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/*

 * logfile.h - Defines for NTFS kernel journal ($LogFile) handling.  Part of

 *             the Linux-NTFS project.

 *

 * Copyright (c) 2000-2005 Anton Altaparmakov

 *

 * This program/include file is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License as published

 * by the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program/include file is distributed in the hope that it will be

 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty

 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program (in the main directory of the Linux-NTFS

 * distribution in the file COPYING); if not, write to the Free Software

 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 */

#ifndef _LINUX_NTFS_LOGFILE_H

#define _LINUX_NTFS_LOGFILE_H

#ifdef NTFS_RW

#include <linux/fs.h>

#include "types.h"

#include "endian.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).

 */

typedef struct {

/*Ofs*/

/*  0   NTFS_RECORD; -- Unfolded here as gcc doesn't like unnamed structs. */

/*  0*/ NTFS_RECORD_TYPE magic; /* The magic is "RSTR". */

/*  4*/ le16 usa_ofs;           /* See NTFS_RECORD definition in layout.h.

                                   When creating, set this to be immediately

                                   after this header structure (without any

                                   alignment). */

/*  6*/ le16 usa_count;         /* See NTFS_RECORD definition in layout.h. */

/*  8*/ leLSN chkdsk_lsn;       /* The last log file sequence number found by

                                   chkdsk.  Only used when the magic is changed

                                   to "CHKD".  Otherwise this is zero. */

/* 16*/ le32 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. */

/* 20*/ le32 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. */

/* 24*/ le16 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. */

/* 26*/ sle16 minor_ver;        /* Log file minor version.  Only check if major

                                   version is 1. */

/* 28*/ sle16 major_ver;        /* Log file major version.  We only support

                                   version 1.1. */

/* sizeof() = 30 (0x1e) bytes */

} __attribute__ ((__packed__)) RESTART_PAGE_HEADER;

/*

 * 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       const_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.

 */

enum {

        RESTART_VOLUME_IS_CLEAN = const_cpu_to_le16(0x0002),

        RESTART_SPACE_FILLER    = const_cpu_to_le16(0xffff), /* gcc: Force enum bit width to 16. */

} __attribute__ ((__packed__));

typedef le16 RESTART_AREA_FLAGS;

/*

 * 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.

 */

typedef struct {

/*Ofs*/

/*  0*/ leLSN 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. */

/*  8*/ le16 log_clients;       /* Number of log client records in the array of

                                   log client records which follows this

                                   restart area.  Must be 1.  */

/* 10*/ le16 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. */

/* 12*/ le16 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. */

/* 14*/ RESTART_AREA_FLAGS 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. */

/* 16*/ le32 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. */

/* 20*/ le16 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)). */

/* 22*/ le16 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. */

/* 24*/ sle64 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

                                   occured.  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. */

/* 32*/ le32 last_lsn_data_length;/* Length of data of last LSN, not including

                                   the log record header.  On create set to

                                   0. */

/* 36*/ le16 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. */

/* 38*/ le16 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. */

/* 40*/ le32 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). */

/* 44*/ le32 reserved;          /* Reserved/alignment to 8-byte boundary. */

/* sizeof() = 48 (0x30) bytes */

} __attribute__ ((__packed__)) RESTART_AREA;

/*

 * 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.

 */

typedef struct {

/*Ofs*/

/*  0*/ leLSN oldest_lsn;       /* Oldest LSN needed by this client.  On create

                                   set to 0. */

/*  8*/ leLSN 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. */

/* 16*/ le16 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. */

/* 18*/ le16 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. */

/* 20*/ le16 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. */

/* 22*/ u8 reserved[6];         /* Reserved/alignment. */

/* 28*/ le32 client_name_length;/* Length of client name in bytes.  Should

                                   always be 8. */

/* 32*/ ntfschar client_name[64];/* Name of the client in Unicode.  Should

                                   always be "NTFS" with the remaining bytes

                                   set to 0. */

/* sizeof() = 160 (0xa0) bytes */

} __attribute__ ((__packed__)) LOG_CLIENT_RECORD;

extern bool ntfs_check_logfile(struct inode *log_vi,

                RESTART_PAGE_HEADER **rp);

extern bool ntfs_is_logfile_clean(struct inode *log_vi,

                const RESTART_PAGE_HEADER *rp);

extern bool ntfs_empty_logfile(struct inode *log_vi);

#endif /* NTFS_RW */

#endif /* _LINUX_NTFS_LOGFILE_H */