]> wimlib.net Git - wimlib/blobdiff - src/dentry.c
struct dentry optimization and stack-based rbtree traversal
[wimlib] / src / dentry.c
index bca9f35e2afc0ca9fa5fdbb38e3536e5d183361b..9306212d82cf4ffef0bec7ca8dbce2ab310efe6c 100644 (file)
@@ -40,6 +40,9 @@
 #include "wimlib_internal.h"
 
 
+/* Calculates the unaligned length, in bytes, of an on-disk WIM dentry that has
+ * a file name and short name that take the specified numbers of bytes.  This
+ * excludes any alternate data stream entries that may follow the dentry. */
 static u64 __dentry_correct_length_unaligned(u16 file_name_len,
                                             u16 short_name_len)
 {
@@ -51,23 +54,25 @@ static u64 __dentry_correct_length_unaligned(u16 file_name_len,
        return length;
 }
 
+/* Calculates the unaligned length, in bytes, of an on-disk WIM dentry, based on
+ * the file name length and short name length.  Note that dentry->length is
+ * ignored; also, this excludes any alternate data stream entries that may
+ * follow the dentry. */
 static u64 dentry_correct_length_unaligned(const struct dentry *dentry)
 {
        return __dentry_correct_length_unaligned(dentry->file_name_len,
                                                 dentry->short_name_len);
 }
 
-/* Return the "correct" value to write in the length field of the dentry, based
- * on the file name length and short name length */
+/* Return the "correct" value to write in the length field of a WIM dentry,
+ * based on the file name length and short name length. */
 static u64 dentry_correct_length(const struct dentry *dentry)
 {
        return (dentry_correct_length_unaligned(dentry) + 7) & ~7;
 }
 
-/*
- * Returns true if @dentry has the UTF-8 file name @name that has length
- * @name_len.
- */
+/* Return %true iff @dentry has the UTF-8 file name @name that has length
+ * @name_len bytes. */
 static bool dentry_has_name(const struct dentry *dentry, const char *name,
                            size_t name_len)
 {
@@ -76,6 +81,8 @@ static bool dentry_has_name(const struct dentry *dentry, const char *name,
        return memcmp(dentry->file_name_utf8, name, name_len) == 0;
 }
 
+/* Return %true iff the alternate data stream entry @entry has the UTF-8 stream
+ * name @name that has length @name_len bytes. */
 static inline bool ads_entry_has_name(const struct ads_entry *entry,
                                      const char *name, size_t name_len)
 {
@@ -163,14 +170,16 @@ static u64 __dentry_total_length(const struct dentry *dentry, u64 length)
        return (length + 7) & ~7;
 }
 
+/* Calculate the aligned *total* length of an on-disk WIM dentry.  This includes
+ * all alternate data streams. */
 u64 dentry_correct_total_length(const struct dentry *dentry)
 {
        return __dentry_total_length(dentry,
                                     dentry_correct_length_unaligned(dentry));
 }
 
-/* Real length of a dentry, including the alternate data stream entries, which
- * are not included in the dentry->length field... */
+/* Like dentry_correct_total_length(), but use the existing dentry->length field
+ * instead of calculating its "correct" value. */
 static u64 dentry_total_length(const struct dentry *dentry)
 {
        return __dentry_total_length(dentry, dentry->length);
@@ -244,6 +253,83 @@ int inode_to_stbuf(const struct inode *inode, struct lookup_table_entry *lte,
 }
 #endif
 
+int for_dentry_in_rbtree(struct rb_node *root,
+                        int (*visitor)(struct dentry *, void *),
+                        void *arg)
+{
+       int ret;
+       struct rb_node *node = root;
+       LIST_HEAD(stack);
+       while (true) {
+               if (node) {
+                       list_add(&rbnode_dentry(node)->tmp_list, &stack);
+                       node = node->rb_left;
+               } else {
+                       struct list_head *next;
+                       struct dentry *dentry;
+
+                       next = stack.next;
+                       if (next == &stack)
+                               return 0;
+                       dentry = container_of(next, struct dentry, tmp_list);
+                       list_del(next);
+                       ret = visitor(dentry, arg);
+                       if (ret != 0)
+                               return ret;
+                       node = dentry->rb_node.rb_right;
+               }
+       }
+}
+
+int for_dentry_tree_in_rbtree(struct rb_node *root,
+                             int (*visitor)(struct dentry*, void*),
+                             void *arg)
+{
+       int ret;
+       struct rb_node *node = root;
+       LIST_HEAD(stack);
+       while (true) {
+               if (node) {
+                       list_add(&rbnode_dentry(node)->tmp_list, &stack);
+                       node = node->rb_left;
+               } else {
+                       struct list_head *next;
+                       struct dentry *dentry;
+
+                       next = stack.next;
+                       if (next == &stack)
+                               return 0;
+                       dentry = container_of(next, struct dentry, tmp_list);
+                       list_del(next);
+                       ret = for_dentry_in_tree(dentry, visitor, 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 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)
+                       return ret;
+       }
+       return 0;
+}
+
 /*
  * Calls a function on all directory entries in a directory tree.  It is called
  * on a parent before its children.
@@ -251,26 +337,12 @@ int inode_to_stbuf(const struct inode *inode, struct lookup_table_entry *lte,
 int for_dentry_in_tree(struct dentry *root,
                       int (*visitor)(struct dentry*, void*), void *arg)
 {
-       int ret;
-       struct dentry *child;
-
-       ret = visitor(root, arg);
-
+       int ret = visitor(root, arg);
        if (ret != 0)
                return ret;
 
-       child = root->d_inode->children;
-
-       if (!child)
-               return 0;
-
-       do {
-               ret = for_dentry_in_tree(child, visitor, arg);
-               if (ret != 0)
-                       return ret;
-               child = child->next;
-       } while (child != root->d_inode->children);
-       return 0;
+       return for_dentry_tree_in_rbtree(root->d_inode->children.rb_node,
+                                        visitor, arg);
 }
 
 /*
@@ -280,20 +352,11 @@ int for_dentry_in_tree(struct dentry *root,
 int for_dentry_in_tree_depth(struct dentry *root,
                             int (*visitor)(struct dentry*, void*), void *arg)
 {
-       int ret;
-       struct dentry *child;
-       struct dentry *next;
 
-       child = root->d_inode->children;
-       if (child) {
-               do {
-                       next = child->next;
-                       ret = for_dentry_in_tree_depth(child, visitor, arg);
-                       if (ret != 0)
-                               return ret;
-                       child = next;
-               } while (child != root->d_inode->children);
-       }
+       int ret = for_dentry_tree_in_rbtree_depth(root->d_inode->children.rb_node,
+                                                 visitor, arg);
+       if (ret != 0)
+               return ret;
        return visitor(root, arg);
 }
 
@@ -347,37 +410,43 @@ oom:
        return WIMLIB_ERR_NOMEM;
 }
 
+static int increment_subdir_offset(struct dentry *dentry, void *subdir_offset_p)
+{
+       *(u64*)subdir_offset_p += dentry_correct_total_length(dentry);
+       return 0;
+}
+
+static int call_calculate_subdir_offsets(struct dentry *dentry,
+                                        void *subdir_offset_p)
+{
+       calculate_subdir_offsets(dentry, subdir_offset_p);
+       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.
+ *                   offset for @dentry.
  */
 void calculate_subdir_offsets(struct dentry *dentry, u64 *subdir_offset_p)
 {
-       struct dentry *child;
+       struct rb_node *node;
 
-       child = dentry->d_inode->children;
        dentry->subdir_offset = *subdir_offset_p;
-
-       if (child) {
+       node = dentry->d_inode->children.rb_node;
+       if (node) {
                /* Advance the subdir offset by the amount of space the children
                 * of this dentry take up. */
-               do {
-                       *subdir_offset_p += dentry_correct_total_length(child);
-                       child = child->next;
-               } while (child != dentry->d_inode->children);
+               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. */
-               do {
-                       calculate_subdir_offsets(child, subdir_offset_p);
-                       child = child->next;
-               } while (child != dentry->d_inode->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
@@ -389,46 +458,74 @@ void calculate_subdir_offsets(struct dentry *dentry, u64 *subdir_offset_p)
        }
 }
 
+static int compare_names(const char *name_1, size_t len_1,
+                        const char *name_2, size_t len_2)
+{
+       if (len_1 < len_2)
+               return -1;
+       else if (len_1 > len_2)
+               return 1;
+       else
+               return memcmp(name_1, name_2, len_1);
+}
+
+static int dentry_compare_names(const struct dentry *d1, const struct dentry *d2)
+{
+       return compare_names(d1->file_name_utf8, d1->file_name_utf8_len,
+                            d2->file_name_utf8, d2->file_name_utf8_len);
+}
+
+
+static struct dentry *
+get_rbtree_child_with_name(const struct rb_node *node,
+                          const char *name, size_t name_len)
+{
+       do {
+               struct dentry *child = rbnode_dentry(node);
+               int result = compare_names(name, name_len,
+                                          child->file_name_utf8,
+                                          child->file_name_utf8_len);
+               if (result < 0)
+                       node = node->rb_left;
+               else if (result > 0)
+                       node = node->rb_right;
+               else
+                       return child;
+       } while (node);
+       return NULL;
+}
+
 /* Returns the child of @dentry that has the file name @name.
  * Returns NULL if no child has the name. */
 struct dentry *get_dentry_child_with_name(const struct dentry *dentry,
                                          const char *name)
 {
-       struct dentry *child;
-       size_t name_len;
-
-       child = dentry->d_inode->children;
-       if (child) {
-               name_len = strlen(name);
-               do {
-                       if (dentry_has_name(child, name, name_len))
-                               return child;
-                       child = child->next;
-               } while (child != dentry->d_inode->children);
-       }
-       return NULL;
+       struct rb_node *node = dentry->d_inode->children.rb_node;
+       if (node)
+               return get_rbtree_child_with_name(node, name, strlen(name));
+       else
+               return NULL;
 }
 
 /* Retrieves the dentry that has the UTF-8 @path relative to the dentry
- * @cur_dir.  Returns NULL if no dentry having the path is found. */
-static struct dentry *get_dentry_relative_path(struct dentry *cur_dir,
+ * @cur_dentry.  Returns NULL if no dentry having the path is found. */
+static struct dentry *get_dentry_relative_path(struct dentry *cur_dentry,
                                               const char *path)
 {
-       struct dentry *child;
-       size_t base_len;
-       const char *new_path;
-
        if (*path == '\0')
-               return cur_dir;
+               return cur_dentry;
+
+       struct rb_node *node = cur_dentry->d_inode->children.rb_node;
+       if (node) {
+               struct dentry *child;
+               size_t base_len;
+               const char *new_path;
 
-       child = cur_dir->d_inode->children;
-       if (child) {
                new_path = path_next_part(path, &base_len);
-               do {
-                       if (dentry_has_name(child, path, base_len))
-                               return get_dentry_relative_path(child, new_path);
-                       child = child->next;
-               } while (child != cur_dir->d_inode->children);
+
+               child = get_rbtree_child_with_name(node, path, base_len);
+               if (child)
+                       return get_dentry_relative_path(child, new_path);
        }
        return NULL;
 }
@@ -447,10 +544,10 @@ struct inode *wim_pathname_to_inode(WIMStruct *w, const char *path)
 {
        struct dentry *dentry;
        dentry = get_dentry(w, path);
-       if (!dentry)
-               return NULL;
-       else
+       if (dentry)
                return dentry->d_inode;
+       else
+               return NULL;
 }
 
 /* Returns the dentry that corresponds to the parent directory of @path, or NULL
@@ -632,8 +729,6 @@ struct dentry *new_dentry(const char *name)
        if (change_dentry_name(dentry, name) != 0)
                goto err;
 
-       dentry->next   = dentry;
-       dentry->prev   = dentry;
        dentry->parent = dentry;
 
        return dentry;
@@ -730,9 +825,7 @@ static void put_inode(struct inode *inode)
  */
 void free_dentry(struct dentry *dentry)
 {
-       wimlib_assert(dentry);
-       struct inode *inode;
-
+       wimlib_assert(dentry != NULL);
        FREE(dentry->file_name);
        FREE(dentry->file_name_utf8);
        FREE(dentry->short_name);
@@ -744,8 +837,8 @@ void free_dentry(struct dentry *dentry)
 
 void put_dentry(struct dentry *dentry)
 {
-       wimlib_assert(dentry);
-       wimlib_assert(dentry->refcnt);
+       wimlib_assert(dentry != NULL);
+       wimlib_assert(dentry->refcnt != 0);
 
        if (--dentry->refcnt == 0)
                free_dentry(dentry);
@@ -803,25 +896,34 @@ int increment_dentry_refcnt(struct dentry *dentry, void *ignore)
  * @dentry: The dentry to link.
  * @parent: The dentry that will be the parent of @dentry.
  */
-void link_dentry(struct dentry *dentry, struct dentry *parent)
+bool dentry_add_child(struct dentry * restrict parent,
+                     struct dentry * restrict child)
 {
        wimlib_assert(dentry_is_directory(parent));
-       dentry->parent = parent;
-       if (parent->d_inode->children) {
-               /* Not an only child; link to siblings. */
-               dentry->next = parent->d_inode->children;
-               dentry->prev = parent->d_inode->children->prev;
-               dentry->next->prev = dentry;
-               dentry->prev->next = dentry;
-       } else {
-               /* Only child; link to parent. */
-               parent->d_inode->children = dentry;
-               dentry->next = dentry;
-               dentry->prev = dentry;
+
+       struct rb_root *root = &parent->d_inode->children;
+       struct rb_node **new = &(root->rb_node);
+       struct rb_node *rb_parent = NULL;
+
+       while (*new) {
+               struct dentry *this = rbnode_dentry(*new);
+               int result = dentry_compare_names(child, this);
+
+               rb_parent = *new;
+
+               if (result < 0)
+                       new = &((*new)->rb_left);
+               else if (result > 0)
+                       new = &((*new)->rb_right);
+               else
+                       return false;
        }
+       child->parent = parent;
+       rb_link_node(&child->rb_node, rb_parent, new);
+       rb_insert_color(&child->rb_node, root);
+       return true;
 }
 
-
 #ifdef WITH_FUSE
 /*
  * Unlink a dentry from the directory tree.
@@ -830,16 +932,10 @@ void link_dentry(struct dentry *dentry, struct dentry *parent)
  */
 void unlink_dentry(struct dentry *dentry)
 {
-       if (dentry_is_root(dentry))
+       struct dentry *parent = dentry->parent;
+       if (parent == dentry)
                return;
-       if (dentry_is_only_child(dentry)) {
-               dentry->parent->d_inode->children = NULL;
-       } else {
-               if (dentry_is_first_sibling(dentry))
-                       dentry->parent->d_inode->children = dentry->next;
-               dentry->next->prev = dentry->prev;
-               dentry->prev->next = dentry->next;
-       }
+       rb_erase(&dentry->rb_node, &parent->d_inode->children);
 }
 #endif
 
@@ -891,7 +987,7 @@ static int verify_inode(struct inode *inode, const WIMStruct *w)
                                WARNING("The following lookup table entry "
                                        "has a reference count of %u, but",
                                        lte->refcnt);
-                               WARNING("We found %zu references to it",
+                               WARNING("We found %u references to it",
                                        lte->real_refcnt);
                                WARNING("(One dentry referencing it is at `%s')",
                                         first_dentry->full_path_utf8);
@@ -941,21 +1037,19 @@ out:
 /* Run some miscellaneous verifications on a WIM dentry */
 int verify_dentry(struct dentry *dentry, void *wim)
 {
-       const WIMStruct *w = wim;
-       const struct inode *inode = dentry->d_inode;
-       int ret = WIMLIB_ERR_INVALID_DENTRY;
+       int ret;
 
        if (!dentry->d_inode->verified) {
-               ret = verify_inode(dentry->d_inode, w);
+               ret = verify_inode(dentry->d_inode, wim);
                if (ret != 0)
-                       goto out;
+                       return ret;
        }
 
        /* Cannot have a short name but no long name */
        if (dentry->short_name_len && !dentry->file_name_len) {
                ERROR("Dentry `%s' has a short name but no long name",
                      dentry->full_path_utf8);
-               goto out;
+               return WIMLIB_ERR_INVALID_DENTRY;
        }
 
        /* Make sure root dentry is unnamed */
@@ -963,7 +1057,7 @@ int verify_dentry(struct dentry *dentry, void *wim)
                if (dentry->file_name_len) {
                        ERROR("The root dentry is named `%s', but it must "
                              "be unnamed", dentry->file_name_utf8);
-                       goto out;
+                       return WIMLIB_ERR_INVALID_DENTRY;
                }
        }
 
@@ -976,9 +1070,7 @@ int verify_dentry(struct dentry *dentry, void *wim)
        }
 #endif
 
-       ret = 0;
-out:
-       return ret;
+       return 0;
 }
 
 
@@ -1370,7 +1462,8 @@ int read_dentry(const u8 metadata_resource[], u64 metadata_resource_len,
                      "short_name_len = %hu, file_name_len = %hu)",
                      calculated_size, dentry->length,
                      short_name_len, file_name_len);
-               return WIMLIB_ERR_INVALID_DENTRY;
+               ret = WIMLIB_ERR_INVALID_DENTRY;
+               goto out_free_inode;
        }
 
        /* Read the filename if present.  Note: if the filename is empty, there
@@ -1380,7 +1473,8 @@ int read_dentry(const u8 metadata_resource[], u64 metadata_resource_len,
                if (!file_name) {
                        ERROR("Failed to allocate %hu bytes for dentry file name",
                              file_name_len);
-                       return WIMLIB_ERR_NOMEM;
+                       ret = WIMLIB_ERR_NOMEM;
+                       goto out_free_inode;
                }
                p = get_bytes(p, file_name_len, file_name);
 
@@ -1445,7 +1539,7 @@ int read_dentry(const u8 metadata_resource[], u64 metadata_resource_len,
 
                p = get_bytes(p, short_name_len, short_name);
                if (*(u16*)p)
-                       WARNING("Expected two zero bytes following the file name "
+                       WARNING("Expected two zero bytes following the short name of "
                                "`%s', but found non-zero bytes", file_name_utf8);
                p += 2;
        }
@@ -1460,22 +1554,39 @@ int read_dentry(const u8 metadata_resource[], u64 metadata_resource_len,
         * included in the dentry->length field for some reason.
         */
        if (inode->num_ads != 0) {
-               if (calculated_size > metadata_resource_len - offset) {
-                       ERROR("Not enough space in metadata resource for "
-                             "alternate stream entries");
-                       ret = WIMLIB_ERR_INVALID_DENTRY;
-                       goto out_free_short_name;
+
+               /* Trying different lengths is just a hack to make sure we have
+                * a chance of reading the ADS entries correctly despite the
+                * poor documentation. */
+
+               if (calculated_size != dentry->length) {
+                       WARNING("Trying calculated dentry length (%"PRIu64") "
+                               "instead of dentry->length field (%"PRIu64") "
+                               "to read ADS entries",
+                               calculated_size, dentry->length);
                }
-               ret = read_ads_entries(&metadata_resource[offset + calculated_size],
-                                      inode,
-                                      metadata_resource_len - offset - calculated_size);
-               if (ret != 0)
-                       goto out_free_short_name;
+               u64 lengths_to_try[3] = {calculated_size,
+                                        (dentry->length + 7) & ~7,
+                                        dentry->length};
+               ret = WIMLIB_ERR_INVALID_DENTRY;
+               for (size_t i = 0; i < ARRAY_LEN(lengths_to_try); i++) {
+                       if (lengths_to_try[i] > metadata_resource_len - offset)
+                               continue;
+                       ret = read_ads_entries(&metadata_resource[offset + lengths_to_try[i]],
+                                              inode,
+                                              metadata_resource_len - offset - lengths_to_try[i]);
+                       if (ret == 0)
+                               goto out;
+               }
+               ERROR("Failed to read alternate data stream "
+                     "entries of `%s'", dentry->file_name_utf8);
+               goto out_free_short_name;
        }
+out:
 
        /* We've read all the data for this dentry.  Set the names and their
         * lengths, and we've done. */
-       dentry->d_inode              = inode;
+       dentry->d_inode            = inode;
        dentry->file_name          = file_name;
        dentry->file_name_utf8     = file_name_utf8;
        dentry->short_name         = short_name;
@@ -1553,15 +1664,8 @@ int read_dentry_tree(const u8 metadata_resource[], u64 metadata_resource_len,
                }
                memcpy(child, &cur_child, sizeof(struct dentry));
 
-               if (prev_child) {
-                       prev_child->next = child;
-                       child->prev = prev_child;
-               } else {
-                       first_child = child;
-               }
+               dentry_add_child(dentry, child);
 
-               child->parent = dentry;
-               prev_child = child;
                inode_add_dentry(child, child->d_inode);
 
                /* If there are children of this child, call this procedure
@@ -1580,14 +1684,6 @@ int read_dentry_tree(const u8 metadata_resource[], u64 metadata_resource_len,
                 * entries. */
                cur_offset += dentry_total_length(child);
        }
-
-       /* Link last child to first one, and set parent's children pointer to
-        * the first child.  */
-       if (prev_child) {
-               prev_child->next = first_child;
-               first_child->prev = prev_child;
-       }
-       dentry->d_inode->children = first_child;
        return ret;
 }
 
@@ -1671,12 +1767,26 @@ static u8 *write_dentry(const struct dentry *dentry, u8 *p)
        return p;
 }
 
+static int write_dentry_cb(struct dentry *dentry, void *_p)
+{
+       u8 **p = _p;
+       *p = write_dentry(dentry, *p);
+       return 0;
+}
+
+static u8 *write_dentry_tree_recursive(const struct dentry *parent, u8 *p);
+
+static int write_dentry_tree_recursive_cb(struct dentry *dentry, void *_p)
+{
+       u8 **p = _p;
+       *p = write_dentry_tree_recursive(dentry, *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 dentry *parent, u8 *p)
 {
-       const struct dentry *child;
-
        /* Nothing to do if this dentry has no children. */
        if (parent->subdir_offset == 0)
                return p;
@@ -1687,24 +1797,14 @@ static u8 *write_dentry_tree_recursive(const struct dentry *parent, u8 *p)
         * 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! */
-       child = parent->d_inode->children;
-       if (child) {
-               do {
-                       p = write_dentry(child, p);
-                       child = child->next;
-               } while (child != parent->d_inode->children);
-       }
+       for_dentry_in_rbtree(parent->d_inode->children.rb_node, write_dentry_cb, &p);
 
        /* write end of directory entry */
        p = put_u64(p, 0);
 
        /* Recurse on children. */
-       if (child) {
-               do {
-                       p = write_dentry_tree_recursive(child, p);
-                       child = child->next;
-               } while (child != parent->d_inode->children);
-       }
+       for_dentry_in_rbtree(parent->d_inode->children.rb_node,
+                            write_dentry_tree_recursive_cb, &p);
        return p;
 }
 
@@ -1717,6 +1817,7 @@ static u8 *write_dentry_tree_recursive(const struct dentry *parent, u8 *p)
  */
 u8 *write_dentry_tree(const struct 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