Root/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 */
100typedef 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 */
118enum {
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
142typedef 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 */
150enum {
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
156typedef 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 */
169typedef 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
201extern bool ntfs_stamp_usnjrnl(ntfs_volume *vol);
202
203#endif /* NTFS_RW */
204
205#endif /* _LINUX_NTFS_USNJRNL_H */
206

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