Commit 47e98814 authored by Mike Snitzer's avatar Mike Snitzer Committed by Anna Schumaker
Browse files

nfsd: add nfsd_serv_try_get and nfsd_serv_put 



Introduce nfsd_serv_try_get and nfsd_serv_put and update the nfsd code
to prevent nfsd_destroy_serv from destroying nn->nfsd_serv until any
caller of nfsd_serv_try_get releases their reference using nfsd_serv_put.

A percpu_ref is used to implement the interlock between
nfsd_destroy_serv and any caller of nfsd_serv_try_get.

This interlock is needed to properly wait for the completion of client
initiated localio calls to nfsd (that are _not_ in the context of nfsd).

Signed-off-by: default avatarMike Snitzer <snitzer@kernel.org>
Reviewed-by: default avatarChuck Lever <chuck.lever@oracle.com>
Reviewed-by: default avatarJeff Layton <jlayton@kernel.org>
Reviewed-by: default avatarNeilBrown <neilb@suse.de>
Signed-off-by: default avatarAnna Schumaker <anna.schumaker@oracle.com>
parent c63f0e48

fs/nfsd/netns.h

+7 −1
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ 
#include <linux/filelock.h>

#include <linux/nfs4.h>

#include <linux/percpu_counter.h>

#include <linux/percpu-refcount.h>

#include <linux/siphash.h>

#include <linux/sunrpc/stats.h>
@@ -139,7 +140,9 @@ struct nfsd_net { 


	struct svc_info nfsd_info;

#define nfsd_serv nfsd_info.serv



	struct percpu_ref nfsd_serv_ref;

	struct completion nfsd_serv_confirm_done;

	struct completion nfsd_serv_free_done;



	/*

	 * clientid and stateid data for construction of net unique COPY
@@ -222,6 +225,9 @@ struct nfsd_net { 
extern bool nfsd_support_version(int vers);

extern unsigned int nfsd_net_id;



bool nfsd_serv_try_get(struct net *net);

void nfsd_serv_put(struct net *net);



void nfsd_copy_write_verifier(__be32 verf[2], struct nfsd_net *nn);

void nfsd_reset_write_verifier(struct nfsd_net *nn);

#endif /* __NFSD_NETNS_H__ */

fs/nfsd/nfssvc.c

+43 −0
Original line number Diff line number Diff line
@@ -193,6 +193,34 @@ int nfsd_minorversion(struct nfsd_net *nn, u32 minorversion, enum vers_op change 
	return 0;

}



bool nfsd_serv_try_get(struct net *net)

{

	struct nfsd_net *nn = net_generic(net, nfsd_net_id);



	return (nn && percpu_ref_tryget_live(&nn->nfsd_serv_ref));

}



void nfsd_serv_put(struct net *net)

{

	struct nfsd_net *nn = net_generic(net, nfsd_net_id);



	percpu_ref_put(&nn->nfsd_serv_ref);

}



static void nfsd_serv_done(struct percpu_ref *ref)

{

	struct nfsd_net *nn = container_of(ref, struct nfsd_net, nfsd_serv_ref);



	complete(&nn->nfsd_serv_confirm_done);

}



static void nfsd_serv_free(struct percpu_ref *ref)

{

	struct nfsd_net *nn = container_of(ref, struct nfsd_net, nfsd_serv_ref);



	complete(&nn->nfsd_serv_free_done);

}



/*

 * Maximum number of nfsd processes

 */
@@ -392,6 +420,7 @@ static void nfsd_shutdown_net(struct net *net) 
		lockd_down(net);

		nn->lockd_up = false;

	}

	percpu_ref_exit(&nn->nfsd_serv_ref);

	nn->nfsd_net_up = false;

	nfsd_shutdown_generic();

}
@@ -471,6 +500,13 @@ void nfsd_destroy_serv(struct net *net) 
	struct nfsd_net *nn = net_generic(net, nfsd_net_id);

	struct svc_serv *serv = nn->nfsd_serv;



	lockdep_assert_held(&nfsd_mutex);



	percpu_ref_kill_and_confirm(&nn->nfsd_serv_ref, nfsd_serv_done);

	wait_for_completion(&nn->nfsd_serv_confirm_done);

	wait_for_completion(&nn->nfsd_serv_free_done);

	/* percpu_ref_exit is called in nfsd_shutdown_net */



	spin_lock(&nfsd_notifier_lock);

	nn->nfsd_serv = NULL;

	spin_unlock(&nfsd_notifier_lock);
@@ -595,6 +631,13 @@ int nfsd_create_serv(struct net *net) 
	if (nn->nfsd_serv)

		return 0;



	error = percpu_ref_init(&nn->nfsd_serv_ref, nfsd_serv_free,

				0, GFP_KERNEL);

	if (error)

		return error;

	init_completion(&nn->nfsd_serv_free_done);

	init_completion(&nn->nfsd_serv_confirm_done);



	if (nfsd_max_blksize == 0)

		nfsd_max_blksize = nfsd_get_default_max_blksize();

	nfsd_reset_versions(nn);