- 根目录:
- fs
- btrfs
- zlib.c
/*
* 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.
*
* Based on jffs2 zlib code:
* Copyright © 2001-2007 Red Hat, Inc.
* Created by David Woodhouse <dwmw2@infradead.org>
*/
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/zlib.h>
#include <linux/zutil.h>
#include <linux/vmalloc.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/sched.h>
#include <linux/pagemap.h>
#include <linux/bio.h>
#include "compression.h"
struct workspace {
z_stream inf_strm;
z_stream def_strm;
char *buf;
struct list_head list;
};
static void zlib_free_workspace(struct list_head *ws)
{
struct workspace *workspace = list_entry(ws, struct workspace, list);
vfree(workspace->def_strm.workspace);
vfree(workspace->inf_strm.workspace);
kfree(workspace->buf);
kfree(workspace);
}
static struct list_head *zlib_alloc_workspace(void)
{
struct workspace *workspace;
workspace = kzalloc(sizeof(*workspace), GFP_NOFS);
if (!workspace)
return ERR_PTR(-ENOMEM);
workspace->def_strm.workspace = vmalloc(zlib_deflate_workspacesize(
MAX_WBITS, MAX_MEM_LEVEL));
workspace->inf_strm.workspace = vmalloc(zlib_inflate_workspacesize());
workspace->buf = kmalloc(PAGE_CACHE_SIZE, GFP_NOFS);
if (!workspace->def_strm.workspace ||
!workspace->inf_strm.workspace || !workspace->buf)
goto fail;
INIT_LIST_HEAD(&workspace->list);
return &workspace->list;
fail:
zlib_free_workspace(&workspace->list);
return ERR_PTR(-ENOMEM);
}
static int zlib_compress_pages(struct list_head *ws,
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)
{
struct workspace *workspace = list_entry(ws, struct workspace, list);
int ret;
char *data_in;
char *cpage_out;
int nr_pages = 0;
struct page *in_page = NULL;
struct page *out_page = NULL;
unsigned long bytes_left;
*out_pages = 0;
*total_out = 0;
*total_in = 0;
if (Z_OK != zlib_deflateInit(&workspace->def_strm, 3)) {
printk(KERN_WARNING "deflateInit failed\n");
ret = -1;
goto out;
}
workspace->def_strm.total_in = 0;
workspace->def_strm.total_out = 0;
in_page = find_get_page(mapping, start >> PAGE_CACHE_SHIFT);
data_in = kmap(in_page);
out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
if (out_page == NULL) {
ret = -1;
goto out;
}
cpage_out = kmap(out_page);
pages[0] = out_page;
nr_pages = 1;
workspace->def_strm.next_in = data_in;
workspace->def_strm.next_out = cpage_out;
workspace->def_strm.avail_out = PAGE_CACHE_SIZE;
workspace->def_strm.avail_in = min(len, PAGE_CACHE_SIZE);
while (workspace->def_strm.total_in < len) {
ret = zlib_deflate(&workspace->def_strm, Z_SYNC_FLUSH);
if (ret != Z_OK) {
printk(KERN_DEBUG "btrfs deflate in loop returned %d\n",
ret);
zlib_deflateEnd(&workspace->def_strm);
ret = -1;
goto out;
}
/* we're making it bigger, give up */
if (workspace->def_strm.total_in > 8192 &&
workspace->def_strm.total_in <
workspace->def_strm.total_out) {
ret = -1;
goto out;
}
/* we need another page for writing out. Test this
* before the total_in so we will pull in a new page for
* the stream end if required
*/
if (workspace->def_strm.avail_out == 0) {
kunmap(out_page);
if (nr_pages == nr_dest_pages) {
out_page = NULL;
ret = -1;
goto out;
}
out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
if (out_page == NULL) {
ret = -1;
goto out;
}
cpage_out = kmap(out_page);
pages[nr_pages] = out_page;
nr_pages++;
workspace->def_strm.avail_out = PAGE_CACHE_SIZE;
workspace->def_strm.next_out = cpage_out;
}
/* we're all done */
if (workspace->def_strm.total_in >= len)
break;
/* we've read in a full page, get a new one */
if (workspace->def_strm.avail_in == 0) {
if (workspace->def_strm.total_out > max_out)
break;
bytes_left = len - workspace->def_strm.total_in;
kunmap(in_page);
page_cache_release(in_page);
start += PAGE_CACHE_SIZE;
in_page = find_get_page(mapping,
start >> PAGE_CACHE_SHIFT);
data_in = kmap(in_page);
workspace->def_strm.avail_in = min(bytes_left,
PAGE_CACHE_SIZE);
workspace->def_strm.next_in = data_in;
}
}
workspace->def_strm.avail_in = 0;
ret = zlib_deflate(&workspace->def_strm, Z_FINISH);
zlib_deflateEnd(&workspace->def_strm);
if (ret != Z_STREAM_END) {
ret = -1;
goto out;
}
if (workspace->def_strm.total_out >= workspace->def_strm.total_in) {
ret = -1;
goto out;
}
ret = 0;
*total_out = workspace->def_strm.total_out;
*total_in = workspace->def_strm.total_in;
out:
*out_pages = nr_pages;
if (out_page)
kunmap(out_page);
if (in_page) {
kunmap(in_page);
page_cache_release(in_page);
}
return ret;
}
static int zlib_decompress_biovec(struct list_head *ws, struct page **pages_in,
u64 disk_start,
struct bio_vec *bvec,
int vcnt,
size_t srclen)
{
struct workspace *workspace = list_entry(ws, struct workspace, list);
int ret = 0, ret2;
int wbits = MAX_WBITS;
char *data_in;
size_t total_out = 0;
unsigned long page_in_index = 0;
unsigned long page_out_index = 0;
unsigned long total_pages_in = (srclen + PAGE_CACHE_SIZE - 1) /
PAGE_CACHE_SIZE;
unsigned long buf_start;
unsigned long pg_offset;
data_in = kmap(pages_in[page_in_index]);
workspace->inf_strm.next_in = data_in;
workspace->inf_strm.avail_in = min_t(size_t, srclen, PAGE_CACHE_SIZE);
workspace->inf_strm.total_in = 0;
workspace->inf_strm.total_out = 0;
workspace->inf_strm.next_out = workspace->buf;
workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;
pg_offset = 0;
/* If it's deflate, and it's got no preset dictionary, then
we can tell zlib to skip the adler32 check. */
if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
((data_in[0] & 0x0f) == Z_DEFLATED) &&
!(((data_in[0]<<8) + data_in[1]) % 31)) {
wbits = -((data_in[0] >> 4) + 8);
workspace->inf_strm.next_in += 2;
workspace->inf_strm.avail_in -= 2;
}
if (Z_OK != zlib_inflateInit2(&workspace->inf_strm, wbits)) {
printk(KERN_WARNING "inflateInit failed\n");
return -1;
}
while (workspace->inf_strm.total_in < srclen) {
ret = zlib_inflate(&workspace->inf_strm, Z_NO_FLUSH);
if (ret != Z_OK && ret != Z_STREAM_END)
break;
buf_start = total_out;
total_out = workspace->inf_strm.total_out;
/* we didn't make progress in this inflate call, we're done */
if (buf_start == total_out)
break;
ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
total_out, disk_start,
bvec, vcnt,
&page_out_index, &pg_offset);
if (ret2 == 0) {
ret = 0;
goto done;
}
workspace->inf_strm.next_out = workspace->buf;
workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;
if (workspace->inf_strm.avail_in == 0) {
unsigned long tmp;
kunmap(pages_in[page_in_index]);
page_in_index++;
if (page_in_index >= total_pages_in) {
data_in = NULL;
break;
}
data_in = kmap(pages_in[page_in_index]);
workspace->inf_strm.next_in = data_in;
tmp = srclen - workspace->inf_strm.total_in;
workspace->inf_strm.avail_in = min(tmp,
PAGE_CACHE_SIZE);
}
}
if (ret != Z_STREAM_END)
ret = -1;
else
ret = 0;
done:
zlib_inflateEnd(&workspace->inf_strm);
if (data_in)
kunmap(pages_in[page_in_index]);
return ret;
}
static int zlib_decompress(struct list_head *ws, unsigned char *data_in,
struct page *dest_page,
unsigned long start_byte,
size_t srclen, size_t destlen)
{
struct workspace *workspace = list_entry(ws, struct workspace, list);
int ret = 0;
int wbits = MAX_WBITS;
unsigned long bytes_left = destlen;
unsigned long total_out = 0;
char *kaddr;
workspace->inf_strm.next_in = data_in;
workspace->inf_strm.avail_in = srclen;
workspace->inf_strm.total_in = 0;
workspace->inf_strm.next_out = workspace->buf;
workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;
workspace->inf_strm.total_out = 0;
/* If it's deflate, and it's got no preset dictionary, then
we can tell zlib to skip the adler32 check. */
if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
((data_in[0] & 0x0f) == Z_DEFLATED) &&
!(((data_in[0]<<8) + data_in[1]) % 31)) {
wbits = -((data_in[0] >> 4) + 8);
workspace->inf_strm.next_in += 2;
workspace->inf_strm.avail_in -= 2;
}
if (Z_OK != zlib_inflateInit2(&workspace->inf_strm, wbits)) {
printk(KERN_WARNING "inflateInit failed\n");
return -1;
}
while (bytes_left > 0) {
unsigned long buf_start;
unsigned long buf_offset;
unsigned long bytes;
unsigned long pg_offset = 0;
ret = zlib_inflate(&workspace->inf_strm, Z_NO_FLUSH);
if (ret != Z_OK && ret != Z_STREAM_END)
break;
buf_start = total_out;
total_out = workspace->inf_strm.total_out;
if (total_out == buf_start) {
ret = -1;
break;
}
if (total_out <= start_byte)
goto next;
if (total_out > start_byte && buf_start < start_byte)
buf_offset = start_byte - buf_start;
else
buf_offset = 0;
bytes = min(PAGE_CACHE_SIZE - pg_offset,
PAGE_CACHE_SIZE - buf_offset);
bytes = min(bytes, bytes_left);
kaddr = kmap_atomic(dest_page, KM_USER0);
memcpy(kaddr + pg_offset, workspace->buf + buf_offset, bytes);
kunmap_atomic(kaddr, KM_USER0);
pg_offset += bytes;
bytes_left -= bytes;
next:
workspace->inf_strm.next_out = workspace->buf;
workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;
}
if (ret != Z_STREAM_END && bytes_left != 0)
ret = -1;
else
ret = 0;
zlib_inflateEnd(&workspace->inf_strm);
return ret;
}
struct btrfs_compress_op btrfs_zlib_compress = {
.alloc_workspace = zlib_alloc_workspace,
.free_workspace = zlib_free_workspace,
.compress_pages = zlib_compress_pages,
.decompress_biovec = zlib_decompress_biovec,
.decompress = zlib_decompress,
};