fs/btrfs/compression.c - kernel/msm-4.19 - Gitiles

 /*
  * 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/backing-dev.h>
 #include <linux/mpage.h>
 #include <linux/swap.h>
 #include <linux/writeback.h>
 #include <linux/bit_spinlock.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_I(inode)->flags & BTRFS_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_FS);
 		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);
 		read_lock(&em_tree->lock);
 		em = lookup_extent_mapping(em_tree, last_offset,
 					   PAGE_CACHE_SIZE);
 		read_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 */
 	read_lock(&em_tree->lock);
 	em = lookup_extent_mapping(em_tree,
 				   page_offset(bio->bi_io_vec->bv_page),
 				   PAGE_CACHE_SIZE);
 	read_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_I(inode)->flags & BTRFS_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_I(inode)->flags & BTRFS_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;
 }
	/*
	* 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/backing-dev.h>
	#include <linux/mpage.h>
	#include <linux/swap.h>
	#include <linux/writeback.h>
	#include <linux/bit_spinlock.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_I(inode)->flags & BTRFS_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_FS);
	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);
	read_lock(&em_tree->lock);
	em = lookup_extent_mapping(em_tree, last_offset,
	PAGE_CACHE_SIZE);
	read_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 */
	read_lock(&em_tree->lock);
	em = lookup_extent_mapping(em_tree,
	page_offset(bio->bi_io_vec->bv_page),
	PAGE_CACHE_SIZE);
	read_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_I(inode)->flags & BTRFS_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_I(inode)->flags & BTRFS_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;
	}