Path: news.gmane.org!not-for-mail From: Niels de Vos Newsgroups: gmane.linux.kernel,gmane.linux.file-systems Subject: [PATCH v2] fs: Invalidate the cache for a parent block-device if fsync() is called for a partition Date: Mon, 23 Jan 2012 10:38:29 +0000 Lines: 58 Approved: news@gmane.org Message-ID: <1327315109-7740-1-git-send-email-ndevos@redhat.com> References: <4F19356E.3020708@redhat.com> NNTP-Posting-Host: lo.gmane.org X-Trace: dough.gmane.org 1327315263 30652 80.91.229.12 (23 Jan 2012 10:41:03 GMT) X-Complaints-To: usenet@dough.gmane.org NNTP-Posting-Date: Mon, 23 Jan 2012 10:41:03 +0000 (UTC) Cc: linux-kernel@vger.kernel.org, Niels de Vos , "Bryn M. Reeves" , Mikulas Patocka To: linux-fsdevel@vger.kernel.org Original-X-From: linux-kernel-owner@vger.kernel.org Mon Jan 23 11:40:58 2012 Return-path: Envelope-to: glk-linux-kernel-3@lo.gmane.org Original-Received: from vger.kernel.org ([209.132.180.67]) by lo.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1RpHKb-0008Bu-Fh for glk-linux-kernel-3@lo.gmane.org; Mon, 23 Jan 2012 11:40:57 +0100 Original-Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753263Ab2AWKkt (ORCPT ); Mon, 23 Jan 2012 05:40:49 -0500 Original-Received: from mx1.redhat.com ([209.132.183.28]:58739 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751990Ab2AWKks (ORCPT ); Mon, 23 Jan 2012 05:40:48 -0500 Original-Received: from int-mx12.intmail.prod.int.phx2.redhat.com (int-mx12.intmail.prod.int.phx2.redhat.com [10.5.11.25]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id q0NAelMx027033 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Mon, 23 Jan 2012 05:40:47 -0500 Original-Received: from ndevos.usersys.redhat.com (dhcp-1-51.fab.redhat.com [10.33.1.51]) by int-mx12.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id q0NAejLn013691; Mon, 23 Jan 2012 05:40:46 -0500 In-Reply-To: <4F19356E.3020708@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.25 Original-Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Xref: news.gmane.org gmane.linux.kernel:1242432 gmane.linux.file-systems:60751 Archived-At: Executing an fsync() on a file-descriptor of a partition flushes the caches for that partition by calling blkdev_issue_flush(). However, it seems that reading data through the parent device will still return the old cached data. The cache for the block-device is not synced if the block-device is kept open (due to a mounted partition, for example). Only when all users for the disk have exited, the cache for the disk is made consistent again. Calling invalidate_bdev() on the parent block-device in case blkdev_fsync() was called for a partition, fixes this. The problem can be worked around by forcing the caches to be flushed with either # blockdev --flushbufs ${dev_disk} or # echo 3 > /proc/sys/vm/drop_caches CC: Bryn M. Reeves CC: Mikulas Patocka Signed-off-by: Niels de Vos --- v2: - Do not call invalidate_bdev() from blkdev_issue_flush() and prevent performance degration with journalled filesystems. Suggested was to call invalidate_bdev() in fsync_bdev(), but this is not in the call-path of mkfs.ext3 and similar tools. Hence the issue persists. - Correct phrasing a little, changing ioctl-BLKFLSBUF is not required. - This issue also occurs when doing an ioctl-BLKFLSBUF on a partition. Reading the whole disk will still return cached data. If this is an issue, it will need a seperate patch. --- fs/block_dev.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-) diff --git a/fs/block_dev.c b/fs/block_dev.c index 0e575d1..433c4de 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -424,6 +424,10 @@ int blkdev_fsync(struct file *filp, loff_t start, loff_t end, int datasync) if (error == -EOPNOTSUPP) error = 0; + /* invalidate parent block_device */ + if (!error && bdev != bdev->bd_contains) + invalidate_bdev(bdev->bd_contains); + return error; } EXPORT_SYMBOL(blkdev_fsync); -- 1.7.6.5