NFSD: Add tracepoints to NFSD's duplicate reply cache

Try to capture DRC failures.

Two additional clean-ups:
- Introduce Doxygen-style comments for the main entry points
- Remove a dprintk that fires for an allocation failure. This was
  the only dprintk in the REPCACHE class.

Reported-by: kbuild test robot <lkp@intel.com>
[ cel: force typecast for display of checksum values ]
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

1 files changed, 59 insertions, 0 deletions

diff --git a/fs/nfsd/trace.h b/fs/nfsd/trace.h
index 78c574251c60..371dc198d28e 100644
--- a/fs/nfsd/trace.h
+++ b/fs/nfsd/trace.h
@@ -432,6 +432,65 @@ TRACE_EVENT(nfsd_file_fsnotify_handle_event,
 			__entry->nlink, __entry->mode, __entry->mask)
 );
 
+#include "cache.h"
+
+TRACE_DEFINE_ENUM(RC_DROPIT);
+TRACE_DEFINE_ENUM(RC_REPLY);
+TRACE_DEFINE_ENUM(RC_DOIT);
+
+#define show_drc_retval(x)						\
+	__print_symbolic(x,						\
+		{ RC_DROPIT, "DROPIT" },				\
+		{ RC_REPLY, "REPLY" },					\
+		{ RC_DOIT, "DOIT" })
+
+TRACE_EVENT(nfsd_drc_found,
+	TP_PROTO(
+		const struct nfsd_net *nn,
+		const struct svc_rqst *rqstp,
+		int result
+	),
+	TP_ARGS(nn, rqstp, result),
+	TP_STRUCT__entry(
+		__field(unsigned long long, boot_time)
+		__field(unsigned long, result)
+		__field(u32, xid)
+	),
+	TP_fast_assign(
+		__entry->boot_time = nn->boot_time;
+		__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))
+
+);
+
+TRACE_EVENT(nfsd_drc_mismatch,
+	TP_PROTO(
+		const struct nfsd_net *nn,
+		const struct svc_cacherep *key,
+		const struct svc_cacherep *rp
+	),
+	TP_ARGS(nn, key, rp),
+	TP_STRUCT__entry(
+		__field(unsigned long long, boot_time)
+		__field(u32, xid)
+		__field(u32, cached)
+		__field(u32, ingress)
+	),
+	TP_fast_assign(
+		__entry->boot_time = nn->boot_time;
+		__entry->xid = be32_to_cpu(key->c_key.k_xid);
+		__entry->cached = (__force u32)key->c_key.k_csum;
+		__entry->ingress = (__force u32)rp->c_key.k_csum;
+	),
+	TP_printk("boot_time=%16llx xid=0x%08x cached-csum=0x%08x ingress-csum=0x%08x",
+		__entry->boot_time, __entry->xid, __entry->cached,
+		__entry->ingress)
+);
+
 #endif /* _NFSD_TRACE_H */
 
 #undef TRACE_INCLUDE_PATH