1 files changed, 454 insertions, 0 deletions

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
new file mode 100644
index 0000000..c547036
--- /dev/null
+++ b/fs/btrfs/compression.c
@@ -0,0 +1,454 @@
+/*
+ * 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 "ctree.h"
+#include "disk-io.h"
+#include "transaction.h"
+#include "btrfs_inode.h"
+#include "volumes.h"
+#include "ordered-data.h"
+#include "compat.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;
+
+	/* for reads, this is the bio we are copying the data into */
+	struct bio *orig_bio;
+};
+
+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;
+}
+
+/* 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;
+
+	/* ok, we're the last bio for this extent, lets start
+	 * the decompression.
+	 */
+	inode = cb->inode;
+	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);
+	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
+		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(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;
+	tree->ops->writepage_end_io_hook(cb->compressed_pages[0],
+					 cb->start,
+					 cb->start + cb->len - 1,
+					 NULL, 1);
+
+	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(sizeof(*cb), GFP_NOFS);
+	atomic_set(&cb->pending_bios, 0);
+	cb->errors = 0;
+	cb->inode = inode;
+	cb->start = start;
+	cb->len = len;
+	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;
+
+	ret = btrfs_csum_file_bytes(root, inode, start, len);
+	BUG_ON(ret);
+
+	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;
+	while(bytes_left > 0) {
+		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;
+
+		if (ret || bio_add_page(bio, page, PAGE_CACHE_SIZE, 0) <
+		    PAGE_CACHE_SIZE) {
+			bio_get(bio);
+
+			ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0);
+			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);
+			atomic_inc(&cb->pending_bios);
+			bio->bi_private = cb;
+			bio->bi_end_io = end_compressed_bio_write;
+			bio_add_page(bio, page, PAGE_CACHE_SIZE, 0);
+		}
+		page_index++;
+		bytes_left -= PAGE_CACHE_SIZE;
+		first_byte += PAGE_CACHE_SIZE;
+	}
+	bio_get(bio);
+
+	ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0);
+	BUG_ON(ret);
+
+	ret = btrfs_map_bio(root, WRITE, bio, 0, 1);
+	BUG_ON(ret);
+
+	bio_put(bio);
+	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;
+	struct extent_map *em;
+	int ret;
+
+	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);
+
+	cb = kmalloc(sizeof(*cb), GFP_NOFS);
+	atomic_set(&cb->pending_bios, 0);
+	cb->errors = 0;
+	cb->inode = inode;
+
+	cb->start = em->start;
+	compressed_len = em->block_len;
+	free_extent_map(em);
+
+	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;
+
+	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;
+		if (comp_bio->bi_size)
+			ret = tree->ops->merge_bio_hook(page, 0,
+							PAGE_CACHE_SIZE,
+							comp_bio, 0);
+		else
+			ret = 0;
+
+		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);
+
+			ret = btrfs_map_bio(root, READ, comp_bio, 0, 0);
+			BUG_ON(ret);
+
+			bio_put(comp_bio);
+
+			comp_bio = compressed_bio_alloc(bdev, cur_disk_byte,
+							GFP_NOFS);
+			atomic_inc(&cb->pending_bios);
+			bio->bi_private = cb;
+			bio->bi_end_io = end_compressed_bio_write;
+			bio_add_page(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);
+
+	ret = btrfs_map_bio(root, READ, comp_bio, 0, 0);
+	BUG_ON(ret);
+
+	bio_put(comp_bio);
+	return 0;
+}