On Thu, Jul 30, 2015 at 09:52:15AM -0400, Jeff Layton wrote:
> Currently, nfsd uses a singlethread workqueue for this, but that's
> probably not necessary. If we have multiple namespaces, then there's no
> need to serialize the laundromat runs. They can run in parallel.
Running a singled-threaded workqueue for each namespace is one thing,
but if we're allowing multiple work items for one namespace to run
simultaneously then this would need more of an argument.
However... I guess we only requeue this from the end of the work
itself, so there's no risk of concurrent execution here, OK, fine.
--b.
>
> Also, create_singlethread_workqueue adds the WQ_MEM_RECLAIM flag, which
> doesn't really seem to be necessary. The laundromat jobs are always
> kicked off via a timer, and not from memory reclaim paths. There's no
> need for a rescuer thread.
>
> Signed-off-by: Jeff Layton <jeff.layton@xxxxxxxxxxxxxxx>
> ---
> fs/nfsd/nfs4state.c | 23 +++++------------------
> fs/nfsd/nfsd.h | 1 +
> fs/nfsd/nfssvc.c | 14 +++++++++++++-
> 3 files changed, 19 insertions(+), 19 deletions(-)
>
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 79795c898dd1..977a8aee9122 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -4376,7 +4376,6 @@ nfs4_laundromat(struct nfsd_net *nn)
> return new_timeo;
> }
>
> -static struct workqueue_struct *laundry_wq;
> static void laundromat_main(struct work_struct *);
>
> static void
> @@ -4390,7 +4389,7 @@ laundromat_main(struct work_struct *laundry)
>
> t = nfs4_laundromat(nn);
> dprintk("NFSD: laundromat_main - sleeping for %ld seconds\n", t);
> - queue_delayed_work(laundry_wq, &nn->laundromat_work, t*HZ);
> + queue_delayed_work(nfsd_laundry_wq, &nn->laundromat_work, t*HZ);
> }
>
> static inline __be32 nfs4_check_fh(struct svc_fh *fhp, struct nfs4_stid *stp)
> @@ -6587,7 +6586,8 @@ nfs4_state_start_net(struct net *net)
> nfsd4_client_tracking_init(net);
> printk(KERN_INFO "NFSD: starting %ld-second grace period (net %p)\n",
> nn->nfsd4_grace, net);
> - queue_delayed_work(laundry_wq, &nn->laundromat_work, nn->nfsd4_grace * HZ);
> + queue_delayed_work(nfsd_laundry_wq, &nn->laundromat_work,
> + nn->nfsd4_grace * HZ);
> return 0;
> }
>
> @@ -6601,22 +6601,10 @@ nfs4_state_start(void)
> ret = set_callback_cred();
> if (ret)
> return -ENOMEM;
> - laundry_wq = create_singlethread_workqueue("nfsd4");
> - if (laundry_wq == NULL) {
> - ret = -ENOMEM;
> - goto out_recovery;
> - }
> ret = nfsd4_create_callback_queue();
> - if (ret)
> - goto out_free_laundry;
> -
> - set_max_delegations();
> -
> - return 0;
> + if (!ret)
> + set_max_delegations();
>
> -out_free_laundry:
> - destroy_workqueue(laundry_wq);
> -out_recovery:
> return ret;
> }
>
> @@ -6653,7 +6641,6 @@ nfs4_state_shutdown_net(struct net *net)
> void
> nfs4_state_shutdown(void)
> {
> - destroy_workqueue(laundry_wq);
> nfsd4_destroy_callback_queue();
> }
>
> diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
> index cf980523898b..0199415344ff 100644
> --- a/fs/nfsd/nfsd.h
> +++ b/fs/nfsd/nfsd.h
> @@ -62,6 +62,7 @@ struct readdir_cd {
> extern struct svc_program nfsd_program;
> extern struct svc_version nfsd_version2, nfsd_version3,
> nfsd_version4;
> +extern struct workqueue_struct *nfsd_laundry_wq;
> extern struct mutex nfsd_mutex;
> extern spinlock_t nfsd_drc_lock;
> extern unsigned long nfsd_drc_max_mem;
> diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
> index ad4e2377dd63..ced9944201a0 100644
> --- a/fs/nfsd/nfssvc.c
> +++ b/fs/nfsd/nfssvc.c
> @@ -17,6 +17,7 @@
> #include <linux/lockd/bind.h>
> #include <linux/nfsacl.h>
> #include <linux/seq_file.h>
> +#include <linux/workqueue.h>
> #include <net/net_namespace.h>
> #include "nfsd.h"
> #include "cache.h"
> @@ -28,6 +29,9 @@
> extern struct svc_program nfsd_program;
> static int nfsd(void *vrqstp);
>
> +/* A workqueue for nfsd-related cleanup tasks */
> +struct workqueue_struct *nfsd_laundry_wq;
> +
> /*
> * nfsd_mutex protects nn->nfsd_serv -- both the pointer itself and the members
> * of the svc_serv struct. In particular, ->sv_nrthreads but also to some
> @@ -224,11 +228,19 @@ static int nfsd_startup_generic(int nrservs)
> if (ret)
> goto dec_users;
>
> + ret = -ENOMEM;
> + nfsd_laundry_wq = alloc_workqueue("%s", WQ_UNBOUND, 0, "nfsd-laundry");
> + if (!nfsd_laundry_wq)
> + goto out_racache;
> +
> ret = nfs4_state_start();
> if (ret)
> - goto out_racache;
> + goto out_wq;
> return 0;
>
> +out_wq:
> + destroy_workqueue(nfsd_laundry_wq);
> + nfsd_laundry_wq = NULL;
> out_racache:
> nfsd_racache_shutdown();
> dec_users:
> --
> 2.4.3
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