Btrfs can optionally compress all file data transparently during reads
and writes. This code takes pages and sends them down to zlib. Working
pages are allocated to hold the compressed/uncompressed result from zlib
and bios are submitted to send the compressed IOs.
The interfaces here allow the compression code to limit the max size
of the compressed result. This is used to make sure a compressed extent
isn't too large to decompress later to satisfy random reads.
The compression code includes checks to make sure it is actually making
the data smaller, and it bails early if it is not being effective.
Checksumming in btrfs is done based on the data on disk (the compressed data),
so the bios are sent through the checksumming routines as appropriate.
Signed-off-by: Chris Mason <chris.mason@xxxxxxxxxx>
diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
new file mode 100644
index 0000000..ee848d8
--- /dev/null
+++ b/fs/btrfs/compression.c
@@ -0,0 +1,709 @@
+/*
+ * Copyright (C) 2008 Oracle. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#include <linux/kernel.h>
+#include <linux/bio.h>
+#include <linux/buffer_head.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/pagemap.h>
+#include <linux/highmem.h>
+#include <linux/time.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/smp_lock.h>
+#include <linux/backing-dev.h>
+#include <linux/mpage.h>
+#include <linux/swap.h>
+#include <linux/writeback.h>
+#include <linux/bit_spinlock.h>
+#include <linux/version.h>
+#include <linux/pagevec.h>
+#include "compat.h"
+#include "ctree.h"
+#include "disk-io.h"
+#include "transaction.h"
+#include "btrfs_inode.h"
+#include "volumes.h"
+#include "ordered-data.h"
+#include "compression.h"
+#include "extent_io.h"
+#include "extent_map.h"
+
+struct compressed_bio {
+ /* number of bios pending for this compressed extent */
+ atomic_t pending_bios;
+
+ /* the pages with the compressed data on them */
+ struct page **compressed_pages;
+
+ /* inode that owns this data */
+ struct inode *inode;
+
+ /* starting offset in the inode for our pages */
+ u64 start;
+
+ /* number of bytes in the inode we're working on */
+ unsigned long len;
+
+ /* number of bytes on disk */
+ unsigned long compressed_len;
+
+ /* number of compressed pages in the array */
+ unsigned long nr_pages;
+
+ /* IO errors */
+ int errors;
+ int mirror_num;
+
+ /* for reads, this is the bio we are copying the data into */
+ struct bio *orig_bio;
+
+ /*
+ * the start of a variable length array of checksums only
+ * used by reads
+ */
+ u32 sums;
+};
+
+static inline int compressed_bio_size(struct btrfs_root *root,
+ unsigned long disk_size)
+{
+ u16 csum_size = btrfs_super_csum_size(&root->fs_info->super_copy);
+ return sizeof(struct compressed_bio) +
+ ((disk_size + root->sectorsize - 1) / root->sectorsize) *
+ csum_size;
+}
+
+static struct bio *compressed_bio_alloc(struct block_device *bdev,
+ u64 first_byte, gfp_t gfp_flags)
+{
+ struct bio *bio;
+ int nr_vecs;
+
+ nr_vecs = bio_get_nr_vecs(bdev);
+ bio = bio_alloc(gfp_flags, nr_vecs);
+
+ if (bio == NULL && (current->flags & PF_MEMALLOC)) {
+ while (!bio && (nr_vecs /= 2))
+ bio = bio_alloc(gfp_flags, nr_vecs);
+ }
+
+ if (bio) {
+ bio->bi_size = 0;
+ bio->bi_bdev = bdev;
+ bio->bi_sector = first_byte >> 9;
+ }
+ return bio;
+}
+
+static int check_compressed_csum(struct inode *inode,
+ struct compressed_bio *cb,
+ u64 disk_start)
+{
+ int ret;
+ struct btrfs_root *root = BTRFS_I(inode)->root;
+ struct page *page;
+ unsigned long i;
+ char *kaddr;
+ u32 csum;
+ u32 *cb_sum = &cb->sums;
+
+ if (btrfs_test_flag(inode, NODATASUM))
+ return 0;
+
+ for (i = 0; i < cb->nr_pages; i++) {
+ page = cb->compressed_pages[i];
+ csum = ~(u32)0;
+
+ kaddr = kmap_atomic(page, KM_USER0);
+ csum = btrfs_csum_data(root, kaddr, csum, PAGE_CACHE_SIZE);
+ btrfs_csum_final(csum, (char *)&csum);
+ kunmap_atomic(kaddr, KM_USER0);
+
+ if (csum != *cb_sum) {
+ printk(KERN_INFO "btrfs csum failed ino %lu "
+ "extent %llu csum %u "
+ "wanted %u mirror %d\n", inode->i_ino,
+ (unsigned long long)disk_start,
+ csum, *cb_sum, cb->mirror_num);
+ ret = -EIO;
+ goto fail;
+ }
+ cb_sum++;
+
+ }
+ ret = 0;
+fail:
+ return ret;
+}
+
+/* when we finish reading compressed pages from the disk, we
+ * decompress them and then run the bio end_io routines on the
+ * decompressed pages (in the inode address space).
+ *
+ * This allows the checksumming and other IO error handling routines
+ * to work normally
+ *
+ * The compressed pages are freed here, and it must be run
+ * in process context
+ */
+static void end_compressed_bio_read(struct bio *bio, int err)
+{
+ struct extent_io_tree *tree;
+ struct compressed_bio *cb = bio->bi_private;
+ struct inode *inode;
+ struct page *page;
+ unsigned long index;
+ int ret;
+
+ if (err)
+ cb->errors = 1;
+
+ /* if there are more bios still pending for this compressed
+ * extent, just exit
+ */
+ if (!atomic_dec_and_test(&cb->pending_bios))
+ goto out;
+
+ inode = cb->inode;
+ ret = check_compressed_csum(inode, cb, (u64)bio->bi_sector << 9);
+ if (ret)
+ goto csum_failed;
+
+ /* ok, we're the last bio for this extent, lets start
+ * the decompression.
+ */
+ tree = &BTRFS_I(inode)->io_tree;
+ ret = btrfs_zlib_decompress_biovec(cb->compressed_pages,
+ cb->start,
+ cb->orig_bio->bi_io_vec,
+ cb->orig_bio->bi_vcnt,
+ cb->compressed_len);
+csum_failed:
+ if (ret)
+ cb->errors = 1;
+
+ /* release the compressed pages */
+ index = 0;
+ for (index = 0; index < cb->nr_pages; index++) {
+ page = cb->compressed_pages[index];
+ page->mapping = NULL;
+ page_cache_release(page);
+ }
+
+ /* do io completion on the original bio */
+ if (cb->errors) {
+ bio_io_error(cb->orig_bio);
+ } else {
+ int bio_index = 0;
+ struct bio_vec *bvec = cb->orig_bio->bi_io_vec;
+
+ /*
+ * we have verified the checksum already, set page
+ * checked so the end_io handlers know about it
+ */
+ while (bio_index < cb->orig_bio->bi_vcnt) {
+ SetPageChecked(bvec->bv_page);
+ bvec++;
+ bio_index++;
+ }
+ bio_endio(cb->orig_bio, 0);
+ }
+
+ /* finally free the cb struct */
+ kfree(cb->compressed_pages);
+ kfree(cb);
+out:
+ bio_put(bio);
+}
+
+/*
+ * Clear the writeback bits on all of the file
+ * pages for a compressed write
+ */
+static noinline int end_compressed_writeback(struct inode *inode, u64 start,
+ unsigned long ram_size)
+{
+ unsigned long index = start >> PAGE_CACHE_SHIFT;
+ unsigned long end_index = (start + ram_size - 1) >> PAGE_CACHE_SHIFT;
+ struct page *pages[16];
+ unsigned long nr_pages = end_index - index + 1;
+ int i;
+ int ret;
+
+ while (nr_pages > 0) {
+ ret = find_get_pages_contig(inode->i_mapping, index,
+ min_t(unsigned long,
+ nr_pages, ARRAY_SIZE(pages)), pages);
+ if (ret == 0) {
+ nr_pages -= 1;
+ index += 1;
+ continue;
+ }
+ for (i = 0; i < ret; i++) {
+ end_page_writeback(pages[i]);
+ page_cache_release(pages[i]);
+ }
+ nr_pages -= ret;
+ index += ret;
+ }
+ /* the inode may be gone now */
+ return 0;
+}
+
+/*
+ * do the cleanup once all the compressed pages hit the disk.
+ * This will clear writeback on the file pages and free the compressed
+ * pages.
+ *
+ * This also calls the writeback end hooks for the file pages so that
+ * metadata and checksums can be updated in the file.
+ */
+static void end_compressed_bio_write(struct bio *bio, int err)
+{
+ struct extent_io_tree *tree;
+ struct compressed_bio *cb = bio->bi_private;
+ struct inode *inode;
+ struct page *page;
+ unsigned long index;
+
+ if (err)
+ cb->errors = 1;
+
+ /* if there are more bios still pending for this compressed
+ * extent, just exit
+ */
+ if (!atomic_dec_and_test(&cb->pending_bios))
+ goto out;
+
+ /* ok, we're the last bio for this extent, step one is to
+ * call back into the FS and do all the end_io operations
+ */
+ inode = cb->inode;
+ tree = &BTRFS_I(inode)->io_tree;
+ cb->compressed_pages[0]->mapping = cb->inode->i_mapping;
+ tree->ops->writepage_end_io_hook(cb->compressed_pages[0],
+ cb->start,
+ cb->start + cb->len - 1,
+ NULL, 1);
+ cb->compressed_pages[0]->mapping = NULL;
+
+ end_compressed_writeback(inode, cb->start, cb->len);
+ /* note, our inode could be gone now */
+
+ /*
+ * release the compressed pages, these came from alloc_page and
+ * are not attached to the inode at all
+ */
+ index = 0;
+ for (index = 0; index < cb->nr_pages; index++) {
+ page = cb->compressed_pages[index];
+ page->mapping = NULL;
+ page_cache_release(page);
+ }
+
+ /* finally free the cb struct */
+ kfree(cb->compressed_pages);
+ kfree(cb);
+out:
+ bio_put(bio);
+}
+
+/*
+ * worker function to build and submit bios for previously compressed pages.
+ * The corresponding pages in the inode should be marked for writeback
+ * and the compressed pages should have a reference on them for dropping
+ * when the IO is complete.
+ *
+ * This also checksums the file bytes and gets things ready for
+ * the end io hooks.
+ */
+int btrfs_submit_compressed_write(struct inode *inode, u64 start,
+ unsigned long len, u64 disk_start,
+ unsigned long compressed_len,
+ struct page **compressed_pages,
+ unsigned long nr_pages)
+{
+ struct bio *bio = NULL;
+ struct btrfs_root *root = BTRFS_I(inode)->root;
+ struct compressed_bio *cb;
+ unsigned long bytes_left;
+ struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
+ int page_index = 0;
+ struct page *page;
+ u64 first_byte = disk_start;
+ struct block_device *bdev;
+ int ret;
+
+ WARN_ON(start & ((u64)PAGE_CACHE_SIZE - 1));
+ cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS);
+ atomic_set(&cb->pending_bios, 0);
+ cb->errors = 0;
+ cb->inode = inode;
+ cb->start = start;
+ cb->len = len;
+ cb->mirror_num = 0;
+ cb->compressed_pages = compressed_pages;
+ cb->compressed_len = compressed_len;
+ cb->orig_bio = NULL;
+ cb->nr_pages = nr_pages;
+
+ bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
+
+ bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
+ bio->bi_private = cb;
+ bio->bi_end_io = end_compressed_bio_write;
+ atomic_inc(&cb->pending_bios);
+
+ /* create and submit bios for the compressed pages */
+ bytes_left = compressed_len;
+ for (page_index = 0; page_index < cb->nr_pages; page_index++) {
+ page = compressed_pages[page_index];
+ page->mapping = inode->i_mapping;
+ if (bio->bi_size)
+ ret = io_tree->ops->merge_bio_hook(page, 0,
+ PAGE_CACHE_SIZE,
+ bio, 0);
+ else
+ ret = 0;
+
+ page->mapping = NULL;
+ if (ret || bio_add_page(bio, page, PAGE_CACHE_SIZE, 0) <
+ PAGE_CACHE_SIZE) {
+ bio_get(bio);
+
+ /*
+ * inc the count before we submit the bio so
+ * we know the end IO handler won't happen before
+ * we inc the count. Otherwise, the cb might get
+ * freed before we're done setting it up
+ */
+ atomic_inc(&cb->pending_bios);
+ ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0);
+ BUG_ON(ret);
+
+ ret = btrfs_csum_one_bio(root, inode, bio, start, 1);
+ BUG_ON(ret);
+
+ ret = btrfs_map_bio(root, WRITE, bio, 0, 1);
+ BUG_ON(ret);
+
+ bio_put(bio);
+
+ bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
+ bio->bi_private = cb;
+ bio->bi_end_io = end_compressed_bio_write;
+ bio_add_page(bio, page, PAGE_CACHE_SIZE, 0);
+ }
+ if (bytes_left < PAGE_CACHE_SIZE) {
+ printk("bytes left %lu compress len %lu nr %lu\n",
+ bytes_left, cb->compressed_len, cb->nr_pages);
+ }
+ bytes_left -= PAGE_CACHE_SIZE;
+ first_byte += PAGE_CACHE_SIZE;
+ cond_resched();
+ }
+ bio_get(bio);
+
+ ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0);
+ BUG_ON(ret);
+
+ ret = btrfs_csum_one_bio(root, inode, bio, start, 1);
+ BUG_ON(ret);
+
+ ret = btrfs_map_bio(root, WRITE, bio, 0, 1);
+ BUG_ON(ret);
+
+ bio_put(bio);
+ return 0;
+}
+
+static noinline int add_ra_bio_pages(struct inode *inode,
+ u64 compressed_end,
+ struct compressed_bio *cb)
+{
+ unsigned long end_index;
+ unsigned long page_index;
+ u64 last_offset;
+ u64 isize = i_size_read(inode);
+ int ret;
+ struct page *page;
+ unsigned long nr_pages = 0;
+ struct extent_map *em;
+ struct address_space *mapping = inode->i_mapping;
+ struct pagevec pvec;
+ struct extent_map_tree *em_tree;
+ struct extent_io_tree *tree;
+ u64 end;
+ int misses = 0;
+
+ page = cb->orig_bio->bi_io_vec[cb->orig_bio->bi_vcnt - 1].bv_page;
+ last_offset = (page_offset(page) + PAGE_CACHE_SIZE);
+ em_tree = &BTRFS_I(inode)->extent_tree;
+ tree = &BTRFS_I(inode)->io_tree;
+
+ if (isize == 0)
+ return 0;
+
+ end_index = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;
+
+ pagevec_init(&pvec, 0);
+ while (last_offset < compressed_end) {
+ page_index = last_offset >> PAGE_CACHE_SHIFT;
+
+ if (page_index > end_index)
+ break;
+
+ rcu_read_lock();
+ page = radix_tree_lookup(&mapping->page_tree, page_index);
+ rcu_read_unlock();
+ if (page) {
+ misses++;
+ if (misses > 4)
+ break;
+ goto next;
+ }
+
+ page = alloc_page(mapping_gfp_mask(mapping) | GFP_NOFS);
+ if (!page)
+ break;
+
+ page->index = page_index;
+ /*
+ * what we want to do here is call add_to_page_cache_lru,
+ * but that isn't exported, so we reproduce it here
+ */
+ if (add_to_page_cache(page, mapping,
+ page->index, GFP_NOFS)) {
+ page_cache_release(page);
+ goto next;
+ }
+
+ /* open coding of lru_cache_add, also not exported */
+ page_cache_get(page);
+ if (!pagevec_add(&pvec, page))
+ __pagevec_lru_add_file(&pvec);
+
+ end = last_offset + PAGE_CACHE_SIZE - 1;
+ /*
+ * at this point, we have a locked page in the page cache
+ * for these bytes in the file. But, we have to make
+ * sure they map to this compressed extent on disk.
+ */
+ set_page_extent_mapped(page);
+ lock_extent(tree, last_offset, end, GFP_NOFS);
+ spin_lock(&em_tree->lock);
+ em = lookup_extent_mapping(em_tree, last_offset,
+ PAGE_CACHE_SIZE);
+ spin_unlock(&em_tree->lock);
+
+ if (!em || last_offset < em->start ||
+ (last_offset + PAGE_CACHE_SIZE > extent_map_end(em)) ||
+ (em->block_start >> 9) != cb->orig_bio->bi_sector) {
+ free_extent_map(em);
+ unlock_extent(tree, last_offset, end, GFP_NOFS);
+ unlock_page(page);
+ page_cache_release(page);
+ break;
+ }
+ free_extent_map(em);
+
+ if (page->index == end_index) {
+ char *userpage;
+ size_t zero_offset = isize & (PAGE_CACHE_SIZE - 1);
+
+ if (zero_offset) {
+ int zeros;
+ zeros = PAGE_CACHE_SIZE - zero_offset;
+ userpage = kmap_atomic(page, KM_USER0);
+ memset(userpage + zero_offset, 0, zeros);
+ flush_dcache_page(page);
+ kunmap_atomic(userpage, KM_USER0);
+ }
+ }
+
+ ret = bio_add_page(cb->orig_bio, page,
+ PAGE_CACHE_SIZE, 0);
+
+ if (ret == PAGE_CACHE_SIZE) {
+ nr_pages++;
+ page_cache_release(page);
+ } else {
+ unlock_extent(tree, last_offset, end, GFP_NOFS);
+ unlock_page(page);
+ page_cache_release(page);
+ break;
+ }
+next:
+ last_offset += PAGE_CACHE_SIZE;
+ }
+ if (pagevec_count(&pvec))
+ __pagevec_lru_add_file(&pvec);
+ return 0;
+}
+
+/*
+ * for a compressed read, the bio we get passed has all the inode pages
+ * in it. We don't actually do IO on those pages but allocate new ones
+ * to hold the compressed pages on disk.
+ *
+ * bio->bi_sector points to the compressed extent on disk
+ * bio->bi_io_vec points to all of the inode pages
+ * bio->bi_vcnt is a count of pages
+ *
+ * After the compressed pages are read, we copy the bytes into the
+ * bio we were passed and then call the bio end_io calls
+ */
+int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
+ int mirror_num, unsigned long bio_flags)
+{
+ struct extent_io_tree *tree;
+ struct extent_map_tree *em_tree;
+ struct compressed_bio *cb;
+ struct btrfs_root *root = BTRFS_I(inode)->root;
+ unsigned long uncompressed_len = bio->bi_vcnt * PAGE_CACHE_SIZE;
+ unsigned long compressed_len;
+ unsigned long nr_pages;
+ unsigned long page_index;
+ struct page *page;
+ struct block_device *bdev;
+ struct bio *comp_bio;
+ u64 cur_disk_byte = (u64)bio->bi_sector << 9;
+ u64 em_len;
+ u64 em_start;
+ struct extent_map *em;
+ int ret;
+ u32 *sums;
+
+ tree = &BTRFS_I(inode)->io_tree;
+ em_tree = &BTRFS_I(inode)->extent_tree;
+
+ /* we need the actual starting offset of this extent in the file */
+ spin_lock(&em_tree->lock);
+ em = lookup_extent_mapping(em_tree,
+ page_offset(bio->bi_io_vec->bv_page),
+ PAGE_CACHE_SIZE);
+ spin_unlock(&em_tree->lock);
+
+ compressed_len = em->block_len;
+ cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS);
+ atomic_set(&cb->pending_bios, 0);
+ cb->errors = 0;
+ cb->inode = inode;
+ cb->mirror_num = mirror_num;
+ sums = &cb->sums;
+
+ cb->start = em->orig_start;
+ em_len = em->len;
+ em_start = em->start;
+
+ free_extent_map(em);
+ em = NULL;
+
+ cb->len = uncompressed_len;
+ cb->compressed_len = compressed_len;
+ cb->orig_bio = bio;
+
+ nr_pages = (compressed_len + PAGE_CACHE_SIZE - 1) /
+ PAGE_CACHE_SIZE;
+ cb->compressed_pages = kmalloc(sizeof(struct page *) * nr_pages,
+ GFP_NOFS);
+ bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
+
+ for (page_index = 0; page_index < nr_pages; page_index++) {
+ cb->compressed_pages[page_index] = alloc_page(GFP_NOFS |
+ __GFP_HIGHMEM);
+ }
+ cb->nr_pages = nr_pages;
+
+ add_ra_bio_pages(inode, em_start + em_len, cb);
+
+ /* include any pages we added in add_ra-bio_pages */
+ uncompressed_len = bio->bi_vcnt * PAGE_CACHE_SIZE;
+ cb->len = uncompressed_len;
+
+ comp_bio = compressed_bio_alloc(bdev, cur_disk_byte, GFP_NOFS);
+ comp_bio->bi_private = cb;
+ comp_bio->bi_end_io = end_compressed_bio_read;
+ atomic_inc(&cb->pending_bios);
+
+ for (page_index = 0; page_index < nr_pages; page_index++) {
+ page = cb->compressed_pages[page_index];
+ page->mapping = inode->i_mapping;
+ page->index = em_start >> PAGE_CACHE_SHIFT;
+
+ if (comp_bio->bi_size)
+ ret = tree->ops->merge_bio_hook(page, 0,
+ PAGE_CACHE_SIZE,
+ comp_bio, 0);
+ else
+ ret = 0;
+
+ page->mapping = NULL;
+ if (ret || bio_add_page(comp_bio, page, PAGE_CACHE_SIZE, 0) <
+ PAGE_CACHE_SIZE) {
+ bio_get(comp_bio);
+
+ ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0);
+ BUG_ON(ret);
+
+ /*
+ * inc the count before we submit the bio so
+ * we know the end IO handler won't happen before
+ * we inc the count. Otherwise, the cb might get
+ * freed before we're done setting it up
+ */
+ atomic_inc(&cb->pending_bios);
+
+ if (!btrfs_test_flag(inode, NODATASUM)) {
+ btrfs_lookup_bio_sums(root, inode, comp_bio,
+ sums);
+ }
+ sums += (comp_bio->bi_size + root->sectorsize - 1) /
+ root->sectorsize;
+
+ ret = btrfs_map_bio(root, READ, comp_bio,
+ mirror_num, 0);
+ BUG_ON(ret);
+
+ bio_put(comp_bio);
+
+ comp_bio = compressed_bio_alloc(bdev, cur_disk_byte,
+ GFP_NOFS);
+ comp_bio->bi_private = cb;
+ comp_bio->bi_end_io = end_compressed_bio_read;
+
+ bio_add_page(comp_bio, page, PAGE_CACHE_SIZE, 0);
+ }
+ cur_disk_byte += PAGE_CACHE_SIZE;
+ }
+ bio_get(comp_bio);
+
+ ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0);
+ BUG_ON(ret);
+
+ if (!btrfs_test_flag(inode, NODATASUM))
+ btrfs_lookup_bio_sums(root, inode, comp_bio, sums);
+
+ ret = btrfs_map_bio(root, READ, comp_bio, mirror_num, 0);
+ BUG_ON(ret);
+
+ bio_put(comp_bio);
+ return 0;
+}
diff --git a/fs/btrfs/compression.h b/fs/btrfs/compression.h
new file mode 100644
index 0000000..421f5b4
--- /dev/null
+++ b/fs/btrfs/compression.h
@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2008 Oracle. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#ifndef __BTRFS_COMPRESSION_
+#define __BTRFS_COMPRESSION_
+
+int btrfs_zlib_decompress(unsigned char *data_in,
+ struct page *dest_page,
+ unsigned long start_byte,
+ size_t srclen, size_t destlen);
+int btrfs_zlib_compress_pages(struct address_space *mapping,
+ u64 start, unsigned long len,
+ struct page **pages,
+ unsigned long nr_dest_pages,
+ unsigned long *out_pages,
+ unsigned long *total_in,
+ unsigned long *total_out,
+ unsigned long max_out);
+int btrfs_zlib_decompress_biovec(struct page **pages_in,
+ u64 disk_start,
+ struct bio_vec *bvec,
+ int vcnt,
+ size_t srclen);
+void btrfs_zlib_exit(void);
+int btrfs_submit_compressed_write(struct inode *inode, u64 start,
+ unsigned long len, u64 disk_start,
+ unsigned long compressed_len,
+ struct page **compressed_pages,
+ unsigned long nr_pages);
+int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
+ int mirror_num, unsigned long bio_flags);
+#endif
--
1.6.0.2
--
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