+ 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 $Extend.
+ */
+ mutex_lock(&vol->extend_ino->i_mutex);
+ mref = ntfs_lookup_inode_by_name(NTFS_I(vol->extend_ino), UsnJrnl, 8,
+ &name);
+ mutex_unlock(&vol->extend_ino->i_mutex);
+ if (IS_ERR_MREF(mref)) {
+ /*
+ * If the file does not exist, transaction logging is disabled,
+ * just return success.
+ */
+ if (MREF_ERR(mref) == -ENOENT) {
+ ntfs_debug("$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%zx 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;