fuse: add store request

Userspace filesystem can request data to be stored in the inode's
mapping.  This request is synchronous and has no reply.  If the write
to the fuse device returns an error then the store request was not
fully completed (but may have updated some pages).

If the stored data overflows the current file size, then the size is
extended, similarly to a write(2) on the filesystem.

Pages which have been completely stored are marked uptodate.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

include/linux/fuse.h

@@ -37,6 +37,9 @@
  *
  * 7.14
  *  - add splice support to fuse device
+ *
+ * 7.15
+ *  - add store notify
  */
 
 #ifndef _LINUX_FUSE_H
@@ -68,7 +71,7 @@
 #define FUSE_KERNEL_VERSION 7
 
 /** Minor version number of this interface */
-#define FUSE_KERNEL_MINOR_VERSION 14
+#define FUSE_KERNEL_MINOR_VERSION 15
 
 /** The node ID of the root inode */
 #define FUSE_ROOT_ID 1
@@ -260,6 +263,7 @@ enum fuse_notify_code {
 	FUSE_NOTIFY_POLL   = 1,
 	FUSE_NOTIFY_INVAL_INODE = 2,
 	FUSE_NOTIFY_INVAL_ENTRY = 3,
+	FUSE_NOTIFY_STORE = 4,
 	FUSE_NOTIFY_CODE_MAX,
 };
 
@@ -568,4 +572,11 @@ struct fuse_notify_inval_entry_out {
 	__u32	padding;
 };
 
+struct fuse_notify_store_out {
+	__u64	nodeid;
+	__u64	offset;
+	__u32	size;
+	__u32	padding;
+};
+
 #endif /* _LINUX_FUSE_H */