ANDROID: fs/passthrough: Fix compatibility with R/O file system

Look at the passthrough file and check to see if its mount is read-only.

Bug: 297482438
Signed-off-by: Lyon Wang <lyon.wang@mediatek.com>
Change-Id: I0f483c6bcb1effe395eee07b6d721f343840d115
(cherry picked from commit dbeed231965e1a01bf0d70ea5439fbfacc7c4aae)
diff --git a/fs/fuse/passthrough.c b/fs/fuse/passthrough.c
index c0ae306..2449558 100644
--- a/fs/fuse/passthrough.c
+++ b/fs/fuse/passthrough.c
@@ -214,7 +214,8 @@
 	}
 
 	if (!passthrough_filp->f_op->read_iter ||
-	    !passthrough_filp->f_op->write_iter) {
+	    !((passthrough_filp->f_path.mnt->mnt_flags | MNT_READONLY) ||
+	       passthrough_filp->f_op->write_iter)) {
 		pr_err("FUSE: passthrough file misses file operations.\n");
 		res = -EBADF;
 		goto err_free_file;