btrfs: backref: move btrfs_backref_(node|edge|cache) structures to backref.h
These 3 structures are the main part of btrfs backref cache, move them
to backref.h to build the basis for later reuse.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/backref.h b/fs/btrfs/backref.h
index 46faf9b..55f1f56 100644
--- a/fs/btrfs/backref.h
+++ b/fs/btrfs/backref.h
@@ -150,4 +150,120 @@ static inline void btrfs_backref_iter_release(struct btrfs_backref_iter *iter)
memset(&iter->cur_key, 0, sizeof(iter->cur_key));
}
+/*
+ * Backref cache related structures
+ *
+ * The whole objective of backref_cache is to build a bi-directional map
+ * of tree blocks (represented by backref_node) and all their parents.
+ */
+
+/*
+ * Represent a tree block in the backref cache
+ */
+struct btrfs_backref_node {
+ struct rb_node rb_node;
+ u64 bytenr;
+
+ u64 new_bytenr;
+ /* Objectid of tree block owner, can be not uptodate */
+ u64 owner;
+ /* Link to pending, changed or detached list */
+ struct list_head list;
+
+ /* List of upper level edges, which link this node to its parents */
+ struct list_head upper;
+ /* List of lower level edges, which link this node to its children */
+ struct list_head lower;
+
+ /* NULL if this node is not tree root */
+ struct btrfs_root *root;
+ /* Extent buffer got by COWing the block */
+ struct extent_buffer *eb;
+ /* Level of the tree block */
+ unsigned int level:8;
+ /* Is the block in non-reference counted tree */
+ unsigned int cowonly:1;
+ /* 1 if no child node is in the cache */
+ unsigned int lowest:1;
+ /* Is the extent buffer locked */
+ unsigned int locked:1;
+ /* Has the block been processed */
+ unsigned int processed:1;
+ /* Have backrefs of this block been checked */
+ unsigned int checked:1;
+ /*
+ * 1 if corresponding block has been COWed but some upper level block
+ * pointers may not point to the new location
+ */
+ unsigned int pending:1;
+ /* 1 if the backref node isn't connected to any other backref node */
+ unsigned int detached:1;
+
+ /*
+ * For generic purpose backref cache, where we only care if it's a reloc
+ * root, doesn't care the source subvolid.
+ */
+ unsigned int is_reloc_root:1;
+};
+
+#define LOWER 0
+#define UPPER 1
+
+/*
+ * Represent an edge connecting upper and lower backref nodes.
+ */
+struct btrfs_backref_edge {
+ /*
+ * list[LOWER] is linked to btrfs_backref_node::upper of lower level
+ * node, and list[UPPER] is linked to btrfs_backref_node::lower of
+ * upper level node.
+ *
+ * Also, build_backref_tree() uses list[UPPER] for pending edges, before
+ * linking list[UPPER] to its upper level nodes.
+ */
+ struct list_head list[2];
+
+ /* Two related nodes */
+ struct btrfs_backref_node *node[2];
+};
+
+struct btrfs_backref_cache {
+ /* Red black tree of all backref nodes in the cache */
+ struct rb_root rb_root;
+ /* For passing backref nodes to btrfs_reloc_cow_block */
+ struct btrfs_backref_node *path[BTRFS_MAX_LEVEL];
+ /*
+ * List of blocks that have been COWed but some block pointers in upper
+ * level blocks may not reflect the new location
+ */
+ struct list_head pending[BTRFS_MAX_LEVEL];
+ /* List of backref nodes with no child node */
+ struct list_head leaves;
+ /* List of blocks that have been COWed in current transaction */
+ struct list_head changed;
+ /* List of detached backref node. */
+ struct list_head detached;
+
+ u64 last_trans;
+
+ int nr_nodes;
+ int nr_edges;
+
+ /* List of unchecked backref edges during backref cache build */
+ struct list_head pending_edge;
+
+ /* List of useless backref nodes during backref cache build */
+ struct list_head useless_node;
+
+ struct btrfs_fs_info *fs_info;
+
+ /*
+ * Whether this cache is for relocation
+ *
+ * Reloction backref cache require more info for reloc root compared
+ * to generic backref cache.
+ */
+ unsigned int is_reloc;
+};
+
#endif