ext4: add operations on extent status tree

This patch adds operations on a extent status tree.

CC: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: Allison Henderson <achender@linux.vnet.ibm.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/ext4/Makefile

@@ -7,7 +7,7 @@ obj-$(CONFIG_EXT4_FS) += ext4.o
 ext4-y	:= balloc.o bitmap.o dir.o file.o fsync.o ialloc.o inode.o page-io.o \
 		ioctl.o namei.o super.o symlink.o hash.o resize.o extents.o \
 		ext4_jbd2.o migrate.o mballoc.o block_validity.o move_extent.o \
-		mmp.o indirect.o
+		mmp.o indirect.o extents_status.o
 
 ext4-$(CONFIG_EXT4_FS_XATTR)		+= xattr.o xattr_user.o xattr_trusted.o
 ext4-$(CONFIG_EXT4_FS_POSIX_ACL)	+= acl.o

fs/ext4/extents_status.h

@@ -11,6 +11,15 @@
 #ifndef _EXT4_EXTENTS_STATUS_H
 #define _EXT4_EXTENTS_STATUS_H
 
+/*
+ * Turn on ES_DEBUG__ to get lots of info about extent status operations.
+ */
+#ifdef ES_DEBUG__
+#define es_debug(fmt, ...)	printk(fmt, ##__VA_ARGS__)
+#else
+#define es_debug(fmt, ...)	no_printk(fmt, ##__VA_ARGS__)
+#endif
+
 struct extent_status {
 	struct rb_node rb_node;
 	ext4_lblk_t start;	/* first block extent covers */
@@ -22,4 +31,15 @@ struct ext4_es_tree {
 	struct extent_status *cache_es;	/* recently accessed extent */
 };
 
+extern int __init ext4_init_es(void);
+extern void ext4_exit_es(void);
+extern void ext4_es_init_tree(struct ext4_es_tree *tree);
+
+extern int ext4_es_insert_extent(struct inode *inode, ext4_lblk_t start,
+				 ext4_lblk_t len);
+extern int ext4_es_remove_extent(struct inode *inode, ext4_lblk_t start,
+				 ext4_lblk_t len);
+extern ext4_lblk_t ext4_es_find_extent(struct inode *inode,
+				struct extent_status *es);
+
 #endif /* _EXT4_EXTENTS_STATUS_H */