Re: [PATCH 0/3] nfsd: fix error handling in write_ports interfaces

["J. Bruce Fields" <bfields@fieldses.org>]

On Mon, Jun 07, 2010 at 11:33:17AM -0400, Jeff Layton wrote:
> This patchset fixes some problems with refcounting when there are
> problems starting up nfsd. The easiest way to reproduce this is to have
> rpcbind down and then try to start nfsd. The write_ports calls will
> generally return failure at that point due to the fact that lockd can't
> register its ports. That leaves the nfsd_serv pointer set, with the
> sv_threads count set at 0. The first two patches fix this problem.
> 
> The third patch, I'm not 100% sure on. It looks correct to me, but the
> intent of the existing code is not very clear. I know this interface is
> used by the rdma code, and I may be missing the point of doing it this
> way. If the existing code is correct as-is, I'll plan to do a patch to
> add some clarifying comments.
> 
> It also seems suspicious to me that __write_ports_addfd/delfd take and
> put lockd references, but the addxprt/delxprt interfaces do not. If
> someone were to addfd a socket and then delxprt it, it'll leave a lockd
> reference dangling.

I haven't looked at this closely enough to have any though beyond: boy,
it seems confusing to use sv_nrthreads this way.  What is the
refcounting actually meant to accomplish, and if we were designing it
from scratch, what would we do?

--b.

> 
> Should we be taking and putting lockd references in those codepaths as
> well?
> 
> Jeff Layton (3):
>   nfsd: don't try to shut down nfs4 state handling unless it's up
>   nfsd: fix error handling when starting nfsd with rpcbind down
>   nfsd: fix error handling in __write_ports_addxprt
> 
>  fs/nfsd/nfs4state.c |    2 ++
>  fs/nfsd/nfsctl.c    |   18 ++++++++++++------
>  2 files changed, 14 insertions(+), 6 deletions(-)
>