xref: /titanic_44/usr/src/uts/common/fs/zfs/zio_compress.c (revision b17f03d7d89b75b69b9b7db22f2316b700e3a5a8)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 
22 /*
23  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 /*
27  * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
28  */
29 
30 #include <sys/zfs_context.h>
31 #include <sys/compress.h>
32 #include <sys/spa.h>
33 #include <sys/zio.h>
34 #include <sys/zio_compress.h>
35 
36 /*
37  * Compression vectors.
38  */
39 
40 zio_compress_info_t zio_compress_table[ZIO_COMPRESS_FUNCTIONS] = {
41 	{NULL,			NULL,			0,	"inherit"},
42 	{NULL,			NULL,			0,	"on"},
43 	{NULL,			NULL,			0,	"uncompressed"},
44 	{lzjb_compress,		lzjb_decompress,	0,	"lzjb"},
45 	{NULL,			NULL,			0,	"empty"},
46 	{gzip_compress,		gzip_decompress,	1,	"gzip-1"},
47 	{gzip_compress,		gzip_decompress,	2,	"gzip-2"},
48 	{gzip_compress,		gzip_decompress,	3,	"gzip-3"},
49 	{gzip_compress,		gzip_decompress,	4,	"gzip-4"},
50 	{gzip_compress,		gzip_decompress,	5,	"gzip-5"},
51 	{gzip_compress,		gzip_decompress,	6,	"gzip-6"},
52 	{gzip_compress,		gzip_decompress,	7,	"gzip-7"},
53 	{gzip_compress,		gzip_decompress,	8,	"gzip-8"},
54 	{gzip_compress,		gzip_decompress,	9,	"gzip-9"},
55 	{zle_compress,		zle_decompress,		64,	"zle"},
56 	{lz4_compress,		lz4_decompress,		0,	"lz4"},
57 };
58 
59 enum zio_compress
60 zio_compress_select(enum zio_compress child, enum zio_compress parent)
61 {
62 	ASSERT(child < ZIO_COMPRESS_FUNCTIONS);
63 	ASSERT(parent < ZIO_COMPRESS_FUNCTIONS);
64 	ASSERT(parent != ZIO_COMPRESS_INHERIT && parent != ZIO_COMPRESS_ON);
65 
66 	if (child == ZIO_COMPRESS_INHERIT)
67 		return (parent);
68 
69 	if (child == ZIO_COMPRESS_ON)
70 		return (ZIO_COMPRESS_ON_VALUE);
71 
72 	return (child);
73 }
74 
75 size_t
76 zio_compress_data(enum zio_compress c, void *src, void *dst, size_t s_len)
77 {
78 	uint64_t *word, *word_end;
79 	size_t c_len, d_len, r_len;
80 	zio_compress_info_t *ci = &zio_compress_table[c];
81 
82 	ASSERT((uint_t)c < ZIO_COMPRESS_FUNCTIONS);
83 	ASSERT((uint_t)c == ZIO_COMPRESS_EMPTY || ci->ci_compress != NULL);
84 
85 	/*
86 	 * If the data is all zeroes, we don't even need to allocate
87 	 * a block for it.  We indicate this by returning zero size.
88 	 */
89 	word_end = (uint64_t *)((char *)src + s_len);
90 	for (word = src; word < word_end; word++)
91 		if (*word != 0)
92 			break;
93 
94 	if (word == word_end)
95 		return (0);
96 
97 	if (c == ZIO_COMPRESS_EMPTY)
98 		return (s_len);
99 
100 	/* Compress at least 12.5% */
101 	d_len = P2ALIGN(s_len - (s_len >> 3), (size_t)SPA_MINBLOCKSIZE);
102 	if (d_len == 0)
103 		return (s_len);
104 
105 	c_len = ci->ci_compress(src, dst, s_len, d_len, ci->ci_level);
106 
107 	if (c_len > d_len)
108 		return (s_len);
109 
110 	/*
111 	 * Cool.  We compressed at least as much as we were hoping to.
112 	 * For both security and repeatability, pad out the last sector.
113 	 */
114 	r_len = P2ROUNDUP(c_len, (size_t)SPA_MINBLOCKSIZE);
115 	if (r_len > c_len) {
116 		bzero((char *)dst + c_len, r_len - c_len);
117 		c_len = r_len;
118 	}
119 
120 	ASSERT3U(c_len, <=, d_len);
121 	ASSERT(P2PHASE(c_len, (size_t)SPA_MINBLOCKSIZE) == 0);
122 
123 	return (c_len);
124 }
125 
126 int
127 zio_decompress_data(enum zio_compress c, void *src, void *dst,
128     size_t s_len, size_t d_len)
129 {
130 	zio_compress_info_t *ci = &zio_compress_table[c];
131 
132 	if ((uint_t)c >= ZIO_COMPRESS_FUNCTIONS || ci->ci_decompress == NULL)
133 		return (EINVAL);
134 
135 	return (ci->ci_decompress(src, dst, s_len, d_len, ci->ci_level));
136 }
137