vfs: reorder checks in vfs_copy_file_range()

Other read/write ops do the rw_verify_area() after having checked the file
descriptor for being the right type.  Do the same here.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

fs/read_write.c

diff --git a/fs/read_write.c b/fs/read_write.c
index 538af11..f87cdb2 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1521,14 +1521,6 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
 	if (flags != 0)
 		return -EINVAL;
 
-	ret = rw_verify_area(READ, file_in, &pos_in, len);
-	if (unlikely(ret))
-		return ret;
-
-	ret = rw_verify_area(WRITE, file_out, &pos_out, len);
-	if (unlikely(ret))
-		return ret;
-
 	if (!(file_in->f_mode & FMODE_PREAD) ||
 	    !(file_out->f_mode & FMODE_PWRITE))
 		return -ESPIPE;
@@ -1538,6 +1530,14 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
 	    (file_out->f_flags & O_APPEND))
 		return -EBADF;
 
+	ret = rw_verify_area(READ, file_in, &pos_in, len);
+	if (unlikely(ret))
+		return ret;
+
+	ret = rw_verify_area(WRITE, file_out, &pos_out, len);
+	if (unlikely(ret))
+		return ret;
+
 	/* this could be relaxed once a method supports cross-fs copies */
 	if (inode_in->i_sb != inode_out->i_sb)
 		return -EXDEV;