NFSv4/pnfs: Add tracing for the deviceid cache

Add tracepoints to allow debugging of the deviceid cache.
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

fs/nfs/nfs4proc.c

@@ -9662,6 +9662,8 @@ _nfs4_proc_getdeviceinfo(struct nfs_server *server,
 	if (res.notification != args.notify_types)
 		pdev->nocache = 1;
 
+	trace_nfs4_getdeviceinfo(server, &pdev->dev_id, status);
+
 	dprintk("<-- %s status=%d\n", __func__, status);
 
 	return status;

fs/nfs/nfs4trace.h

@@ -2189,6 +2189,81 @@ DEFINE_PNFS_LAYOUT_EVENT(pnfs_mds_fallback_write_done);
 DEFINE_PNFS_LAYOUT_EVENT(pnfs_mds_fallback_read_pagelist);
 DEFINE_PNFS_LAYOUT_EVENT(pnfs_mds_fallback_write_pagelist);
 
+DECLARE_EVENT_CLASS(nfs4_deviceid_event,
+		TP_PROTO(
+			const struct nfs_client *clp,
+			const struct nfs4_deviceid *deviceid
+		),
+
+		TP_ARGS(clp, deviceid),
+
+		TP_STRUCT__entry(
+			__string(dstaddr, clp->cl_hostname)
+			__array(unsigned char, deviceid, NFS4_DEVICEID4_SIZE)
+		),
+
+		TP_fast_assign(
+			__assign_str(dstaddr, clp->cl_hostname);
+			memcpy(__entry->deviceid, deviceid->data,
+			       NFS4_DEVICEID4_SIZE);
+		),
+
+		TP_printk(
+			"deviceid=%s, dstaddr=%s",
+			__print_hex(__entry->deviceid, NFS4_DEVICEID4_SIZE),
+			__get_str(dstaddr)
+		)
+);
+#define DEFINE_PNFS_DEVICEID_EVENT(name) \
+	DEFINE_EVENT(nfs4_deviceid_event, name, \
+			TP_PROTO(const struct nfs_client *clp, \
+				const struct nfs4_deviceid *deviceid \
+			), \
+			TP_ARGS(clp, deviceid))
+DEFINE_PNFS_DEVICEID_EVENT(nfs4_deviceid_free);
+
+DECLARE_EVENT_CLASS(nfs4_deviceid_status,
+		TP_PROTO(
+			const struct nfs_server *server,
+			const struct nfs4_deviceid *deviceid,
+			int status
+		),
+
+		TP_ARGS(server, deviceid, status),
+
+		TP_STRUCT__entry(
+			__field(dev_t, dev)
+			__field(int, status)
+			__string(dstaddr, server->nfs_client->cl_hostname)
+			__array(unsigned char, deviceid, NFS4_DEVICEID4_SIZE)
+		),
+
+		TP_fast_assign(
+			__entry->dev = server->s_dev;
+			__entry->status = status;
+			__assign_str(dstaddr, server->nfs_client->cl_hostname);
+			memcpy(__entry->deviceid, deviceid->data,
+			       NFS4_DEVICEID4_SIZE);
+		),
+
+		TP_printk(
+			"dev=%02x:%02x: deviceid=%s, dstaddr=%s, status=%d",
+			MAJOR(__entry->dev), MINOR(__entry->dev),
+			__print_hex(__entry->deviceid, NFS4_DEVICEID4_SIZE),
+			__get_str(dstaddr),
+			__entry->status
+		)
+);
+#define DEFINE_PNFS_DEVICEID_STATUS(name) \
+	DEFINE_EVENT(nfs4_deviceid_status, name, \
+			TP_PROTO(const struct nfs_server *server, \
+				const struct nfs4_deviceid *deviceid, \
+				int status \
+			), \
+			TP_ARGS(server, deviceid, status))
+DEFINE_PNFS_DEVICEID_STATUS(nfs4_getdeviceinfo);
+DEFINE_PNFS_DEVICEID_STATUS(nfs4_find_deviceid);
+
 DECLARE_EVENT_CLASS(nfs4_flexfiles_io_event,
 		TP_PROTO(
 			const struct nfs_pgio_header *hdr

fs/nfs/pnfs_dev.c

@@ -34,6 +34,8 @@
 #include "internal.h"
 #include "pnfs.h"
 
+#include "nfs4trace.h"
+
 #define NFSDBG_FACILITY		NFSDBG_PNFS
 
 /*
@@ -192,24 +194,28 @@ nfs4_find_get_deviceid(struct nfs_server *server,
 
 	d = __nfs4_find_get_deviceid(server, id, hash);
 	if (d)
-		return d;
+		goto found;
 
 	new = nfs4_get_device_info(server, id, cred, gfp_mask);
-	if (!new)
+	if (!new) {
+		trace_nfs4_find_deviceid(server, id, -ENOENT);
 		return new;
+	}
 
 	spin_lock(&nfs4_deviceid_lock);
 	d = __nfs4_find_get_deviceid(server, id, hash);
 	if (d) {
 		spin_unlock(&nfs4_deviceid_lock);
 		server->pnfs_curr_ld->free_deviceid_node(new);
-		return d;
+	} else {
+		atomic_inc(&new->ref);
+		hlist_add_head_rcu(&new->node, &nfs4_deviceid_cache[hash]);
+		spin_unlock(&nfs4_deviceid_lock);
+		d = new;
 	}
-	hlist_add_head_rcu(&new->node, &nfs4_deviceid_cache[hash]);
-	atomic_inc(&new->ref);
-	spin_unlock(&nfs4_deviceid_lock);
-
-	return new;
+found:
+	trace_nfs4_find_deviceid(server, id, 0);
+	return d;
 }
 EXPORT_SYMBOL_GPL(nfs4_find_get_deviceid);
 
@@ -278,6 +284,7 @@ nfs4_put_deviceid_node(struct nfs4_deviceid_node *d)
 	}
 	if (!atomic_dec_and_test(&d->ref))
 		return false;
+	trace_nfs4_deviceid_free(d->nfs_client, &d->deviceid);
 	d->ld->free_deviceid_node(d);
 	return true;
 }