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
153 lines
3.9 KiB
C
153 lines
3.9 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/highmem.h>
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#include <linux/fs.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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#include "page_actor.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_LZ4
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static const struct squashfs_decompressor squashfs_lz4_comp_ops = {
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NULL, NULL, NULL, NULL, LZ4_COMPRESSION, "lz4", 0
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};
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#endif
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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_lz4_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 *comp_opts, *buffer = NULL;
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struct page *page;
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struct squashfs_page_actor *actor = NULL;
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int length = 0;
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if (!SQUASHFS_COMP_OPTS(flags))
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return squashfs_comp_opts(msblk, buffer, length);
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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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page = alloc_page(GFP_KERNEL);
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if (!page)
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return ERR_PTR(-ENOMEM);
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actor = squashfs_page_actor_init(&page, 1, 0, NULL);
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if (actor == NULL) {
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comp_opts = ERR_PTR(-ENOMEM);
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goto actor_error;
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}
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length = squashfs_read_data(sb,
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sizeof(struct squashfs_super_block), 0, NULL, actor);
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if (length < 0) {
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comp_opts = ERR_PTR(length);
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goto read_error;
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}
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buffer = kmap_atomic(page);
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comp_opts = squashfs_comp_opts(msblk, buffer, length);
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kunmap_atomic(buffer);
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read_error:
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squashfs_page_actor_free(actor, 0);
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actor_error:
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__free_page(page);
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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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