Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 4601df20 authored by Trond Myklebust's avatar Trond Myklebust
Browse files

NFSv4: Avoid thundering herd issues with nfs_release_seqid 



Store a pointer to the rpc_task in struct nfs_seqid so that we can wake up
only that request that is able to grab the lock after we've released it.

Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
parent 82b0a4c3

fs/nfs/nfs4_fs.h

+1 −0
Original line number Diff line number Diff line
@@ -71,6 +71,7 @@ struct nfs_seqid_counter { 
struct nfs_seqid {

	struct nfs_seqid_counter *sequence;

	struct list_head list;

	struct rpc_task *task;

};



static inline void nfs_confirm_seqid(struct nfs_seqid_counter *seqid, int status)

fs/nfs/nfs4state.c

+15 −6
Original line number Diff line number Diff line
@@ -916,20 +916,28 @@ struct nfs_seqid *nfs_alloc_seqid(struct nfs_seqid_counter *counter, gfp_t gfp_m 
	if (new != NULL) {

		new->sequence = counter;

		INIT_LIST_HEAD(&new->list);

		new->task = NULL;

	}

	return new;

}



void nfs_release_seqid(struct nfs_seqid *seqid)

{

	if (!list_empty(&seqid->list)) {

		struct nfs_seqid_counter *sequence = seqid->sequence;

	struct nfs_seqid_counter *sequence;



	if (list_empty(&seqid->list))

		return;

	sequence = seqid->sequence;

	spin_lock(&sequence->lock);

	list_del_init(&seqid->list);

		spin_unlock(&sequence->lock);

		rpc_wake_up(&sequence->wait);

	if (!list_empty(&sequence->list)) {

		struct nfs_seqid *next;



		next = list_first_entry(&sequence->list,

				struct nfs_seqid, list);

		rpc_wake_up_queued_task(&sequence->wait, next->task);

	}

	spin_unlock(&sequence->lock);

}



void nfs_free_seqid(struct nfs_seqid *seqid)
@@ -1000,6 +1008,7 @@ int nfs_wait_on_sequence(struct nfs_seqid *seqid, struct rpc_task *task) 
	int status = 0;



	spin_lock(&sequence->lock);

	seqid->task = task;

	if (list_empty(&seqid->list))

		list_add_tail(&seqid->list, &sequence->list);

	if (list_first_entry(&sequence->list, struct nfs_seqid, list) == seqid)