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/* SPDX-License-Identifier: GPL-2.0-or-later */
* usnjrnl.h - Defines for NTFS kernel transaction log ($UsnJrnl) handling.
* Part of the Linux-NTFS project.
* Copyright (c) 2005 Anton Altaparmakov
#ifdef NTFS_RW
#include "types.h"
#include "endian.h"
#include "layout.h"
#include "volume.h"
* Transaction log ($UsnJrnl) organization:
* The transaction log records whenever a file is modified in any way. So for
* example it will record that file "blah" was written to at a particular time
* but not what was written. If will record that a file was deleted or
* created, that a file was truncated, etc. See below for all the reason
* codes used.
* The transaction log is in the $Extend directory which is in the root
* directory of each volume. If it is not present it means transaction
* logging is disabled. If it is present it means transaction logging is
* either enabled or in the process of being disabled in which case we can
* ignore it as it will go away as soon as Windows gets its hands on it.
* To determine whether the transaction logging is enabled or in the process
* of being disabled, need to check the volume flags in the
* $VOLUME_INFORMATION attribute in the $Volume system file (which is present
* in the root directory and has a fixed mft record number, see layout.h).
* If the flag VOLUME_DELETE_USN_UNDERWAY is set it means the transaction log
* is in the process of being disabled and if this flag is clear it means the
* transaction log is enabled.
* The transaction log consists of two parts; the $DATA/$Max attribute as well
* as the $DATA/$J attribute. $Max is a header describing the transaction
* log whilst $J is the transaction log data itself as a sequence of variable
* sized USN_RECORDs (see below for all the structures).
* We do not care about transaction logging at this point in time but we still
* need to let windows know that the transaction log is out of date. To do
* this we need to stamp the transaction log. This involves setting the
* lowest_valid_usn field in the $DATA/$Max attribute to the usn to be used
* for the next added USN_RECORD to the $DATA/$J attribute as well as
* generating a new journal_id in $DATA/$Max.
* The journal_id is as of the current version (2.0) of the transaction log
* simply the 64-bit timestamp of when the journal was either created or last
* stamped.
* To determine the next usn there are two ways. The first is to parse
* $DATA/$J and to find the last USN_RECORD in it and to add its record_length
* to its usn (which is the byte offset in the $DATA/$J attribute). The
* second is simply to take the data size of the attribute. Since the usns
* are simply byte offsets into $DATA/$J, this is exactly the next usn. For
* obvious reasons we use the second method as it is much simpler and faster.
* As an aside, note that to actually disable the transaction log, one would
* need to set the VOLUME_DELETE_USN_UNDERWAY flag (see above), then go
* through all the mft records on the volume and set the usn field in their
* $STANDARD_INFORMATION attribute to zero. Once that is done, one would need
* to delete the transaction log file, i.e. \$Extent\$UsnJrnl, and finally,
* one would need to clear the VOLUME_DELETE_USN_UNDERWAY flag.
* Note that if a volume is unmounted whilst the transaction log is being
* disabled, the process will continue the next time the volume is mounted.
* This is why we can safely mount read-write when we see a transaction log
* in the process of being deleted.
/* Some $UsnJrnl related constants. */
#define UsnJrnlMajorVer 2
#define UsnJrnlMinorVer 0
* $DATA/$Max attribute. This is (always?) resident and has a fixed size of
* 32 bytes. It contains the header describing the transaction log.
typedef struct {
/* 0*/sle64 maximum_size; /* The maximum on-disk size of the $DATA/$J
attribute. */
/* 8*/sle64 allocation_delta; /* Number of bytes by which to increase the
size of the $DATA/$J attribute. */
/*0x10*/sle64 journal_id; /* Current id of the transaction log. */
/*0x18*/leUSN lowest_valid_usn; /* Lowest valid usn in $DATA/$J for the
current journal_id. */
/* sizeof() = 32 (0x20) bytes */
} __attribute__ ((__packed__)) USN_HEADER;
* Reason flags (32-bit). Cumulative flags describing the change(s) to the
* file since it was last opened. I think the names speak for themselves but
* if you disagree check out the descriptions in the Linux NTFS project NTFS
* documentation:
enum {
USN_REASON_DATA_OVERWRITE = cpu_to_le32(0x00000001),
USN_REASON_DATA_EXTEND = cpu_to_le32(0x00000002),
USN_REASON_DATA_TRUNCATION = cpu_to_le32(0x00000004),
USN_REASON_NAMED_DATA_OVERWRITE = cpu_to_le32(0x00000010),
USN_REASON_NAMED_DATA_EXTEND = cpu_to_le32(0x00000020),
USN_REASON_NAMED_DATA_TRUNCATION= cpu_to_le32(0x00000040),
USN_REASON_FILE_CREATE = cpu_to_le32(0x00000100),
USN_REASON_FILE_DELETE = cpu_to_le32(0x00000200),
USN_REASON_EA_CHANGE = cpu_to_le32(0x00000400),
USN_REASON_SECURITY_CHANGE = cpu_to_le32(0x00000800),
USN_REASON_RENAME_OLD_NAME = cpu_to_le32(0x00001000),
USN_REASON_RENAME_NEW_NAME = cpu_to_le32(0x00002000),
USN_REASON_INDEXABLE_CHANGE = cpu_to_le32(0x00004000),
USN_REASON_BASIC_INFO_CHANGE = cpu_to_le32(0x00008000),
USN_REASON_HARD_LINK_CHANGE = cpu_to_le32(0x00010000),
USN_REASON_COMPRESSION_CHANGE = cpu_to_le32(0x00020000),
USN_REASON_ENCRYPTION_CHANGE = cpu_to_le32(0x00040000),
USN_REASON_OBJECT_ID_CHANGE = cpu_to_le32(0x00080000),
USN_REASON_REPARSE_POINT_CHANGE = cpu_to_le32(0x00100000),
USN_REASON_STREAM_CHANGE = cpu_to_le32(0x00200000),
USN_REASON_CLOSE = cpu_to_le32(0x80000000),
typedef le32 USN_REASON_FLAGS;
* Source info flags (32-bit). Information about the source of the change(s)
* to the file. For detailed descriptions of what these mean, see the Linux
* NTFS project NTFS documentation:
enum {
USN_SOURCE_DATA_MANAGEMENT = cpu_to_le32(0x00000001),
USN_SOURCE_AUXILIARY_DATA = cpu_to_le32(0x00000002),
USN_SOURCE_REPLICATION_MANAGEMENT = cpu_to_le32(0x00000004),
* $DATA/$J attribute. This is always non-resident, is marked as sparse, and
* is of variabled size. It consists of a sequence of variable size
* USN_RECORDS. The minimum allocated_size is allocation_delta as
* specified in $DATA/$Max. When the maximum_size specified in $DATA/$Max is
* exceeded by more than allocation_delta bytes, allocation_delta bytes are
* allocated and appended to the $DATA/$J attribute and an equal number of
* bytes at the beginning of the attribute are freed and made sparse. Note the
* making sparse only happens at volume checkpoints and hence the actual
* $DATA/$J size can exceed maximum_size + allocation_delta temporarily.
typedef struct {
/* 0*/le32 length; /* Byte size of this record (8-byte
aligned). */
/* 4*/le16 major_ver; /* Major version of the transaction log used
for this record. */
/* 6*/le16 minor_ver; /* Minor version of the transaction log used
for this record. */
/* 8*/leMFT_REF mft_reference;/* The mft reference of the file (or
directory) described by this record. */
/*0x10*/leMFT_REF parent_directory;/* The mft reference of the parent
directory of the file described by this
record. */
/*0x18*/leUSN usn; /* The usn of this record. Equals the offset
within the $DATA/$J attribute. */
/*0x20*/sle64 time; /* Time when this record was created. */
/*0x28*/USN_REASON_FLAGS reason;/* Reason flags (see above). */
/*0x2c*/USN_SOURCE_INFO_FLAGS source_info;/* Source info flags (see above). */
/*0x30*/le32 security_id; /* File security_id copied from
/*0x34*/FILE_ATTR_FLAGS file_attributes; /* File attributes copied from
sure which). */
/*0x38*/le16 file_name_size; /* Size of the file name in bytes. */
/*0x3a*/le16 file_name_offset; /* Offset to the file name in bytes from the
start of this record. */
/*0x3c*/ntfschar file_name[0]; /* Use when creating only. When reading use
file_name_offset to determine the location
of the name. */
/* sizeof() = 60 (0x3c) bytes */
} __attribute__ ((__packed__)) USN_RECORD;
extern bool ntfs_stamp_usnjrnl(ntfs_volume *vol);
#endif /* NTFS_RW */
#endif /* _LINUX_NTFS_USNJRNL_H */