9p: statfs should not override server f_type

Allow a 9p2000.L server to supply the statfs f_type value rather than
hardwiring V9FS_MAGIC.  It is desirable to give the server this option
in some applications, e.g. I/O forwarding.

Signed-off-by: Jim Garlick <garlick@llnl.gov>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

fs/9p/vfs_super.c

@@ -260,7 +260,7 @@ static int v9fs_statfs(struct dentry *dentry, struct kstatfs *buf)
 	if (v9fs_proto_dotl(v9ses)) {
 		res = p9_client_statfs(fid, &rs);
 		if (res == 0) {
-			buf->f_type = V9FS_MAGIC;
+			buf->f_type = rs.type;
 			buf->f_bsize = rs.bsize;
 			buf->f_blocks = rs.blocks;
 			buf->f_bfree = rs.bfree;