devcgroup: fix race against rmdir()
[linux-2.6/mini2440.git] / fs / ubifs / compress.c
blob5bb51dac3c165f3e9df9962ac20411aae2ab2422
1 /*
2 * This file is part of UBIFS.
4 * Copyright (C) 2006-2008 Nokia Corporation.
5 * Copyright (C) 2006, 2007 University of Szeged, Hungary
7 * This program is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU General Public License version 2 as published by
9 * the Free Software Foundation.
11 * This program is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
14 * more details.
16 * You should have received a copy of the GNU General Public License along with
17 * this program; if not, write to the Free Software Foundation, Inc., 51
18 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
20 * Authors: Adrian Hunter
21 * Artem Bityutskiy (Битюцкий Артём)
22 * Zoltan Sogor
26 * This file provides a single place to access to compression and
27 * decompression.
30 #include <linux/crypto.h>
31 #include "ubifs.h"
33 /* Fake description object for the "none" compressor */
34 static struct ubifs_compressor none_compr = {
35 .compr_type = UBIFS_COMPR_NONE,
36 .name = "no compression",
37 .capi_name = "",
40 #ifdef CONFIG_UBIFS_FS_LZO
41 static DEFINE_MUTEX(lzo_mutex);
43 static struct ubifs_compressor lzo_compr = {
44 .compr_type = UBIFS_COMPR_LZO,
45 .comp_mutex = &lzo_mutex,
46 .name = "LZO",
47 .capi_name = "lzo",
49 #else
50 static struct ubifs_compressor lzo_compr = {
51 .compr_type = UBIFS_COMPR_LZO,
52 .name = "LZO",
54 #endif
56 #ifdef CONFIG_UBIFS_FS_ZLIB
57 static DEFINE_MUTEX(deflate_mutex);
58 static DEFINE_MUTEX(inflate_mutex);
60 static struct ubifs_compressor zlib_compr = {
61 .compr_type = UBIFS_COMPR_ZLIB,
62 .comp_mutex = &deflate_mutex,
63 .decomp_mutex = &inflate_mutex,
64 .name = "zlib",
65 .capi_name = "deflate",
67 #else
68 static struct ubifs_compressor zlib_compr = {
69 .compr_type = UBIFS_COMPR_ZLIB,
70 .name = "zlib",
72 #endif
74 /* All UBIFS compressors */
75 struct ubifs_compressor *ubifs_compressors[UBIFS_COMPR_TYPES_CNT];
77 /**
78 * ubifs_compress - compress data.
79 * @in_buf: data to compress
80 * @in_len: length of the data to compress
81 * @out_buf: output buffer where compressed data should be stored
82 * @out_len: output buffer length is returned here
83 * @compr_type: type of compression to use on enter, actually used compression
84 * type on exit
86 * This function compresses input buffer @in_buf of length @in_len and stores
87 * the result in the output buffer @out_buf and the resulting length in
88 * @out_len. If the input buffer does not compress, it is just copied to the
89 * @out_buf. The same happens if @compr_type is %UBIFS_COMPR_NONE or if
90 * compression error occurred.
92 * Note, if the input buffer was not compressed, it is copied to the output
93 * buffer and %UBIFS_COMPR_NONE is returned in @compr_type.
95 * This functions returns %0 on success or a negative error code on failure.
97 void ubifs_compress(const void *in_buf, int in_len, void *out_buf, int *out_len,
98 int *compr_type)
100 int err;
101 struct ubifs_compressor *compr = ubifs_compressors[*compr_type];
103 if (*compr_type == UBIFS_COMPR_NONE)
104 goto no_compr;
106 /* If the input data is small, do not even try to compress it */
107 if (in_len < UBIFS_MIN_COMPR_LEN)
108 goto no_compr;
110 if (compr->comp_mutex)
111 mutex_lock(compr->comp_mutex);
112 err = crypto_comp_compress(compr->cc, in_buf, in_len, out_buf,
113 out_len);
114 if (compr->comp_mutex)
115 mutex_unlock(compr->comp_mutex);
116 if (unlikely(err)) {
117 ubifs_warn("cannot compress %d bytes, compressor %s, "
118 "error %d, leave data uncompressed",
119 in_len, compr->name, err);
120 goto no_compr;
124 * Presently, we just require that compression results in less data,
125 * rather than any defined minimum compression ratio or amount.
127 if (ALIGN(*out_len, 8) >= ALIGN(in_len, 8))
128 goto no_compr;
130 return;
132 no_compr:
133 memcpy(out_buf, in_buf, in_len);
134 *out_len = in_len;
135 *compr_type = UBIFS_COMPR_NONE;
139 * ubifs_decompress - decompress data.
140 * @in_buf: data to decompress
141 * @in_len: length of the data to decompress
142 * @out_buf: output buffer where decompressed data should
143 * @out_len: output length is returned here
144 * @compr_type: type of compression
146 * This function decompresses data from buffer @in_buf into buffer @out_buf.
147 * The length of the uncompressed data is returned in @out_len. This functions
148 * returns %0 on success or a negative error code on failure.
150 int ubifs_decompress(const void *in_buf, int in_len, void *out_buf,
151 int *out_len, int compr_type)
153 int err;
154 struct ubifs_compressor *compr;
156 if (unlikely(compr_type < 0 || compr_type >= UBIFS_COMPR_TYPES_CNT)) {
157 ubifs_err("invalid compression type %d", compr_type);
158 return -EINVAL;
161 compr = ubifs_compressors[compr_type];
163 if (unlikely(!compr->capi_name)) {
164 ubifs_err("%s compression is not compiled in", compr->name);
165 return -EINVAL;
168 if (compr_type == UBIFS_COMPR_NONE) {
169 memcpy(out_buf, in_buf, in_len);
170 *out_len = in_len;
171 return 0;
174 if (compr->decomp_mutex)
175 mutex_lock(compr->decomp_mutex);
176 err = crypto_comp_decompress(compr->cc, in_buf, in_len, out_buf,
177 out_len);
178 if (compr->decomp_mutex)
179 mutex_unlock(compr->decomp_mutex);
180 if (err)
181 ubifs_err("cannot decompress %d bytes, compressor %s, "
182 "error %d", in_len, compr->name, err);
184 return err;
188 * compr_init - initialize a compressor.
189 * @compr: compressor description object
191 * This function initializes the requested compressor and returns zero in case
192 * of success or a negative error code in case of failure.
194 static int __init compr_init(struct ubifs_compressor *compr)
196 if (compr->capi_name) {
197 compr->cc = crypto_alloc_comp(compr->capi_name, 0, 0);
198 if (IS_ERR(compr->cc)) {
199 ubifs_err("cannot initialize compressor %s, error %ld",
200 compr->name, PTR_ERR(compr->cc));
201 return PTR_ERR(compr->cc);
205 ubifs_compressors[compr->compr_type] = compr;
206 return 0;
210 * compr_exit - de-initialize a compressor.
211 * @compr: compressor description object
213 static void compr_exit(struct ubifs_compressor *compr)
215 if (compr->capi_name)
216 crypto_free_comp(compr->cc);
217 return;
221 * ubifs_compressors_init - initialize UBIFS compressors.
223 * This function initializes the compressor which were compiled in. Returns
224 * zero in case of success and a negative error code in case of failure.
226 int __init ubifs_compressors_init(void)
228 int err;
230 err = compr_init(&lzo_compr);
231 if (err)
232 return err;
234 err = compr_init(&zlib_compr);
235 if (err)
236 goto out_lzo;
238 ubifs_compressors[UBIFS_COMPR_NONE] = &none_compr;
239 return 0;
241 out_lzo:
242 compr_exit(&lzo_compr);
243 return err;
247 * ubifs_compressors_exit - de-initialize UBIFS compressors.
249 void __exit ubifs_compressors_exit(void)
251 compr_exit(&lzo_compr);
252 compr_exit(&zlib_compr);