From patchwork Thu Feb 2 20:44:27 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Wilcox X-Patchwork-Id: 13126721 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 BA857C6379F for ; Thu, 2 Feb 2023 20:44:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232904AbjBBUog (ORCPT ); Thu, 2 Feb 2023 15:44:36 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41640 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229761AbjBBUof (ORCPT ); Thu, 2 Feb 2023 15:44:35 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C73128A43; 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=EKEz4nt5nAILCQ0WhorvddY3Ohu5ukrqmYNOFRKi6c4=; b=GX1QllwrfhDN5IKVNAciO3qEvo z1zvwuCrdT1EFPb+2uaPsl1XDsVWPvzn1FMeJ0+uKpjTftB94HKpr9d9x2074LhVEQcw+hsfCA4Ah s0I0YoFtRcRZl1R//0GffZdIIGKtEY0+gAXCMMK0Mm9Ix40T/P2zrT8FUsuOIUPpX32dwL6SOxTnF gk//hnp9hqX5Yqrk1rLBCmuZ4pue3Y9IMSfFWn25PJEwgpTvGYpLCzE5iewZvsAyqxTGcrgxzqePp RKnecjNgS+kjWIwJOXmaxQBJ1Iao/OKNm8LAHXcXxtyy6p30R/c2HxpHN4V3gsFGa6jwPx5TOr/eO tKTST7YQ==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1pNgRb-00Di7j-LB; Thu, 02 Feb 2023 20:44:31 +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 5/5] btrfs: Zero bytes after 'oldsize' if we're expanding the file Date: Thu, 2 Feb 2023 20:44:27 +0000 Message-Id: <20230202204428.3267832-6-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. Signed-off-by: Matthew Wilcox (Oracle) --- fs/btrfs/inode.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 98a800b8bd43..b61ec4bb9cf0 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -5234,6 +5234,7 @@ static int btrfs_setsize(struct inode *inode, struct iattr *attr) i_size_write(inode, newsize); btrfs_inode_safe_disk_i_size_write(BTRFS_I(inode), 0); pagecache_isize_extended(inode, oldsize, newsize); + truncate_pagecache(inode, oldsize); ret = btrfs_update_inode(trans, root, BTRFS_I(inode)); btrfs_drew_write_unlock(&root->snapshot_lock); btrfs_end_transaction(trans);