Commit 0cc11a61 authored by Jeff Layton's avatar Jeff Layton Committed by J. Bruce Fields
Browse files

nfsd: move blocked lock handling under a dedicated spinlock 



Bruce was hitting some lockdep warnings in testing, showing that we
could hit a deadlock with the new CB_NOTIFY_LOCK handling, involving a
rather complex situation involving four different spinlocks.

The crux of the matter is that we end up taking the nn->client_lock in
the lm_notify handler. The simplest fix is to just declare a new
per-nfsd_net spinlock to protect the new CB_NOTIFY_LOCK structures.

Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
parent 07d9a380

fs/nfsd/netns.h

+5 −0
Original line number Diff line number Diff line
@@ -84,6 +84,8 @@ struct nfsd_net { 
	struct list_head client_lru;

	struct list_head close_lru;

	struct list_head del_recall_lru;



	/* protected by blocked_locks_lock */

	struct list_head blocked_locks_lru;



	struct delayed_work laundromat_work;
@@ -91,6 +93,9 @@ struct nfsd_net { 
	/* client_lock protects the client lru list and session hash table */

	spinlock_t client_lock;



	/* protects blocked_locks_lru */

	spinlock_t blocked_locks_lock;



	struct file *rec_file;

	bool in_grace;

	const struct nfsd4_client_tracking_ops *client_tracking_ops;

fs/nfsd/nfs4state.c

+15 −13
Original line number Diff line number Diff line
@@ -217,7 +217,7 @@ find_blocked_lock(struct nfs4_lockowner *lo, struct knfsd_fh *fh, 
{

	struct nfsd4_blocked_lock *cur, *found = NULL;



	spin_lock(&nn->client_lock);

	spin_lock(&nn->blocked_locks_lock);

	list_for_each_entry(cur, &lo->lo_blocked, nbl_list) {

		if (fh_match(fh, &cur->nbl_fh)) {

			list_del_init(&cur->nbl_list);
@@ -226,7 +226,7 @@ find_blocked_lock(struct nfs4_lockowner *lo, struct knfsd_fh *fh, 
			break;

		}

	}

	spin_unlock(&nn->client_lock);

	spin_unlock(&nn->blocked_locks_lock);

	if (found)

		posix_unblock_lock(&found->nbl_lock);

	return found;
@@ -4665,7 +4665,7 @@ nfs4_laundromat(struct nfsd_net *nn) 
	 * indefinitely once the lock does become free.

	 */

	BUG_ON(!list_empty(&reaplist));

	spin_lock(&nn->client_lock);

	spin_lock(&nn->blocked_locks_lock);

	while (!list_empty(&nn->blocked_locks_lru)) {

		nbl = list_first_entry(&nn->blocked_locks_lru,

					struct nfsd4_blocked_lock, nbl_lru);
@@ -4678,7 +4678,7 @@ nfs4_laundromat(struct nfsd_net *nn) 
		list_move(&nbl->nbl_lru, &reaplist);

		list_del_init(&nbl->nbl_list);

	}

	spin_unlock(&nn->client_lock);

	spin_unlock(&nn->blocked_locks_lock);



	while (!list_empty(&reaplist)) {

		nbl = list_first_entry(&nn->blocked_locks_lru,
@@ -5439,13 +5439,13 @@ nfsd4_lm_notify(struct file_lock *fl) 
	bool queue = false;



	/* An empty list means that something else is going to be using it */

	spin_lock(&nn->client_lock);

	spin_lock(&nn->blocked_locks_lock);

	if (!list_empty(&nbl->nbl_list)) {

		list_del_init(&nbl->nbl_list);

		list_del_init(&nbl->nbl_lru);

		queue = true;

	}

	spin_unlock(&nn->client_lock);

	spin_unlock(&nn->blocked_locks_lock);



	if (queue)

		nfsd4_run_cb(&nbl->nbl_cb);
@@ -5868,10 +5868,10 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, 


	if (fl_flags & FL_SLEEP) {

		nbl->nbl_time = jiffies;

		spin_lock(&nn->client_lock);

		spin_lock(&nn->blocked_locks_lock);

		list_add_tail(&nbl->nbl_list, &lock_sop->lo_blocked);

		list_add_tail(&nbl->nbl_lru, &nn->blocked_locks_lru);

		spin_unlock(&nn->client_lock);

		spin_unlock(&nn->blocked_locks_lock);

	}



	err = vfs_lock_file(filp, F_SETLK, file_lock, conflock);
@@ -5900,10 +5900,10 @@ out: 
	if (nbl) {

		/* dequeue it if we queued it before */

		if (fl_flags & FL_SLEEP) {

			spin_lock(&nn->client_lock);

			spin_lock(&nn->blocked_locks_lock);

			list_del_init(&nbl->nbl_list);

			list_del_init(&nbl->nbl_lru);

			spin_unlock(&nn->client_lock);

			spin_unlock(&nn->blocked_locks_lock);

		}

		free_blocked_lock(nbl);

	}
@@ -6943,9 +6943,11 @@ static int nfs4_state_create_net(struct net *net) 
	INIT_LIST_HEAD(&nn->client_lru);

	INIT_LIST_HEAD(&nn->close_lru);

	INIT_LIST_HEAD(&nn->del_recall_lru);

	INIT_LIST_HEAD(&nn->blocked_locks_lru);

	spin_lock_init(&nn->client_lock);



	spin_lock_init(&nn->blocked_locks_lock);

	INIT_LIST_HEAD(&nn->blocked_locks_lru);



	INIT_DELAYED_WORK(&nn->laundromat_work, laundromat_main);

	get_net(net);
@@ -7063,14 +7065,14 @@ nfs4_state_shutdown_net(struct net *net) 
	}



	BUG_ON(!list_empty(&reaplist));

	spin_lock(&nn->client_lock);

	spin_lock(&nn->blocked_locks_lock);

	while (!list_empty(&nn->blocked_locks_lru)) {

		nbl = list_first_entry(&nn->blocked_locks_lru,

					struct nfsd4_blocked_lock, nbl_lru);

		list_move(&nbl->nbl_lru, &reaplist);

		list_del_init(&nbl->nbl_list);

	}

	spin_unlock(&nn->client_lock);

	spin_unlock(&nn->blocked_locks_lock);



	while (!list_empty(&reaplist)) {

		nbl = list_first_entry(&nn->blocked_locks_lru,

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