mm/filemap: simplify generic_file_read_iter

Avoid the pointless goto out just for returning retval.

Link: https://lkml.kernel.org/r/20210122160140.223228-19-willy@infradead.org
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Kent Overstreet <kent.overstreet@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/filemap.c

@@ -2543,7 +2543,7 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
 	ssize_t retval = 0;
 
 	if (!count)
-		goto out; /* skip atime */
+		return 0; /* skip atime */
 
 	if (iocb->ki_flags & IOCB_DIRECT) {
 		struct file *file = iocb->ki_filp;
@@ -2561,7 +2561,7 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
 						iocb->ki_pos,
 					        iocb->ki_pos + count - 1);
 			if (retval < 0)
-				goto out;
+				return retval;
 		}
 
 		file_accessed(file);
@@ -2585,12 +2585,10 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
 		 */
 		if (retval < 0 || !count || iocb->ki_pos >= size ||
 		    IS_DAX(inode))
-			goto out;
+			return retval;
 	}
 
-	retval = filemap_read(iocb, iter, retval);
-out:
-	return retval;
+	return filemap_read(iocb, iter, retval);
 }
 EXPORT_SYMBOL(generic_file_read_iter);