ext4: add data structures for the extent status tree

This patch adds two structures that supports extent status tree, extent_status
and ext4_es_tree.  Currently extent_status is used to track a delay extent for
an inode, which record the start block and the length of the delay extent.
ext4_es_tree is used to store all extent_status for an inode in memory.

Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: Allison Henderson <achender@linux.vnet.ibm.com>
Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 25 insertions, 0 deletions

diff --git a/fs/ext4/extents_status.h b/fs/ext4/extents_status.h
new file mode 100644
index 000000000000..8be2ab9c9425
--- /dev/null
+++ b/fs/ext4/extents_status.h
@@ -0,0 +1,25 @@
+/*
+ *  fs/ext4/extents_status.h
+ *
+ * Written by Yongqiang Yang <xiaoqiangnk@gmail.com>
+ * Modified by
+ *      Allison Henderson <achender@linux.vnet.ibm.com>
+ *      Zheng Liu <wenqing.lz@taobao.com>
+ *
+ */
+
+#ifndef _EXT4_EXTENTS_STATUS_H
+#define _EXT4_EXTENTS_STATUS_H
+
+struct extent_status {
+        struct rb_node rb_node;
+        ext4_lblk_t start;      /* first block extent covers */
+        ext4_lblk_t len;        /* length of extent in block */
+};
+
+struct ext4_es_tree {
+        struct rb_root root;
+        struct extent_status *cache_es; /* recently accessed extent */
+};
+
+#endif /* _EXT4_EXTENTS_STATUS_H */