Re: [PATCH v2 1/2] gfs2: Convert gfs2 to fs_context

[Andrew Price <anprice@redhat.com>]

On 19/03/2019 17:05, David Howells wrote:
> Andrew Price <anprice@redhat.com> wrote:
> 
>> +			pr_warn("-o debug and -o errors=panic are mutually exclusive\n");
>> +			return -EINVAL;
> 
> return invalf(fc, "gfs2: -o debug and -o errors=panic are mutually exclusive");

Thanks.

> 
> (Note: no "\n")
> 
>> +		if (result.int_32 > 0)
>> +			args->ar_quota = opt_quota_values[result.int_32];
>> +		else if (result.negated)
>> +			args->ar_quota = GFS2_QUOTA_OFF;
>> +		else
>> +			args->ar_quota = GFS2_QUOTA_ON;
> 
> I recommend checking result.negated first.

OK

> 
>> +	/* Not allowed to change locking details */
>> +	if (strcmp(newargs->ar_lockproto, oldargs->ar_lockproto) ||
>> +	    strcmp(newargs->ar_locktable, oldargs->ar_locktable) ||
>> +	    strcmp(newargs->ar_hostdata, oldargs->ar_hostdata))
>> +		return -EINVAL;
> 
> Use errorf().  (Not invalf - the parameter isn't exactly invalid, it's just
> that you're not allowed to do this operation).

Yes, that makes more sense.

>> +			error = gfs2_make_fs_ro(sdp);
>> +		else
>> +			error = gfs2_make_fs_rw(sdp);
>> +		if (error)
>> +			return error;
> 
> Might want to call errorf() here too.
> 
>> -	s = sget(&gfs2_fs_type, test_gfs2_super, set_meta_super, flags,
>> +	s = sget(&gfs2_fs_type, test_meta_super, set_meta_super, flags,
> 
> Try and use sget_fc() please.

That happens in patch 2/2 for gfs2meta. I might just roll both patches 
together in v3 so there's no intermediate churn.

> If you look at the fuse patchset I cc'd you on,
> there's a commit there that adds a ->bdev and ->bdev_mode to fs_context that
> may be of use to you.

Yes, that looks useful - thanks.

> Can you use vfs_get_block_super()?

It might be possible if we can rearrange things so that this can be done 
outside of the function:

         if (args->ar_meta)
                 fc->root = dget(sdp->sd_master_dir);
         else
                 fc->root = dget(sdp->sd_root_dir);

but we can't do that in our fill_super() because it needs to be selected 
whether we have an existing mount or not.

> Would it be of use to export
> test_bdev_super_fc() and set_bdev_super_fc()?

There's only a little maintenance value in it, I think, but we could 
certainly use them in gfs2 if we can't solve the fc->root selection issue.

Andy