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
120 lines
2.5 KiB
C
120 lines
2.5 KiB
C
/*
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* Copyright (c) 2013, 2014
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* Phillip Lougher <phillip@squashfs.org.uk>
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*
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* This work is licensed under the terms of the GNU GPL, version 2. See
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* the COPYING file in the top-level directory.
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*/
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#include <linux/buffer_head.h>
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#include <linux/mutex.h>
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#include <linux/slab.h>
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#include <linux/vmalloc.h>
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#include <linux/lz4.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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#define LZ4_LEGACY 1
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struct lz4_comp_opts {
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__le32 version;
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__le32 flags;
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};
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struct squashfs_lz4 {
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void *input;
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void *output;
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};
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static void *lz4_comp_opts(struct squashfs_sb_info *msblk,
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void *buff, int len)
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{
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struct lz4_comp_opts *comp_opts = buff;
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/* LZ4 compressed filesystems always have compression options */
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if (comp_opts == NULL || len < sizeof(*comp_opts))
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return ERR_PTR(-EIO);
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if (le32_to_cpu(comp_opts->version) != LZ4_LEGACY) {
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/* LZ4 format currently used by the kernel is the 'legacy'
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* format */
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ERROR("Unknown LZ4 version\n");
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return ERR_PTR(-EINVAL);
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}
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return NULL;
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}
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static void *lz4_init(struct squashfs_sb_info *msblk, void *buff)
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{
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int block_size = max_t(int, msblk->block_size, SQUASHFS_METADATA_SIZE);
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struct squashfs_lz4 *stream;
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stream = kzalloc(sizeof(*stream), GFP_KERNEL);
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if (stream == NULL)
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goto failed;
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stream->input = vmalloc(block_size);
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if (stream->input == NULL)
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goto failed2;
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stream->output = vmalloc(block_size);
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if (stream->output == NULL)
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goto failed3;
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return stream;
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failed3:
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vfree(stream->input);
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failed2:
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kfree(stream);
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failed:
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ERROR("Failed to initialise LZ4 decompressor\n");
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return ERR_PTR(-ENOMEM);
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}
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static void lz4_free(void *strm)
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{
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struct squashfs_lz4 *stream = strm;
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if (stream) {
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vfree(stream->input);
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vfree(stream->output);
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}
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kfree(stream);
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}
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static int lz4_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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int res;
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size_t dest_len = output->length;
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struct squashfs_lz4 *stream = strm;
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squashfs_bh_to_buf(bh, b, stream->input, offset, length,
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msblk->devblksize);
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res = lz4_decompress_unknownoutputsize(stream->input, length,
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stream->output, &dest_len);
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if (res)
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return -EIO;
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squashfs_buf_to_actor(stream->output, output, dest_len);
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return dest_len;
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}
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const struct squashfs_decompressor squashfs_lz4_comp_ops = {
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.init = lz4_init,
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.comp_opts = lz4_comp_opts,
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.free = lz4_free,
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.decompress = lz4_uncompress,
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.id = LZ4_COMPRESSION,
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.name = "lz4",
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.supported = 1
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};
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