logfile.h (13072B)
1/* SPDX-License-Identifier: GPL-2.0-or-later */ 2/* 3 * logfile.h - Defines for NTFS kernel journal ($LogFile) handling. Part of 4 * the Linux-NTFS project. 5 * 6 * Copyright (c) 2000-2005 Anton Altaparmakov 7 */ 8 9#ifndef _LINUX_NTFS_LOGFILE_H 10#define _LINUX_NTFS_LOGFILE_H 11 12#ifdef NTFS_RW 13 14#include <linux/fs.h> 15 16#include "types.h" 17#include "endian.h" 18#include "layout.h" 19 20/* 21 * Journal ($LogFile) organization: 22 * 23 * Two restart areas present in the first two pages (restart pages, one restart 24 * area in each page). When the volume is dismounted they should be identical, 25 * except for the update sequence array which usually has a different update 26 * sequence number. 27 * 28 * These are followed by log records organized in pages headed by a log record 29 * header going up to log file size. Not all pages contain log records when a 30 * volume is first formatted, but as the volume ages, all records will be used. 31 * When the log file fills up, the records at the beginning are purged (by 32 * modifying the oldest_lsn to a higher value presumably) and writing begins 33 * at the beginning of the file. Effectively, the log file is viewed as a 34 * circular entity. 35 * 36 * NOTE: Windows NT, 2000, and XP all use log file version 1.1 but they accept 37 * versions <= 1.x, including 0.-1. (Yes, that is a minus one in there!) We 38 * probably only want to support 1.1 as this seems to be the current version 39 * and we don't know how that differs from the older versions. The only 40 * exception is if the journal is clean as marked by the two restart pages 41 * then it doesn't matter whether we are on an earlier version. We can just 42 * reinitialize the logfile and start again with version 1.1. 43 */ 44 45/* Some $LogFile related constants. */ 46#define MaxLogFileSize 0x100000000ULL 47#define DefaultLogPageSize 4096 48#define MinLogRecordPages 48 49 50/* 51 * Log file restart page header (begins the restart area). 52 */ 53typedef struct { 54/*Ofs*/ 55/* 0 NTFS_RECORD; -- Unfolded here as gcc doesn't like unnamed structs. */ 56/* 0*/ NTFS_RECORD_TYPE magic; /* The magic is "RSTR". */ 57/* 4*/ le16 usa_ofs; /* See NTFS_RECORD definition in layout.h. 58 When creating, set this to be immediately 59 after this header structure (without any 60 alignment). */ 61/* 6*/ le16 usa_count; /* See NTFS_RECORD definition in layout.h. */ 62 63/* 8*/ leLSN chkdsk_lsn; /* The last log file sequence number found by 64 chkdsk. Only used when the magic is changed 65 to "CHKD". Otherwise this is zero. */ 66/* 16*/ le32 system_page_size; /* Byte size of system pages when the log file 67 was created, has to be >= 512 and a power of 68 2. Use this to calculate the required size 69 of the usa (usa_count) and add it to usa_ofs. 70 Then verify that the result is less than the 71 value of the restart_area_offset. */ 72/* 20*/ le32 log_page_size; /* Byte size of log file pages, has to be >= 73 512 and a power of 2. The default is 4096 74 and is used when the system page size is 75 between 4096 and 8192. Otherwise this is 76 set to the system page size instead. */ 77/* 24*/ le16 restart_area_offset;/* Byte offset from the start of this header to 78 the RESTART_AREA. Value has to be aligned 79 to 8-byte boundary. When creating, set this 80 to be after the usa. */ 81/* 26*/ sle16 minor_ver; /* Log file minor version. Only check if major 82 version is 1. */ 83/* 28*/ sle16 major_ver; /* Log file major version. We only support 84 version 1.1. */ 85/* sizeof() = 30 (0x1e) bytes */ 86} __attribute__ ((__packed__)) RESTART_PAGE_HEADER; 87 88/* 89 * Constant for the log client indices meaning that there are no client records 90 * in this particular client array. Also inside the client records themselves, 91 * this means that there are no client records preceding or following this one. 92 */ 93#define LOGFILE_NO_CLIENT cpu_to_le16(0xffff) 94#define LOGFILE_NO_CLIENT_CPU 0xffff 95 96/* 97 * These are the so far known RESTART_AREA_* flags (16-bit) which contain 98 * information about the log file in which they are present. 99 */ 100enum { 101 RESTART_VOLUME_IS_CLEAN = cpu_to_le16(0x0002), 102 RESTART_SPACE_FILLER = cpu_to_le16(0xffff), /* gcc: Force enum bit width to 16. */ 103} __attribute__ ((__packed__)); 104 105typedef le16 RESTART_AREA_FLAGS; 106 107/* 108 * Log file restart area record. The offset of this record is found by adding 109 * the offset of the RESTART_PAGE_HEADER to the restart_area_offset value found 110 * in it. See notes at restart_area_offset above. 111 */ 112typedef struct { 113/*Ofs*/ 114/* 0*/ leLSN current_lsn; /* The current, i.e. last LSN inside the log 115 when the restart area was last written. 116 This happens often but what is the interval? 117 Is it just fixed time or is it every time a 118 check point is written or somethine else? 119 On create set to 0. */ 120/* 8*/ le16 log_clients; /* Number of log client records in the array of 121 log client records which follows this 122 restart area. Must be 1. */ 123/* 10*/ le16 client_free_list; /* The index of the first free log client record 124 in the array of log client records. 125 LOGFILE_NO_CLIENT means that there are no 126 free log client records in the array. 127 If != LOGFILE_NO_CLIENT, check that 128 log_clients > client_free_list. On Win2k 129 and presumably earlier, on a clean volume 130 this is != LOGFILE_NO_CLIENT, and it should 131 be 0, i.e. the first (and only) client 132 record is free and thus the logfile is 133 closed and hence clean. A dirty volume 134 would have left the logfile open and hence 135 this would be LOGFILE_NO_CLIENT. On WinXP 136 and presumably later, the logfile is always 137 open, even on clean shutdown so this should 138 always be LOGFILE_NO_CLIENT. */ 139/* 12*/ le16 client_in_use_list;/* The index of the first in-use log client 140 record in the array of log client records. 141 LOGFILE_NO_CLIENT means that there are no 142 in-use log client records in the array. If 143 != LOGFILE_NO_CLIENT check that log_clients 144 > client_in_use_list. On Win2k and 145 presumably earlier, on a clean volume this 146 is LOGFILE_NO_CLIENT, i.e. there are no 147 client records in use and thus the logfile 148 is closed and hence clean. A dirty volume 149 would have left the logfile open and hence 150 this would be != LOGFILE_NO_CLIENT, and it 151 should be 0, i.e. the first (and only) 152 client record is in use. On WinXP and 153 presumably later, the logfile is always 154 open, even on clean shutdown so this should 155 always be 0. */ 156/* 14*/ RESTART_AREA_FLAGS flags;/* Flags modifying LFS behaviour. On Win2k 157 and presumably earlier this is always 0. On 158 WinXP and presumably later, if the logfile 159 was shutdown cleanly, the second bit, 160 RESTART_VOLUME_IS_CLEAN, is set. This bit 161 is cleared when the volume is mounted by 162 WinXP and set when the volume is dismounted, 163 thus if the logfile is dirty, this bit is 164 clear. Thus we don't need to check the 165 Windows version to determine if the logfile 166 is clean. Instead if the logfile is closed, 167 we know it must be clean. If it is open and 168 this bit is set, we also know it must be 169 clean. If on the other hand the logfile is 170 open and this bit is clear, we can be almost 171 certain that the logfile is dirty. */ 172/* 16*/ le32 seq_number_bits; /* How many bits to use for the sequence 173 number. This is calculated as 67 - the 174 number of bits required to store the logfile 175 size in bytes and this can be used in with 176 the specified file_size as a consistency 177 check. */ 178/* 20*/ le16 restart_area_length;/* Length of the restart area including the 179 client array. Following checks required if 180 version matches. Otherwise, skip them. 181 restart_area_offset + restart_area_length 182 has to be <= system_page_size. Also, 183 restart_area_length has to be >= 184 client_array_offset + (log_clients * 185 sizeof(log client record)). */ 186/* 22*/ le16 client_array_offset;/* Offset from the start of this record to 187 the first log client record if versions are 188 matched. When creating, set this to be 189 after this restart area structure, aligned 190 to 8-bytes boundary. If the versions do not 191 match, this is ignored and the offset is 192 assumed to be (sizeof(RESTART_AREA) + 7) & 193 ~7, i.e. rounded up to first 8-byte 194 boundary. Either way, client_array_offset 195 has to be aligned to an 8-byte boundary. 196 Also, restart_area_offset + 197 client_array_offset has to be <= 510. 198 Finally, client_array_offset + (log_clients 199 * sizeof(log client record)) has to be <= 200 system_page_size. On Win2k and presumably 201 earlier, this is 0x30, i.e. immediately 202 following this record. On WinXP and 203 presumably later, this is 0x40, i.e. there 204 are 16 extra bytes between this record and 205 the client array. This probably means that 206 the RESTART_AREA record is actually bigger 207 in WinXP and later. */ 208/* 24*/ sle64 file_size; /* Usable byte size of the log file. If the 209 restart_area_offset + the offset of the 210 file_size are > 510 then corruption has 211 occurred. This is the very first check when 212 starting with the restart_area as if it 213 fails it means that some of the above values 214 will be corrupted by the multi sector 215 transfer protection. The file_size has to 216 be rounded down to be a multiple of the 217 log_page_size in the RESTART_PAGE_HEADER and 218 then it has to be at least big enough to 219 store the two restart pages and 48 (0x30) 220 log record pages. */ 221/* 32*/ le32 last_lsn_data_length;/* Length of data of last LSN, not including 222 the log record header. On create set to 223 0. */ 224/* 36*/ le16 log_record_header_length;/* Byte size of the log record header. 225 If the version matches then check that the 226 value of log_record_header_length is a 227 multiple of 8, i.e. 228 (log_record_header_length + 7) & ~7 == 229 log_record_header_length. When creating set 230 it to sizeof(LOG_RECORD_HEADER), aligned to 231 8 bytes. */ 232/* 38*/ le16 log_page_data_offset;/* Offset to the start of data in a log record 233 page. Must be a multiple of 8. On create 234 set it to immediately after the update 235 sequence array of the log record page. */ 236/* 40*/ le32 restart_log_open_count;/* A counter that gets incremented every 237 time the logfile is restarted which happens 238 at mount time when the logfile is opened. 239 When creating set to a random value. Win2k 240 sets it to the low 32 bits of the current 241 system time in NTFS format (see time.h). */ 242/* 44*/ le32 reserved; /* Reserved/alignment to 8-byte boundary. */ 243/* sizeof() = 48 (0x30) bytes */ 244} __attribute__ ((__packed__)) RESTART_AREA; 245 246/* 247 * Log client record. The offset of this record is found by adding the offset 248 * of the RESTART_AREA to the client_array_offset value found in it. 249 */ 250typedef struct { 251/*Ofs*/ 252/* 0*/ leLSN oldest_lsn; /* Oldest LSN needed by this client. On create 253 set to 0. */ 254/* 8*/ leLSN client_restart_lsn;/* LSN at which this client needs to restart 255 the volume, i.e. the current position within 256 the log file. At present, if clean this 257 should = current_lsn in restart area but it 258 probably also = current_lsn when dirty most 259 of the time. At create set to 0. */ 260/* 16*/ le16 prev_client; /* The offset to the previous log client record 261 in the array of log client records. 262 LOGFILE_NO_CLIENT means there is no previous 263 client record, i.e. this is the first one. 264 This is always LOGFILE_NO_CLIENT. */ 265/* 18*/ le16 next_client; /* The offset to the next log client record in 266 the array of log client records. 267 LOGFILE_NO_CLIENT means there are no next 268 client records, i.e. this is the last one. 269 This is always LOGFILE_NO_CLIENT. */ 270/* 20*/ le16 seq_number; /* On Win2k and presumably earlier, this is set 271 to zero every time the logfile is restarted 272 and it is incremented when the logfile is 273 closed at dismount time. Thus it is 0 when 274 dirty and 1 when clean. On WinXP and 275 presumably later, this is always 0. */ 276/* 22*/ u8 reserved[6]; /* Reserved/alignment. */ 277/* 28*/ le32 client_name_length;/* Length of client name in bytes. Should 278 always be 8. */ 279/* 32*/ ntfschar client_name[64];/* Name of the client in Unicode. Should 280 always be "NTFS" with the remaining bytes 281 set to 0. */ 282/* sizeof() = 160 (0xa0) bytes */ 283} __attribute__ ((__packed__)) LOG_CLIENT_RECORD; 284 285extern bool ntfs_check_logfile(struct inode *log_vi, 286 RESTART_PAGE_HEADER **rp); 287 288extern bool ntfs_is_logfile_clean(struct inode *log_vi, 289 const RESTART_PAGE_HEADER *rp); 290 291extern bool ntfs_empty_logfile(struct inode *log_vi); 292 293#endif /* NTFS_RW */ 294 295#endif /* _LINUX_NTFS_LOGFILE_H */