/*
* 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;
/* 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_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(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;
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_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_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;
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->orig_start;
compressed_len = em->block_len;
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);
if (!btrfs_test_opt(root, NODATASUM) &&
!btrfs_test_flag(inode, NODATASUM)) {
btrfs_lookup_bio_sums(root, inode, cb->orig_bio);
}
/* 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;
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);
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);
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);
ret = btrfs_map_bio(root, READ, comp_bio, 0, 0);
BUG_ON(ret);
bio_put(comp_bio);
return 0;
}
