1 /* 2 * Squashfs - a compressed read only filesystem for Linux 3 * 4 * Copyright (c) 2016-present, Facebook, Inc. 5 * All rights reserved. 6 * 7 * This program is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public License 9 * as published by the Free Software Foundation; either version 2, 10 * or (at your option) any later version. 11 * 12 * This program is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 * GNU General Public License for more details. 16 * 17 * zstd_wrapper.c 18 */ 19 20 #include <linux/mutex.h> 21 #include <linux/buffer_head.h> 22 #include <linux/slab.h> 23 #include <linux/zstd.h> 24 #include <linux/vmalloc.h> 25 26 #include "squashfs_fs.h" 27 #include "squashfs_fs_sb.h" 28 #include "squashfs.h" 29 #include "decompressor.h" 30 #include "page_actor.h" 31 32 struct workspace { 33 void *mem; 34 size_t mem_size; 35 size_t window_size; 36 }; 37 38 static void *zstd_init(struct squashfs_sb_info *msblk, void *buff) 39 { 40 struct workspace *wksp = kmalloc(sizeof(*wksp), GFP_KERNEL); 41 42 if (wksp == NULL) 43 goto failed; 44 wksp->window_size = max_t(size_t, 45 msblk->block_size, SQUASHFS_METADATA_SIZE); 46 wksp->mem_size = ZSTD_DStreamWorkspaceBound(wksp->window_size); 47 wksp->mem = vmalloc(wksp->mem_size); 48 if (wksp->mem == NULL) 49 goto failed; 50 51 return wksp; 52 53 failed: 54 ERROR("Failed to allocate zstd workspace\n"); 55 kfree(wksp); 56 return ERR_PTR(-ENOMEM); 57 } 58 59 60 static void zstd_free(void *strm) 61 { 62 struct workspace *wksp = strm; 63 64 if (wksp) 65 vfree(wksp->mem); 66 kfree(wksp); 67 } 68 69 70 static int zstd_uncompress(struct squashfs_sb_info *msblk, void *strm, 71 struct buffer_head **bh, int b, int offset, int length, 72 struct squashfs_page_actor *output) 73 { 74 struct workspace *wksp = strm; 75 ZSTD_DStream *stream; 76 size_t total_out = 0; 77 size_t zstd_err; 78 int k = 0; 79 ZSTD_inBuffer in_buf = { NULL, 0, 0 }; 80 ZSTD_outBuffer out_buf = { NULL, 0, 0 }; 81 82 stream = ZSTD_initDStream(wksp->window_size, wksp->mem, wksp->mem_size); 83 84 if (!stream) { 85 ERROR("Failed to initialize zstd decompressor\n"); 86 goto out; 87 } 88 89 out_buf.size = PAGE_SIZE; 90 out_buf.dst = squashfs_first_page(output); 91 92 do { 93 if (in_buf.pos == in_buf.size && k < b) { 94 int avail = min(length, msblk->devblksize - offset); 95 96 length -= avail; 97 in_buf.src = bh[k]->b_data + offset; 98 in_buf.size = avail; 99 in_buf.pos = 0; 100 offset = 0; 101 } 102 103 if (out_buf.pos == out_buf.size) { 104 out_buf.dst = squashfs_next_page(output); 105 if (out_buf.dst == NULL) { 106 /* Shouldn't run out of pages 107 * before stream is done. 108 */ 109 squashfs_finish_page(output); 110 goto out; 111 } 112 out_buf.pos = 0; 113 out_buf.size = PAGE_SIZE; 114 } 115 116 total_out -= out_buf.pos; 117 zstd_err = ZSTD_decompressStream(stream, &out_buf, &in_buf); 118 total_out += out_buf.pos; /* add the additional data produced */ 119 120 if (in_buf.pos == in_buf.size && k < b) 121 put_bh(bh[k++]); 122 } while (zstd_err != 0 && !ZSTD_isError(zstd_err)); 123 124 squashfs_finish_page(output); 125 126 if (ZSTD_isError(zstd_err)) { 127 ERROR("zstd decompression error: %d\n", 128 (int)ZSTD_getErrorCode(zstd_err)); 129 goto out; 130 } 131 132 if (k < b) 133 goto out; 134 135 return (int)total_out; 136 137 out: 138 for (; k < b; k++) 139 put_bh(bh[k]); 140 141 return -EIO; 142 } 143 144 const struct squashfs_decompressor squashfs_zstd_comp_ops = { 145 .init = zstd_init, 146 .free = zstd_free, 147 .decompress = zstd_uncompress, 148 .id = ZSTD_COMPRESSION, 149 .name = "zstd", 150 .supported = 1 151 }; 152