fuse: update fuse_conn_init() and separate out fuse_conn_kill()

Update fuse_conn_init() such that it doesn't take @sb and move bdi
registration into a separate function.  Also separate out
fuse_conn_kill() from fuse_put_super().

These will be used to implement cuse.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index ef2e1f3..2efcf12 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -394,6 +394,9 @@
 	/** Filesystem supports NFS exporting.  Only set in INIT */
 	unsigned export_support:1;
 
+	/** Set if bdi is valid */
+	unsigned bdi_initialized:1;
+
 	/*
 	 * The following bitfields are only for optimization purposes
 	 * and hence races in setting them will not cause malfunction
@@ -662,7 +665,7 @@
 /**
  * Initialize fuse_conn
  */
-int fuse_conn_init(struct fuse_conn *fc, struct super_block *sb);
+void fuse_conn_init(struct fuse_conn *fc);
 
 /**
  * Release reference to fuse_conn