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authorChuck Lever <chuck.lever@oracle.com>2014-11-09 04:15:09 +0300
committerAnna Schumaker <Anna.Schumaker@Netapp.com>2014-11-26 00:22:15 +0300
commitedef1297f33a4546559d905457b435a5ea160bab (patch)
treec14a3b6d62e72cb8b46a3a8cc09679b343831b49 /net/sunrpc
parent5d01410fe4d92081f349b013a2e7a95429e4f2c9 (diff)
downloadlinux-edef1297f33a4546559d905457b435a5ea160bab.tar.xz
SUNRPC: serialize iostats updates
Occasionally mountstats reports a negative retransmission rate. Ensure that two RPCs completing concurrently don't confuse the sums in the transport's op_metrics array. Since pNFS filelayout can invoke rpc_count_iostats() on another transport from xprt_release(), we can't rely on simply holding the transport_lock in xprt_release(). There's nothing for it but hard serialization. One spin lock per RPC operation should make this as painless as it can be. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Diffstat (limited to 'net/sunrpc')
-rw-r--r--net/sunrpc/stats.c21
1 files changed, 16 insertions, 5 deletions
diff --git a/net/sunrpc/stats.c b/net/sunrpc/stats.c
index 54530490944e..9711a155bc50 100644
--- a/net/sunrpc/stats.c
+++ b/net/sunrpc/stats.c
@@ -116,7 +116,15 @@ EXPORT_SYMBOL_GPL(svc_seq_show);
*/
struct rpc_iostats *rpc_alloc_iostats(struct rpc_clnt *clnt)
{
- return kcalloc(clnt->cl_maxproc, sizeof(struct rpc_iostats), GFP_KERNEL);
+ struct rpc_iostats *stats;
+ int i;
+
+ stats = kcalloc(clnt->cl_maxproc, sizeof(*stats), GFP_KERNEL);
+ if (stats) {
+ for (i = 0; i < clnt->cl_maxproc; i++)
+ spin_lock_init(&stats[i].om_lock);
+ }
+ return stats;
}
EXPORT_SYMBOL_GPL(rpc_alloc_iostats);
@@ -135,20 +143,21 @@ EXPORT_SYMBOL_GPL(rpc_free_iostats);
* rpc_count_iostats - tally up per-task stats
* @task: completed rpc_task
* @stats: array of stat structures
- *
- * Relies on the caller for serialization.
*/
void rpc_count_iostats(const struct rpc_task *task, struct rpc_iostats *stats)
{
struct rpc_rqst *req = task->tk_rqstp;
struct rpc_iostats *op_metrics;
- ktime_t delta;
+ ktime_t delta, now;
if (!stats || !req)
return;
+ now = ktime_get();
op_metrics = &stats[task->tk_msg.rpc_proc->p_statidx];
+ spin_lock(&op_metrics->om_lock);
+
op_metrics->om_ops++;
op_metrics->om_ntrans += req->rq_ntrans;
op_metrics->om_timeouts += task->tk_timeouts;
@@ -161,8 +170,10 @@ void rpc_count_iostats(const struct rpc_task *task, struct rpc_iostats *stats)
op_metrics->om_rtt = ktime_add(op_metrics->om_rtt, req->rq_rtt);
- delta = ktime_sub(ktime_get(), task->tk_start);
+ delta = ktime_sub(now, task->tk_start);
op_metrics->om_execute = ktime_add(op_metrics->om_execute, delta);
+
+ spin_unlock(&op_metrics->om_lock);
}
EXPORT_SYMBOL_GPL(rpc_count_iostats);