master
1/* $NetBSD: wapbl_replay.h,v 1.1 2008/11/24 16:05:21 joerg Exp $ */
2
3/*-
4 * Copyright (c) 2003,2008 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Wasabi Systems, Inc.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32#ifndef _SYS_WAPBL_REPLAY_H
33#define _SYS_WAPBL_REPLAY_H
34
35#include <sys/types.h>
36
37/* The WAPBL journal layout.
38 *
39 * The journal consists of a header followed by a circular buffer
40 * region. The circular data area is described by the header
41 * wc_circ_off, wc_circ_size, wc_head and wc_tail fields as bytes
42 * from the start of the journal header. New records are inserted
43 * at wc_head and the oldest valid record can be found at wc_tail.
44 * When ((wc_head == wc_tail) && (wc_head == 0)), the journal is empty.
45 * The condition of ((wc_head == wc_tail) && (wc_head != 0))
46 * indicates a full journal, although this condition is rare.
47 *
48 * The journal header as well as its records are marked by a 32bit
49 * type tag and length for ease of parsing. Journal records are
50 * padded so as to fall on journal device block boundaries.
51 */
52
53/*
54 * The following are the 4 record types used by the journal:
55 * Each tag indicates journal data organized by one of the
56 * structures used below.
57 */
58enum {
59 WAPBL_WC_HEADER = 0x5741424c, /* "WABL", struct wapbl_wc_header */
60 WAPBL_WC_INODES, /* struct wapbl_wc_inodelist */
61 WAPBL_WC_REVOCATIONS, /* struct wapbl_wc_blocklist */
62 WAPBL_WC_BLOCKS, /* struct wapbl_wc_blocklist */
63};
64
65/* null entry (on disk) */
66/* This structure isn't used directly, but shares its header
67 * layout with all the other log structures for the purpose
68 * of reading a log structure and determining its type
69 */
70struct wapbl_wc_null {
71 uint32_t wc_type; /* WAPBL_WC_* */
72 int32_t wc_len;
73 uint8_t wc_spare[0]; /* actually longer */
74};
75
76/* journal header (on-disk)
77 * This record is found at the start of the
78 * journal, but not within the circular buffer region. As well as
79 * describing the journal parameters and matching filesystem, it
80 * additionally serves as the atomic update record for journal
81 * updates.
82 */
83struct wapbl_wc_header {
84 uint32_t wc_type; /* WAPBL_WC_HEADER log magic number */
85 int32_t wc_len; /* length of this journal entry */
86 uint32_t wc_checksum;
87 uint32_t wc_generation;
88 int32_t wc_fsid[2];
89 uint64_t wc_time;
90 uint32_t wc_timensec;
91 uint32_t wc_version;
92 uint32_t wc_log_dev_bshift;
93 uint32_t wc_fs_dev_bshift;
94 int64_t wc_head;
95 int64_t wc_tail;
96 int64_t wc_circ_off; /* offset of of circ buffer region */
97 int64_t wc_circ_size; /* size of circular buffer region */
98 uint8_t wc_spare[0]; /* actually longer */
99};
100
101/* list of blocks (on disk)
102 * This record is used to describe a set of filesystem blocks,
103 * and is used with two type tags, WAPBL_WC_BLOCKS and
104 * WAPBL_WC_REVOCATIONS.
105 *
106 * For WAPBL_WC_BLOCKS, a copy of each listed block can be found
107 * starting at the next log device blocksize boundary. starting at
108 * one log device block since the start of the record. This contains
109 * the bulk of the filesystem journal data which is written using
110 * these records before being written into the filesystem.
111 *
112 * The WAPBL_WC_REVOCATIONS record is used to indicate that any
113 * previously listed blocks should not be written into the filesystem.
114 * This is important so that deallocated and reallocated data blocks
115 * do not get overwritten with stale data from the journal. The
116 * revocation records do not contain a copy of any actual block data.
117 */
118struct wapbl_wc_blocklist {
119 uint32_t wc_type; /* WAPBL_WC_{REVOCATIONS,BLOCKS} */
120 int32_t wc_len;
121 int32_t wc_blkcount;
122 int32_t wc_unused;
123 struct {
124 int64_t wc_daddr;
125 int32_t wc_unused;
126 int32_t wc_dlen;
127 } wc_blocks[0]; /* actually longer */
128};
129
130/* list of inodes (on disk)
131 * This record is used to describe the set of inodes which
132 * may be allocated but are unlinked. Inodes end up listed here
133 * while they are in the process of being initialized and
134 * deinitialized. Inodes unlinked while in use by a process
135 * will be listed here and the actual deletion must be completed
136 * on journal replay.
137 */
138struct wapbl_wc_inodelist {
139 uint32_t wc_type; /* WAPBL_WC_INODES */
140 int32_t wc_len;
141 int32_t wc_inocnt;
142 int32_t wc_clear; /* set if previously listed inodes
143 hould be ignored */
144 struct {
145 uint32_t wc_inumber;
146 uint32_t wc_imode;
147 } wc_inodes[0]; /* actually longer */
148};
149
150#endif /* _SYS_WAPBL_REPLAY_H */