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Linux/fs/squashfs/zstd_wrapper.c

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  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 
 23 struct workspace {
 24         void *mem;
 25         size_t mem_size;
 26         size_t window_size;
 27 };
 28 
 29 static 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_DStreamWorkspaceBound(wksp->window_size);
 38         wksp->mem = vmalloc(wksp->mem_size);
 39         if (wksp->mem == NULL)
 40                 goto failed;
 41 
 42         return wksp;
 43 
 44 failed:
 45         ERROR("Failed to allocate zstd workspace\n");
 46         kfree(wksp);
 47         return ERR_PTR(-ENOMEM);
 48 }
 49 
 50 
 51 static 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 
 61 static 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_inBuffer in_buf = { NULL, 0, 0 };
 70         ZSTD_outBuffer 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_initDStream(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 
 84         for (;;) {
 85                 size_t zstd_err;
 86 
 87                 if (in_buf.pos == in_buf.size) {
 88                         const void *data;
 89                         int avail;
 90 
 91                         if (!bio_next_segment(bio, &iter_all)) {
 92                                 error = -EIO;
 93                                 break;
 94                         }
 95 
 96                         avail = min(length, ((int)bvec->bv_len) - offset);
 97                         data = page_address(bvec->bv_page) + bvec->bv_offset;
 98                         length -= avail;
 99                         in_buf.src = data + offset;
100                         in_buf.size = avail;
101                         in_buf.pos = 0;
102                         offset = 0;
103                 }
104 
105                 if (out_buf.pos == out_buf.size) {
106                         out_buf.dst = squashfs_next_page(output);
107                         if (out_buf.dst == NULL) {
108                                 /* Shouldn't run out of pages
109                                  * before stream is done.
110                                  */
111                                 error = -EIO;
112                                 break;
113                         }
114                         out_buf.pos = 0;
115                         out_buf.size = PAGE_SIZE;
116                 }
117 
118                 total_out -= out_buf.pos;
119                 zstd_err = ZSTD_decompressStream(stream, &out_buf, &in_buf);
120                 total_out += out_buf.pos; /* add the additional data produced */
121                 if (zstd_err == 0)
122                         break;
123 
124                 if (ZSTD_isError(zstd_err)) {
125                         ERROR("zstd decompression error: %d\n",
126                                         (int)ZSTD_getErrorCode(zstd_err));
127                         error = -EIO;
128                         break;
129                 }
130         }
131 
132         squashfs_finish_page(output);
133 
134         return error ? error : total_out;
135 }
136 
137 const struct squashfs_decompressor squashfs_zstd_comp_ops = {
138         .init = zstd_init,
139         .free = zstd_free,
140         .decompress = zstd_uncompress,
141         .id = ZSTD_COMPRESSION,
142         .name = "zstd",
143         .supported = 1
144 };
145 

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