NTFS: Stamp the transaction log ($UsnJrnl), aka user space journal, if it

      is active on the volume and we are mounting read-write or remounting
      from read-only to read-write.

Signed-off-by: Anton Altaparmakov <aia21@cantab.net>

fs/ntfs/ChangeLog

@@ -1,6 +1,5 @@
 ToDo/Notes:
 	- Find and fix bugs.
-	- Checkpoint or disable the user space journal ($UsnJrnl).
 	- In between ntfs_prepare/commit_write, need exclusion between
 	  simultaneous file extensions.  This is given to us by holding i_sem
 	  on the inode.  The only places in the kernel when a file is resized
@@ -119,6 +118,9 @@ ToDo/Notes:
 	- Use C99 style structure initialization after memory allocation where
 	  possible (fs/ntfs/{attrib.c,index.c,super.c}).  Thanks to Al Viro and
 	  Pekka Enberg.
+	- Stamp the transaction log ($UsnJrnl), aka user space journal, if it
+	  is active on the volume and we are mounting read-write or remounting
+	  from read-only to read-write.
 
 2.1.22 - Many bug and race fixes and error handling improvements.
 

fs/ntfs/Makefile

@@ -15,5 +15,5 @@ endif
 ifeq ($(CONFIG_NTFS_RW),y)
 EXTRA_CFLAGS += -DNTFS_RW
 
-ntfs-objs += bitmap.o lcnalloc.o logfile.o quota.o
+ntfs-objs += bitmap.o lcnalloc.o logfile.o quota.o usnjrnl.o
 endif

fs/ntfs/layout.h

@@ -936,20 +936,12 @@ typedef struct {
 		/* 56*/	le64 quota_charged;	/* Byte size of the charge to
 				the quota for all streams of the file. Note: Is
 				zero if quotas are disabled. */
-		/* 64*/	le64 usn;		/* Last update sequence number
-				of the file. This is a direct index into the
-				change (aka usn) journal file. It is zero if
-				the usn journal is disabled.
-				NOTE: To disable the journal need to delete
-				the journal file itself and to then walk the
-				whole mft and set all Usn entries in all mft
-				records to zero! (This can take a while!)
-				The journal is FILE_Extend/$UsnJrnl. Win2k
-				will recreate the journal and initiate
-				logging if necessary when mounting the
-				partition. This, in contrast to disabling the
-				journal is a very fast process, so the user
-				won't even notice it. */
+		/* 64*/	USN usn;		/* Last update sequence number
+				of the file.  This is a direct index into the
+				transaction log file ($UsnJrnl).  It is zero if
+				the usn journal is disabled or this file has
+				not been subject to logging yet.  See usnjrnl.h
+				for details. */
 		} __attribute__ ((__packed__)) v3;
 	/* sizeof() = 72 bytes (NTFS 3.x) */
 	} __attribute__ ((__packed__)) ver;
@@ -1912,7 +1904,7 @@ enum {
 	VOLUME_FLAGS_MASK		= const_cpu_to_le16(0x803f),
 
 	/* To make our life easier when checking if we must mount read-only. */
-	VOLUME_MUST_MOUNT_RO_MASK	= const_cpu_to_le16(0x8037),
+	VOLUME_MUST_MOUNT_RO_MASK	= const_cpu_to_le16(0x8027),
 } __attribute__ ((__packed__));
 
 typedef le16 VOLUME_FLAGS;

fs/ntfs/super.c

@@ -34,6 +34,7 @@
 #include "sysctl.h"
 #include "logfile.h"
 #include "quota.h"
+#include "usnjrnl.h"
 #include "dir.h"
 #include "debug.h"
 #include "index.h"
@@ -497,6 +498,12 @@ static int ntfs_remount(struct super_block *sb, int *flags, char *opt)
 			NVolSetErrors(vol);
 			return -EROFS;
 		}
+		if (!ntfs_stamp_usnjrnl(vol)) {
+			ntfs_error(sb, "Failed to stamp transation log "
+					"($UsnJrnl)%s", es);
+			NVolSetErrors(vol);
+			return -EROFS;
+		}
 	} else if (!(sb->s_flags & MS_RDONLY) && (*flags & MS_RDONLY)) {
 		/* Remounting read-only. */
 		if (!NVolErrors(vol)) {
@@ -1218,6 +1225,167 @@ static BOOL load_and_init_quota(ntfs_volume *vol)
 	return TRUE;
 }
 
+/**
+ * load_and_init_usnjrnl - load and setup the transaction log if present
+ * @vol:	ntfs super block describing device whose usnjrnl file to load
+ *
+ * Return TRUE on success or FALSE on error.
+ *
+ * If $UsnJrnl is not present or in the process of being disabled, we set
+ * NVolUsnJrnlStamped() and return success.
+ *
+ * If the $UsnJrnl $DATA/$J attribute has a size equal to the lowest valid usn,
+ * i.e. transaction logging has only just been enabled or the journal has been
+ * stamped and nothing has been logged since, we also set NVolUsnJrnlStamped()
+ * and return success.
+ */
+static BOOL load_and_init_usnjrnl(ntfs_volume *vol)
+{
+	MFT_REF mref;
+	struct inode *tmp_ino;
+	ntfs_inode *tmp_ni;
+	struct page *page;
+	ntfs_name *name = NULL;
+	USN_HEADER *uh;
+	static const ntfschar UsnJrnl[9] = { const_cpu_to_le16('$'),
+			const_cpu_to_le16('U'), const_cpu_to_le16('s'),
+			const_cpu_to_le16('n'), const_cpu_to_le16('J'),
+			const_cpu_to_le16('r'), const_cpu_to_le16('n'),
+			const_cpu_to_le16('l'), 0 };
+	static ntfschar Max[5] = { const_cpu_to_le16('$'),
+			const_cpu_to_le16('M'), const_cpu_to_le16('a'),
+			const_cpu_to_le16('x'), 0 };
+	static ntfschar J[3] = { const_cpu_to_le16('$'),
+			const_cpu_to_le16('J'), 0 };
+
+	ntfs_debug("Entering.");
+	/*
+	 * Find the inode number for the transaction log file by looking up the
+	 * filename $UsnJrnl in the extended system files directory $Extend.
+	 */
+	down(&vol->extend_ino->i_sem);
+	mref = ntfs_lookup_inode_by_name(NTFS_I(vol->extend_ino), UsnJrnl, 8,
+			&name);
+	up(&vol->extend_ino->i_sem);
+	if (IS_ERR_MREF(mref)) {
+		/*
+		 * If the file does not exist, transaction logging is disabled,
+		 * just return success.
+		 */
+		if (MREF_ERR(mref) == -ENOENT) {
+			ntfs_debug("$UsnJrnl not present.  Volume does not "
+					"have transaction logging enabled.");
+not_enabled:
+			/*
+			 * No need to try to stamp the transaction log if
+			 * transaction logging is not enabled.
+			 */
+			NVolSetUsnJrnlStamped(vol);
+			return TRUE;
+		}
+		/* A real error occured. */
+		ntfs_error(vol->sb, "Failed to find inode number for "
+				"$UsnJrnl.");
+		return FALSE;
+	}
+	/* We do not care for the type of match that was found. */
+	kfree(name);
+	/* Get the inode. */
+	tmp_ino = ntfs_iget(vol->sb, MREF(mref));
+	if (unlikely(IS_ERR(tmp_ino) || is_bad_inode(tmp_ino))) {
+		if (!IS_ERR(tmp_ino))
+			iput(tmp_ino);
+		ntfs_error(vol->sb, "Failed to load $UsnJrnl.");
+		return FALSE;
+	}
+	vol->usnjrnl_ino = tmp_ino;
+	/*
+	 * If the transaction log is in the process of being deleted, we can
+	 * ignore it.
+	 */
+	if (unlikely(vol->vol_flags & VOLUME_DELETE_USN_UNDERWAY)) {
+		ntfs_debug("$UsnJrnl in the process of being disabled.  "
+				"Volume does not have transaction logging "
+				"enabled.");
+		goto not_enabled;
+	}
+	/* Get the $DATA/$Max attribute. */
+	tmp_ino = ntfs_attr_iget(vol->usnjrnl_ino, AT_DATA, Max, 4);
+	if (IS_ERR(tmp_ino)) {
+		ntfs_error(vol->sb, "Failed to load $UsnJrnl/$DATA/$Max "
+				"attribute.");
+		return FALSE;
+	}
+	vol->usnjrnl_max_ino = tmp_ino;
+	if (unlikely(i_size_read(tmp_ino) < sizeof(USN_HEADER))) {
+		ntfs_error(vol->sb, "Found corrupt $UsnJrnl/$DATA/$Max "
+				"attribute (size is 0x%llx but should be at "
+				"least 0x%x bytes).", i_size_read(tmp_ino),
+				sizeof(USN_HEADER));
+		return FALSE;
+	}
+	/* Get the $DATA/$J attribute. */
+	tmp_ino = ntfs_attr_iget(vol->usnjrnl_ino, AT_DATA, J, 2);
+	if (IS_ERR(tmp_ino)) {
+		ntfs_error(vol->sb, "Failed to load $UsnJrnl/$DATA/$J "
+				"attribute.");
+		return FALSE;
+	}
+	vol->usnjrnl_j_ino = tmp_ino;
+	/* Verify $J is non-resident and sparse. */
+	tmp_ni = NTFS_I(vol->usnjrnl_j_ino);
+	if (unlikely(!NInoNonResident(tmp_ni) || !NInoSparse(tmp_ni))) {
+		ntfs_error(vol->sb, "$UsnJrnl/$DATA/$J attribute is resident "
+				"and/or not sparse.");
+		return FALSE;
+	}
+	/* Read the USN_HEADER from $DATA/$Max. */
+	page = ntfs_map_page(vol->usnjrnl_max_ino->i_mapping, 0);
+	if (IS_ERR(page)) {
+		ntfs_error(vol->sb, "Failed to read from $UsnJrnl/$DATA/$Max "
+				"attribute.");
+		return FALSE;
+	}
+	uh = (USN_HEADER*)page_address(page);
+	/* Sanity check the $Max. */
+	if (unlikely(sle64_to_cpu(uh->allocation_delta) >
+			sle64_to_cpu(uh->maximum_size))) {
+		ntfs_error(vol->sb, "Allocation delta (0x%llx) exceeds "
+				"maximum size (0x%llx).  $UsnJrnl is corrupt.",
+				(long long)sle64_to_cpu(uh->allocation_delta),
+				(long long)sle64_to_cpu(uh->maximum_size));
+		ntfs_unmap_page(page);
+		return FALSE;
+	}
+	/*
+	 * If the transaction log has been stamped and nothing has been written
+	 * to it since, we do not need to stamp it.
+	 */
+	if (unlikely(sle64_to_cpu(uh->lowest_valid_usn) >=
+			i_size_read(vol->usnjrnl_j_ino))) {
+		if (likely(sle64_to_cpu(uh->lowest_valid_usn) ==
+				i_size_read(vol->usnjrnl_j_ino))) {
+			ntfs_unmap_page(page);
+			ntfs_debug("$UsnJrnl is enabled but nothing has been "
+					"logged since it was last stamped.  "
+					"Treating this as if the volume does "
+					"not have transaction logging "
+					"enabled.");
+			goto not_enabled;
+		}
+		ntfs_error(vol->sb, "$UsnJrnl has lowest valid usn (0x%llx) "
+				"which is out of bounds (0x%llx).  $UsnJrnl "
+				"is corrupt.",
+				(long long)sle64_to_cpu(uh->lowest_valid_usn),
+				i_size_read(vol->usnjrnl_j_ino));
+		ntfs_unmap_page(page);
+		return FALSE;
+	}
+	ntfs_unmap_page(page);
+	ntfs_debug("Done.");
+	return TRUE;
+}
+
 /**
  * load_and_init_attrdef - load the attribute definitions table for a volume
  * @vol:	ntfs super block describing device whose attrdef to load
@@ -1653,7 +1821,7 @@ get_ctx_vol_failed:
 		goto iput_logfile_err_out;
 	}
 	/* If on NTFS versions before 3.0, we are done. */
-	if (vol->major_ver < 3)
+	if (unlikely(vol->major_ver < 3))
 		return TRUE;
 	/* NTFS 3.0+ specific initialization. */
 	/* Get the security descriptors inode. */
@@ -1664,7 +1832,7 @@ get_ctx_vol_failed:
 		ntfs_error(sb, "Failed to load $Secure.");
 		goto iput_root_err_out;
 	}
-	// FIXME: Initialize security.
+	// TODO: Initialize security.
 	/* Get the extended system files' directory inode. */
 	vol->extend_ino = ntfs_iget(sb, FILE_Extend);
 	if (IS_ERR(vol->extend_ino) || is_bad_inode(vol->extend_ino)) {
@@ -1715,10 +1883,60 @@ get_ctx_vol_failed:
 		sb->s_flags |= MS_RDONLY | MS_NOATIME | MS_NODIRATIME;
 		NVolSetErrors(vol);
 	}
-	// TODO: Delete or checkpoint the $UsnJrnl if it exists.
+	/*
+	 * Find the transaction log file ($UsnJrnl), load it if present, check
+	 * it, and set it up.
+	 */
+	if (!load_and_init_usnjrnl(vol)) {
+		static const char *es1 = "Failed to load $UsnJrnl";
+		static const char *es2 = ".  Run chkdsk.";
+
+		/* If a read-write mount, convert it to a read-only mount. */
+		if (!(sb->s_flags & MS_RDONLY)) {
+			if (!(vol->on_errors & (ON_ERRORS_REMOUNT_RO |
+					ON_ERRORS_CONTINUE))) {
+				ntfs_error(sb, "%s and neither on_errors="
+						"continue nor on_errors="
+						"remount-ro was specified%s",
+						es1, es2);
+				goto iput_usnjrnl_err_out;
+			}
+			sb->s_flags |= MS_RDONLY | MS_NOATIME | MS_NODIRATIME;
+			ntfs_error(sb, "%s.  Mounting read-only%s", es1, es2);
+		} else
+			ntfs_warning(sb, "%s.  Will not be able to remount "
+					"read-write%s", es1, es2);
+		/* This will prevent a read-write remount. */
+		NVolSetErrors(vol);
+	}
+	/* If (still) a read-write mount, stamp the transaction log. */
+	if (!(sb->s_flags & MS_RDONLY) && !ntfs_stamp_usnjrnl(vol)) {
+		static const char *es1 = "Failed to stamp transaction log "
+				"($UsnJrnl)";
+		static const char *es2 = ".  Run chkdsk.";
+
+		/* Convert to a read-only mount. */
+		if (!(vol->on_errors & (ON_ERRORS_REMOUNT_RO |
+				ON_ERRORS_CONTINUE))) {
+			ntfs_error(sb, "%s and neither on_errors=continue nor "
+					"on_errors=remount-ro was specified%s",
+					es1, es2);
+			goto iput_usnjrnl_err_out;
+		}
+		ntfs_error(sb, "%s.  Mounting read-only%s", es1, es2);
+		sb->s_flags |= MS_RDONLY | MS_NOATIME | MS_NODIRATIME;
+		NVolSetErrors(vol);
+	}
 #endif /* NTFS_RW */
 	return TRUE;
 #ifdef NTFS_RW
+iput_usnjrnl_err_out:
+	if (vol->usnjrnl_j_ino)
+		iput(vol->usnjrnl_j_ino);
+	if (vol->usnjrnl_max_ino)
+		iput(vol->usnjrnl_max_ino);
+	if (vol->usnjrnl_ino)
+		iput(vol->usnjrnl_ino);
 iput_quota_err_out:
 	if (vol->quota_q_ino)
 		iput(vol->quota_q_ino);
@@ -1792,6 +2010,12 @@ static void ntfs_put_super(struct super_block *sb)
 
 	/* NTFS 3.0+ specific. */
 	if (vol->major_ver >= 3) {
+		if (vol->usnjrnl_j_ino)
+			ntfs_commit_inode(vol->usnjrnl_j_ino);
+		if (vol->usnjrnl_max_ino)
+			ntfs_commit_inode(vol->usnjrnl_max_ino);
+		if (vol->usnjrnl_ino)
+			ntfs_commit_inode(vol->usnjrnl_ino);
 		if (vol->quota_q_ino)
 			ntfs_commit_inode(vol->quota_q_ino);
 		if (vol->quota_ino)
@@ -1847,6 +2071,18 @@ static void ntfs_put_super(struct super_block *sb)
 	/* NTFS 3.0+ specific clean up. */
 	if (vol->major_ver >= 3) {
 #ifdef NTFS_RW
+		if (vol->usnjrnl_j_ino) {
+			iput(vol->usnjrnl_j_ino);
+			vol->usnjrnl_j_ino = NULL;
+		}
+		if (vol->usnjrnl_max_ino) {
+			iput(vol->usnjrnl_max_ino);
+			vol->usnjrnl_max_ino = NULL;
+		}
+		if (vol->usnjrnl_ino) {
+			iput(vol->usnjrnl_ino);
+			vol->usnjrnl_ino = NULL;
+		}
 		if (vol->quota_q_ino) {
 			iput(vol->quota_q_ino);
 			vol->quota_q_ino = NULL;
@@ -2463,6 +2699,18 @@ static int ntfs_fill_super(struct super_block *sb, void *opt, const int silent)
 	/* NTFS 3.0+ specific clean up. */
 	if (vol->major_ver >= 3) {
 #ifdef NTFS_RW
+		if (vol->usnjrnl_j_ino) {
+			iput(vol->usnjrnl_j_ino);
+			vol->usnjrnl_j_ino = NULL;
+		}
+		if (vol->usnjrnl_max_ino) {
+			iput(vol->usnjrnl_max_ino);
+			vol->usnjrnl_max_ino = NULL;
+		}
+		if (vol->usnjrnl_ino) {
+			iput(vol->usnjrnl_ino);
+			vol->usnjrnl_ino = NULL;
+		}
 		if (vol->quota_q_ino) {
 			iput(vol->quota_q_ino);
 			vol->quota_q_ino = NULL;

fs/ntfs/types.h

@@ -2,7 +2,7 @@
  * types.h - Defines for NTFS Linux kernel driver specific types.
  *	     Part of the Linux-NTFS project.
  *
- * Copyright (c) 2001-2004 Anton Altaparmakov
+ * Copyright (c) 2001-2005 Anton Altaparmakov
  *
  * This program/include file is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License as published
@@ -53,6 +53,14 @@ typedef sle64 leLCN;
 typedef s64 LSN;
 typedef sle64 leLSN;
 
+/*
+ * The NTFS transaction log $UsnJrnl uses usn which are signed 64-bit values.
+ * We define our own type USN, to allow for type checking and better code
+ * readability.
+ */
+typedef s64 USN;
+typedef sle64 leUSN;
+
 typedef enum {
 	FALSE = 0,
 	TRUE = 1

fs/ntfs/usnjrnl.c

@@ -0,0 +1,84 @@
+/*
+ * usnjrnl.h - NTFS kernel transaction log ($UsnJrnl) handling.  Part of the
+ *	       Linux-NTFS project.
+ *
+ * Copyright (c) 2005 Anton Altaparmakov
+ *
+ * This program/include file is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as published
+ * by the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program/include file is distributed in the hope that it will be
+ * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program (in the main directory of the Linux-NTFS
+ * distribution in the file COPYING); if not, write to the Free Software
+ * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#ifdef NTFS_RW
+
+#include <linux/fs.h>
+#include <linux/highmem.h>
+#include <linux/mm.h>
+
+#include "aops.h"
+#include "debug.h"
+#include "endian.h"
+#include "time.h"
+#include "types.h"
+#include "usnjrnl.h"
+#include "volume.h"
+
+/**
+ * ntfs_stamp_usnjrnl - stamp the transaction log ($UsnJrnl) on an ntfs volume
+ * @vol:	ntfs volume on which to stamp the transaction log
+ *
+ * Stamp the transaction log ($UsnJrnl) on the ntfs volume @vol and return
+ * TRUE on success and FALSE on error.
+ *
+ * This function assumes that the transaction log has already been loaded and
+ * consistency checked by a call to fs/ntfs/super.c::load_and_init_usnjrnl().
+ */
+BOOL ntfs_stamp_usnjrnl(ntfs_volume *vol)
+{
+	ntfs_debug("Entering.");
+	if (likely(!NVolUsnJrnlStamped(vol))) {
+		sle64 stamp;
+		struct page *page;
+		USN_HEADER *uh;
+
+		page = ntfs_map_page(vol->usnjrnl_max_ino->i_mapping, 0);
+		if (IS_ERR(page)) {
+			ntfs_error(vol->sb, "Failed to read from "
+					"$UsnJrnl/$DATA/$Max attribute.");
+			return FALSE;
+		}
+		uh = (USN_HEADER*)page_address(page);
+		stamp = get_current_ntfs_time();
+		ntfs_debug("Stamping transaction log ($UsnJrnl): old "
+				"journal_id 0x%llx, old lowest_valid_usn "
+				"0x%llx, new journal_id 0x%llx, new "
+				"lowest_valid_usn 0x%llx.",
+				(long long)sle64_to_cpu(uh->journal_id),
+				(long long)sle64_to_cpu(uh->lowest_valid_usn),
+				(long long)sle64_to_cpu(stamp),
+				i_size_read(vol->usnjrnl_j_ino));
+		uh->lowest_valid_usn =
+				cpu_to_sle64(i_size_read(vol->usnjrnl_j_ino));
+		uh->journal_id = stamp;
+		flush_dcache_page(page);
+		set_page_dirty(page);
+		ntfs_unmap_page(page);
+		/* Set the flag so we do not have to do it again on remount. */
+		NVolSetUsnJrnlStamped(vol);
+	}
+	ntfs_debug("Done.");
+	return TRUE;
+}
+
+#endif /* NTFS_RW */

fs/ntfs/usnjrnl.h

@@ -0,0 +1,205 @@
+/*
+ * usnjrnl.h - Defines for NTFS kernel transaction log ($UsnJrnl) handling.
+ *	       Part of the Linux-NTFS project.
+ *
+ * Copyright (c) 2005 Anton Altaparmakov
+ *
+ * This program/include file is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as published
+ * by the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program/include file is distributed in the hope that it will be
+ * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program (in the main directory of the Linux-NTFS
+ * distribution in the file COPYING); if not, write to the Free Software
+ * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#ifndef _LINUX_NTFS_USNJRNL_H
+#define _LINUX_NTFS_USNJRNL_H
+
+#ifdef NTFS_RW
+
+#include "types.h"
+#include "endian.h"
+#include "layout.h"
+#include "volume.h"
+
+/*
+ * Transaction log ($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://linux-ntfs.sourceforge.net/ntfs/files/usnjrnl.html
+ */
+enum {
+	USN_REASON_DATA_OVERWRITE	= const_cpu_to_le32(0x00000001),
+	USN_REASON_DATA_EXTEND		= const_cpu_to_le32(0x00000002),
+	USN_REASON_DATA_TRUNCATION	= const_cpu_to_le32(0x00000004),
+	USN_REASON_NAMED_DATA_OVERWRITE	= const_cpu_to_le32(0x00000010),
+	USN_REASON_NAMED_DATA_EXTEND	= const_cpu_to_le32(0x00000020),
+	USN_REASON_NAMED_DATA_TRUNCATION= const_cpu_to_le32(0x00000040),
+	USN_REASON_FILE_CREATE		= const_cpu_to_le32(0x00000100),
+	USN_REASON_FILE_DELETE		= const_cpu_to_le32(0x00000200),
+	USN_REASON_EA_CHANGE		= const_cpu_to_le32(0x00000400),
+	USN_REASON_SECURITY_CHANGE	= const_cpu_to_le32(0x00000800),
+	USN_REASON_RENAME_OLD_NAME	= const_cpu_to_le32(0x00001000),
+	USN_REASON_RENAME_NEW_NAME	= const_cpu_to_le32(0x00002000),
+	USN_REASON_INDEXABLE_CHANGE	= const_cpu_to_le32(0x00004000),
+	USN_REASON_BASIC_INFO_CHANGE	= const_cpu_to_le32(0x00008000),
+	USN_REASON_HARD_LINK_CHANGE	= const_cpu_to_le32(0x00010000),
+	USN_REASON_COMPRESSION_CHANGE	= const_cpu_to_le32(0x00020000),
+	USN_REASON_ENCRYPTION_CHANGE	= const_cpu_to_le32(0x00040000),
+	USN_REASON_OBJECT_ID_CHANGE	= const_cpu_to_le32(0x00080000),
+	USN_REASON_REPARSE_POINT_CHANGE	= const_cpu_to_le32(0x00100000),
+	USN_REASON_STREAM_CHANGE	= const_cpu_to_le32(0x00200000),
+	USN_REASON_CLOSE		= const_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://linux-ntfs.sourceforge.net/ntfs/files/usnjrnl.html
+ */
+enum {
+	USN_SOURCE_DATA_MANAGEMENT	  = const_cpu_to_le32(0x00000001),
+	USN_SOURCE_AUXILIARY_DATA	  = const_cpu_to_le32(0x00000002),
+	USN_SOURCE_REPLICATION_MANAGEMENT = const_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 */

fs/ntfs/volume.h

@@ -125,6 +125,10 @@ typedef struct {
 	/* $Quota stuff is NTFS3.0+ specific.  Unused/NULL otherwise. */
 	struct inode *quota_ino;	/* The VFS inode of $Quota. */
 	struct inode *quota_q_ino;	/* Attribute inode for $Quota/$Q. */
+	/* $UsnJrnl stuff is NTFS3.0+ specific.  Unused/NULL otherwise. */
+	struct inode *usnjrnl_ino;	/* The VFS inode of $UsnJrnl. */
+	struct inode *usnjrnl_max_ino;	/* Attribute inode for $UsnJrnl/$Max. */
+	struct inode *usnjrnl_j_ino;	/* Attribute inode for $UsnJrnl/$J. */
 #endif /* NTFS_RW */
 	struct nls_table *nls_map;
 } ntfs_volume;
@@ -141,6 +145,7 @@ typedef enum {
 				      file names in WIN32 namespace. */
 	NV_LogFileEmpty,	/* 1: $LogFile journal is empty. */
 	NV_QuotaOutOfDate,	/* 1: $Quota is out of date. */
+	NV_UsnJrnlStamped,	/* 1: $UsnJrnl has been stamped. */
 	NV_SparseEnabled,	/* 1: May create sparse files. */
 } ntfs_volume_flags;
 
@@ -168,6 +173,7 @@ NVOL_FNS(ShowSystemFiles)
 NVOL_FNS(CaseSensitive)
 NVOL_FNS(LogFileEmpty)
 NVOL_FNS(QuotaOutOfDate)
+NVOL_FNS(UsnJrnlStamped)
 NVOL_FNS(SparseEnabled)
 
 #endif /* _LINUX_NTFS_VOLUME_H */