From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stanislav Kinsbursky Subject: Re: [PATCH 2/4] NFS: replace per-net client lock by mutex Date: Mon, 27 Feb 2012 19:42:49 +0400 Message-ID: <4F4BA479.60907@parallels.com> References: <20120227134623.13371.61185.stgit@localhost6.localdomain6> <20120227134900.13371.96849.stgit@localhost6.localdomain6> <1330354815.5541.24.camel@lade.trondhjem.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: "linux-nfs@vger.kernel.org" , Pavel Emelianov , "neilb@suse.de" , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , James Bottomley , "bfields@fieldses.org" , "davem@davemloft.net" , "devel@openvz.org" To: "Myklebust, Trond" Return-path: In-Reply-To: <1330354815.5541.24.camel@lade.trondhjem.org> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org 27.02.2012 19:00, Myklebust, Trond =D0=BF=D0=B8=D1=88=D0=B5=D1=82: > On Mon, 2012-02-27 at 17:49 +0400, Stanislav Kinsbursky wrote: >> Lockdep is sad otherwise, because inode mutex is taken on PipeFS den= try >> creation, which can be called on mount notification, where this per-= net client >> lock is taken on clients list walk. >> >> Note: I used simple mutex instead of rw semaphore because of >> nfs_put_client->atomic_dec_and_mutex_lock() call. Probably, there is= a better >> solution here. >> >> Signed-off-by: Stanislav Kinsbursky >> > > This is overkill... We end up blocking NFSv4 callbacks while the > rpc_pipefs notifier runs through the nfs_clients creating or destroyi= ng > idmapper dentries. > > Surely the rpc_pipefs_event() can take a reference to the nfs_client = and > then drop the spin_lock if it sees that it needs to create or destroy= a > dentry? > Sure, thanks for notice. Looks like this logic also works to SUNRPC clients. I'll send updated version soon. --=20 Best regards, Stanislav Kinsbursky