linux-hardened/fs/squashfs/decompressor_multi_percpu.c
Phillip Lougher 846b730e99 Squashfs: Generalise paging handling in the decompressors
Further generalise the decompressors by adding a page handler
abstraction.  This adds helpers to allow the decompressors
to access and process the output buffers in an implementation
independant manner.

This allows different types of output buffer to be passed
to the decompressors, with the implementation specific
aspects handled at decompression time, but without the
knowledge being held in the decompressor wrapper code.

This will allow the decompressors to handle Squashfs
cache buffers, and page cache pages.

This patch adds the abstraction and an implementation for
the caches.

Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Reviewed-by: Minchan Kim <minchan@kernel.org>
2013-11-20 03:59:01 +00:00

97 lines
2.3 KiB
C

/*
* Copyright (c) 2013
* Phillip Lougher <phillip@squashfs.org.uk>
*
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
*/
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/percpu.h>
#include <linux/buffer_head.h>
#include "squashfs_fs.h"
#include "squashfs_fs_sb.h"
#include "decompressor.h"
#include "squashfs.h"
/*
* This file implements multi-threaded decompression using percpu
* variables, one thread per cpu core.
*/
struct squashfs_stream {
void *stream;
};
void *squashfs_decompressor_create(struct squashfs_sb_info *msblk,
void *comp_opts)
{
struct squashfs_stream *stream;
struct squashfs_stream __percpu *percpu;
int err, cpu;
percpu = alloc_percpu(struct squashfs_stream);
if (percpu == NULL)
return ERR_PTR(-ENOMEM);
for_each_possible_cpu(cpu) {
stream = per_cpu_ptr(percpu, cpu);
stream->stream = msblk->decompressor->init(msblk, comp_opts);
if (IS_ERR(stream->stream)) {
err = PTR_ERR(stream->stream);
goto out;
}
}
kfree(comp_opts);
return (__force void *) percpu;
out:
for_each_possible_cpu(cpu) {
stream = per_cpu_ptr(percpu, cpu);
if (!IS_ERR_OR_NULL(stream->stream))
msblk->decompressor->free(stream->stream);
}
free_percpu(percpu);
return ERR_PTR(err);
}
void squashfs_decompressor_destroy(struct squashfs_sb_info *msblk)
{
struct squashfs_stream __percpu *percpu =
(struct squashfs_stream __percpu *) msblk->stream;
struct squashfs_stream *stream;
int cpu;
if (msblk->stream) {
for_each_possible_cpu(cpu) {
stream = per_cpu_ptr(percpu, cpu);
msblk->decompressor->free(stream->stream);
}
free_percpu(percpu);
}
}
int squashfs_decompress(struct squashfs_sb_info *msblk, struct buffer_head **bh,
int b, int offset, int length, struct squashfs_page_actor *output)
{
struct squashfs_stream __percpu *percpu =
(struct squashfs_stream __percpu *) msblk->stream;
struct squashfs_stream *stream = get_cpu_ptr(percpu);
int res = msblk->decompressor->decompress(msblk, stream->stream, bh, b,
offset, length, output);
put_cpu_ptr(stream);
if (res < 0)
ERROR("%s decompression failed, data probably corrupt\n",
msblk->decompressor->name);
return res;
}
int squashfs_max_decompressors(void)
{
return num_possible_cpus();
}