btrfs: extent_io: Introduce needed structure for recoding set/clear bits

Add a new structure, extent_change_set, to record how many bytes are
changed in one set/clear_extent_bits() operation, with detailed changed
ranges info.

This provides the needed facilities for later qgroup reserve framework.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index c668f36898d3a4c2dd2e0e18456dd2cfa6c55747..3107a6eb8e78d66510b721337d819d28eb3f833a 100644 (file)
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -2,6 +2,7 @@
 #define __EXTENTIO__
 
 #include <linux/rbtree.h>
+#include "ulist.h"
 
 /* bits for the extent state */
 #define EXTENT_DIRTY           (1U << 0)
@@ -161,6 +162,17 @@ struct extent_buffer {
 #endif
 };
 
+/*
+ * Structure to record how many bytes and which ranges are set/cleared
+ */
+struct extent_changeset {
+       /* How many bytes are set/cleared in this operation */
+       u64 bytes_changed;
+
+       /* Changed ranges */
+       struct ulist *range_changed;
+};
+
 static inline void extent_set_compress_type(unsigned long *bio_flags,
                                            int compress_type)
 {