On Thu, Jun 19, 2014 at 10:49:08AM -0400, Jeff Layton wrote:
> From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
>
> state_lock is a heavily contended global lock. We don't want to grab
> that while simultaneously holding the inode->i_lock
> Instead do the list manipulations from the work queue context prior to
> starting the rpc call.
The description should mention that a new lock is added to facilitate this.
> void nfsd4_init_callback(struct nfsd4_callback *cb)
> {
> INIT_WORK(&cb->cb_work, nfsd4_do_callback_rpc);
> }
We still call nfsd4_init_callback for delegations after this patch,
and thus first initialize the work item to nfsd4_do_callback_rpc
and later overide it. But I think initializing the work item
before queueing up the callback is pretty silly anyway, so I'd suggest
adding a patch before this one to just kill nfsd4_init_callback and
initialize the item in do_probe_callback and nfsd4_cb_recall directly.
> -static void nfsd_break_one_deleg(struct nfs4_delegation *dp)
> +void nfsd4_prepare_cb_recall(struct nfs4_delegation *dp)
> {
> struct nfs4_client *clp = dp->dl_stid.sc_client;
> struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);
>
> - lockdep_assert_held(&state_lock);
> + /*
> + * We can't do this in nfsd_break_deleg_cb because it is
> + * already holding inode->i_lock
> + */
Can't is a little too strong given that it did indeed work before.
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