fuse: support BSD locking semantics

It is trivial to add support for flock(2) semantics to the existing protocol,
by setting the lock owner field to the file pointer, and passing a new
FUSE_LK_FLOCK flag with the locking request.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/fuse.h b/include/linux/fuse.h
index 4360470..015a8b1 100644
--- a/include/linux/fuse.h
+++ b/include/linux/fuse.h
@@ -13,6 +13,7 @@
  *
  * 7.9:
  *  - new fuse_getattr_in input argument of GETATTR
+ *  - add lk_flags in fuse_lk_in
  */
 
 #include <asm/types.h>
@@ -113,6 +114,11 @@
  */
 #define FUSE_GETATTR_FH		(1 << 0)
 
+/**
+ * Lock flags
+ */
+#define FUSE_LK_FLOCK		(1 << 0)
+
 enum fuse_opcode {
 	FUSE_LOOKUP	   = 1,
 	FUSE_FORGET	   = 2,  /* no reply */
@@ -295,6 +301,8 @@
 	__u64	fh;
 	__u64	owner;
 	struct fuse_file_lock lk;
+	__u32	lk_flags;
+	__u32	padding;
 };
 
 struct fuse_lk_out {