fs/squashfs/decompressor_multi.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  *  Copyright (c) 2013
0004  *  Minchan Kim <minchan@kernel.org>
0005  */
0006 #include <linux/types.h>
0007 #include <linux/mutex.h>
0008 #include <linux/slab.h>
0009 #include <linux/bio.h>
0010 #include <linux/sched.h>
0011 #include <linux/wait.h>
0012 #include <linux/cpumask.h>
0013
0014 #include "squashfs_fs.h"
0015 #include "squashfs_fs_sb.h"
0016 #include "decompressor.h"
0017 #include "squashfs.h"
0018
0019 /*
0020  * This file implements multi-threaded decompression in the
0021  * decompressor framework
0022  */
0023
0024
0025 /*
0026  * The reason that multiply two is that a CPU can request new I/O
0027  * while it is waiting previous request.
0028  */
0029 #define MAX_DECOMPRESSOR    (num_online_cpus() * 2)
0030
0031
0032 int squashfs_max_decompressors(void)
0033 {
0034     return MAX_DECOMPRESSOR;
0035 }
0036
0037
0038 struct squashfs_stream {
0039     void            *comp_opts;
0040     struct list_head    strm_list;
0041     struct mutex        mutex;
0042     int         avail_decomp;
0043     wait_queue_head_t   wait;
0044 };
0045
0046
0047 struct decomp_stream {
0048     void *stream;
0049     struct list_head list;
0050 };
0051
0052
0053 static void put_decomp_stream(struct decomp_stream *decomp_strm,
0054                 struct squashfs_stream *stream)
0055 {
0056     mutex_lock(&stream->mutex);
0057     list_add(&decomp_strm->list, &stream->strm_list);
0058     mutex_unlock(&stream->mutex);
0059     wake_up(&stream->wait);
0060 }
0061
0062 void *squashfs_decompressor_create(struct squashfs_sb_info *msblk,
0063                 void *comp_opts)
0064 {
0065     struct squashfs_stream *stream;
0066     struct decomp_stream *decomp_strm = NULL;
0067     int err = -ENOMEM;
0068
0069     stream = kzalloc(sizeof(*stream), GFP_KERNEL);
0070     if (!stream)
0071         goto out;
0072
0073     stream->comp_opts = comp_opts;
0074     mutex_init(&stream->mutex);
0075     INIT_LIST_HEAD(&stream->strm_list);
0076     init_waitqueue_head(&stream->wait);
0077
0078     /*
0079      * We should have a decompressor at least as default
0080      * so if we fail to allocate new decompressor dynamically,
0081      * we could always fall back to default decompressor and
0082      * file system works.
0083      */
0084     decomp_strm = kmalloc(sizeof(*decomp_strm), GFP_KERNEL);
0085     if (!decomp_strm)
0086         goto out;
0087
0088     decomp_strm->stream = msblk->decompressor->init(msblk,
0089                         stream->comp_opts);
0090     if (IS_ERR(decomp_strm->stream)) {
0091         err = PTR_ERR(decomp_strm->stream);
0092         goto out;
0093     }
0094
0095     list_add(&decomp_strm->list, &stream->strm_list);
0096     stream->avail_decomp = 1;
0097     return stream;
0098
0099 out:
0100     kfree(decomp_strm);
0101     kfree(stream);
0102     return ERR_PTR(err);
0103 }
0104
0105
0106 void squashfs_decompressor_destroy(struct squashfs_sb_info *msblk)
0107 {
0108     struct squashfs_stream *stream = msblk->stream;
0109     if (stream) {
0110         struct decomp_stream *decomp_strm;
0111
0112         while (!list_empty(&stream->strm_list)) {
0113             decomp_strm = list_entry(stream->strm_list.prev,
0114                         struct decomp_stream, list);
0115             list_del(&decomp_strm->list);
0116             msblk->decompressor->free(decomp_strm->stream);
0117             kfree(decomp_strm);
0118             stream->avail_decomp--;
0119         }
0120         WARN_ON(stream->avail_decomp);
0121         kfree(stream->comp_opts);
0122         kfree(stream);
0123     }
0124 }
0125
0126
0127 static struct decomp_stream *get_decomp_stream(struct squashfs_sb_info *msblk,
0128                     struct squashfs_stream *stream)
0129 {
0130     struct decomp_stream *decomp_strm;
0131
0132     while (1) {
0133         mutex_lock(&stream->mutex);
0134
0135         /* There is available decomp_stream */
0136         if (!list_empty(&stream->strm_list)) {
0137             decomp_strm = list_entry(stream->strm_list.prev,
0138                 struct decomp_stream, list);
0139             list_del(&decomp_strm->list);
0140             mutex_unlock(&stream->mutex);
0141             break;
0142         }
0143
0144         /*
0145          * If there is no available decomp and already full,
0146          * let's wait for releasing decomp from other users.
0147          */
0148         if (stream->avail_decomp >= MAX_DECOMPRESSOR)
0149             goto wait;
0150
0151         /* Let's allocate new decomp */
0152         decomp_strm = kmalloc(sizeof(*decomp_strm), GFP_KERNEL);
0153         if (!decomp_strm)
0154             goto wait;
0155
0156         decomp_strm->stream = msblk->decompressor->init(msblk,
0157                         stream->comp_opts);
0158         if (IS_ERR(decomp_strm->stream)) {
0159             kfree(decomp_strm);
0160             goto wait;
0161         }
0162
0163         stream->avail_decomp++;
0164         WARN_ON(stream->avail_decomp > MAX_DECOMPRESSOR);
0165
0166         mutex_unlock(&stream->mutex);
0167         break;
0168 wait:
0169         /*
0170          * If system memory is tough, let's for other's
0171          * releasing instead of hurting VM because it could
0172          * make page cache thrashing.
0173          */
0174         mutex_unlock(&stream->mutex);
0175         wait_event(stream->wait,
0176             !list_empty(&stream->strm_list));
0177     }
0178
0179     return decomp_strm;
0180 }
0181
0182
0183 int squashfs_decompress(struct squashfs_sb_info *msblk, struct bio *bio,
0184             int offset, int length,
0185             struct squashfs_page_actor *output)
0186 {
0187     int res;
0188     struct squashfs_stream *stream = msblk->stream;
0189     struct decomp_stream *decomp_stream = get_decomp_stream(msblk, stream);
0190     res = msblk->decompressor->decompress(msblk, decomp_stream->stream,
0191         bio, offset, length, output);
0192     put_decomp_stream(decomp_stream, stream);
0193     if (res < 0)
0194         ERROR("%s decompression failed, data probably corrupt\n",
0195             msblk->decompressor->name);
0196     return res;
0197 }