NFSD: Instrument fh_verify()

Capture file handles and how they map to local inodes. In particular,
NFSv4 PUTFH uses fh_verify() so we can now observe which file handles
are the target of OPEN, LOOKUP, RENAME, and so on.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/nfsfh.c

@@ -331,8 +331,6 @@ fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type, int access)
 	struct dentry	*dentry;
 	__be32		error;
 
-	dprintk("nfsd: fh_verify(%s)\n", SVCFH_fmt(fhp));
-
 	if (!fhp->fh_dentry) {
 		error = nfsd_set_fh_dentry(rqstp, fhp);
 		if (error)
@@ -340,6 +338,9 @@ fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type, int access)
 	}
 	dentry = fhp->fh_dentry;
 	exp = fhp->fh_export;
+
+	trace_nfsd_fh_verify(rqstp, fhp, type, access);
+
 	/*
 	 * We still have to do all these permission checks, even when
 	 * fh_dentry is already set:

fs/nfsd/trace.h

@@ -171,6 +171,52 @@ TRACE_EVENT(nfsd_compound_encode_err,
 		__entry->opnum, __entry->status)
 );
 
+#define show_fs_file_type(x) \
+	__print_symbolic(x, \
+		{ S_IFLNK,		"LNK" }, \
+		{ S_IFREG,		"REG" }, \
+		{ S_IFDIR,		"DIR" }, \
+		{ S_IFCHR,		"CHR" }, \
+		{ S_IFBLK,		"BLK" }, \
+		{ S_IFIFO,		"FIFO" }, \
+		{ S_IFSOCK,		"SOCK" })
+
+TRACE_EVENT(nfsd_fh_verify,
+	TP_PROTO(
+		const struct svc_rqst *rqstp,
+		const struct svc_fh *fhp,
+		umode_t type,
+		int access
+	),
+	TP_ARGS(rqstp, fhp, type, access),
+	TP_STRUCT__entry(
+		__field(unsigned int, netns_ino)
+		__sockaddr(server, rqstp->rq_xprt->xpt_remotelen)
+		__sockaddr(client, rqstp->rq_xprt->xpt_remotelen)
+		__field(u32, xid)
+		__field(u32, fh_hash)
+		__field(void *, inode)
+		__field(unsigned long, type)
+		__field(unsigned long, access)
+	),
+	TP_fast_assign(
+		__entry->netns_ino = SVC_NET(rqstp)->ns.inum;
+		__assign_sockaddr(server, &rqstp->rq_xprt->xpt_local,
+		       rqstp->rq_xprt->xpt_locallen);
+		__assign_sockaddr(client, &rqstp->rq_xprt->xpt_remote,
+				  rqstp->rq_xprt->xpt_remotelen);
+		__entry->xid = be32_to_cpu(rqstp->rq_xid);
+		__entry->fh_hash = knfsd_fh_hash(&fhp->fh_handle);
+		__entry->inode = d_inode(fhp->fh_dentry);
+		__entry->type = type;
+		__entry->access = access;
+	),
+	TP_printk("xid=0x%08x fh_hash=0x%08x inode=%p type=%s access=%s",
+		__entry->xid, __entry->fh_hash, __entry->inode,
+		show_fs_file_type(__entry->type),
+		show_nfsd_may_flags(__entry->access)
+	)
+);
 
 DECLARE_EVENT_CLASS(nfsd_fh_err_class,
 	TP_PROTO(struct svc_rqst *rqstp,