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![Phillip Lougher](/assets/img/avatar_default.png)
The decompressor interface and code was written from the point of view of single-threaded operation. In doing so it mixed a lot of single-threaded implementation specific aspects into the decompressor code and elsewhere which makes it difficult to seamlessly support multiple different decompressor implementations. This patch does the following: 1. It removes compressor_options parsing from the decompressor init() function. This allows the decompressor init() function to be dynamically called to instantiate multiple decompressors, without the compressor options needing to be read and parsed each time. 2. It moves threading and all sleeping operations out of the decompressors. In doing so, it makes the decompressors non-blocking wrappers which only deal with interfacing with the decompressor implementation. 3. It splits decompressor.[ch] into decompressor generic functions in decompressor.[ch], and moves the single threaded decompressor implementation into decompressor_single.c. The result of this patch is Squashfs should now be able to support multiple decompressors by adding new decompressor_xxx.c files with specialised implementations of the functions in decompressor_single.c Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk> Reviewed-by: Minchan Kim <minchan@kernel.org>
133 lines
3.4 KiB
C
133 lines
3.4 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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* decompressor.c
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*/
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#include <linux/types.h>
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#include <linux/mutex.h>
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#include <linux/slab.h>
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#include <linux/buffer_head.h>
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#include "squashfs_fs.h"
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#include "squashfs_fs_sb.h"
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#include "decompressor.h"
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#include "squashfs.h"
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/*
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* This file (and decompressor.h) implements a decompressor framework for
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* Squashfs, allowing multiple decompressors to be easily supported
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*/
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static const struct squashfs_decompressor squashfs_lzma_unsupported_comp_ops = {
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NULL, NULL, NULL, NULL, LZMA_COMPRESSION, "lzma", 0
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};
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#ifndef CONFIG_SQUASHFS_LZO
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static const struct squashfs_decompressor squashfs_lzo_comp_ops = {
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NULL, NULL, NULL, NULL, LZO_COMPRESSION, "lzo", 0
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};
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#endif
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#ifndef CONFIG_SQUASHFS_XZ
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static const struct squashfs_decompressor squashfs_xz_comp_ops = {
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NULL, NULL, NULL, NULL, XZ_COMPRESSION, "xz", 0
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};
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#endif
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#ifndef CONFIG_SQUASHFS_ZLIB
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static const struct squashfs_decompressor squashfs_zlib_comp_ops = {
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NULL, NULL, NULL, NULL, ZLIB_COMPRESSION, "zlib", 0
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};
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#endif
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static const struct squashfs_decompressor squashfs_unknown_comp_ops = {
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NULL, NULL, NULL, NULL, 0, "unknown", 0
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};
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static const struct squashfs_decompressor *decompressor[] = {
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&squashfs_zlib_comp_ops,
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&squashfs_lzo_comp_ops,
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&squashfs_xz_comp_ops,
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&squashfs_lzma_unsupported_comp_ops,
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&squashfs_unknown_comp_ops
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};
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const struct squashfs_decompressor *squashfs_lookup_decompressor(int id)
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{
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int i;
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for (i = 0; decompressor[i]->id; i++)
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if (id == decompressor[i]->id)
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break;
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return decompressor[i];
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}
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static void *get_comp_opts(struct super_block *sb, unsigned short flags)
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{
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struct squashfs_sb_info *msblk = sb->s_fs_info;
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void *buffer = NULL, *comp_opts;
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int length = 0;
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/*
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* Read decompressor specific options from file system if present
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*/
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if (SQUASHFS_COMP_OPTS(flags)) {
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buffer = kmalloc(PAGE_CACHE_SIZE, GFP_KERNEL);
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if (buffer == NULL) {
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comp_opts = ERR_PTR(-ENOMEM);
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goto out;
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}
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length = squashfs_read_data(sb, &buffer,
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sizeof(struct squashfs_super_block), 0, NULL,
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PAGE_CACHE_SIZE, 1);
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if (length < 0) {
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comp_opts = ERR_PTR(length);
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goto out;
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}
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}
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comp_opts = squashfs_comp_opts(msblk, buffer, length);
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out:
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kfree(buffer);
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return comp_opts;
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}
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void *squashfs_decompressor_setup(struct super_block *sb, unsigned short flags)
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{
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struct squashfs_sb_info *msblk = sb->s_fs_info;
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void *stream, *comp_opts = get_comp_opts(sb, flags);
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if (IS_ERR(comp_opts))
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return comp_opts;
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stream = squashfs_decompressor_create(msblk, comp_opts);
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if (IS_ERR(stream))
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kfree(comp_opts);
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return stream;
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}
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