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Diffstat (limited to 'fs/ntfs/usnjrnl.h')
| -rw-r--r-- | fs/ntfs/usnjrnl.h | 191 |
1 files changed, 191 insertions, 0 deletions
diff --git a/fs/ntfs/usnjrnl.h b/fs/ntfs/usnjrnl.h new file mode 100644 index 000000000..85f531b59 --- /dev/null +++ b/fs/ntfs/usnjrnl.h @@ -0,0 +1,191 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * usnjrnl.h - Defines for NTFS kernel transaction log ($UsnJrnl) handling. + * Part of the Linux-NTFS project. + * + * Copyright (c) 2005 Anton Altaparmakov + */ + +#ifndef _LINUX_NTFS_USNJRNL_H +#define _LINUX_NTFS_USNJRNL_H + +#ifdef NTFS_RW + +#include "types.h" +#include "endian.h" +#include "layout.h" +#include "volume.h" + +/* + * Transaction log ($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about transaction logging at this point in time but we still + * need to let windows know that the transaction log is out of date.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 { +/*Ofs*/ +/* 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: http://www.linux-ntfs.org/ + */ +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: + * http://www.linux-ntfs.org/ + */ +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), +}; + +typedef le32 USN_SOURCE_INFO_FLAGS; + +/* + * $DATA/$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 { +/*Ofs*/ +/* 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 + $STANDARD_INFORMATION. */ +/*0x34*/FILE_ATTR_FLAGS file_attributes; /* File attributes copied from + $STANDARD_INFORMATION or $FILE_NAME (not + 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 */ |