417aca479b
This patch essentially does 3 things:
1/ Always use an array of page to store the data instead of a mix of
buffers and pages.
2/ It is now possible to have 'holes' in a page actor, i.e. NULL
pages in the array.
When reading a block (default 128K), squashfs tries to grab all
the pages covering this block. If a single page is up-to-date or
locked, it falls back to using an intermediate buffer to do the
read and then copy the pages in the actor. Allowing holes in the
page actor remove the need for this intermediate buffer.
3/ Refactor the wrappers to share code that deals with page actors.
Signed-off-by: Adrien Schildknecht <adriens@google.com>
Change-Id: I98128bed5d518cf31b67e788a85b275e9a323bec
147 lines
3.3 KiB
C
147 lines
3.3 KiB
C
/*
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* Squashfs - a compressed read only filesystem for Linux
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*
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* Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
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* Phillip Lougher <phillip@squashfs.org.uk>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2,
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* or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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* zlib_wrapper.c
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*/
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#include <linux/mutex.h>
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#include <linux/buffer_head.h>
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#include <linux/slab.h>
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#include <linux/zlib.h>
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#include <linux/vmalloc.h>
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#include "squashfs_fs.h"
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#include "squashfs_fs_sb.h"
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#include "squashfs.h"
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#include "decompressor.h"
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#include "page_actor.h"
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static void *zlib_init(struct squashfs_sb_info *dummy, void *buff)
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{
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z_stream *stream = kmalloc(sizeof(z_stream), GFP_KERNEL);
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if (stream == NULL)
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goto failed;
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stream->workspace = vmalloc(zlib_inflate_workspacesize());
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if (stream->workspace == NULL)
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goto failed;
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return stream;
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failed:
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ERROR("Failed to allocate zlib workspace\n");
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kfree(stream);
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return ERR_PTR(-ENOMEM);
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}
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static void zlib_free(void *strm)
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{
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z_stream *stream = strm;
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if (stream)
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vfree(stream->workspace);
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kfree(stream);
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}
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static int zlib_uncompress(struct squashfs_sb_info *msblk, void *strm,
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struct buffer_head **bh, int b, int offset, int length,
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struct squashfs_page_actor *output)
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{
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void *buf = NULL;
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int zlib_err, zlib_init = 0, k = 0;
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z_stream *stream = strm;
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stream->avail_out = PAGE_CACHE_SIZE;
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stream->next_out = squashfs_first_page(output);
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stream->avail_in = 0;
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do {
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if (stream->avail_in == 0 && k < b) {
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int avail = min(length, msblk->devblksize - offset);
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length -= avail;
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stream->next_in = bh[k]->b_data + offset;
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stream->avail_in = avail;
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offset = 0;
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}
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if (stream->avail_out == 0) {
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stream->next_out = squashfs_next_page(output);
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if (!IS_ERR(stream->next_out))
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stream->avail_out = PAGE_CACHE_SIZE;
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}
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if (!stream->next_out) {
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if (!buf) {
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buf = kmalloc(PAGE_CACHE_SIZE, GFP_ATOMIC);
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if (!buf)
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goto out;
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}
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stream->next_out = buf;
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}
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if (!zlib_init) {
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zlib_err = zlib_inflateInit(stream);
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if (zlib_err != Z_OK) {
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squashfs_finish_page(output);
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goto out;
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}
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zlib_init = 1;
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}
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zlib_err = zlib_inflate(stream, Z_SYNC_FLUSH);
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if (stream->avail_in == 0 && k < b)
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put_bh(bh[k++]);
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} while (zlib_err == Z_OK);
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squashfs_finish_page(output);
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if (zlib_err != Z_STREAM_END)
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goto out;
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zlib_err = zlib_inflateEnd(stream);
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if (zlib_err != Z_OK)
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goto out;
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if (k < b)
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goto out;
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kfree(buf);
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return stream->total_out;
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out:
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for (; k < b; k++)
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put_bh(bh[k]);
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kfree(buf);
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return -EIO;
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}
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const struct squashfs_decompressor squashfs_zlib_comp_ops = {
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.init = zlib_init,
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.free = zlib_free,
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.decompress = zlib_uncompress,
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.id = ZLIB_COMPRESSION,
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.name = "zlib",
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.supported = 1
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};
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