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NFSv4: Avoid thundering herd issues with nfs_release_seqid

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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: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Trond Myklebust 2012-01-20 18:47:05 -05:00
parent 82b0a4c3c1
commit 4601df20fb
2 changed files with 16 additions and 6 deletions
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1
fs/nfs/nfs4_fs.h
View File

@ -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)

21
fs/nfs/nfs4state.c
View File

@ -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;
spin_lock(&sequence->lock);
list_del_init(&seqid->list);
spin_unlock(&sequence->lock);
rpc_wake_up(&sequence->wait);
if (list_empty(&seqid->list))
return;
sequence = seqid->sequence;
spin_lock(&sequence->lock);
list_del_init(&seqid->list);
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)