[PATCH v6 07/12] NFSD: Record DRC population in lookup tracepoints

[Chuck Lever <cel@kernel.org>]

nfsd_drc_found reports the outcome of a lookup but not how full the
cache was at the time, so a trace cannot show whether retransmits are
being caught while the cache runs near its cap.

Assisted-by: LLM
Signed-off-by: Chuck Lever <cel@kernel.org>
---
 fs/nfsd/nfscache.c |  4 +++-
 fs/nfsd/trace.h    | 11 +++++++----
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c
index 1cdb53e9e807..0e01ae4f2218 100644
--- a/fs/nfsd/nfscache.c
+++ b/fs/nfsd/nfscache.c
@@ -486,6 +486,7 @@ int nfsd_cache_lookup(struct svc_rqst *rqstp, unsigned int start,
 	struct nfsd_drc_bucket	*b;
 	int type = ntli->ntli_cachetype;
 	LIST_HEAD(dispose);
+	unsigned int entries;
 	int rtn = RC_DOIT;
 
 	if (type == RC_NOCACHE) {
@@ -555,7 +556,8 @@ int nfsd_cache_lookup(struct svc_rqst *rqstp, unsigned int start,
 	}
 
 out_trace:
-	trace_nfsd_drc_found(nn, rqstp, rtn);
+	entries = atomic_read(&nn->num_drc_entries);
+	trace_nfsd_drc_found(nn, entries, rqstp, rtn);
 out_unlock:
 	spin_unlock(&b->cache_lock);
 out:
diff --git a/fs/nfsd/trace.h b/fs/nfsd/trace.h
index ed4efcfa3961..631682a76f9c 100644
--- a/fs/nfsd/trace.h
+++ b/fs/nfsd/trace.h
@@ -1513,23 +1513,26 @@ TRACE_DEFINE_ENUM(RC_DOIT);
 TRACE_EVENT(nfsd_drc_found,
 	TP_PROTO(
 		const struct nfsd_net *nn,
+		unsigned int num_drc_entries,
 		const struct svc_rqst *rqstp,
 		int result
 	),
-	TP_ARGS(nn, rqstp, result),
+	TP_ARGS(nn, num_drc_entries, rqstp, result),
 	TP_STRUCT__entry(
 		__field(unsigned long long, boot_time)
+		__field(unsigned int, num_drc_entries)
 		__field(unsigned long, result)
 		__field(u32, xid)
 	),
 	TP_fast_assign(
 		__entry->boot_time = nn->boot_time;
+		__entry->num_drc_entries = num_drc_entries;
 		__entry->result = result;
 		__entry->xid = be32_to_cpu(rqstp->rq_xid);
 	),
-	TP_printk("boot_time=%16llx xid=0x%08x result=%s",
-		__entry->boot_time, __entry->xid,
-		show_drc_retval(__entry->result))
+	TP_printk("boot_time=%16llx entries=%u xid=0x%08x result=%s",
+		__entry->boot_time, __entry->num_drc_entries,
+		__entry->xid, show_drc_retval(__entry->result))
 
 );
 

-- 
2.55.0