Root/fs/ntfs/logfile.h

1/*
2 * logfile.h - Defines for NTFS kernel journal ($LogFile) handling. Part of
3 * the Linux-NTFS project.
4 *
5 * Copyright (c) 2000-2005 Anton Altaparmakov
6 *
7 * This program/include file is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License as published
9 * by the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program/include file is distributed in the hope that it will be
13 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
14 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program (in the main directory of the Linux-NTFS
19 * distribution in the file COPYING); if not, write to the Free Software
20 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21 */
22
23#ifndef _LINUX_NTFS_LOGFILE_H
24#define _LINUX_NTFS_LOGFILE_H
25
26#ifdef NTFS_RW
27
28#include <linux/fs.h>
29
30#include "types.h"
31#include "endian.h"
32#include "layout.h"
33
34/*
35 * Journal ($LogFile) organization:
36 *
37 * Two restart areas present in the first two pages (restart pages, one restart
38 * area in each page). When the volume is dismounted they should be identical,
39 * except for the update sequence array which usually has a different update
40 * sequence number.
41 *
42 * These are followed by log records organized in pages headed by a log record
43 * header going up to log file size. Not all pages contain log records when a
44 * volume is first formatted, but as the volume ages, all records will be used.
45 * When the log file fills up, the records at the beginning are purged (by
46 * modifying the oldest_lsn to a higher value presumably) and writing begins
47 * at the beginning of the file. Effectively, the log file is viewed as a
48 * circular entity.
49 *
50 * NOTE: Windows NT, 2000, and XP all use log file version 1.1 but they accept
51 * versions <= 1.x, including 0.-1. (Yes, that is a minus one in there!) We
52 * probably only want to support 1.1 as this seems to be the current version
53 * and we don't know how that differs from the older versions. The only
54 * exception is if the journal is clean as marked by the two restart pages
55 * then it doesn't matter whether we are on an earlier version. We can just
56 * reinitialize the logfile and start again with version 1.1.
57 */
58
59/* Some $LogFile related constants. */
60#define MaxLogFileSize 0x100000000ULL
61#define DefaultLogPageSize 4096
62#define MinLogRecordPages 48
63
64/*
65 * Log file restart page header (begins the restart area).
66 */
67typedef struct {
68/*Ofs*/
69/* 0 NTFS_RECORD; -- Unfolded here as gcc doesn't like unnamed structs. */
70/* 0*/ NTFS_RECORD_TYPE magic; /* The magic is "RSTR". */
71/* 4*/ le16 usa_ofs; /* See NTFS_RECORD definition in layout.h.
72                   When creating, set this to be immediately
73                   after this header structure (without any
74                   alignment). */
75/* 6*/ le16 usa_count; /* See NTFS_RECORD definition in layout.h. */
76
77/* 8*/ leLSN chkdsk_lsn; /* The last log file sequence number found by
78                   chkdsk. Only used when the magic is changed
79                   to "CHKD". Otherwise this is zero. */
80/* 16*/ le32 system_page_size; /* Byte size of system pages when the log file
81                   was created, has to be >= 512 and a power of
82                   2. Use this to calculate the required size
83                   of the usa (usa_count) and add it to usa_ofs.
84                   Then verify that the result is less than the
85                   value of the restart_area_offset. */
86/* 20*/ le32 log_page_size; /* Byte size of log file pages, has to be >=
87                   512 and a power of 2. The default is 4096
88                   and is used when the system page size is
89                   between 4096 and 8192. Otherwise this is
90                   set to the system page size instead. */
91/* 24*/ le16 restart_area_offset;/* Byte offset from the start of this header to
92                   the RESTART_AREA. Value has to be aligned
93                   to 8-byte boundary. When creating, set this
94                   to be after the usa. */
95/* 26*/ sle16 minor_ver; /* Log file minor version. Only check if major
96                   version is 1. */
97/* 28*/ sle16 major_ver; /* Log file major version. We only support
98                   version 1.1. */
99/* sizeof() = 30 (0x1e) bytes */
100} __attribute__ ((__packed__)) RESTART_PAGE_HEADER;
101
102/*
103 * Constant for the log client indices meaning that there are no client records
104 * in this particular client array. Also inside the client records themselves,
105 * this means that there are no client records preceding or following this one.
106 */
107#define LOGFILE_NO_CLIENT cpu_to_le16(0xffff)
108#define LOGFILE_NO_CLIENT_CPU 0xffff
109
110/*
111 * These are the so far known RESTART_AREA_* flags (16-bit) which contain
112 * information about the log file in which they are present.
113 */
114enum {
115    RESTART_VOLUME_IS_CLEAN = cpu_to_le16(0x0002),
116    RESTART_SPACE_FILLER = cpu_to_le16(0xffff), /* gcc: Force enum bit width to 16. */
117} __attribute__ ((__packed__));
118
119typedef le16 RESTART_AREA_FLAGS;
120
121/*
122 * Log file restart area record. The offset of this record is found by adding
123 * the offset of the RESTART_PAGE_HEADER to the restart_area_offset value found
124 * in it. See notes at restart_area_offset above.
125 */
126typedef struct {
127/*Ofs*/
128/* 0*/ leLSN current_lsn; /* The current, i.e. last LSN inside the log
129                   when the restart area was last written.
130                   This happens often but what is the interval?
131                   Is it just fixed time or is it every time a
132                   check point is written or somethine else?
133                   On create set to 0. */
134/* 8*/ le16 log_clients; /* Number of log client records in the array of
135                   log client records which follows this
136                   restart area. Must be 1. */
137/* 10*/ le16 client_free_list; /* The index of the first free log client record
138                   in the array of log client records.
139                   LOGFILE_NO_CLIENT means that there are no
140                   free log client records in the array.
141                   If != LOGFILE_NO_CLIENT, check that
142                   log_clients > client_free_list. On Win2k
143                   and presumably earlier, on a clean volume
144                   this is != LOGFILE_NO_CLIENT, and it should
145                   be 0, i.e. the first (and only) client
146                   record is free and thus the logfile is
147                   closed and hence clean. A dirty volume
148                   would have left the logfile open and hence
149                   this would be LOGFILE_NO_CLIENT. On WinXP
150                   and presumably later, the logfile is always
151                   open, even on clean shutdown so this should
152                   always be LOGFILE_NO_CLIENT. */
153/* 12*/ le16 client_in_use_list;/* The index of the first in-use log client
154                   record in the array of log client records.
155                   LOGFILE_NO_CLIENT means that there are no
156                   in-use log client records in the array. If
157                   != LOGFILE_NO_CLIENT check that log_clients
158                   > client_in_use_list. On Win2k and
159                   presumably earlier, on a clean volume this
160                   is LOGFILE_NO_CLIENT, i.e. there are no
161                   client records in use and thus the logfile
162                   is closed and hence clean. A dirty volume
163                   would have left the logfile open and hence
164                   this would be != LOGFILE_NO_CLIENT, and it
165                   should be 0, i.e. the first (and only)
166                   client record is in use. On WinXP and
167                   presumably later, the logfile is always
168                   open, even on clean shutdown so this should
169                   always be 0. */
170/* 14*/ RESTART_AREA_FLAGS flags;/* Flags modifying LFS behaviour. On Win2k
171                   and presumably earlier this is always 0. On
172                   WinXP and presumably later, if the logfile
173                   was shutdown cleanly, the second bit,
174                   RESTART_VOLUME_IS_CLEAN, is set. This bit
175                   is cleared when the volume is mounted by
176                   WinXP and set when the volume is dismounted,
177                   thus if the logfile is dirty, this bit is
178                   clear. Thus we don't need to check the
179                   Windows version to determine if the logfile
180                   is clean. Instead if the logfile is closed,
181                   we know it must be clean. If it is open and
182                   this bit is set, we also know it must be
183                   clean. If on the other hand the logfile is
184                   open and this bit is clear, we can be almost
185                   certain that the logfile is dirty. */
186/* 16*/ le32 seq_number_bits; /* How many bits to use for the sequence
187                   number. This is calculated as 67 - the
188                   number of bits required to store the logfile
189                   size in bytes and this can be used in with
190                   the specified file_size as a consistency
191                   check. */
192/* 20*/ le16 restart_area_length;/* Length of the restart area including the
193                   client array. Following checks required if
194                   version matches. Otherwise, skip them.
195                   restart_area_offset + restart_area_length
196                   has to be <= system_page_size. Also,
197                   restart_area_length has to be >=
198                   client_array_offset + (log_clients *
199                   sizeof(log client record)). */
200/* 22*/ le16 client_array_offset;/* Offset from the start of this record to
201                   the first log client record if versions are
202                   matched. When creating, set this to be
203                   after this restart area structure, aligned
204                   to 8-bytes boundary. If the versions do not
205                   match, this is ignored and the offset is
206                   assumed to be (sizeof(RESTART_AREA) + 7) &
207                   ~7, i.e. rounded up to first 8-byte
208                   boundary. Either way, client_array_offset
209                   has to be aligned to an 8-byte boundary.
210                   Also, restart_area_offset +
211                   client_array_offset has to be <= 510.
212                   Finally, client_array_offset + (log_clients
213                   * sizeof(log client record)) has to be <=
214                   system_page_size. On Win2k and presumably
215                   earlier, this is 0x30, i.e. immediately
216                   following this record. On WinXP and
217                   presumably later, this is 0x40, i.e. there
218                   are 16 extra bytes between this record and
219                   the client array. This probably means that
220                   the RESTART_AREA record is actually bigger
221                   in WinXP and later. */
222/* 24*/ sle64 file_size; /* Usable byte size of the log file. If the
223                   restart_area_offset + the offset of the
224                   file_size are > 510 then corruption has
225                   occurred. This is the very first check when
226                   starting with the restart_area as if it
227                   fails it means that some of the above values
228                   will be corrupted by the multi sector
229                   transfer protection. The file_size has to
230                   be rounded down to be a multiple of the
231                   log_page_size in the RESTART_PAGE_HEADER and
232                   then it has to be at least big enough to
233                   store the two restart pages and 48 (0x30)
234                   log record pages. */
235/* 32*/ le32 last_lsn_data_length;/* Length of data of last LSN, not including
236                   the log record header. On create set to
237                   0. */
238/* 36*/ le16 log_record_header_length;/* Byte size of the log record header.
239                   If the version matches then check that the
240                   value of log_record_header_length is a
241                   multiple of 8, i.e.
242                   (log_record_header_length + 7) & ~7 ==
243                   log_record_header_length. When creating set
244                   it to sizeof(LOG_RECORD_HEADER), aligned to
245                   8 bytes. */
246/* 38*/ le16 log_page_data_offset;/* Offset to the start of data in a log record
247                   page. Must be a multiple of 8. On create
248                   set it to immediately after the update
249                   sequence array of the log record page. */
250/* 40*/ le32 restart_log_open_count;/* A counter that gets incremented every
251                   time the logfile is restarted which happens
252                   at mount time when the logfile is opened.
253                   When creating set to a random value. Win2k
254                   sets it to the low 32 bits of the current
255                   system time in NTFS format (see time.h). */
256/* 44*/ le32 reserved; /* Reserved/alignment to 8-byte boundary. */
257/* sizeof() = 48 (0x30) bytes */
258} __attribute__ ((__packed__)) RESTART_AREA;
259
260/*
261 * Log client record. The offset of this record is found by adding the offset
262 * of the RESTART_AREA to the client_array_offset value found in it.
263 */
264typedef struct {
265/*Ofs*/
266/* 0*/ leLSN oldest_lsn; /* Oldest LSN needed by this client. On create
267                   set to 0. */
268/* 8*/ leLSN client_restart_lsn;/* LSN at which this client needs to restart
269                   the volume, i.e. the current position within
270                   the log file. At present, if clean this
271                   should = current_lsn in restart area but it
272                   probably also = current_lsn when dirty most
273                   of the time. At create set to 0. */
274/* 16*/ le16 prev_client; /* The offset to the previous log client record
275                   in the array of log client records.
276                   LOGFILE_NO_CLIENT means there is no previous
277                   client record, i.e. this is the first one.
278                   This is always LOGFILE_NO_CLIENT. */
279/* 18*/ le16 next_client; /* The offset to the next log client record in
280                   the array of log client records.
281                   LOGFILE_NO_CLIENT means there are no next
282                   client records, i.e. this is the last one.
283                   This is always LOGFILE_NO_CLIENT. */
284/* 20*/ le16 seq_number; /* On Win2k and presumably earlier, this is set
285                   to zero every time the logfile is restarted
286                   and it is incremented when the logfile is
287                   closed at dismount time. Thus it is 0 when
288                   dirty and 1 when clean. On WinXP and
289                   presumably later, this is always 0. */
290/* 22*/ u8 reserved[6]; /* Reserved/alignment. */
291/* 28*/ le32 client_name_length;/* Length of client name in bytes. Should
292                   always be 8. */
293/* 32*/ ntfschar client_name[64];/* Name of the client in Unicode. Should
294                   always be "NTFS" with the remaining bytes
295                   set to 0. */
296/* sizeof() = 160 (0xa0) bytes */
297} __attribute__ ((__packed__)) LOG_CLIENT_RECORD;
298
299extern bool ntfs_check_logfile(struct inode *log_vi,
300        RESTART_PAGE_HEADER **rp);
301
302extern bool ntfs_is_logfile_clean(struct inode *log_vi,
303        const RESTART_PAGE_HEADER *rp);
304
305extern bool ntfs_empty_logfile(struct inode *log_vi);
306
307#endif /* NTFS_RW */
308
309#endif /* _LINUX_NTFS_LOGFILE_H */
310

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