On Tue, May 03, 2016 at 11:34:50PM +0300, Yauhen Kharuzhy wrote:
> On Tue, May 03, 2016 at 07:31:48PM +0200, David Sterba wrote:
> > On Thu, Apr 14, 2016 at 06:24:10PM +0800, Anand Jain wrote:
> > > Yauhen reported in the ML that s_bdev is null at mount, and
> > > s_bdev gets updated to some device when missing device is
> > > replaced, as because bdev is null for missing device, things
> > > gets matched up. Fix this by checking if s_bdev is set. I
> > > didn't want to completely remove updating s_bdev because
> > > the future multi device support at vfs layer may need it.
> > >
> > > Signed-off-by: Anand Jain <anand.jain@xxxxxxxxxx>
> > > Reported-by: Yauhen Kharuzhy <yauhen.kharuzhy@xxxxxxxxxxxxx>
> >
> > Do you have a testcase for that? As there are more patches touching the
> > device pointers I'd rather see some test coverage. Thanks.
>
> Testcase is ('global spare' patchset is needed for device closing
> support):
>
> 1) create RAID, mount -> s_bdev is NULL
sorry, for match old s_bdev (NULL) with replaced device:
1.1) remove latest drive and touch FS to make device missing -> device->bdev is NULL
> 2) replace latest device by another -> s_bdev is bdev of new drive
> 3) remove drive added by replace
> 4) touch mountpount and do btrfs fi sync (device will be closed and
> marked as missing here) -> s_bdev is invalid pointer to closed and freed
> bdev
> 5) unmount FS -> oops
>
> Something like:
>
> mkfs.btrfs -d raid5 -m raid5 <dev1> <dev2>... <devN-1>
> mount <dev1> /mnt
_devmgt_remove <devN-1>
touch /mnt
btrfs fi sync /mnt
btrfs replace start -B <missing devid> <devN> /mnt
> _devmgt_remove <devN> # _devmgt_remove is helper for detaching scsi device
> touch /mnt
> btrfs fi sync /mnt
> umount /mnt
>
>
> I will try to make xfstest scripts for this case and for other cases
> reported by me.
>
> --
> Yauhen Kharuzhy
--
Yauhen Kharuzhy
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