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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Copyright (c) 20134 * Minchan Kim <minchan@kernel.org>5 */6#include <linux/types.h>7#include <linux/mutex.h>8#include <linux/slab.h>9#include <linux/bio.h>10#include <linux/sched.h>11#include <linux/wait.h>12#include <linux/cpumask.h>13 14#include "squashfs_fs.h"15#include "squashfs_fs_sb.h"16#include "decompressor.h"17#include "squashfs.h"18 19/*20 * This file implements multi-threaded decompression in the21 * decompressor framework22 */23 24 25/*26 * The reason that multiply two is that a CPU can request new I/O27 * while it is waiting previous request.28 */29#define MAX_DECOMPRESSOR (num_online_cpus() * 2)30 31 32static int squashfs_max_decompressors(void)33{34 return MAX_DECOMPRESSOR;35}36 37struct squashfs_stream {38 void *comp_opts;39 struct list_head strm_list;40 struct mutex mutex;41 int avail_decomp;42 wait_queue_head_t wait;43};44 45 46struct decomp_stream {47 void *stream;48 struct list_head list;49};50 51 52static void put_decomp_stream(struct decomp_stream *decomp_strm,53 struct squashfs_stream *stream)54{55 mutex_lock(&stream->mutex);56 list_add(&decomp_strm->list, &stream->strm_list);57 mutex_unlock(&stream->mutex);58 wake_up(&stream->wait);59}60 61static void *squashfs_decompressor_create(struct squashfs_sb_info *msblk,62 void *comp_opts)63{64 struct squashfs_stream *stream;65 struct decomp_stream *decomp_strm = NULL;66 int err = -ENOMEM;67 68 stream = kzalloc(sizeof(*stream), GFP_KERNEL);69 if (!stream)70 goto out;71 72 stream->comp_opts = comp_opts;73 mutex_init(&stream->mutex);74 INIT_LIST_HEAD(&stream->strm_list);75 init_waitqueue_head(&stream->wait);76 77 /*78 * We should have a decompressor at least as default79 * so if we fail to allocate new decompressor dynamically,80 * we could always fall back to default decompressor and81 * file system works.82 */83 decomp_strm = kmalloc(sizeof(*decomp_strm), GFP_KERNEL);84 if (!decomp_strm)85 goto out;86 87 decomp_strm->stream = msblk->decompressor->init(msblk,88 stream->comp_opts);89 if (IS_ERR(decomp_strm->stream)) {90 err = PTR_ERR(decomp_strm->stream);91 goto out;92 }93 94 list_add(&decomp_strm->list, &stream->strm_list);95 stream->avail_decomp = 1;96 return stream;97 98out:99 kfree(decomp_strm);100 kfree(stream);101 return ERR_PTR(err);102}103 104 105static void squashfs_decompressor_destroy(struct squashfs_sb_info *msblk)106{107 struct squashfs_stream *stream = msblk->stream;108 if (stream) {109 struct decomp_stream *decomp_strm;110 111 while (!list_empty(&stream->strm_list)) {112 decomp_strm = list_entry(stream->strm_list.prev,113 struct decomp_stream, list);114 list_del(&decomp_strm->list);115 msblk->decompressor->free(decomp_strm->stream);116 kfree(decomp_strm);117 stream->avail_decomp--;118 }119 WARN_ON(stream->avail_decomp);120 kfree(stream->comp_opts);121 kfree(stream);122 }123}124 125 126static struct decomp_stream *get_decomp_stream(struct squashfs_sb_info *msblk,127 struct squashfs_stream *stream)128{129 struct decomp_stream *decomp_strm;130 131 while (1) {132 mutex_lock(&stream->mutex);133 134 /* There is available decomp_stream */135 if (!list_empty(&stream->strm_list)) {136 decomp_strm = list_entry(stream->strm_list.prev,137 struct decomp_stream, list);138 list_del(&decomp_strm->list);139 mutex_unlock(&stream->mutex);140 break;141 }142 143 /*144 * If there is no available decomp and already full,145 * let's wait for releasing decomp from other users.146 */147 if (stream->avail_decomp >= msblk->max_thread_num)148 goto wait;149 150 /* Let's allocate new decomp */151 decomp_strm = kmalloc(sizeof(*decomp_strm), GFP_KERNEL);152 if (!decomp_strm)153 goto wait;154 155 decomp_strm->stream = msblk->decompressor->init(msblk,156 stream->comp_opts);157 if (IS_ERR(decomp_strm->stream)) {158 kfree(decomp_strm);159 goto wait;160 }161 162 stream->avail_decomp++;163 WARN_ON(stream->avail_decomp > msblk->max_thread_num);164 165 mutex_unlock(&stream->mutex);166 break;167wait:168 /*169 * If system memory is tough, let's for other's170 * releasing instead of hurting VM because it could171 * make page cache thrashing.172 */173 mutex_unlock(&stream->mutex);174 wait_event(stream->wait,175 !list_empty(&stream->strm_list));176 }177 178 return decomp_strm;179}180 181 182static int squashfs_decompress(struct squashfs_sb_info *msblk, struct bio *bio,183 int offset, int length,184 struct squashfs_page_actor *output)185{186 int res;187 struct squashfs_stream *stream = msblk->stream;188 struct decomp_stream *decomp_stream = get_decomp_stream(msblk, stream);189 res = msblk->decompressor->decompress(msblk, decomp_stream->stream,190 bio, offset, length, output);191 put_decomp_stream(decomp_stream, stream);192 if (res < 0)193 ERROR("%s decompression failed, data probably corrupt\n",194 msblk->decompressor->name);195 return res;196}197 198const struct squashfs_decompressor_thread_ops squashfs_decompressor_multi = {199 .create = squashfs_decompressor_create,200 .destroy = squashfs_decompressor_destroy,201 .decompress = squashfs_decompress,202 .max_decompressors = squashfs_max_decompressors,203};204