bios for the compressed pages */
371 bytes_left = compressed_len;
372 for (pg_index = 0; pg_index < cb->nr_pages; pg_index++) {
373 page = compressed_pages[pg_index];
374 page->mapping = inode->i_mapping;
376 ret = io_tree->ops->merge_bio_hook(WRITE, page, 0,
382 page->mapping = NULL;
383 if (ret || bio_add_page(bio, page, PAGE_CACHE_SIZE, 0) <
388 * inc the count before we submit the bio so
389 * we know the end IO handler won't happen before
390 * we inc the count. Otherwise, the cb might get
391 * freed before we're done setting it up
393 atomic_inc(&cb->pending_bios);
394 ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0);
395 BUG_ON(ret); /* -ENOMEM */
398 ret = btrfs_csum_one_bio(root, inode, bio,
400 BUG_ON(ret); /* -ENOMEM */
403 ret = btrfs_map_bio(root, WRITE, bio, 0, 1);
404 BUG_ON(ret); /* -ENOMEM */
408 bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
410 bio->bi_private = cb;
411 bio->bi_end_io = end_compressed_bio_write;
412 bio_add_page(bio, page, PAGE_CACHE_SIZE, 0);
414 if (bytes_left < PAGE_CACHE_SIZE) {
415 printk("bytes left %lu compress len %lu nr %lu\n",
416 bytes_left, cb->compressed_len, cb->nr_pages);
418 bytes_left -= PAGE_CACHE_SIZE;
419 first_byte += PAGE_CACHE_SIZE;
424 ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0);
425 BUG_ON(ret); /* -ENOMEM */
428 ret = btrfs_csum_one_bio(root, inode, bio, start, 1);
429 BUG_ON(ret); /* -ENOMEM */
432 ret = btrfs_map_bio(root, WRITE, bio, 0, 1);
433 BUG_ON(ret); /* -ENOMEM */
439 static noinline int add_ra_bio_pages(struct inode *inode,
441 struct compressed_bio *cb)
443 unsigned long end_index;
444 unsigned long pg_index;
446 u64 isize = i_size_read(inode);
449 unsigned long nr_pages = 0;
450 struct extent_map *em;
451 struct address_space *mapping = inode->i_mapping;
452 struct extent_map_tree *em_tree;
453 struct extent_io_tree *tree;
457 page = cb->orig_bio->bi_io_vec[cb->orig_bio->bi_vcnt - 1].bv_page;
458 last_offset = (page_offset(page) + PAGE_CACHE_SIZE);
459 em_tree = &BTRFS_I(inode)->extent_tree;
460 tree = &BTRFS_I(inode)->io_tree;
465 end_index = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;
467 while (last_offset < compressed_end) {
468 pg_index = last_offset >> PAGE_CACHE_SHIFT;
470 if (pg_index > end_index)
474 page = radix_tree_lookup(&mapping->page_tree, pg_index);
483 page = __page_cache_alloc(mapping_gfp_mask(mapping) &
488 if (add_to_page_cache_lru(page, mapping, pg_index,
490 page_cache_release(page);
494 end = last_offset + PAGE_CACHE_SIZE - 1;
496 * at this point, we have a locked page in the page cache
497 * for these bytes in the file. But, we have to make
498 * sure they map to this compressed extent on disk.
500 set_page_extent_mapped(page);
501 lock_extent(tree, last_offset, end);
502 read_lock(&em_tree->lock);
503 em = lookup_extent_mapping(em_tree, last_offset,
505 read_unlock(&em_tree->lock);
507 if (!em || last_offset < em->start ||
508 (last_offset + PAGE_CACHE_SIZE > extent_map_end(em)) ||
509 (em->block_start >> 9) != cb->orig_bio->bi_sector) {
511 unlock_extent(tree, last_offset, end);
513 page_cache_release(page);
518 if (page->index == end_index) {
520 size_t zero_offset = isize & (PAGE_CACHE_SIZE - 1);
524 zeros = PAGE_CACHE_SIZE - zero_offset;
525 userpage = kmap_atomic(page);
526 memset(userpage + zero_offset, 0, zeros);
527 flush_dcache_page(page);
528 kunmap_atomic(userpage);
532 ret = bio_add_page(cb->orig_bio, page,
535 if (ret == PAGE_CACHE_SIZE) {
537 page_cache_release(page);
539 unlock_extent(tree, last_offset, end);
541 page_cache_release(page);
545 last_offset += PAGE_CACHE_SIZE;
551 * for a compressed read, the bio we get passed has all the inode pages
552 * in it. We don't actually do IO on those pages but allocate new ones
553 * to hold the compressed pages on disk.
555 * bio->bi_sector points to the compressed extent on disk
556 * bio->bi_io_vec points to all of the inode pages
557 * bio->bi_vcnt is a count of pages
559 * After the compressed pages are read, we copy the bytes into the
560 * bio we were passed and then call the bio end_io calls
562 int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
563 int mirror_num, unsigned long bio_flags)
565 struct extent_io_tree *tree;
566 struct extent_map_tree *em_tree;
567 struct compressed_bio *cb;
568 struct btrfs_root *root = BTRFS_I(inode)->root;
569 unsigned long uncompressed_len = bio->bi_vcnt * PAGE_CACHE_SIZE;
570 unsigned long compressed_len;
571 unsigned long nr_pages;
572 unsigned long pg_index;
574 struct block_device *bdev;
575 struct bio *comp_bio;
576 u64 cur_disk_byte = (u64)bio->bi_sector << 9;
579 struct extent_map *em;
584 tree = &BTRFS_I(inode)->io_tree;
585 em_tree = &BTRFS_I(inode)->extent_tree;
587 /* we need the actual starting offset of this extent in the file */
588 read_lock(&em_tree->lock);
589 em = lookup_extent_mapping(em_tree,
590 page_offset(bio->bi_io_vec->bv_page),
592 read_unlock(&em_tree->lock);
596 compressed_len = em->block_len;
597 cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS);
601 atomic_set(&cb->pending_bios, 0);
604 cb->mirror_num = mirror_num;
607 cb->start = em->orig_start;
609 em_start = em->start;
614 cb->len = uncompressed_len;
615 cb->compressed_len = compressed_len;
616 cb->compress_type = extent_compress_type(bio_flags);
619 nr_pages = (compressed_len + PAGE_CACHE_SIZE - 1) /
621 cb->compressed_pages = kzalloc(sizeof(struct page *) * nr_pages,
623 if (!cb->compressed_pages)
626 bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
628 for (pg_index = 0; pg_index < nr_pages; pg_index++) {
629 cb->compressed_pages[pg_index] = alloc_page(GFP_NOFS |
631 if (!cb->compressed_pages[pg_index]) {
632 faili = pg_index - 1;
637 faili = nr_pages - 1;
638 cb->nr_pages = nr_pages;
640 /* In the parent-locked case, we only locked the range we are
641 * interested in. In all other cases, we can opportunistically
642 * cache decompressed data that goes beyond the requested range. */
643 if (!(bio_flags & EXTENT_BIO_PARENT_LOCKED))
644 add_ra_bio_pages(inode, em_start + em_len, cb);
646 /* include any pages we added in add_ra-bio_pages */
647 uncompressed_len = bio->bi_vcnt * PAGE_CACHE_SIZE;
648 cb->len = uncompressed_len;
650 comp_bio = compressed_bio_alloc(bdev, cur_disk_byte, GFP_NOFS);
653 comp_bio->bi_private = cb;
654 comp_bio->bi_end_io = end_compressed_bio_read;
655 atomic_inc(&cb->pending_bios);
657 for (pg_index = 0; pg_index < nr_pages; pg_index++) {
658 page = cb->compressed_pages[pg_index];
659 page->mapping = inode->i_mapping;
660 page->index = em_start >> PAGE_CACHE_SHIFT;
662 if (comp_bio->bi_size)
663 ret = tree->ops->merge_bio_hook(READ, page, 0,
669 page->mapping = NULL;
670 if (ret || bio_add_page(comp_bio, page, PAGE_CACHE_SIZE, 0) <
674 ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0);
675 BUG_ON(ret); /* -ENOMEM */
678 * inc the count before we submit the bio so
679 * we know the end IO handler won't happen before
680 * we inc the count. Otherwise, the cb might get
681 * freed before we're done setting it up
683 atomic_inc(&cb->pending_bios);
685 if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
686 ret = btrfs_lookup_bio_sums(root, inode,
688 BUG_ON(ret); /* -ENOMEM */
690 sums += (comp_bio->bi_size + root->sectorsize - 1) /
693 ret = btrfs_map_bio(root, READ, comp_bio,
696 bio_endio(comp_bio, ret);
700 comp_bio = compressed_bio_alloc(bdev, cur_disk_byte,
703 comp_bio->bi_private = cb;
704 comp_bio->bi_end_io = end_compressed_bio_read;
706 bio_add_page(comp_bio, page, PAGE_CACHE_SIZE, 0);
708 cur_disk_byte += PAGE_CACHE_SIZE;
712 ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0);
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_tail(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))
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))
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))
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;