fs/ntfs/usnjrnl.h

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  48  * need to let windows know that the transaction log is out of date.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