Re: [RFC PATCH 3/4] nfs/blocklayout: Fix premature PR key unregistration

[Christoph Hellwig <hch@lst.de>]

On Thu, Jun 20, 2024 at 09:52:59AM -0400, Benjamin Coddington wrote:
> On 20 Jun 2024, at 1:06, Christoph Hellwig wrote:
> 
> > On Wed, Jun 19, 2024 at 01:39:33PM -0400, cel@kernel.org wrote:
> >> -	if (test_bit(NFS_DEVICEID_UNAVAILABLE, &node->flags) == 0)
> >> +	if (test_bit(NFS_DEVICEID_UNAVAILABLE, &node->flags) == 0) {
> >
> > It might be worth to invert this and keep the unavailable handling in
> > the branch as that's the exceptional case.   That code is also woefully
> > under-documented and could have really used a comment.
> 
> The transient device handling in general, or just this bit of it?

Basically the code behind this NFS_DEVICEID_UNAVAILABLE check here.

> >> +		if (d->pr_reg)
> >> +			if (d->pr_reg(d) < 0)
> >> +				goto out_put;
> >
> > Empty line after variable declarations.  Also is there anything that
> > synchronizes the lookups here so that we don't do multiple registrations
> > in parallel?
> 
> I don't think there is.  Do we get an error if we register twice?

Yes.  That's the basically the same condition as the one that made
Chuck create this series.