linux/fuse.h: Pull in from Linux

Update the linux/fuse.h standard header from the kernel development tree
that implements FUSE submounts.

This adds the fuse_attr.flags field, the FUSE_ATTR_FLAGS INIT flag, and
the FUSE_ATTR_SUBMOUNT flag for fuse_attr.flags.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200909184028.262297-2-mreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

include/standard-headers/linux/fuse.h

@@ -227,7 +227,7 @@ struct fuse_attr {
 	uint32_t	gid;
 	uint32_t	rdev;
 	uint32_t	blksize;
-	uint32_t	padding;
+	uint32_t	flags;
 };
 
 struct fuse_kstatfs {
@@ -310,6 +310,7 @@ struct fuse_file_lock {
  * FUSE_NO_OPENDIR_SUPPORT: kernel supports zero-message opendir
  * FUSE_EXPLICIT_INVAL_DATA: only invalidate cached pages on explicit request
  * FUSE_MAP_ALIGNMENT: map_alignment field is valid
+ * FUSE_ATTR_FLAGS: fuse_attr.flags is present and valid
  */
 #define FUSE_ASYNC_READ		(1 << 0)
 #define FUSE_POSIX_LOCKS	(1 << 1)
@@ -338,6 +339,7 @@ struct fuse_file_lock {
 #define FUSE_NO_OPENDIR_SUPPORT (1 << 24)
 #define FUSE_EXPLICIT_INVAL_DATA (1 << 25)
 #define FUSE_MAP_ALIGNMENT	(1 << 26)
+#define FUSE_ATTR_FLAGS		(1 << 27)
 
 /**
  * CUSE INIT request/reply flags
@@ -413,6 +415,13 @@ struct fuse_file_lock {
  */
 #define FUSE_FSYNC_FDATASYNC	(1 << 0)
 
+/**
+ * fuse_attr flags
+ *
+ * FUSE_ATTR_SUBMOUNT: File/directory is a submount point
+ */
+#define FUSE_ATTR_SUBMOUNT      (1 << 0)
+
 enum fuse_opcode {
 	FUSE_LOOKUP		= 1,
 	FUSE_FORGET		= 2,  /* no reply */