Re: [PATCH] Btrfs: fix how we freeze

[Josef Bacik <josef@redhat.com>]

On Tue, Mar 23, 2010 at 11:25:18PM +0800, Wengang Wang wrote:
> On 10-03-23 11:03, Josef Bacik wrote:
> > On Tue, Mar 23, 2010 at 10:54:08PM +0800, Wengang Wang wrote:
> > > Hi,
> > > 
> > > If the only thing is returning 0 in the freeze/unfreeze member functions, why
> > > not just remove the two functions?
> > > 
> > 
> > Because if the fs doesn't provide a freeze/unfreeze function, trying to do a
> > freeze will return -EOPNOTSUPP, which is not what we want.  Thanks,
> 
> How does freeze_fs()/unfreeze_fs() get called in btrfs? I think they
> called by freeze_bdev()/unfreeze_fs() respectively. And I don't see
> -EOPNOTSUPP is returned in the later two functions.
> 

its in ioctl_fsfreeze,

        /* If filesystem doesn't support freeze feature, return. */
        if (sb->s_op->freeze_fs == NULL)
                return -EOPNOTSUPP;

Thanks,

Josef