fs/squashfs/decompressor_multi.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  Copyright (c) 2013
   4  *  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 the
  21  * decompressor framework
  22  */
  23
  24
  25 /*
  26  * The reason that multiply two is that a CPU can request new I/O
  27  * while it is waiting previous request.
  28  */
  29 #define MAX_DECOMPRESSOR        (num_online_cpus() * 2)
  30
  31
  32 static int squashfs_max_decompressors(void)
  33 {
  34         return MAX_DECOMPRESSOR;
  35 }
  36
  37 struct 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
  46 struct decomp_stream {
  47         void *stream;
  48         struct list_head list;
  49 };
  50
  51
  52 static 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
  61 static 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 default
  79          * so if we fail to allocate new decompressor dynamically,
  80          * we could always fall back to default decompressor and
  81          * 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
  98 out:
  99         kfree(decomp_strm);
 100         kfree(stream);
 101         return ERR_PTR(err);
 102 }
 103
 104
 105 static 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
 126 static 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;
 167 wait:
 168                 /*
 169                  * If system memory is tough, let's for other's
 170                  * releasing instead of hurting VM because it could
 171                  * 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
 182 static 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
 198 const 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 };