From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752278AbdK1KVK (ORCPT ); Tue, 28 Nov 2017 05:21:10 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:56994 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752541AbdK1KVH (ORCPT ); Tue, 28 Nov 2017 05:21:07 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Theodore Tso , Amir Goldstein Subject: [PATCH 3.18 20/67] ext4: fix interaction between i_size, fallocate, and delalloc after a crash Date: Tue, 28 Nov 2017 11:19:19 +0100 Message-Id: <20171128100422.864159864@linuxfoundation.org> X-Mailer: git-send-email 2.15.0 In-Reply-To: <20171128100420.274075224@linuxfoundation.org> References: <20171128100420.274075224@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Theodore Ts'o commit 51e3ae81ec58e95f10a98ef3dd6d7bce5d8e35a2 upstream. If there are pending writes subject to delayed allocation, then i_size will show size after the writes have completed, while i_disksize contains the value of i_size on the disk (since the writes have not been persisted to disk). If fallocate(2) is called with the FALLOC_FL_KEEP_SIZE flag, either with or without the FALLOC_FL_ZERO_RANGE flag set, and the new size after the fallocate(2) is between i_size and i_disksize, then after a crash, if a journal commit has resulted in the changes made by the fallocate() call to be persisted after a crash, but the delayed allocation write has not resolved itself, i_size would not be updated, and this would cause the following e2fsck complaint: Inode 12, end of extent exceeds allowed value (logical block 33, physical block 33441, len 7) This can only take place on a sparse file, where the fallocate(2) call is allocating blocks in a range which is before a pending delayed allocation write which is extending i_size. Since this situation is quite rare, and the window in which the crash must take place is typically < 30 seconds, in practice this condition will rarely happen. Nevertheless, it can be triggered in testing, and in particular by xfstests generic/456. Signed-off-by: Theodore Ts'o Reported-by: Amir Goldstein Signed-off-by: Greg Kroah-Hartman --- fs/ext4/extents.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -4807,7 +4807,8 @@ static long ext4_zero_range(struct file } if (!(mode & FALLOC_FL_KEEP_SIZE) && - offset + len > i_size_read(inode)) { + (offset + len > i_size_read(inode) || + offset + len > EXT4_I(inode)->i_disksize)) { new_size = offset + len; ret = inode_newsize_ok(inode, new_size); if (ret) @@ -4951,7 +4952,8 @@ long ext4_fallocate(struct file *file, i } if (!(mode & FALLOC_FL_KEEP_SIZE) && - offset + len > i_size_read(inode)) { + (offset + len > i_size_read(inode) || + offset + len > EXT4_I(inode)->i_disksize)) { new_size = offset + len; ret = inode_newsize_ok(inode, new_size); if (ret)