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/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* Defines for NTFS kernel journal (LogFile) handling.
*
* Copyright (c) 2000-2005 Anton Altaparmakov
*/
#ifndef _LINUX_NTFS_LOGFILE_H
#define _LINUX_NTFS_LOGFILE_H
#include "layout.h"
/*
* Journal (LogFile) organization:
*
* Two restart areas present in the first two pages (restart pages, one restart
* area in each page). When the volume is dismounted they should be identical,
* except for the update sequence array which usually has a different update
* sequence number.
*
* These are followed by log records organized in pages headed by a log record
* header going up to log file size. Not all pages contain log records when a
* volume is first formatted, but as the volume ages, all records will be used.
* When the log file fills up, the records at the beginning are purged (by
* modifying the oldest_lsn to a higher value presumably) and writing begins
* at the beginning of the file. Effectively, the log file is viewed as a
* circular entity.
*
* NOTE: Windows NT, 2000, and XP all use log file version 1.1 but they accept
* versions <= 1.x, including 0.-1. (Yes, that is a minus one in there!) We
* probably only want to support 1.1 as this seems to be the current version
* and we don't know how that differs from the older versions. The only
* exception is if the journal is clean as marked by the two restart pages
* then it doesn't matter whether we are on an earlier version. We can just
* reinitialize the logfile and start again with version 1.1.
*/
/* Some LogFile related constants. */
#define MaxLogFileSize 0x100000000ULL
#define DefaultLogPageSize 4096
#define MinLogRecordPages 48
/*
* Log file restart page header (begins the restart area).
*
* @magic: The magic is "RSTR".
* @usa_ofs: See ntfs_record struct definition in layout.h. When creating,
* set this to be immediately after this header structure (without any
* alignment).
* @usa_count: See ntfs_record struct definition in layout.h.
* @chkdsk_lsn: The last log file sequence number found by chkdsk. Only
* used when the magic is changed to "CHKD". Otherwise this is zero.
* @system_page_size: Byte size of system pages when the log file was
* created, has to be >= 512 and a power of 2. Use this to calculate
* the required size of the usa (usa_count) and add it to usa_ofs. Then
* verify that the result is less than the value of
* the restart_area_offset.
* @log_page_size: Byte size of log file pages, has to be >= 512 and
* a power of 2. The default is 4096 and is used when the system page
* size is between 4096 and 8192. Otherwise this is set to the system
* page size instead.
* @restart_area_offset: Byte offset from the start of this header to
* the RESTART_AREA. Value has to be aligned to 8-byte boundary. When
* creating, set this to be after the usa.
* @minor_ver: Log file minor version. Only check if major version is 1.
* @major_ver: Log file major version. We only support version 1.1.
*/
struct restart_page_header {
__le32 magic;
__le16 usa_ofs;
__le16 usa_count;
__le64 chkdsk_lsn;
__le32 system_page_size;
__le32 log_page_size;
__le16 restart_area_offset;
__le16 minor_ver;
__le16 major_ver;
} __packed;
/*
* Constant for the log client indices meaning that there are no client records
* in this particular client array. Also inside the client records themselves,
* this means that there are no client records preceding or following this one.
*/
#define LOGFILE_NO_CLIENT cpu_to_le16(0xffff)
#define LOGFILE_NO_CLIENT_CPU 0xffff
/*
* These are the so far known RESTART_AREA_* flags (16-bit) which contain
* information about the log file in which they are present.
* gcc: Force enum bit width to 16.
*/
enum {
RESTART_VOLUME_IS_CLEAN = cpu_to_le16(0x0002),
RESTART_SPACE_FILLER = cpu_to_le16(0xffff),
} __packed;
/*
* Log file restart area record. The offset of this record is found by adding
* the offset of the RESTART_PAGE_HEADER to the restart_area_offset value found
* in it. See notes at restart_area_offset above.
*
* @current_lsn: The current, i.e. last LSN inside the log when
* the restart area was last written. This happens often but what is
* the interval? Is it just fixed time or is it every time a check point
* is written or somethine else? On create set to 0.
* @log_clients: Number of log client records in the array of log client
* records which follows this restart area. Must be 1.
* @client_free_list: The index of the first free log client record in
* the array of log client records. LOGFILE_NO_CLIENT means that there
* are no free log client records in the array. If != LOGFILE_NO_CLIENT,
* check that log_clients > client_free_list. On Win2k and presumably
* earlier, on a clean volume this is != LOGFILE_NO_CLIENT, and it should
* be 0, i.e. the first (and only) client record is free and thus
* the logfile is closed and hence clean. A dirty volume would have left
* the logfile open and hence this would be LOGFILE_NO_CLIENT. On WinXP
* and presumably later, the logfile is always open, even on clean
* shutdown so this should always be LOGFILE_NO_CLIENT.
* @client_in_use_list: The index of the first in-use log client record in
* the array of log client records. LOGFILE_NO_CLIENT means that there
* are no in-use log client records in the array.
* If != LOGFILE_NO_CLIENT check that log_clients > client_in_use_list.
* On Win2k and presumably earlier, on a clean volume this is
* LOGFILE_NO_CLIENT, i.e. there are no client records in use and thus
* the logfile is closed and hence clean. A dirty volume would have left
* the logfile open and hence this would be != LOGFILE_NO_CLIENT, and it
* should be 0, i.e. the first (and only) client record is in use. On
* WinXP and presumably later, the logfile is always open, even on clean
* shutdown so this should always be 0.
* @flags: Flags modifying LFS behaviour. On Win2k and presumably earlier
* this is always 0. On WinXP and presumably later, if the logfile was
* shutdown cleanly, the second bit, RESTART_VOLUME_IS_CLEAN, is set.
* This bit is cleared when the volume is mounted by WinXP and set when
* the volume is dismounted, thus if the logfile is dirty, this bit is
* clear. Thus we don't need to check the Windows version to determine
* if the logfile is clean. Instead if the logfile is closed, we know
* it must be clean. If it is open and this bit is set, we also know
* it must be clean. If on the other hand the logfile is open and this
* bit is clear, we can be almost certain that the logfile is dirty.
* @seq_number_bits: How many bits to use for the sequence number. This
* is calculated as 67 - the number of bits required to store the logfile
* size in bytes and this can be used in with the specified file_size as
* a consistency check.
* @restart_area_length: Length of the restart area including the client
* array. Following checks required if version matches. Otherwise,
* skip them. restart_area_offset + restart_area_length has to be
* <= system_page_size. Also, restart_area_length has to be >=
* client_array_offset + (log_clients * sizeof(log client record)).
* @client_array_offset: Offset from the start of this record to the first
* log client record if versions are matched. When creating, set this
* to be after this restart area structure, aligned to 8-bytes boundary.
* If the versions do not match, this is ignored and the offset is
* assumed to be (sizeof(RESTART_AREA) + 7) & ~7, i.e. rounded up to
* first 8-byte boundary. Either way, client_array_offset has to be
* aligned to an 8-byte boundary. Also, restart_area_offset +
* client_array_offset has to be <= 510. Finally, client_array_offset +
* (log_clients * sizeof(log client record)) has to be <= system_page_size.
* On Win2k and presumably earlier, this is 0x30, i.e. immediately
* following this record. On WinXP and presumably later, this is 0x40,
* i.e. there are 16 extra bytes between this record and the client
* array. This probably means that the RESTART_AREA record is actually
* bigger in WinXP and later.
* @file_size: Usable byte size of the log file.
* If the restart_area_offset + the offset of the file_size are > 510
* then corruption has occurred. This is the very first check when
* starting with the restart_area as if it fails it means that some of
* the above values will be corrupted by the multi sector transfer
* protection. The file_size has to be rounded down to be a multiple
* of the log_page_size in the RESTART_PAGE_HEADER and then it has to be
* at least big enough to store the two restart pages and 48 (0x30) log
* record pages.
* @last_lsn_data_length: Length of data of last LSN, not including the log
* record header. On create set to 0.
* @log_record_header_length: Byte size of the log record header. If the
* version matches then check that the value of log_record_header_length
* is a multiple of 8, i.e. (log_record_header_length + 7) & ~7 ==
* log_record_header_length. When creating set it to
* sizeof(LOG_RECORD_HEADER), aligned to 8 bytes.
* @log_page_data_offset: Offset to the start of data in a log record page.
* Must be a multiple of 8. On create set it to immediately after
* the update sequence array of the log record page.
* @restart_log_open_count: A counter that gets incremented every time
* the logfile is restarted which happens at mount time when the logfile
* is opened. When creating set to a random value. Win2k sets it to
* the low 32 bits of the current system time in NTFS format (see time.h).
* @reserved: Reserved/alignment to 8-byte boundary.
*/
struct restart_area {
__le64 current_lsn;
__le16 log_clients;
__le16 client_free_list;
__le16 client_in_use_list;
__le16 flags;
__le32 seq_number_bits;
__le16 restart_area_length;
__le16 client_array_offset;
__le64 file_size;
__le32 last_lsn_data_length;
__le16 log_record_header_length;
__le16 log_page_data_offset;
__le32 restart_log_open_count;
__le32 reserved;
} __packed;
/*
* Log client record. The offset of this record is found by adding the offset
* of the RESTART_AREA to the client_array_offset value found in it.
*
* @oldest_lsn: Oldest LSN needed by this client. On create set to 0.
* @client_restart_lsn: LSN at which this client needs to restart
* the volume, i.e. the current position within the log file.
* At present, if clean this should = current_lsn in restart area but it
* probably also = current_lsn when dirty most of the time.
* At create set to 0.
* @prev_client: The offset to the previous log client record in the array
* of log client records. LOGFILE_NO_CLIENT means there is no previous
* client record, i.e. this is the first one. This is always
* LOGFILE_NO_CLIENT.
* @next_client: The offset to the next log client record in the array of
* log client records. LOGFILE_NO_CLIENT means there are no next client
* records, i.e. this is the last one. This is always LOGFILE_NO_CLIENT.
* @seq_number: On Win2k and presumably earlier, this is set to zero every
* time the logfile is restarted and it is incremented when the logfile
* is closed at dismount time. Thus it is 0 when dirty and 1 when clean.
* On WinXP and presumably later, this is always 0.
* @reserved[6]: Reserved/alignment.
* @client_name_length: Length of client name in bytes. Should always be 8.
* @client_name[64]: Name of the client in Unicode. Should always be "NTFS"
* with the remaining bytes set to 0.
*/
struct log_client_record {
__le64 oldest_lsn;
__le64 client_restart_lsn;
__le16 prev_client;
__le16 next_client;
__le16 seq_number;
u8 reserved[6];
__le32 client_name_length;
__le16 client_name[64];
} __packed;
bool ntfs_check_logfile(struct inode *log_vi,
struct restart_page_header **rp);
bool ntfs_empty_logfile(struct inode *log_vi);
#endif /* _LINUX_NTFS_LOGFILE_H */
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