/* TODO: Make this go away entirely. */
BlueSkyFS *bluesky_new_fs(gchar *name);
+/* Linked list update functions for LRU lists. */
+void bluesky_list_unlink(GList *head, GList *item);
+GList *bluesky_list_prepend(GList *head, BlueSkyInode *inode);
+GList *bluesky_list_append(GList *head, BlueSkyInode *inode);
+BlueSkyInode *bluesky_list_head(GList *head);
+BlueSkyInode *bluesky_list_tail(GList *head);
+
/* Serialization and deserialization of filesystem data for storing to
* persistent storage. */
void bluesky_serialize_superblock(GString *out, BlueSkyFS *fs);
* data includes dirty data). Updates to these variables must be made
* atomically. */
gint cache_total, cache_dirty;
+
+ /* Linked list of inodes, sorted by access/modification times for cache
+ * management. Editing these lists is protected by the filesystem lock; to
+ * avoid deadlock do not attempt to take any other locks while the FS lock
+ * is held for list editing purposes. Items at the head of the list are
+ * most recently accessed/modified. */
+ GList dirty_list, accessed_list;
} BlueSkyFS;
/* Inode number of the root directory. */
/* Additional state for tracking cache writeback status. */
uint64_t change_pending; /* change_count version currently being committed to storage */
+ /* Pointers to the linked-list elements for this inode in the accessed and
+ * dirty linked lists. We re-use the GList structure, using ->next to
+ * point to the head of the list and ->prev to point to the tail. The data
+ * element is unused. */
+ GList *accessed_list, *dirty_list;
+
int64_t atime; /* Microseconds since the Unix epoch */
int64_t ctime;
int64_t mtime;
if (inode->change_count == inode->change_commit) {
/* If inode is no longer dirty... */
inode->change_time = 0;
+ g_mutex_lock(inode->fs->lock);
+ bluesky_list_unlink(&inode->fs->dirty_list, inode->dirty_list);
+ inode->dirty_list = NULL;
+ g_mutex_unlock(inode->fs->lock);
}
g_mutex_unlock(inode->lock);
g_print("Cached inodes: %u\tNext inode: %"PRIu64"\n",
g_hash_table_size(fs->inodes), fs->next_inum);
+ GList *item;
+ g_print("Dirty inode LRU list:");
+ for (item = fs->dirty_list.next; item != NULL; item = item->next) {
+ g_print(" %"PRIu64";", ((BlueSkyInode *)item->data)->inum);
+ }
+ g_print("\n");
+ g_print("Accessed inode LRU list:");
+ for (item = fs->accessed_list.next; item != NULL; item = item->next) {
+ g_print(" %"PRIu64";", ((BlueSkyInode *)item->data)->inum);
+ }
+ g_print("\n");
+
g_hash_table_foreach(fs->inodes, inode_dump, fs);
}
if (bluesky_options.writethrough_cache)
bluesky_file_flush(inode, NULL);
+
+ g_mutex_lock(inode->fs->lock);
+ bluesky_list_unlink(&inode->fs->dirty_list, inode->dirty_list);
+ inode->dirty_list = bluesky_list_prepend(&inode->fs->dirty_list, inode);
+ bluesky_list_unlink(&inode->fs->accessed_list, inode->accessed_list);
+ inode->accessed_list = bluesky_list_prepend(&inode->fs->accessed_list, inode);
+ g_mutex_unlock(inode->fs->lock);
}
/* Unfortunately a glib hash table is only guaranteed to be able to store
root->nlink = 1;
root->mode = 0755;
bluesky_insert_inode(fs, root);
+ bluesky_inode_update_ctime(root, TRUE);
bluesky_inode_flush(fs, root);
bluesky_superblock_flush(fs);
inode->inum);
/* Sanity check: Is the inode clean? */
- if (inode->change_commit < inode->change_count) {
- g_warning("Dropping inode which is not clean (commit %"PRIi64" < change %"PRIi64")\n", inode->change_commit, inode->change_count);
+ if (inode->change_commit < inode->change_count
+ || inode->dirty_list != NULL) {
+ g_warning("Dropping inode which is not clean (commit %"PRIi64" < change %"PRIi64"; dirty_list = %p)\n", inode->change_commit, inode->change_count, inode->dirty_list);
}
+ g_mutex_lock(inode->fs->lock);
+ bluesky_list_unlink(&inode->fs->accessed_list, inode->accessed_list);
+ bluesky_list_unlink(&inode->fs->dirty_list, inode->dirty_list);
+ g_mutex_unlock(inode->fs->lock);
+
/* Free file type specific data. It should be an error for there to be
* dirty data to commit when the reference count has reaches zero. */
switch (inode->type) {
}
inode->access_time = bluesky_get_current_time();
+ g_mutex_lock(inode->fs->lock);
+ inode->accessed_list = bluesky_list_prepend(&inode->fs->accessed_list, inode);
+ g_mutex_unlock(inode->fs->lock);
g_mutex_unlock(inode->lock);
bluesky_inode_unref(inode);
string->data = g_realloc(string->data, len);
string->len = len;
}
+
+/* Cache LRU list management functions. These manage the doubly-linked list of
+ * inodes sorted by accessed/modified time. The FS lock should be held while
+ * calling these.
+ *
+ * _remove will unlink an inode from the linked list.
+ *
+ * _prepend and _append insert an inode at the head or tail of the linked list,
+ * and return a pointer to the linked list element (which should be stored in
+ * the inode); the inode should not already be in the list.
+ *
+ * _head and _tail simply return the first or last item inode in the list. */
+void bluesky_list_unlink(GList *head, GList *item)
+{
+ if (item == NULL)
+ return;
+
+ if (head->prev == item)
+ head->prev = item->prev;
+ head->next = g_list_delete_link(head->next, item);
+}
+
+GList *bluesky_list_prepend(GList *head, BlueSkyInode *inode)
+{
+ head->next = g_list_prepend(head->next, inode);
+ if (head->prev == NULL)
+ head->prev = g_list_last(head->next);
+ return head->next;
+}
+
+GList *bluesky_list_append(GList *head, BlueSkyInode *inode)
+{
+ if (head->next == NULL)
+ return bluesky_list_prepend(head, inode);
+
+ g_assert(head->prev != NULL && head->prev->next == NULL);
+
+ GList *link = g_list_alloc();
+ link->data = inode;
+ link->next = NULL;
+ link->prev = head->prev;
+ head->prev->next = link;
+ head->prev = link;
+ return link;
+}
+
+BlueSkyInode *bluesky_list_head(GList *head)
+{
+ if (head->next == NULL)
+ return NULL;
+ else
+ return (BlueSkyInode *)head->next->data;
+}
+
+BlueSkyInode *bluesky_list_tail(GList *head)
+{
+ if (head->prev == NULL)
+ return NULL;
+ else
+ return (BlueSkyInode *)head->prev->data;
+}
projects / bluesky.git / commitdiff