The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/fs/ntfs/logfile.h

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    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  */
   67 typedef 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  */
  114 enum {
  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 
  119 typedef 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  */
  126 typedef 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  */
  264 typedef 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 
  299 extern bool ntfs_check_logfile(struct inode *log_vi,
  300                 RESTART_PAGE_HEADER **rp);
  301 
  302 extern bool ntfs_is_logfile_clean(struct inode *log_vi,
  303                 const RESTART_PAGE_HEADER *rp);
  304 
  305 extern bool ntfs_empty_logfile(struct inode *log_vi);
  306 
  307 #endif /* NTFS_RW */
  308 
  309 #endif /* _LINUX_NTFS_LOGFILE_H */

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