[PATCH v3 01/21] btrfs: extent_io: Introduce needed structure for recoding set/clear bits

[Qu Wenruo <quwenruo@cn.fujitsu.com>]

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>
---
v3:
  Newly introduced, to reuse existing extent_io facilities.
---
 fs/btrfs/extent_io.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index c668f36..3107a6e 100644
--- 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)
 {
-- 
2.6.1