// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2013
 * Phillip Lougher <phillip@squashfs.org.uk>
 */

#include <linux/types.h>
#include <linux/slab.h>
#include <linux/percpu.h>
#include <linux/local_lock.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;
        local_lock_t    lock;
};

static 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;
                }
                local_lock_init(&stream->lock);
        }

        kfree(comp_opts);
        return (void *)(__force unsigned long) 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);
}

static void squashfs_decompressor_destroy(struct squashfs_sb_info *msblk)
{
        struct squashfs_stream __percpu *percpu =
                        (void __percpu *)(unsigned long) 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);
        }
}

static int squashfs_decompress(struct squashfs_sb_info *msblk, struct bio *bio,
        int offset, int length, struct squashfs_page_actor *output)
{
        struct squashfs_stream *stream;
        struct squashfs_stream __percpu *percpu =
                        (void __percpu *)(unsigned long) msblk->stream;
        int res;

        local_lock(&percpu->lock);
        stream = this_cpu_ptr(percpu);

        res = msblk->decompressor->decompress(msblk, stream->stream, bio,
                                              offset, length, output);

        local_unlock(&percpu->lock);

        if (res < 0)
                ERROR("%s decompression failed, data probably corrupt\n",
                        msblk->decompressor->name);

        return res;
}

static int squashfs_max_decompressors(void)
{
        return num_possible_cpus();
}

const struct squashfs_decompressor_thread_ops squashfs_decompressor_percpu = {
        .create = squashfs_decompressor_create,
        .destroy = squashfs_decompressor_destroy,
        .decompress = squashfs_decompress,
        .max_decompressors = squashfs_max_decompressors,
};