On Wed, Jan 03, 2024 at 08:36:52AM -0500, Jeff Layton wrote:
> It's not safe to call nfsd_put once nfsd_last_thread has been called, as
> that function will zero out the nn->nfsd_serv pointer.
>
> Drop the nfsd_put helper altogether and open-code the svc_put in its
> callers instead. That allows us to not be reliant on the value of that
> pointer when handling an error.
>
> Fixes: 2a501f55cd64 ("nfsd: call nfsd_last_thread() before final nfsd_put()")
> Reported-by: Zhi Li <yieli@xxxxxxxxxx>
> Cc: NeilBrown <neilb@xxxxxxx>
> Signed-off-by: Jeffrey Layton <jlayton@xxxxxxxxxx>
> ---
> I know it's late, but it would be good to get this into v6.7 if
> possible. I think it's fairly straightforward.
How is Zhi finding these? Are there administrative API tests that
can be shared with the community (say, by adding them to kdevops)?
> ---
> fs/nfsd/nfsctl.c | 31 +++++++++++++++++--------------
> fs/nfsd/nfsd.h | 7 -------
> 2 files changed, 17 insertions(+), 21 deletions(-)
>
> diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
> index 7cd513e59305..87fed75808ff 100644
> --- a/fs/nfsd/nfsctl.c
> +++ b/fs/nfsd/nfsctl.c
> @@ -693,6 +693,7 @@ static ssize_t __write_ports_addfd(char *buf, struct net *net, const struct cred
> char *mesg = buf;
> int fd, err;
> struct nfsd_net *nn = net_generic(net, nfsd_net_id);
> + struct svc_serv *serv;
>
> err = get_int(&mesg, &fd);
> if (err != 0 || fd < 0)
> @@ -703,15 +704,15 @@ static ssize_t __write_ports_addfd(char *buf, struct net *net, const struct cred
> if (err != 0)
> return err;
>
> - err = svc_addsock(nn->nfsd_serv, net, fd, buf, SIMPLE_TRANSACTION_LIMIT, cred);
> + serv = nn->nfsd_serv;
> + err = svc_addsock(serv, net, fd, buf, SIMPLE_TRANSACTION_LIMIT, cred);
>
> - if (err < 0 && !nn->nfsd_serv->sv_nrthreads && !nn->keep_active)
> + if (err < 0 && !serv->sv_nrthreads && !nn->keep_active)
> nfsd_last_thread(net);
> - else if (err >= 0 &&
> - !nn->nfsd_serv->sv_nrthreads && !xchg(&nn->keep_active, 1))
> - svc_get(nn->nfsd_serv);
> + else if (err >= 0 && !serv->sv_nrthreads && !xchg(&nn->keep_active, 1))
> + svc_get(serv);
>
> - nfsd_put(net);
> + svc_put(serv);
> return err;
> }
>
> @@ -725,6 +726,7 @@ static ssize_t __write_ports_addxprt(char *buf, struct net *net, const struct cr
> struct svc_xprt *xprt;
> int port, err;
> struct nfsd_net *nn = net_generic(net, nfsd_net_id);
> + struct svc_serv *serv;
>
> if (sscanf(buf, "%15s %5u", transport, &port) != 2)
> return -EINVAL;
> @@ -737,32 +739,33 @@ static ssize_t __write_ports_addxprt(char *buf, struct net *net, const struct cr
> if (err != 0)
> return err;
>
> - err = svc_xprt_create(nn->nfsd_serv, transport, net,
> + serv = nn->nfsd_serv;
> + err = svc_xprt_create(serv, transport, net,
> PF_INET, port, SVC_SOCK_ANONYMOUS, cred);
> if (err < 0)
> goto out_err;
>
> - err = svc_xprt_create(nn->nfsd_serv, transport, net,
> + err = svc_xprt_create(serv, transport, net,
> PF_INET6, port, SVC_SOCK_ANONYMOUS, cred);
> if (err < 0 && err != -EAFNOSUPPORT)
> goto out_close;
>
> - if (!nn->nfsd_serv->sv_nrthreads && !xchg(&nn->keep_active, 1))
> - svc_get(nn->nfsd_serv);
> + if (!serv->sv_nrthreads && !xchg(&nn->keep_active, 1))
> + svc_get(serv);
>
> - nfsd_put(net);
> + svc_put(serv);
> return 0;
> out_close:
> - xprt = svc_find_xprt(nn->nfsd_serv, transport, net, PF_INET, port);
> + xprt = svc_find_xprt(serv, transport, net, PF_INET, port);
> if (xprt != NULL) {
> svc_xprt_close(xprt);
> svc_xprt_put(xprt);
> }
> out_err:
> - if (!nn->nfsd_serv->sv_nrthreads && !nn->keep_active)
> + if (!serv->sv_nrthreads && !nn->keep_active)
> nfsd_last_thread(net);
>
> - nfsd_put(net);
> + svc_put(serv);
> return err;
> }
>
> diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
> index 3286ffacbc56..9ed0e08d16c2 100644
> --- a/fs/nfsd/nfsd.h
> +++ b/fs/nfsd/nfsd.h
> @@ -113,13 +113,6 @@ int nfsd_pool_stats_open(struct inode *, struct file *);
> int nfsd_pool_stats_release(struct inode *, struct file *);
> void nfsd_shutdown_threads(struct net *net);
>
> -static inline void nfsd_put(struct net *net)
> -{
> - struct nfsd_net *nn = net_generic(net, nfsd_net_id);
> -
> - svc_put(nn->nfsd_serv);
> -}
> -
> bool i_am_nfsd(void);
>
> struct nfsdfs_client {
>
> ---
> base-commit: 610a9b8f49fbcf1100716370d3b5f6f884a2835a
> change-id: 20240103-nfsd-fixes-1f1196134a11
>
> Best regards,
> --
> Jeff Layton <jlayton@xxxxxxxxxx>
>
--
Chuck Lever
