fs/ntfs/usnjrnl.h

   1 /*
   2  * usnjrnl.h - Defines for NTFS kernel transaction log ($UsnJrnl) handling.
   3  *             Part of the Linux-NTFS project.
   4  *
   5  * Copyright (c) 2005 Anton Altaparmakov
   6  *
   7  * This program/include file is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License as published
   9  * by the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program/include file is distributed in the hope that it will be
  13  * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
  14  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program (in the main directory of the Linux-NTFS
  19  * distribution in the file COPYING); if not, write to the Free Software
  20  * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  21  */
  22
  23 #ifndef _LINUX_NTFS_USNJRNL_H
  24 #define _LINUX_NTFS_USNJRNL_H
  25
  26 #ifdef NTFS_RW
  27
  28 #include "types.h"
  29 #include "endian.h"
  30 #include "layout.h"
  31 #include "volume.h"
  32
  33 /*
  34  * Transaction log ($UsnJrnl) organization:
  35  *
  36  * The transaction log records whenever a file is modified in any way.  So for
  37  * example it will record that file "blah" was written to at a particular time
  38  * but not what was written.  If will record that a file was deleted or
  39  * created, that a file was truncated, etc.  See below for all the reason
  40  * codes used.
  41  *
  42  * The transaction log is in the $Extend directory which is in the root
  43  * directory of each volume.  If it is not present it means transaction
  44  * logging is disabled.  If it is present it means transaction logging is
  45  * either enabled or in the process of being disabled in which case we can
  46  * ignore it as it will go away as soon as Windows gets its hands on it.
  47  *
  48  * To determine whether the transaction logging is enabled or in the process
  49  * of being disabled, need to check the volume flags in the
  50  * $VOLUME_INFORMATION attribute in the $Volume system file (which is present
  51  * in the root directory and has a fixed mft record number, see layout.h).
  52  * If the flag VOLUME_DELETE_USN_UNDERWAY is set it means the transaction log
  53  * is in the process of being disabled and if this flag is clear it means the
  54  * transaction log is enabled.
  55  *
  56  * The transaction log consists of two parts; the $DATA/$Max attribute as well
  57  * as the $DATA/$J attribute.  $Max is a header describing the transaction
  58  * log whilst $J is the transaction log data itself as a sequence of variable
  59  * sized USN_RECORDs (see below for all the structures).
  60  *
  61  * We do not care about transaction logging at this point in time but we still
  62  * need to let windows know that the transaction log is out of date.  To do
  63  * this we need to stamp the transaction log.  This involves setting the
  64  * lowest_valid_usn field in the $DATA/$Max attribute to the usn to be used
  65  * for the next added USN_RECORD to the $DATA/$J attribute as well as
  66  * generating a new journal_id in $DATA/$Max.
  67  *
  68  * The journal_id is as of the current version (2.0) of the transaction log
  69  * simply the 64-bit timestamp of when the journal was either created or last
  70  * stamped.
  71  *
  72  * To determine the next usn there are two ways.  The first is to parse
  73  * $DATA/$J and to find the last USN_RECORD in it and to add its record_length
  74  * to its usn (which is the byte offset in the $DATA/$J attribute).  The
  75  * second is simply to take the data size of the attribute.  Since the usns
  76  * are simply byte offsets into $DATA/$J, this is exactly the next usn.  For
  77  * obvious reasons we use the second method as it is much simpler and faster.
  78  *
  79  * As an aside, note that to actually disable the transaction log, one would
  80  * need to set the VOLUME_DELETE_USN_UNDERWAY flag (see above), then go
  81  * through all the mft records on the volume and set the usn field in their
  82  * $STANDARD_INFORMATION attribute to zero.  Once that is done, one would need
  83  * to delete the transaction log file, i.e. \$Extent\$UsnJrnl, and finally,
  84  * one would need to clear the VOLUME_DELETE_USN_UNDERWAY flag.
  85  *
  86  * Note that if a volume is unmounted whilst the transaction log is being
  87  * disabled, the process will continue the next time the volume is mounted.
  88  * This is why we can safely mount read-write when we see a transaction log
  89  * in the process of being deleted.
  90  */
  91
  92 /* Some $UsnJrnl related constants. */
  93 #define UsnJrnlMajorVer         2
  94 #define UsnJrnlMinorVer         0
  95
  96 /*
  97  * $DATA/$Max attribute.  This is (always?) resident and has a fixed size of
  98  * 32 bytes.  It contains the header describing the transaction log.
  99  */
 100 typedef struct {
 101 /*Ofs*/
 102 /*   0*/sle64 maximum_size;     /* The maximum on-disk size of the $DATA/$J
 103                                    attribute. */
 104 /*   8*/sle64 allocation_delta; /* Number of bytes by which to increase the
 105                                    size of the $DATA/$J attribute. */
 106 /*0x10*/sle64 journal_id;       /* Current id of the transaction log. */
 107 /*0x18*/leUSN lowest_valid_usn; /* Lowest valid usn in $DATA/$J for the
 108                                    current journal_id. */
 109 /* sizeof() = 32 (0x20) bytes */
 110 } __attribute__ ((__packed__)) USN_HEADER;
 111
 112 /*
 113  * Reason flags (32-bit).  Cumulative flags describing the change(s) to the
 114  * file since it was last opened.  I think the names speak for themselves but
 115  * if you disagree check out the descriptions in the Linux NTFS project NTFS
 116  * documentation: http://www.linux-ntfs.org/
 117  */
 118 enum {
 119         USN_REASON_DATA_OVERWRITE       = cpu_to_le32(0x00000001),
 120         USN_REASON_DATA_EXTEND          = cpu_to_le32(0x00000002),
 121         USN_REASON_DATA_TRUNCATION      = cpu_to_le32(0x00000004),
 122         USN_REASON_NAMED_DATA_OVERWRITE = cpu_to_le32(0x00000010),
 123         USN_REASON_NAMED_DATA_EXTEND    = cpu_to_le32(0x00000020),
 124         USN_REASON_NAMED_DATA_TRUNCATION= cpu_to_le32(0x00000040),
 125         USN_REASON_FILE_CREATE          = cpu_to_le32(0x00000100),
 126         USN_REASON_FILE_DELETE          = cpu_to_le32(0x00000200),
 127         USN_REASON_EA_CHANGE            = cpu_to_le32(0x00000400),
 128         USN_REASON_SECURITY_CHANGE      = cpu_to_le32(0x00000800),
 129         USN_REASON_RENAME_OLD_NAME      = cpu_to_le32(0x00001000),
 130         USN_REASON_RENAME_NEW_NAME      = cpu_to_le32(0x00002000),
 131         USN_REASON_INDEXABLE_CHANGE     = cpu_to_le32(0x00004000),
 132         USN_REASON_BASIC_INFO_CHANGE    = cpu_to_le32(0x00008000),
 133         USN_REASON_HARD_LINK_CHANGE     = cpu_to_le32(0x00010000),
 134         USN_REASON_COMPRESSION_CHANGE   = cpu_to_le32(0x00020000),
 135         USN_REASON_ENCRYPTION_CHANGE    = cpu_to_le32(0x00040000),
 136         USN_REASON_OBJECT_ID_CHANGE     = cpu_to_le32(0x00080000),
 137         USN_REASON_REPARSE_POINT_CHANGE = cpu_to_le32(0x00100000),
 138         USN_REASON_STREAM_CHANGE        = cpu_to_le32(0x00200000),
 139         USN_REASON_CLOSE                = cpu_to_le32(0x80000000),
 140 };
 141
 142 typedef le32 USN_REASON_FLAGS;
 143
 144 /*
 145  * Source info flags (32-bit).  Information about the source of the change(s)
 146  * to the file.  For detailed descriptions of what these mean, see the Linux
 147  * NTFS project NTFS documentation:
 148  *      http://www.linux-ntfs.org/
 149  */
 150 enum {
 151         USN_SOURCE_DATA_MANAGEMENT        = cpu_to_le32(0x00000001),
 152         USN_SOURCE_AUXILIARY_DATA         = cpu_to_le32(0x00000002),
 153         USN_SOURCE_REPLICATION_MANAGEMENT = cpu_to_le32(0x00000004),
 154 };
 155
 156 typedef le32 USN_SOURCE_INFO_FLAGS;
 157
 158 /*
 159  * $DATA/$J attribute.  This is always non-resident, is marked as sparse, and
 160  * is of variabled size.  It consists of a sequence of variable size
 161  * USN_RECORDS.  The minimum allocated_size is allocation_delta as
 162  * specified in $DATA/$Max.  When the maximum_size specified in $DATA/$Max is
 163  * exceeded by more than allocation_delta bytes, allocation_delta bytes are
 164  * allocated and appended to the $DATA/$J attribute and an equal number of
 165  * bytes at the beginning of the attribute are freed and made sparse.  Note the
 166  * making sparse only happens at volume checkpoints and hence the actual
 167  * $DATA/$J size can exceed maximum_size + allocation_delta temporarily.
 168  */
 169 typedef struct {
 170 /*Ofs*/
 171 /*   0*/le32 length;            /* Byte size of this record (8-byte
 172                                    aligned). */
 173 /*   4*/le16 major_ver;         /* Major version of the transaction log used
 174                                    for this record. */
 175 /*   6*/le16 minor_ver;         /* Minor version of the transaction log used
 176                                    for this record. */
 177 /*   8*/leMFT_REF mft_reference;/* The mft reference of the file (or
 178                                    directory) described by this record. */
 179 /*0x10*/leMFT_REF parent_directory;/* The mft reference of the parent
 180                                    directory of the file described by this
 181                                    record. */
 182 /*0x18*/leUSN usn;              /* The usn of this record.  Equals the offset
 183                                    within the $DATA/$J attribute. */
 184 /*0x20*/sle64 time;             /* Time when this record was created. */
 185 /*0x28*/USN_REASON_FLAGS reason;/* Reason flags (see above). */
 186 /*0x2c*/USN_SOURCE_INFO_FLAGS source_info;/* Source info flags (see above). */
 187 /*0x30*/le32 security_id;       /* File security_id copied from
 188                                    $STANDARD_INFORMATION. */
 189 /*0x34*/FILE_ATTR_FLAGS file_attributes;        /* File attributes copied from
 190                                    $STANDARD_INFORMATION or $FILE_NAME (not
 191                                    sure which). */
 192 /*0x38*/le16 file_name_size;    /* Size of the file name in bytes. */
 193 /*0x3a*/le16 file_name_offset;  /* Offset to the file name in bytes from the
 194                                    start of this record. */
 195 /*0x3c*/ntfschar file_name[0];  /* Use when creating only.  When reading use
 196                                    file_name_offset to determine the location
 197                                    of the name. */
 198 /* sizeof() = 60 (0x3c) bytes */
 199 } __attribute__ ((__packed__)) USN_RECORD;
 200
 201 extern bool ntfs_stamp_usnjrnl(ntfs_volume *vol);
 202
 203 #endif /* NTFS_RW */
 204
 205 #endif /* _LINUX_NTFS_USNJRNL_H */