From patchwork Thu Feb 2 20:44:23 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Matthew Wilcox (Oracle)" X-Patchwork-Id: 13126718 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 46237C64EC3 for ; Thu, 2 Feb 2023 20:44:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232999AbjBBUol (ORCPT ); Thu, 2 Feb 2023 15:44:41 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41644 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232111AbjBBUog (ORCPT ); Thu, 2 Feb 2023 15:44:36 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C76919EEA; Thu, 2 Feb 2023 12:44:33 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=3DLfbYeltsUE3NkYQxzmRoc7Gye1xXr71K3DBJBtYI8=; b=My+pp2jnzUtx0mU74aDrHBAfVv 47t6HILhQnY1KaWUmZhAh5Wqw/ZzWZ6ELcjVHzxBAaJVU/zPNhUYV+Oyu8b8NUlzlznAT7362AF5Q gSQhH0el02AH+zggm7MaQts0TQfCLVs/ET3zZFTx6kLY0UFy7JiwRH5IpJXhmrrpwqnp6dChipQdC PEYc0G6v9HjbUwlt4SWnW8UNsQnyNapLR7lOnkWFSFia65JmJyVQlKc6deSxOSY62WoNxa79NTi5h pyqzpXh91k9bcb2gbuVSWm4A6vmNmeqVjxhn6iRYRNaJwId/QFcOjPBC/JShhXajsyYYE1HBY8GMI sUEu9Ryw==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1pNgRa-00Di7L-PL; Thu, 02 Feb 2023 20:44:30 +0000 From: "Matthew Wilcox (Oracle)" To: linux-fsdevel@vger.kernel.org Cc: "Matthew Wilcox (Oracle)" , linux-afs@lists.infradead.org, linux-btrfs@vger.kernel.org, linux-ext4@vger.kernel.org, linux-mm@kvack.org, Hugh Dickins , linux-kernel@vger.kernel.org, fstests@vger.kernel.org Subject: [PATCH 1/5] truncate: Zero bytes after 'oldsize' if we're expanding the file Date: Thu, 2 Feb 2023 20:44:23 +0000 Message-Id: <20230202204428.3267832-2-willy@infradead.org> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20230202204428.3267832-1-willy@infradead.org> References: <20230202204428.3267832-1-willy@infradead.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org POSIX requires that "If the file size is increased, the extended area shall appear as if it were zero-filled". It is possible to use mmap to write past EOF and that data will become visible instead of zeroes. This fixes the problem for the filesystems which simply call truncate_setsize(). More complex filesystems will need their own patches. Signed-off-by: Matthew Wilcox (Oracle) --- mm/truncate.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/mm/truncate.c b/mm/truncate.c index 7b4ea4c4a46b..cebfc5415e9a 100644 --- a/mm/truncate.c +++ b/mm/truncate.c @@ -763,9 +763,12 @@ void truncate_setsize(struct inode *inode, loff_t newsize) loff_t oldsize = inode->i_size; i_size_write(inode, newsize); - if (newsize > oldsize) + if (newsize > oldsize) { pagecache_isize_extended(inode, oldsize, newsize); - truncate_pagecache(inode, newsize); + truncate_pagecache(inode, oldsize); + } else { + truncate_pagecache(inode, newsize); + } } EXPORT_SYMBOL(truncate_setsize);