NFSv4: Final tweak to sequence id
Sacrifice queueing fairness for performance.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index da0861d..c59ef90 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -670,15 +670,12 @@
struct nfs_seqid *nfs_alloc_seqid(struct nfs_seqid_counter *counter)
{
- struct rpc_sequence *sequence = counter->sequence;
struct nfs_seqid *new;
new = kmalloc(sizeof(*new), GFP_KERNEL);
if (new != NULL) {
new->sequence = counter;
- spin_lock(&sequence->lock);
- list_add_tail(&new->list, &sequence->list);
- spin_unlock(&sequence->lock);
+ INIT_LIST_HEAD(&new->list);
}
return new;
}
@@ -687,10 +684,12 @@
{
struct rpc_sequence *sequence = seqid->sequence->sequence;
- spin_lock(&sequence->lock);
- list_del(&seqid->list);
- rpc_wake_up(&sequence->wait);
- spin_unlock(&sequence->lock);
+ if (!list_empty(&seqid->list)) {
+ spin_lock(&sequence->lock);
+ list_del(&seqid->list);
+ spin_unlock(&sequence->lock);
+ }
+ rpc_wake_up_next(&sequence->wait);
kfree(seqid);
}
@@ -746,12 +745,16 @@
struct rpc_sequence *sequence = seqid->sequence->sequence;
int status = 0;
+ if (sequence->list.next == &seqid->list)
+ goto out;
spin_lock(&sequence->lock);
- if (sequence->list.next != &seqid->list) {
+ if (!list_empty(&sequence->list)) {
rpc_sleep_on(&sequence->wait, task, NULL, NULL);
status = -EAGAIN;
- }
+ } else
+ list_add(&seqid->list, &sequence->list);
spin_unlock(&sequence->lock);
+out:
return status;
}