On Wed, May 04, 2016 at 03:23:29PM +0200, David Sterba wrote:
> On Tue, May 03, 2016 at 09:02:56AM +0800, Qu Wenruo wrote:
> >
> >
> > Liu Bo wrote on 2016/05/02 11:15 -0700:
> > > This adds valid checks for super_total_bytes, super_bytes_used and
> > > super_stripesize.
> > >
> > > Reported-by: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
> > > Reported-by: Quentin Casasnovas <quentin.casasnovas@xxxxxxxxxx>
> > > Signed-off-by: Liu Bo <bo.li.liu@xxxxxxxxxx>
> > > ---
> > > fs/btrfs/disk-io.c | 14 ++++++++++++++
> > > 1 file changed, 14 insertions(+)
> > >
> > > diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> > > index 4e47849..988d03f 100644
> > > --- a/fs/btrfs/disk-io.c
> > > +++ b/fs/btrfs/disk-io.c
> > > @@ -4120,6 +4120,20 @@ static int btrfs_check_super_valid(struct btrfs_fs_info *fs_info,
> > > * Hint to catch really bogus numbers, bitflips or so, more exact checks are
> > > * done later
> > > */
> > > + if (btrfs_super_total_bytes(sb) == 0) {
> > > + printk(KERN_ERR "BTRFS: total bytes is zero\n");
> > > + ret = -EINVAL;
> > > + }
> >
> > Would it be better if using "6 * nodesize"?
> >
> > I'd like to use a precious low limit on total bytes, but we don't have
> > such value, so 6 nodesize would be good.
>
> An early check can compare against some reasonable value, but the
> total_bytes value must be equal to the sum of all device sizes
> (disk_total_bytes). I'm not sure if we have enough information to verify
> that at this point though.
That's what I had in mind, the problem is that only the first device information is recorded in superblock.
At this moment We have device_num but we don't know the size of other devices.
Thanks,
-liubo
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