Messages in this thread | | | Date | Mon, 10 Sep 2012 12:43:31 +0400 | From | Stanislav Kinsbursky <> | Subject | Re: [PATCH v2] SUNRPC: check current nsproxy before set of node name on client creation |
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08.09.2012 18:33, Myklebust, Trond пишет: > On Sat, 2012-09-08 at 08:59 +0300, Stanislav Kinsbursky wrote: >> 08.09.2012 01:32, Myklebust, Trond пишет: >>> On Mon, 2012-08-13 at 08:10 -0400, Jeff Layton wrote: >>>> On Mon, 13 Aug 2012 15:37:31 +0400 >>>> Stanislav Kinsbursky <skinsbursky@parallels.com> wrote: >>>> >>>>> v2: >>>>> 1) rpc_clnt_set_nodename() prototype updated. >>>>> 2) fixed errors in comment. >>>>> >>>>> When child reaper exits, it can destroy mount namespace it belongs to, and if >>>>> there are NFS mounts inside, then it will try to umount them. But in this >>>>> point current->nsproxy is set to NULL and all namespaces will be destroyed one >>>>> by one. I.e. we can't dereference current->nsproxy to obtain uts namespace. >>>>> >>>>> Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> >>>>> --- >>>>> net/sunrpc/clnt.c | 16 +++++++++++++--- >>>>> 1 files changed, 13 insertions(+), 3 deletions(-) >>>>> >>>>> diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c >>>>> index 9a9676e..8fbcbc8 100644 >>>>> --- a/net/sunrpc/clnt.c >>>>> +++ b/net/sunrpc/clnt.c >>>>> @@ -277,8 +277,18 @@ void rpc_clients_notifier_unregister(void) >>>>> return rpc_pipefs_notifier_unregister(&rpc_clients_block); >>>>> } >>>>> >>>>> -static void rpc_clnt_set_nodename(struct rpc_clnt *clnt, const char *nodename) >>>>> +static void rpc_clnt_set_nodename(struct rpc_clnt *clnt) >>>>> { >>>>> + const char *nodename; >>>>> + >>>>> + /* >>>>> + * We have to protect against dying child reaper, which has released >>>>> + * its nsproxy already and is trying to destroy mount namespace. >>>>> + */ >>>>> + if (current->nsproxy == NULL) >>>>> + return; >>>>> + >>>>> + nodename = utsname()->nodename; >>>>> clnt->cl_nodelen = strlen(nodename); >>>>> if (clnt->cl_nodelen > UNX_MAXNODENAME) >>>>> clnt->cl_nodelen = UNX_MAXNODENAME; >>>>> @@ -365,7 +375,7 @@ static struct rpc_clnt * rpc_new_client(const struct rpc_create_args *args, stru >>>>> } >>>>> >>>>> /* save the nodename */ >>>>> - rpc_clnt_set_nodename(clnt, utsname()->nodename); >>>>> + rpc_clnt_set_nodename(clnt); >>>>> rpc_register_client(clnt); >>>>> return clnt; >>>>> >>>>> @@ -524,7 +534,7 @@ rpc_clone_client(struct rpc_clnt *clnt) >>>>> err = rpc_setup_pipedir(new, clnt->cl_program->pipe_dir_name); >>>>> if (err != 0) >>>>> goto out_no_path; >>>>> - rpc_clnt_set_nodename(new, utsname()->nodename); >>>>> + rpc_clnt_set_nodename(new); >>>>> if (new->cl_auth) >>>>> atomic_inc(&new->cl_auth->au_count); >>>>> atomic_inc(&clnt->cl_count); >>>>> >>>>> -- >>>>> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in >>>>> the body of a message to majordomo@vger.kernel.org >>>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>>> Acked-by: Jeff Layton <jlayton@redhat.com> >>> OK, colour me confused (again). >> >> What color? >> >>> Why should a umount trigger an >>> rpc_create() or rpc_clone_client()? >> >> It calls nsm_create(). >> Here is the trace (https://bugzilla.redhat.com/show_bug.cgi?id=830862, >> comment 68): > > Right, but if we're using NFSv3 lock monitoring, we know in advance that > we're going to need an nsm call to localhost. Why can't we just cache > the one that we used to start lock monitoring in the first place? >
Do you suggest to cache the call or the client for the call?
-- Best regards, Stanislav Kinsbursky -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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