]> wimlib.net Git - wimlib/blobdiff - src/dentry.c
dentry.c: A couple small optimizations
[wimlib] / src / dentry.c
index 19e4199f76412797c8bda735ad97c22a942a129b..ff4df8be41dce328d7eac452b049c943feee7979 100644 (file)
@@ -9,7 +9,7 @@
  */
 
 /*
- * Copyright (C) 2012, 2013 Eric Biggers
+ * Copyright (C) 2012, 2013, 2014 Eric Biggers
  *
  * This file is part of wimlib, a library for working with WIM files.
  *
@@ -301,93 +301,39 @@ dentry_in_total_length(const struct wim_dentry *dentry)
        return (length + 7) & ~7;
 }
 
-int
-for_dentry_in_rbtree(struct rb_node *root,
-                    int (*visitor)(struct wim_dentry *, void *),
-                    void *arg)
-{
-       int ret;
-       struct rb_node *node = root;
-       LIST_HEAD(stack);
-       while (1) {
-               if (node) {
-                       list_add(&rbnode_dentry(node)->tmp_list, &stack);
-                       node = node->rb_left;
-               } else {
-                       struct list_head *next;
-                       struct wim_dentry *dentry;
-
-                       next = stack.next;
-                       if (next == &stack)
-                               return 0;
-                       dentry = container_of(next, struct wim_dentry, tmp_list);
-                       list_del(next);
-                       ret = visitor(dentry, arg);
-                       if (ret != 0)
-                               return ret;
-                       node = dentry->rb_node.rb_right;
-               }
-       }
-}
-
 static int
-for_dentry_tree_in_rbtree_depth(struct rb_node *node,
-                               int (*visitor)(struct wim_dentry*, void*),
-                               void *arg)
+do_for_dentry_in_tree(struct wim_dentry *dentry,
+                     int (*visitor)(struct wim_dentry *, void *), void *arg)
 {
        int ret;
-       if (node) {
-               ret = for_dentry_tree_in_rbtree_depth(node->rb_left,
-                                                     visitor, arg);
-               if (ret != 0)
-                       return ret;
-               ret = for_dentry_tree_in_rbtree_depth(node->rb_right,
-                                                     visitor, arg);
-               if (ret != 0)
-                       return ret;
-               ret = for_dentry_in_tree_depth(rbnode_dentry(node), visitor, arg);
-               if (ret != 0)
+       struct wim_dentry *child;
+
+       ret = (*visitor)(dentry, arg);
+       if (unlikely(ret))
+               return ret;
+
+       for_dentry_child(child, dentry) {
+               ret = do_for_dentry_in_tree(child, visitor, arg);
+               if (unlikely(ret))
                        return ret;
        }
        return 0;
 }
 
+
 static int
-for_dentry_tree_in_rbtree(struct rb_node *node,
-                         int (*visitor)(struct wim_dentry*, void*),
-                         void *arg)
+do_for_dentry_in_tree_depth(struct wim_dentry *dentry,
+                           int (*visitor)(struct wim_dentry *, void *), void *arg)
 {
        int ret;
-       if (node) {
-               ret = for_dentry_tree_in_rbtree(node->rb_left, visitor, arg);
-               if (ret)
-                       return ret;
-               ret = for_dentry_in_tree(rbnode_dentry(node), visitor, arg);
-               if (ret)
-                       return ret;
-               ret = for_dentry_tree_in_rbtree(node->rb_right, visitor, arg);
-               if (ret)
+       struct wim_dentry *child;
+
+       for_dentry_child_postorder(child, dentry) {
+               ret = do_for_dentry_in_tree_depth(child, visitor, arg);
+               if (unlikely(ret))
                        return ret;
        }
-       return 0;
-}
-
-/*
- * Iterate over all children of @dentry, calling the function @visitor, passing
- * it a child dentry and the extra argument @arg.
- *
- * Note: this function iterates over ALL child dentries, even those with the
- * same case-insensitive name.
- *
- * Note: this function clobbers the tmp_list field of the child dentries.  */
-int
-for_dentry_child(const struct wim_dentry *dentry,
-                int (*visitor)(struct wim_dentry *, void *),
-                void *arg)
-{
-       return for_dentry_in_rbtree(dentry->d_inode->i_children.rb_node,
-                                   visitor,
-                                   arg);
+       return unlikely((*visitor)(dentry, arg));
 }
 
 /* Calls a function on all directory entries in a WIM dentry tree.  Logically,
@@ -396,35 +342,22 @@ for_dentry_child(const struct wim_dentry *dentry,
  * */
 int
 for_dentry_in_tree(struct wim_dentry *root,
-                  int (*visitor)(struct wim_dentry*, void*), void *arg)
+                  int (*visitor)(struct wim_dentry *, void *), void *arg)
 {
-       int ret;
-
-       if (root == NULL)
+       if (unlikely(!root))
                return 0;
-       ret = (*visitor)(root, arg);
-       if (ret)
-               return ret;
-       return for_dentry_tree_in_rbtree(root->d_inode->i_children.rb_node,
-                                        visitor,
-                                        arg);
+       return do_for_dentry_in_tree(root, visitor, arg);
 }
 
 /* Like for_dentry_in_tree(), but the visitor function is always called on a
  * dentry's children before on itself. */
 int
 for_dentry_in_tree_depth(struct wim_dentry *root,
-                        int (*visitor)(struct wim_dentry*, void*), void *arg)
+                        int (*visitor)(struct wim_dentry *, void *), void *arg)
 {
-       int ret;
-
-       if (root == NULL)
+       if (unlikely(!root))
                return 0;
-       ret = for_dentry_tree_in_rbtree_depth(root->d_inode->i_children.rb_node,
-                                             visitor, arg);
-       if (ret)
-               return ret;
-       return (*visitor)(root, arg);
+       return do_for_dentry_in_tree_depth(root, visitor, arg);
 }
 
 /* Calculate the full path of @dentry.  The full path of its parent must have
@@ -522,55 +455,39 @@ dentry_full_path(struct wim_dentry *dentry)
 }
 
 static int
-increment_subdir_offset(struct wim_dentry *dentry, void *subdir_offset_p)
+dentry_calculate_subdir_offset(struct wim_dentry *dentry, void *_subdir_offset_p)
 {
-       *(u64*)subdir_offset_p += dentry_out_total_length(dentry);
-       return 0;
-}
 
-static int
-call_calculate_subdir_offsets(struct wim_dentry *dentry, void *subdir_offset_p)
-{
-       calculate_subdir_offsets(dentry, subdir_offset_p);
+       if (dentry_is_directory(dentry)) {
+               u64 *subdir_offset_p = _subdir_offset_p;
+               struct wim_dentry *child;
+
+               /* Set offset of directory's child dentries  */
+               dentry->subdir_offset = *subdir_offset_p;
+
+               /* Account for child dentries  */
+               for_dentry_child(child, dentry)
+                       *subdir_offset_p += dentry_out_total_length(child);
+
+               /* Account for end-of-directory entry  */
+               *subdir_offset_p += 8;
+       } else {
+               /* Not a directory; set subdir_offset to 0  */
+               dentry->subdir_offset = 0;
+       }
        return 0;
 }
 
 /*
- * Recursively calculates the subdir offsets for a directory tree.
- *
- * @dentry:  The root of the directory tree.
- * @subdir_offset_p:  The current subdirectory offset; i.e., the subdirectory
- *                   offset for @dentry.
+ * Calculates the subdir offsets for a directory tree.
  */
 void
-calculate_subdir_offsets(struct wim_dentry *dentry, u64 *subdir_offset_p)
+calculate_subdir_offsets(struct wim_dentry *root, u64 *subdir_offset_p)
 {
-       struct rb_node *node;
-
-       dentry->subdir_offset = *subdir_offset_p;
-       node = dentry->d_inode->i_children.rb_node;
-       if (node) {
-               /* Advance the subdir offset by the amount of space the children
-                * of this dentry take up. */
-               for_dentry_in_rbtree(node, increment_subdir_offset, subdir_offset_p);
-
-               /* End-of-directory dentry on disk. */
-               *subdir_offset_p += 8;
-
-               /* Recursively call calculate_subdir_offsets() on all the
-                * children. */
-               for_dentry_in_rbtree(node, call_calculate_subdir_offsets, subdir_offset_p);
-       } else {
-               /* On disk, childless directories have a valid subdir_offset
-                * that points to an 8-byte end-of-directory dentry.  Regular
-                * files or reparse points have a subdir_offset of 0. */
-               if (dentry_is_directory(dentry))
-                       *subdir_offset_p += 8;
-               else
-                       dentry->subdir_offset = 0;
-       }
+       for_dentry_in_tree(root, dentry_calculate_subdir_offset, subdir_offset_p);
 }
 
+/* Compare the UTF-16LE long filenames of two dentries case insensitively.  */
 static int
 dentry_compare_names_case_insensitive(const struct wim_dentry *d1,
                                      const struct wim_dentry *d2)
@@ -582,6 +499,7 @@ dentry_compare_names_case_insensitive(const struct wim_dentry *d1,
                                   true);
 }
 
+/* Compare the UTF-16LE long filenames of two dentries case sensitively.  */
 static int
 dentry_compare_names_case_sensitive(const struct wim_dentry *d1,
                                    const struct wim_dentry *d2)
@@ -593,6 +511,28 @@ dentry_compare_names_case_sensitive(const struct wim_dentry *d1,
                                   false);
 }
 
+static int
+_avl_dentry_compare_names_ci(const struct avl_tree_node *n1,
+                            const struct avl_tree_node *n2)
+{
+       const struct wim_dentry *d1, *d2;
+
+       d1 = avl_tree_entry(n1, struct wim_dentry, d_index_node_ci);
+       d2 = avl_tree_entry(n2, struct wim_dentry, d_index_node_ci);
+       return dentry_compare_names_case_insensitive(d1, d2);
+}
+
+static int
+_avl_dentry_compare_names(const struct avl_tree_node *n1,
+                         const struct avl_tree_node *n2)
+{
+       const struct wim_dentry *d1, *d2;
+
+       d1 = avl_tree_entry(n1, struct wim_dentry, d_index_node);
+       d2 = avl_tree_entry(n2, struct wim_dentry, d_index_node);
+       return dentry_compare_names_case_sensitive(d1, d2);
+}
+
 /* Default case sensitivity behavior for searches with
  * WIMLIB_CASE_PLATFORM_DEFAULT specified.  This can be modified by
  * wimlib_global_init().  */
@@ -604,6 +544,36 @@ bool default_ignore_case =
 #endif
 ;
 
+/* Case-sensitive dentry lookup.  Only @file_name and @file_name_nbytes of
+ * @dummy must be valid.  */
+static struct wim_dentry *
+dir_lookup(const struct wim_inode *dir, const struct wim_dentry *dummy)
+{
+       struct avl_tree_node *node;
+
+       node = avl_tree_lookup_node(dir->i_children,
+                                   &dummy->d_index_node,
+                                   _avl_dentry_compare_names);
+       if (!node)
+               return NULL;
+       return avl_tree_entry(node, struct wim_dentry, d_index_node);
+}
+
+/* Case-insensitive dentry lookup.  Only @file_name and @file_name_nbytes of
+ * @dummy must be valid.  */
+static struct wim_dentry *
+dir_lookup_ci(const struct wim_inode *dir, const struct wim_dentry *dummy)
+{
+       struct avl_tree_node *node;
+
+       node = avl_tree_lookup_node(dir->i_children_ci,
+                                   &dummy->d_index_node_ci,
+                                   _avl_dentry_compare_names_ci);
+       if (!node)
+               return NULL;
+       return avl_tree_entry(node, struct wim_dentry, d_index_node_ci);
+}
+
 /* Given a UTF-16LE filename and a directory, look up the dentry for the file.
  * Return it if found, otherwise NULL.  This is case-sensitive on UNIX and
  * case-insensitive on Windows. */
@@ -613,68 +583,52 @@ get_dentry_child_with_utf16le_name(const struct wim_dentry *dentry,
                                   size_t name_nbytes,
                                   CASE_SENSITIVITY_TYPE case_ctype)
 {
-       struct rb_node *node;
-
+       const struct wim_inode *dir = dentry->d_inode;
        bool ignore_case = will_ignore_case(case_ctype);
+       struct wim_dentry dummy;
+       struct wim_dentry *child;
 
-       if (ignore_case)
-               node = dentry->d_inode->i_children_case_insensitive.rb_node;
-       else
-               node = dentry->d_inode->i_children.rb_node;
+       dummy.file_name = (utf16lechar*)name;
+       dummy.file_name_nbytes = name_nbytes;
 
-       struct wim_dentry *child;
-       while (node) {
-               if (ignore_case)
-                       child = rb_entry(node, struct wim_dentry, rb_node_case_insensitive);
-               else
-                       child = rb_entry(node, struct wim_dentry, rb_node);
-
-               int result = cmp_utf16le_strings(name,
-                                                name_nbytes / 2,
-                                                child->file_name,
-                                                child->file_name_nbytes / 2,
-                                                ignore_case);
-               if (result < 0) {
-                       node = node->rb_left;
-               } else if (result > 0) {
-                       node = node->rb_right;
-               } else if (!ignore_case ||
-                       list_empty(&child->case_insensitive_conflict_list)) {
-                       return child;
-               } else {
-                       /* Multiple dentries have the same case-insensitive
-                        * name, and a case-insensitive lookup is being
-                        * performed.  Choose the dentry with the same
-                        * case-sensitive name, if one exists; otherwise print a
-                        * warning and choose one arbitrarily.  */
-                       struct wim_dentry *alt = child;
-                       size_t num_alts = 0;
-
-                       do {
-                               num_alts++;
-                               if (0 == cmp_utf16le_strings(name,
-                                                            name_nbytes / 2,
-                                                            alt->file_name,
-                                                            alt->file_name_nbytes / 2,
-                                                            false))
-                                       return alt;
-                               alt = list_entry(alt->case_insensitive_conflict_list.next,
-                                                struct wim_dentry,
-                                                case_insensitive_conflict_list);
-                       } while (alt != child);
-
-                       WARNING("Result of case-insensitive lookup is ambiguous\n"
-                               "          (returning \"%"TS"\" of %zu "
-                               "possible files, including \"%"TS"\")",
-                               dentry_full_path(child),
-                               num_alts,
-                               dentry_full_path(list_entry(child->case_insensitive_conflict_list.next,
-                                                           struct wim_dentry,
-                                                           case_insensitive_conflict_list)));
-                       return child;
-               }
-       }
-       return NULL;
+       if (!ignore_case)
+               /* Case-sensitive lookup.  */
+               return dir_lookup(dir, &dummy);
+
+       /* Case-insensitive lookup.  */
+
+       child = dir_lookup_ci(dir, &dummy);
+       if (!child)
+               return NULL;
+
+       if (likely(list_empty(&child->d_ci_conflict_list)))
+               /* Only one dentry has this case-insensitive name; return it */
+               return child;
+
+       /* Multiple dentries have the same case-insensitive name.  Choose the
+        * dentry with the same case-sensitive name, if one exists; otherwise
+        * print a warning and choose one of the possible dentries arbitrarily.
+        */
+       struct wim_dentry *alt = child;
+       size_t num_alts = 0;
+
+       do {
+               num_alts++;
+               if (!dentry_compare_names_case_sensitive(&dummy, alt))
+                       return alt;
+               alt = list_entry(alt->d_ci_conflict_list.next,
+                                struct wim_dentry, d_ci_conflict_list);
+       } while (alt != child);
+
+       WARNING("Result of case-insensitive lookup is ambiguous\n"
+               "          (returning \"%"TS"\" of %zu "
+               "possible files, including \"%"TS"\")",
+               dentry_full_path(child),
+               num_alts,
+               dentry_full_path(list_entry(child->d_ci_conflict_list.next,
+                                           struct wim_dentry,
+                                           d_ci_conflict_list)));
+       return child;
 }
 
 /* Returns the child of @dentry that has the file name @name.  Returns NULL if
@@ -1087,40 +1041,58 @@ free_dentry_tree(struct wim_dentry *root, struct wim_lookup_table *lookup_table)
        for_dentry_in_tree_depth(root, do_free_dentry, lookup_table);
 }
 
-/* Insert a dentry into the case insensitive index for a directory.
- *
- * This is a red-black tree, but when multiple dentries share the same
- * case-insensitive name, only one is inserted into the tree itself; the rest
- * are connected in a list.
- */
+/* Insert the @child dentry into the case sensitive index of the @dir directory.
+ * Return NULL if successfully inserted, otherwise a pointer to the
+ * already-inserted duplicate.  */
 static struct wim_dentry *
-dentry_add_child_case_insensitive(struct wim_dentry *parent,
-                                 struct wim_dentry *child)
+dir_index_child(struct wim_inode *dir, struct wim_dentry *child)
 {
-       struct rb_root *root;
-       struct rb_node **new;
-       struct rb_node *rb_parent;
-
-       root = &parent->d_inode->i_children_case_insensitive;
-       new = &root->rb_node;
-       rb_parent = NULL;
-       while (*new) {
-               struct wim_dentry *this = container_of(*new, struct wim_dentry,
-                                                      rb_node_case_insensitive);
-               int result = dentry_compare_names_case_insensitive(child, this);
-
-               rb_parent = *new;
-
-               if (result < 0)
-                       new = &((*new)->rb_left);
-               else if (result > 0)
-                       new = &((*new)->rb_right);
-               else
-                       return this;
-       }
-       rb_link_node(&child->rb_node_case_insensitive, rb_parent, new);
-       rb_insert_color(&child->rb_node_case_insensitive, root);
-       return NULL;
+       struct avl_tree_node *duplicate;
+
+       duplicate = avl_tree_insert(&dir->i_children,
+                                   &child->d_index_node,
+                                   _avl_dentry_compare_names);
+       if (!duplicate)
+               return NULL;
+       return avl_tree_entry(duplicate, struct wim_dentry, d_index_node);
+}
+
+/* Insert the @child dentry into the case insensitive index of the @dir
+ * directory.  Return NULL if successfully inserted, otherwise a pointer to the
+ * already-inserted duplicate.  */
+static struct wim_dentry *
+dir_index_child_ci(struct wim_inode *dir, struct wim_dentry *child)
+{
+       struct avl_tree_node *duplicate;
+
+       duplicate = avl_tree_insert(&dir->i_children_ci,
+                                   &child->d_index_node_ci,
+                                   _avl_dentry_compare_names_ci);
+       if (!duplicate)
+               return NULL;
+       return avl_tree_entry(duplicate, struct wim_dentry, d_index_node_ci);
+}
+
+/* Removes the specified dentry from its directory's case-sensitive index.  */
+static void
+dir_unindex_child(struct wim_inode *dir, struct wim_dentry *child)
+{
+       avl_tree_remove(&dir->i_children, &child->d_index_node);
+}
+
+/* Removes the specified dentry from its directory's case-insensitive index.  */
+static void
+dir_unindex_child_ci(struct wim_inode *dir, struct wim_dentry *child)
+{
+       avl_tree_remove(&dir->i_children_ci, &child->d_index_node_ci);
+}
+
+/* Returns true iff the specified dentry is in its parent directory's
+ * case-insensitive index.  */
+static bool
+dentry_in_ci_index(const struct wim_dentry *dentry)
+{
+       return !avl_tree_node_is_unlinked(&dentry->d_index_node_ci);
 }
 
 /*
@@ -1130,84 +1102,67 @@ dentry_add_child_case_insensitive(struct wim_dentry *parent,
  * @child: The dentry to link.
  *
  * Returns NULL if successful.  If @parent already contains a dentry with the
- * same case-sensitive name as @child, the pointer to this duplicate dentry is
- * returned.
+ * same case-sensitive name as @child, returns a pointer to this duplicate
+ * dentry.
  */
 struct wim_dentry *
-dentry_add_child(struct wim_dentry * restrict parent,
-                struct wim_dentry * restrict child)
+dentry_add_child(struct wim_dentry *parent, struct wim_dentry *child)
 {
-       struct rb_root *root;
-       struct rb_node **new;
-       struct rb_node *rb_parent;
+       struct wim_dentry *duplicate;
+       struct wim_inode *dir;
 
-       wimlib_assert(dentry_is_directory(parent));
        wimlib_assert(parent != child);
 
-       /* Case sensitive child dentry index */
-       root = &parent->d_inode->i_children;
-       new = &root->rb_node;
-       rb_parent = NULL;
-       while (*new) {
-               struct wim_dentry *this = rbnode_dentry(*new);
-               int result = dentry_compare_names_case_sensitive(child, this);
-
-               rb_parent = *new;
-
-               if (result < 0)
-                       new = &((*new)->rb_left);
-               else if (result > 0)
-                       new = &((*new)->rb_right);
-               else
-                       return this;
-       }
-       child->parent = parent;
-       rb_link_node(&child->rb_node, rb_parent, new);
-       rb_insert_color(&child->rb_node, root);
+       dir = parent->d_inode;
 
-       /* Case insensitive child dentry index */
-       {
-               struct wim_dentry *existing;
-               existing = dentry_add_child_case_insensitive(parent, child);
-               if (existing) {
-                       list_add(&child->case_insensitive_conflict_list,
-                                &existing->case_insensitive_conflict_list);
-                       child->rb_node_case_insensitive.__rb_parent_color = 0;
-               } else {
-                       INIT_LIST_HEAD(&child->case_insensitive_conflict_list);
-               }
+       wimlib_assert(inode_is_directory(dir));
+
+       duplicate = dir_index_child(dir, child);
+       if (duplicate)
+               return duplicate;
+
+       duplicate = dir_index_child_ci(dir, child);
+       if (duplicate) {
+               list_add(&child->d_ci_conflict_list, &duplicate->d_ci_conflict_list);
+               avl_tree_node_set_unlinked(&child->d_index_node_ci);
+       } else {
+               INIT_LIST_HEAD(&child->d_ci_conflict_list);
        }
+       child->parent = parent;
        return NULL;
 }
 
-/* Unlink a WIM dentry from the directory entry tree. */
+/* Unlink a WIM dentry from the directory entry tree.  */
 void
 unlink_dentry(struct wim_dentry *dentry)
 {
-       struct wim_dentry *parent = dentry->parent;
+       struct wim_inode *dir;
 
-       if (parent == dentry)
+       if (dentry_is_root(dentry))
                return;
-       rb_erase(&dentry->rb_node, &parent->d_inode->i_children);
 
-       if (dentry->rb_node_case_insensitive.__rb_parent_color) {
-               /* This dentry was in the case-insensitive red-black tree. */
-               rb_erase(&dentry->rb_node_case_insensitive,
-                        &parent->d_inode->i_children_case_insensitive);
-               if (!list_empty(&dentry->case_insensitive_conflict_list)) {
+       dir = dentry->parent->d_inode;
+
+       dir_unindex_child(dir, dentry);
+
+       if (dentry_in_ci_index(dentry)) {
+
+               dir_unindex_child_ci(dir, dentry);
+
+               if (!list_empty(&dentry->d_ci_conflict_list)) {
                        /* Make a different case-insensitively-the-same dentry
-                        * be the "representative" in the red-black tree. */
+                        * be the "representative" in the search index. */
                        struct list_head *next;
                        struct wim_dentry *other;
                        struct wim_dentry *existing;
 
-                       next = dentry->case_insensitive_conflict_list.next;
-                       other = list_entry(next, struct wim_dentry, case_insensitive_conflict_list);
-                       existing = dentry_add_child_case_insensitive(parent, other);
+                       next = dentry->d_ci_conflict_list.next;
+                       other = list_entry(next, struct wim_dentry, d_ci_conflict_list);
+                       existing = dir_index_child_ci(dir, other);
                        wimlib_assert(existing == NULL);
                }
        }
-       list_del(&dentry->case_insensitive_conflict_list);
+       list_del(&dentry->d_ci_conflict_list);
 }
 
 static int
@@ -1357,8 +1312,6 @@ read_dentry(const u8 * restrict buf, size_t buf_len,
        inode->i_attributes = le32_to_cpu(disk_dentry->attributes);
        inode->i_security_id = le32_to_cpu(disk_dentry->security_id);
        dentry->subdir_offset = le64_to_cpu(disk_dentry->subdir_offset);
-       dentry->d_unused_1 = le64_to_cpu(disk_dentry->unused_1);
-       dentry->d_unused_2 = le64_to_cpu(disk_dentry->unused_2);
        inode->i_creation_time = le64_to_cpu(disk_dentry->creation_time);
        inode->i_last_access_time = le64_to_cpu(disk_dentry->last_access_time);
        inode->i_last_write_time = le64_to_cpu(disk_dentry->last_write_time);
@@ -1728,8 +1681,8 @@ write_dentry(const struct wim_dentry * restrict dentry, u8 * restrict p)
        disk_dentry->attributes = cpu_to_le32(inode->i_attributes);
        disk_dentry->security_id = cpu_to_le32(inode->i_security_id);
        disk_dentry->subdir_offset = cpu_to_le64(dentry->subdir_offset);
-       disk_dentry->unused_1 = cpu_to_le64(dentry->d_unused_1);
-       disk_dentry->unused_2 = cpu_to_le64(dentry->d_unused_2);
+       disk_dentry->unused_1 = cpu_to_le64(0);
+       disk_dentry->unused_2 = cpu_to_le64(0);
        disk_dentry->creation_time = cpu_to_le64(inode->i_creation_time);
        disk_dentry->last_access_time = cpu_to_le64(inode->i_last_access_time);
        disk_dentry->last_write_time = cpu_to_le64(inode->i_last_write_time);
@@ -1790,50 +1743,25 @@ write_dentry(const struct wim_dentry * restrict dentry, u8 * restrict p)
 }
 
 static int
-write_dentry_cb(struct wim_dentry *dentry, void *_p)
+write_dir_dentries(struct wim_dentry *dir, void *_pp)
 {
-       u8 **p = _p;
-       *p = write_dentry(dentry, *p);
-       return 0;
-}
+       if (dir->subdir_offset != 0) {
+               u8 **pp = _pp;
+               u8 *p = *pp;
+               struct wim_dentry *child;
 
-static u8 *
-write_dentry_tree_recursive(const struct wim_dentry *parent, u8 *p);
+               /* write child dentries */
+               for_dentry_child(child, dir)
+                       p = write_dentry(child, p);
 
-static int
-write_dentry_tree_recursive_cb(struct wim_dentry *dentry, void *_p)
-{
-       u8 **p = _p;
-       *p = write_dentry_tree_recursive(dentry, *p);
+               /* write end of directory entry */
+               *(u64*)p = 0;
+               p += 8;
+               *pp = p;
+       }
        return 0;
 }
 
-/* Recursive function that writes a dentry tree rooted at @parent, not including
- * @parent itself, which has already been written. */
-static u8 *
-write_dentry_tree_recursive(const struct wim_dentry *parent, u8 *p)
-{
-       /* Nothing to do if this dentry has no children. */
-       if (parent->subdir_offset == 0)
-               return p;
-
-       /* Write child dentries and end-of-directory entry.
-        *
-        * Note: we need to write all of this dentry's children before
-        * recursively writing the directory trees rooted at each of the child
-        * dentries, since the on-disk dentries for a dentry's children are
-        * always located at consecutive positions in the metadata resource! */
-       for_dentry_child(parent, write_dentry_cb, &p);
-
-       /* write end of directory entry */
-       *(le64*)p = cpu_to_le64(0);
-       p += 8;
-
-       /* Recurse on children. */
-       for_dentry_child(parent, write_dentry_tree_recursive_cb, &p);
-       return p;
-}
-
 /* Writes a directory tree to the metadata resource.
  *
  * @root:      Root of the dentry tree.
@@ -1842,20 +1770,18 @@ write_dentry_tree_recursive(const struct wim_dentry *parent, u8 *p)
  * Returns pointer to the byte after the last byte we wrote.
  */
 u8 *
-write_dentry_tree(const struct wim_dentry * restrict root, u8 * restrict p)
+write_dentry_tree(struct wim_dentry *root, u8 *p)
 {
        DEBUG("Writing dentry tree.");
        wimlib_assert(dentry_is_root(root));
 
-       /* If we're the root dentry, we have no parent that already
-        * wrote us, so we need to write ourselves. */
+       /* write root dentry and end-of-directory entry following it */
        p = write_dentry(root, p);
-
-       /* Write end of directory entry after the root dentry just to be safe;
-        * however the root dentry obviously cannot have any siblings. */
-       *(le64*)p = cpu_to_le64(0);
+       *(u64*)p = 0;
        p += 8;
 
-       /* Recursively write the rest of the dentry tree. */
-       return write_dentry_tree_recursive(root, p);
+       /* write the rest of the dentry tree */
+       for_dentry_in_tree(root, write_dir_dentries, &p);
+
+       return p;
 }