Return-Path: linux-nfs-owner@vger.kernel.org Received: from mail-qa0-f45.google.com ([209.85.216.45]:52061 "EHLO mail-qa0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753676AbaIONO3 (ORCPT ); Mon, 15 Sep 2014 09:14:29 -0400 Received: by mail-qa0-f45.google.com with SMTP id s7so3740017qap.18 for ; Mon, 15 Sep 2014 06:14:28 -0700 (PDT) From: Jeff Layton To: bfields@fieldses.org Cc: steved@redhat.com, linux-nfs@vger.kernel.org Subject: [PATCH v4 7/9] nfsd: serialize nfsdcltrack upcalls for a particular client Date: Mon, 15 Sep 2014 09:14:08 -0400 Message-Id: <1410786850-18194-8-git-send-email-jlayton@primarydata.com> In-Reply-To: <1410786850-18194-1-git-send-email-jlayton@primarydata.com> References: <1410786850-18194-1-git-send-email-jlayton@primarydata.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: In a later patch, we want to add a flag that will allow us to reduce the need for upcalls. In order to handle that correctly, we'll need to ensure that racing upcalls for the same client can't occur. In practice it should be rare for this to occur with a well-behaved client, but it is possible. Convert one of the bits in the cl_flags field to be an upcall bitlock, and use it to ensure that upcalls for the same client are serialized. Signed-off-by: Jeff Layton --- fs/nfsd/nfs4recover.c | 29 +++++++++++++++++++++++++++++ fs/nfsd/state.h | 1 + 2 files changed, 30 insertions(+) diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c index d1354d43e9ad..aa04d9f62419 100644 --- a/fs/nfsd/nfs4recover.c +++ b/fs/nfsd/nfs4recover.c @@ -1260,6 +1260,22 @@ nfsd4_umh_cltrack_init(struct net *net) } static void +nfsd4_cltrack_upcall_lock(struct nfs4_client *clp) +{ + wait_on_bit_lock(&clp->cl_flags, NFSD4_CLIENT_UPCALL_LOCK, + TASK_UNINTERRUPTIBLE); +} + +static void +nfsd4_cltrack_upcall_unlock(struct nfs4_client *clp) +{ + smp_mb__before_atomic(); + clear_bit(NFSD4_CLIENT_UPCALL_LOCK, &clp->cl_flags); + smp_mb__after_atomic(); + wake_up_bit(&clp->cl_flags, NFSD4_CLIENT_UPCALL_LOCK); +} + +static void nfsd4_umh_cltrack_create(struct nfs4_client *clp) { char *hexid, *has_session, *grace_start; @@ -1270,9 +1286,14 @@ nfsd4_umh_cltrack_create(struct nfs4_client *clp) dprintk("%s: can't allocate memory for upcall!\n", __func__); return; } + has_session = nfsd4_cltrack_client_has_session(clp); grace_start = nfsd4_cltrack_grace_start(nn->boot_time); + + nfsd4_cltrack_upcall_lock(clp); nfsd4_umh_cltrack_upcall("create", hexid, has_session, grace_start); + nfsd4_cltrack_upcall_unlock(clp); + kfree(has_session); kfree(grace_start); kfree(hexid); @@ -1288,7 +1309,11 @@ nfsd4_umh_cltrack_remove(struct nfs4_client *clp) dprintk("%s: can't allocate memory for upcall!\n", __func__); return; } + + nfsd4_cltrack_upcall_lock(clp); nfsd4_umh_cltrack_upcall("remove", hexid, NULL, NULL); + nfsd4_cltrack_upcall_unlock(clp); + kfree(hexid); } @@ -1306,7 +1331,11 @@ nfsd4_umh_cltrack_check(struct nfs4_client *clp) has_session = nfsd4_cltrack_client_has_session(clp); legacy = nfsd4_cltrack_legacy_recdir(&clp->cl_name); + + nfsd4_cltrack_upcall_lock(clp); ret = nfsd4_umh_cltrack_upcall("check", hexid, has_session, legacy); + nfsd4_cltrack_upcall_unlock(clp); + kfree(has_session); kfree(legacy); kfree(hexid); diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h index 10bfda710f71..a0ed18f00dcb 100644 --- a/fs/nfsd/state.h +++ b/fs/nfsd/state.h @@ -306,6 +306,7 @@ struct nfs4_client { #define NFSD4_CLIENT_STABLE (2) /* client on stable storage */ #define NFSD4_CLIENT_RECLAIM_COMPLETE (3) /* reclaim_complete done */ #define NFSD4_CLIENT_CONFIRMED (4) /* client is confirmed */ +#define NFSD4_CLIENT_UPCALL_LOCK (5) /* upcall serialization */ #define NFSD4_CLIENT_CB_FLAG_MASK (1 << NFSD4_CLIENT_CB_UPDATE | \ 1 << NFSD4_CLIENT_CB_KILL) unsigned long cl_flags; -- 1.9.3