On Thu, Jan 18, 2018 at 12:48:37PM +0800, Anand Jain wrote: > > On 2018/01/16 20:45, Anand Jain wrote: > >> 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. > > Sorry I was wrong. Looks like I have booted wrong kernel to test. > So I see the same problem even you have reverted the patch: > 'btrfs: optimize move uuid_mutex closer to the critical section' > in [1].
Yeah, the revert was result of an unreliable bisect, though I tried to run the reproducers repeatedly. I'm going to consider the patch again. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
