Return-Path: Received: from mail-iw0-f174.google.com ([209.85.214.174]:60343 "EHLO mail-iw0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752483Ab0LXBcg (ORCPT ); Thu, 23 Dec 2010 20:32:36 -0500 Received: by iwn9 with SMTP id 9so6655796iwn.19 for ; Thu, 23 Dec 2010 17:32:36 -0800 (PST) From: Chuck Lever Subject: [PATCH 1/4] NFS: Allow walking nfs_client.cl_superblocks list outside client.c To: trond.myklebust@netapp.com Cc: linux-nfs@vger.kernel.org Date: Thu, 23 Dec 2010 20:32:32 -0500 Message-ID: <20101224013232.2445.72763.stgit@matisse.1015granger.net> In-Reply-To: <20101224012636.2445.41411.stgit@matisse.1015granger.net> References: <20101224012636.2445.41411.stgit@matisse.1015granger.net> Content-Type: text/plain; charset="utf-8" Sender: linux-nfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 We're about to move some fields from struct nfs_client to struct nfs_server. There is a many-to-one relationship between nfs_servers and nfs_clients. After these fields are moved to the nfs_server struct, to visit all of the data in these fields that is owned by one nfs_client, code will need to visit each nfs_server on the cl_superblocks list for that nfs_client. To serialize changes to the cl_superblocks list during these little expeditions, protect the list with RCU. Signed-off-by: Chuck Lever --- fs/nfs/client.c | 44 +++++++++++++++++++++++++------------------- fs/nfs/nfs4renewd.c | 9 +++++++-- 2 files changed, 32 insertions(+), 21 deletions(-) diff --git a/fs/nfs/client.c b/fs/nfs/client.c index 0870d0d..05e2ee2 100644 --- a/fs/nfs/client.c +++ b/fs/nfs/client.c @@ -988,6 +988,27 @@ static void nfs_server_copy_userdata(struct nfs_server *target, struct nfs_serve target->options = source->options; } +static void nfs_server_insert_lists(struct nfs_server *server) +{ + struct nfs_client *clp = server->nfs_client; + + spin_lock(&nfs_client_lock); + list_add_tail_rcu(&server->client_link, &clp->cl_superblocks); + list_add_tail(&server->master_link, &nfs_volume_list); + spin_unlock(&nfs_client_lock); + +} + +static void nfs_server_remove_lists(struct nfs_server *server) +{ + spin_lock(&nfs_client_lock); + list_del_rcu(&server->client_link); + list_del(&server->master_link); + spin_unlock(&nfs_client_lock); + + synchronize_rcu(); +} + /* * Allocate and initialise a server record */ @@ -1029,11 +1050,8 @@ void nfs_free_server(struct nfs_server *server) { dprintk("--> nfs_free_server()\n"); + nfs_server_remove_lists(server); unset_pnfs_layoutdriver(server); - spin_lock(&nfs_client_lock); - list_del(&server->client_link); - list_del(&server->master_link); - spin_unlock(&nfs_client_lock); if (server->destroy != NULL) server->destroy(server); @@ -1108,11 +1126,7 @@ struct nfs_server *nfs_create_server(const struct nfs_parsed_mount_data *data, (unsigned long long) server->fsid.major, (unsigned long long) server->fsid.minor); - spin_lock(&nfs_client_lock); - list_add_tail(&server->client_link, &server->nfs_client->cl_superblocks); - list_add_tail(&server->master_link, &nfs_volume_list); - spin_unlock(&nfs_client_lock); - + nfs_server_insert_lists(server); server->mount_time = jiffies; nfs_free_fattr(fattr); return server; @@ -1342,11 +1356,7 @@ static int nfs4_server_common_setup(struct nfs_server *server, if (server->namelen == 0 || server->namelen > NFS4_MAXNAMLEN) server->namelen = NFS4_MAXNAMLEN; - spin_lock(&nfs_client_lock); - list_add_tail(&server->client_link, &server->nfs_client->cl_superblocks); - list_add_tail(&server->master_link, &nfs_volume_list); - spin_unlock(&nfs_client_lock); - + nfs_server_insert_lists(server); server->mount_time = jiffies; out: nfs_free_fattr(fattr); @@ -1551,11 +1561,7 @@ struct nfs_server *nfs_clone_server(struct nfs_server *source, if (error < 0) goto out_free_server; - spin_lock(&nfs_client_lock); - list_add_tail(&server->client_link, &server->nfs_client->cl_superblocks); - list_add_tail(&server->master_link, &nfs_volume_list); - spin_unlock(&nfs_client_lock); - + nfs_server_insert_lists(server); server->mount_time = jiffies; nfs_free_fattr(fattr_fsinfo); diff --git a/fs/nfs/nfs4renewd.c b/fs/nfs/nfs4renewd.c index 72b6c58..cde5650 100644 --- a/fs/nfs/nfs4renewd.c +++ b/fs/nfs/nfs4renewd.c @@ -63,9 +63,14 @@ nfs4_renew_state(struct work_struct *work) ops = clp->cl_mvops->state_renewal_ops; dprintk("%s: start\n", __func__); - /* Are there any active superblocks? */ - if (list_empty(&clp->cl_superblocks)) + + rcu_read_lock(); + if (list_empty(&clp->cl_superblocks)) { + rcu_read_unlock(); goto out; + } + rcu_read_unlock(); + spin_lock(&clp->cl_lock); lease = clp->cl_lease_time; last = clp->cl_last_renewal;