From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from aserp2120.oracle.com ([141.146.126.78]:44000 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751780AbeAPLoi (ORCPT ); Tue, 16 Jan 2018 06:44:38 -0500 Subject: Re: [PATCH v4 2/4] btrfs: cleanup btrfs_mount() using btrfs_mount_root() To: dsterba@suse.cz, "Misono, Tomohiro" , linux-btrfs@vger.kernel.org References: <7dbb897c-1f1d-b54b-0cea-2a1c6c1d5027@jp.fujitsu.com> <28c4963f-9e87-ce42-7c6a-85d32cd71951@oracle.com> <20180115192615.GF13726@twin.jikos.cz> From: Anand Jain Message-ID: <2e0c866f-42e4-6a9c-a562-e3724062b0f9@oracle.com> Date: Tue, 16 Jan 2018 19:45:35 +0800 MIME-Version: 1.0 In-Reply-To: <20180115192615.GF13726@twin.jikos.cz> Content-Type: text/plain; charset=utf-8; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 01/16/2018 03:26 AM, David Sterba wrote: > On Fri, Jan 12, 2018 at 06:14:40PM +0800, Anand Jain wrote: >> >> Misono, >> >> This change is causing subsequent (subvol) mount to fail when device >> option is specified. The simplest eg for failure is .. >> mkfs.btrfs -qf /dev/sdc /dev/sdb >> mount -o device=/dev/sdb /dev/sdc /btrfs >> mount -o device=/dev/sdb /dev/sdc /btrfs1 >> mount: /dev/sdc is already mounted or /btrfs1 busy >> >> Looks like >> blkdev_get_by_path() <-- is failing. >> btrfs_scan_one_device() >> btrfs_parse_early_options() >> btrfs_mount() >> >> Which is due to different holders (viz. btrfs_root_fs_type and >> btrfs_fs_type) one is used for vfs_mount and other for scan, >> so they form different holders and can't let EXCL open which >> is needed for both scan and open. > > This looks close to what I see in the random test failures. I've > reverted your patch "btrfs: optimize move uuid_mutex closer to the > critical section" as I bisected to it. The uuid mutex around > blkdev_get_path probably protected the concurrent mount and scan so they > did not ask for EXCL at the same time. > > Reverting (or removing the patch from the current misc-next) queue is > simpler for me ATM as I want to get to a stable base now, we can add it > later if we understand the issue with the mount/scan. Right. I don't see above test case failing on your branch [1] which does not have the uuid_mutex patch. Quite strange, there isn't any concurrency (mount and scan) in this test case. [1] git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux.git for-next Ran xfstests, got stuck at btrfs/011 failures, (and will wait for Liubo's v2 patch). OR is there any other test case you were referring to as random test failures ? Thanks, Anand > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >