1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * Squashfs - a compressed read only filesystem for Linux
  4 *
  5 * Copyright (c) 2016-present, Facebook, Inc.
  6 * All rights reserved.
  7 *
  8 * zstd_wrapper.c
  9 */
 10
 11#include <linux/mutex.h>
 12#include <linux/bio.h>
 13#include <linux/slab.h>
 14#include <linux/zstd.h>
 15#include <linux/vmalloc.h>
 16
 17#include "squashfs_fs.h"
 18#include "squashfs_fs_sb.h"
 19#include "squashfs.h"
 20#include "decompressor.h"
 21#include "page_actor.h"
 22
 23struct workspace {
 24	void *mem;
 25	size_t mem_size;
 26	size_t window_size;
 27};
 28
 29static void *zstd_init(struct squashfs_sb_info *msblk, void *buff)
 30{
 31	struct workspace *wksp = kmalloc(sizeof(*wksp), GFP_KERNEL);
 32
 33	if (wksp == NULL)
 34		goto failed;
 35	wksp->window_size = max_t(size_t,
 36			msblk->block_size, SQUASHFS_METADATA_SIZE);
 37	wksp->mem_size = zstd_dstream_workspace_bound(wksp->window_size);
 38	wksp->mem = vmalloc(wksp->mem_size);
 39	if (wksp->mem == NULL)
 40		goto failed;
 41
 42	return wksp;
 43
 44failed:
 45	ERROR("Failed to allocate zstd workspace\n");
 46	kfree(wksp);
 47	return ERR_PTR(-ENOMEM);
 48}
 49
 50
 51static void zstd_free(void *strm)
 52{
 53	struct workspace *wksp = strm;
 54
 55	if (wksp)
 56		vfree(wksp->mem);
 57	kfree(wksp);
 58}
 59
 60
 61static int zstd_uncompress(struct squashfs_sb_info *msblk, void *strm,
 62	struct bio *bio, int offset, int length,
 63	struct squashfs_page_actor *output)
 64{
 65	struct workspace *wksp = strm;
 66	zstd_dstream *stream;
 67	size_t total_out = 0;
 68	int error = 0;
 69	zstd_in_buffer in_buf = { NULL, 0, 0 };
 70	zstd_out_buffer out_buf = { NULL, 0, 0 };
 71	struct bvec_iter_all iter_all = {};
 72	struct bio_vec *bvec = bvec_init_iter_all(&iter_all);
 73
 74	stream = zstd_init_dstream(wksp->window_size, wksp->mem, wksp->mem_size);
 75
 76	if (!stream) {
 77		ERROR("Failed to initialize zstd decompressor\n");
 78		return -EIO;
 79	}
 80
 81	out_buf.size = PAGE_SIZE;
 82	out_buf.dst = squashfs_first_page(output);
 83	if (IS_ERR(out_buf.dst)) {
 84		error = PTR_ERR(out_buf.dst);
 85		goto finish;
 86	}
 87
 88	for (;;) {
 89		size_t zstd_err;
 90
 91		if (in_buf.pos == in_buf.size) {
 92			const void *data;
 93			int avail;
 94
 95			if (!bio_next_segment(bio, &iter_all)) {
 96				error = -EIO;
 97				break;
 98			}
 99
100			avail = min(length, ((int)bvec->bv_len) - offset);
101			data = bvec_virt(bvec);
102			length -= avail;
103			in_buf.src = data + offset;
104			in_buf.size = avail;
105			in_buf.pos = 0;
106			offset = 0;
107		}
108
109		if (out_buf.pos == out_buf.size) {
110			out_buf.dst = squashfs_next_page(output);
111			if (IS_ERR(out_buf.dst)) {
112				error = PTR_ERR(out_buf.dst);
113				break;
114			} else if (out_buf.dst == NULL) {
115				/* Shouldn't run out of pages
116				 * before stream is done.
117				 */
118				error = -EIO;
119				break;
120			}
121			out_buf.pos = 0;
122			out_buf.size = PAGE_SIZE;
123		}
124
125		total_out -= out_buf.pos;
126		zstd_err = zstd_decompress_stream(stream, &out_buf, &in_buf);
127		total_out += out_buf.pos; /* add the additional data produced */
128		if (zstd_err == 0)
129			break;
130
131		if (zstd_is_error(zstd_err)) {
132			ERROR("zstd decompression error: %d\n",
133					(int)zstd_get_error_code(zstd_err));
134			error = -EIO;
135			break;
136		}
137	}
138
139finish:
140
141	squashfs_finish_page(output);
142
143	return error ? error : total_out;
144}
145
146const struct squashfs_decompressor squashfs_zstd_comp_ops = {
147	.init = zstd_init,
148	.free = zstd_free,
149	.decompress = zstd_uncompress,
150	.id = ZSTD_COMPRESSION,
151	.name = "zstd",
152	.alloc_buffer = 1,
153	.supported = 1
154};