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295 lines
13 KiB
295 lines
13 KiB
/* SPDX-License-Identifier: GPL-2.0-or-later */ |
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/* |
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* logfile.h - Defines for NTFS kernel journal ($LogFile) handling. Part of |
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* the Linux-NTFS project. |
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* |
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* Copyright (c) 2000-2005 Anton Altaparmakov |
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*/ |
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#ifndef _LINUX_NTFS_LOGFILE_H |
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#define _LINUX_NTFS_LOGFILE_H |
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#ifdef NTFS_RW |
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#include <linux/fs.h> |
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#include "types.h" |
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#include "endian.h" |
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#include "layout.h" |
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/* |
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* Journal ($LogFile) organization: |
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* |
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* Two restart areas present in the first two pages (restart pages, one restart |
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* area in each page). When the volume is dismounted they should be identical, |
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* except for the update sequence array which usually has a different update |
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* sequence number. |
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* |
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* These are followed by log records organized in pages headed by a log record |
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* header going up to log file size. Not all pages contain log records when a |
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* volume is first formatted, but as the volume ages, all records will be used. |
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* When the log file fills up, the records at the beginning are purged (by |
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* modifying the oldest_lsn to a higher value presumably) and writing begins |
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* at the beginning of the file. Effectively, the log file is viewed as a |
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* circular entity. |
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* |
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* NOTE: Windows NT, 2000, and XP all use log file version 1.1 but they accept |
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* versions <= 1.x, including 0.-1. (Yes, that is a minus one in there!) We |
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* probably only want to support 1.1 as this seems to be the current version |
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* and we don't know how that differs from the older versions. The only |
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* exception is if the journal is clean as marked by the two restart pages |
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* then it doesn't matter whether we are on an earlier version. We can just |
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* reinitialize the logfile and start again with version 1.1. |
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*/ |
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/* Some $LogFile related constants. */ |
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#define MaxLogFileSize 0x100000000ULL |
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#define DefaultLogPageSize 4096 |
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#define MinLogRecordPages 48 |
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/* |
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* Log file restart page header (begins the restart area). |
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*/ |
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typedef struct { |
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/*Ofs*/ |
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/* 0 NTFS_RECORD; -- Unfolded here as gcc doesn't like unnamed structs. */ |
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/* 0*/ NTFS_RECORD_TYPE magic; /* The magic is "RSTR". */ |
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/* 4*/ le16 usa_ofs; /* See NTFS_RECORD definition in layout.h. |
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When creating, set this to be immediately |
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after this header structure (without any |
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alignment). */ |
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/* 6*/ le16 usa_count; /* See NTFS_RECORD definition in layout.h. */ |
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/* 8*/ leLSN chkdsk_lsn; /* The last log file sequence number found by |
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chkdsk. Only used when the magic is changed |
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to "CHKD". Otherwise this is zero. */ |
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/* 16*/ le32 system_page_size; /* Byte size of system pages when the log file |
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was created, has to be >= 512 and a power of |
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2. Use this to calculate the required size |
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of the usa (usa_count) and add it to usa_ofs. |
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Then verify that the result is less than the |
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value of the restart_area_offset. */ |
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/* 20*/ le32 log_page_size; /* Byte size of log file pages, has to be >= |
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512 and a power of 2. The default is 4096 |
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and is used when the system page size is |
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between 4096 and 8192. Otherwise this is |
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set to the system page size instead. */ |
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/* 24*/ le16 restart_area_offset;/* Byte offset from the start of this header to |
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the RESTART_AREA. Value has to be aligned |
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to 8-byte boundary. When creating, set this |
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to be after the usa. */ |
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/* 26*/ sle16 minor_ver; /* Log file minor version. Only check if major |
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version is 1. */ |
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/* 28*/ sle16 major_ver; /* Log file major version. We only support |
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version 1.1. */ |
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/* sizeof() = 30 (0x1e) bytes */ |
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} __attribute__ ((__packed__)) RESTART_PAGE_HEADER; |
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/* |
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* Constant for the log client indices meaning that there are no client records |
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* in this particular client array. Also inside the client records themselves, |
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* this means that there are no client records preceding or following this one. |
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*/ |
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#define LOGFILE_NO_CLIENT cpu_to_le16(0xffff) |
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#define LOGFILE_NO_CLIENT_CPU 0xffff |
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/* |
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* These are the so far known RESTART_AREA_* flags (16-bit) which contain |
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* information about the log file in which they are present. |
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*/ |
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enum { |
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RESTART_VOLUME_IS_CLEAN = cpu_to_le16(0x0002), |
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RESTART_SPACE_FILLER = cpu_to_le16(0xffff), /* gcc: Force enum bit width to 16. */ |
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} __attribute__ ((__packed__)); |
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typedef le16 RESTART_AREA_FLAGS; |
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/* |
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* Log file restart area record. The offset of this record is found by adding |
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* the offset of the RESTART_PAGE_HEADER to the restart_area_offset value found |
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* in it. See notes at restart_area_offset above. |
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*/ |
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typedef struct { |
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/*Ofs*/ |
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/* 0*/ leLSN current_lsn; /* The current, i.e. last LSN inside the log |
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when the restart area was last written. |
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This happens often but what is the interval? |
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Is it just fixed time or is it every time a |
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check point is written or somethine else? |
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On create set to 0. */ |
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/* 8*/ le16 log_clients; /* Number of log client records in the array of |
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log client records which follows this |
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restart area. Must be 1. */ |
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/* 10*/ le16 client_free_list; /* The index of the first free log client record |
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in the array of log client records. |
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LOGFILE_NO_CLIENT means that there are no |
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free log client records in the array. |
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If != LOGFILE_NO_CLIENT, check that |
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log_clients > client_free_list. On Win2k |
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and presumably earlier, on a clean volume |
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this is != LOGFILE_NO_CLIENT, and it should |
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be 0, i.e. the first (and only) client |
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record is free and thus the logfile is |
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closed and hence clean. A dirty volume |
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would have left the logfile open and hence |
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this would be LOGFILE_NO_CLIENT. On WinXP |
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and presumably later, the logfile is always |
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open, even on clean shutdown so this should |
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always be LOGFILE_NO_CLIENT. */ |
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/* 12*/ le16 client_in_use_list;/* The index of the first in-use log client |
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record in the array of log client records. |
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LOGFILE_NO_CLIENT means that there are no |
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in-use log client records in the array. If |
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!= LOGFILE_NO_CLIENT check that log_clients |
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> client_in_use_list. On Win2k and |
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presumably earlier, on a clean volume this |
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is LOGFILE_NO_CLIENT, i.e. there are no |
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client records in use and thus the logfile |
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is closed and hence clean. A dirty volume |
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would have left the logfile open and hence |
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this would be != LOGFILE_NO_CLIENT, and it |
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should be 0, i.e. the first (and only) |
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client record is in use. On WinXP and |
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presumably later, the logfile is always |
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open, even on clean shutdown so this should |
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always be 0. */ |
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/* 14*/ RESTART_AREA_FLAGS flags;/* Flags modifying LFS behaviour. On Win2k |
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and presumably earlier this is always 0. On |
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WinXP and presumably later, if the logfile |
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was shutdown cleanly, the second bit, |
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RESTART_VOLUME_IS_CLEAN, is set. This bit |
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is cleared when the volume is mounted by |
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WinXP and set when the volume is dismounted, |
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thus if the logfile is dirty, this bit is |
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clear. Thus we don't need to check the |
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Windows version to determine if the logfile |
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is clean. Instead if the logfile is closed, |
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we know it must be clean. If it is open and |
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this bit is set, we also know it must be |
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clean. If on the other hand the logfile is |
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open and this bit is clear, we can be almost |
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certain that the logfile is dirty. */ |
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/* 16*/ le32 seq_number_bits; /* How many bits to use for the sequence |
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number. This is calculated as 67 - the |
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number of bits required to store the logfile |
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size in bytes and this can be used in with |
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the specified file_size as a consistency |
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check. */ |
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/* 20*/ le16 restart_area_length;/* Length of the restart area including the |
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client array. Following checks required if |
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version matches. Otherwise, skip them. |
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restart_area_offset + restart_area_length |
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has to be <= system_page_size. Also, |
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restart_area_length has to be >= |
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client_array_offset + (log_clients * |
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sizeof(log client record)). */ |
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/* 22*/ le16 client_array_offset;/* Offset from the start of this record to |
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the first log client record if versions are |
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matched. When creating, set this to be |
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after this restart area structure, aligned |
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to 8-bytes boundary. If the versions do not |
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match, this is ignored and the offset is |
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assumed to be (sizeof(RESTART_AREA) + 7) & |
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~7, i.e. rounded up to first 8-byte |
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boundary. Either way, client_array_offset |
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has to be aligned to an 8-byte boundary. |
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Also, restart_area_offset + |
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client_array_offset has to be <= 510. |
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Finally, client_array_offset + (log_clients |
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* sizeof(log client record)) has to be <= |
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system_page_size. On Win2k and presumably |
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earlier, this is 0x30, i.e. immediately |
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following this record. On WinXP and |
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presumably later, this is 0x40, i.e. there |
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are 16 extra bytes between this record and |
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the client array. This probably means that |
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the RESTART_AREA record is actually bigger |
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in WinXP and later. */ |
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/* 24*/ sle64 file_size; /* Usable byte size of the log file. If the |
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restart_area_offset + the offset of the |
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file_size are > 510 then corruption has |
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occurred. This is the very first check when |
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starting with the restart_area as if it |
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fails it means that some of the above values |
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will be corrupted by the multi sector |
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transfer protection. The file_size has to |
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be rounded down to be a multiple of the |
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log_page_size in the RESTART_PAGE_HEADER and |
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then it has to be at least big enough to |
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store the two restart pages and 48 (0x30) |
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log record pages. */ |
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/* 32*/ le32 last_lsn_data_length;/* Length of data of last LSN, not including |
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the log record header. On create set to |
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0. */ |
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/* 36*/ le16 log_record_header_length;/* Byte size of the log record header. |
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If the version matches then check that the |
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value of log_record_header_length is a |
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multiple of 8, i.e. |
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(log_record_header_length + 7) & ~7 == |
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log_record_header_length. When creating set |
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it to sizeof(LOG_RECORD_HEADER), aligned to |
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8 bytes. */ |
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/* 38*/ le16 log_page_data_offset;/* Offset to the start of data in a log record |
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page. Must be a multiple of 8. On create |
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set it to immediately after the update |
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sequence array of the log record page. */ |
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/* 40*/ le32 restart_log_open_count;/* A counter that gets incremented every |
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time the logfile is restarted which happens |
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at mount time when the logfile is opened. |
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When creating set to a random value. Win2k |
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sets it to the low 32 bits of the current |
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system time in NTFS format (see time.h). */ |
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/* 44*/ le32 reserved; /* Reserved/alignment to 8-byte boundary. */ |
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/* sizeof() = 48 (0x30) bytes */ |
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} __attribute__ ((__packed__)) RESTART_AREA; |
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/* |
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* Log client record. The offset of this record is found by adding the offset |
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* of the RESTART_AREA to the client_array_offset value found in it. |
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*/ |
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typedef struct { |
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/*Ofs*/ |
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/* 0*/ leLSN oldest_lsn; /* Oldest LSN needed by this client. On create |
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set to 0. */ |
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/* 8*/ leLSN client_restart_lsn;/* LSN at which this client needs to restart |
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the volume, i.e. the current position within |
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the log file. At present, if clean this |
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should = current_lsn in restart area but it |
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probably also = current_lsn when dirty most |
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of the time. At create set to 0. */ |
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/* 16*/ le16 prev_client; /* The offset to the previous log client record |
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in the array of log client records. |
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LOGFILE_NO_CLIENT means there is no previous |
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client record, i.e. this is the first one. |
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This is always LOGFILE_NO_CLIENT. */ |
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/* 18*/ le16 next_client; /* The offset to the next log client record in |
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the array of log client records. |
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LOGFILE_NO_CLIENT means there are no next |
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client records, i.e. this is the last one. |
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This is always LOGFILE_NO_CLIENT. */ |
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/* 20*/ le16 seq_number; /* On Win2k and presumably earlier, this is set |
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to zero every time the logfile is restarted |
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and it is incremented when the logfile is |
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closed at dismount time. Thus it is 0 when |
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dirty and 1 when clean. On WinXP and |
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presumably later, this is always 0. */ |
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/* 22*/ u8 reserved[6]; /* Reserved/alignment. */ |
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/* 28*/ le32 client_name_length;/* Length of client name in bytes. Should |
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always be 8. */ |
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/* 32*/ ntfschar client_name[64];/* Name of the client in Unicode. Should |
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always be "NTFS" with the remaining bytes |
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set to 0. */ |
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/* sizeof() = 160 (0xa0) bytes */ |
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} __attribute__ ((__packed__)) LOG_CLIENT_RECORD; |
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extern bool ntfs_check_logfile(struct inode *log_vi, |
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RESTART_PAGE_HEADER **rp); |
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extern bool ntfs_is_logfile_clean(struct inode *log_vi, |
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const RESTART_PAGE_HEADER *rp); |
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extern bool ntfs_empty_logfile(struct inode *log_vi); |
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#endif /* NTFS_RW */ |
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#endif /* _LINUX_NTFS_LOGFILE_H */
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