// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (c) 2013
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* Minchan Kim <minchan@kernel.org>
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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/bio.h>
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#include <linux/sched.h>
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#include <linux/wait.h>
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#include <linux/cpumask.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 implements multi-threaded decompression in the
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* decompressor framework
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*/
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/*
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* The reason that multiply two is that a CPU can request new I/O
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* while it is waiting previous request.
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*/
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#define MAX_DECOMPRESSOR (num_online_cpus() * 2)
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int squashfs_max_decompressors(void)
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{
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return MAX_DECOMPRESSOR;
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}
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struct squashfs_stream {
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void *comp_opts;
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struct list_head strm_list;
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struct mutex mutex;
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int avail_decomp;
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wait_queue_head_t wait;
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};
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struct decomp_stream {
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void *stream;
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struct list_head list;
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};
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static void put_decomp_stream(struct decomp_stream *decomp_strm,
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struct squashfs_stream *stream)
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{
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mutex_lock(&stream->mutex);
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list_add(&decomp_strm->list, &stream->strm_list);
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mutex_unlock(&stream->mutex);
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wake_up(&stream->wait);
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}
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void *squashfs_decompressor_create(struct squashfs_sb_info *msblk,
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void *comp_opts)
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{
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struct squashfs_stream *stream;
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struct decomp_stream *decomp_strm = NULL;
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int err = -ENOMEM;
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stream = kzalloc(sizeof(*stream), GFP_KERNEL);
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if (!stream)
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goto out;
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stream->comp_opts = comp_opts;
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mutex_init(&stream->mutex);
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INIT_LIST_HEAD(&stream->strm_list);
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init_waitqueue_head(&stream->wait);
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/*
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* We should have a decompressor at least as default
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* so if we fail to allocate new decompressor dynamically,
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* we could always fall back to default decompressor and
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* file system works.
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*/
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decomp_strm = kmalloc(sizeof(*decomp_strm), GFP_KERNEL);
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if (!decomp_strm)
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goto out;
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decomp_strm->stream = msblk->decompressor->init(msblk,
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stream->comp_opts);
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if (IS_ERR(decomp_strm->stream)) {
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err = PTR_ERR(decomp_strm->stream);
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goto out;
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}
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list_add(&decomp_strm->list, &stream->strm_list);
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stream->avail_decomp = 1;
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return stream;
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out:
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kfree(decomp_strm);
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kfree(stream);
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return ERR_PTR(err);
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}
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void squashfs_decompressor_destroy(struct squashfs_sb_info *msblk)
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{
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struct squashfs_stream *stream = msblk->stream;
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if (stream) {
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struct decomp_stream *decomp_strm;
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while (!list_empty(&stream->strm_list)) {
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decomp_strm = list_entry(stream->strm_list.prev,
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struct decomp_stream, list);
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list_del(&decomp_strm->list);
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msblk->decompressor->free(decomp_strm->stream);
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kfree(decomp_strm);
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stream->avail_decomp--;
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}
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WARN_ON(stream->avail_decomp);
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kfree(stream->comp_opts);
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kfree(stream);
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}
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}
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static struct decomp_stream *get_decomp_stream(struct squashfs_sb_info *msblk,
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struct squashfs_stream *stream)
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{
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struct decomp_stream *decomp_strm;
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while (1) {
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mutex_lock(&stream->mutex);
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/* There is available decomp_stream */
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if (!list_empty(&stream->strm_list)) {
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decomp_strm = list_entry(stream->strm_list.prev,
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struct decomp_stream, list);
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list_del(&decomp_strm->list);
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mutex_unlock(&stream->mutex);
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break;
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}
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/*
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* If there is no available decomp and already full,
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* let's wait for releasing decomp from other users.
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*/
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if (stream->avail_decomp >= MAX_DECOMPRESSOR)
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goto wait;
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/* Let's allocate new decomp */
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decomp_strm = kmalloc(sizeof(*decomp_strm), GFP_KERNEL);
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if (!decomp_strm)
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goto wait;
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decomp_strm->stream = msblk->decompressor->init(msblk,
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stream->comp_opts);
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if (IS_ERR(decomp_strm->stream)) {
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kfree(decomp_strm);
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goto wait;
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}
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stream->avail_decomp++;
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WARN_ON(stream->avail_decomp > MAX_DECOMPRESSOR);
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mutex_unlock(&stream->mutex);
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break;
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wait:
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/*
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* If system memory is tough, let's for other's
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* releasing instead of hurting VM because it could
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* make page cache thrashing.
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*/
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mutex_unlock(&stream->mutex);
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wait_event(stream->wait,
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!list_empty(&stream->strm_list));
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}
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return decomp_strm;
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}
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int squashfs_decompress(struct squashfs_sb_info *msblk, struct bio *bio,
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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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struct squashfs_stream *stream = msblk->stream;
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struct decomp_stream *decomp_stream = get_decomp_stream(msblk, stream);
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res = msblk->decompressor->decompress(msblk, decomp_stream->stream,
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bio, offset, length, output);
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put_decomp_stream(decomp_stream, stream);
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if (res < 0)
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ERROR("%s decompression failed, data probably corrupt\n",
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msblk->decompressor->name);
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return res;
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}
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