diff --git a/src/libdiod/diod_log.c b/src/libdiod/diod_log.c
index e5a48ce0..1140c841 100644
--- a/src/libdiod/diod_log.c
+++ b/src/libdiod/diod_log.c
@@ -111,9 +111,19 @@ _verr (int errnum, const char *fmt, va_list ap)
 }
 
 void
+diod_log_buf (const char *buf)
+{
+    if (logf && buf) {
+        fputs (buf, logf);
+        fputc ('\n', logf);
+        fflush (logf);
+    }
+}
+
+static void
 diod_log_msg (const char *fmt, va_list ap)
 {
-    char buf[1024]; /* make it large enough for protocol debug output */
+    char buf[1024];
 
     if (logf) {
         vsnprintf (buf, sizeof (buf), fmt, ap);  /* ignore overflow */
diff --git a/src/libdiod/diod_log.h b/src/libdiod/diod_log.h
index d2c5b0c6..909ee8cd 100644
--- a/src/libdiod/diod_log.h
+++ b/src/libdiod/diod_log.h
@@ -17,7 +17,7 @@ void diod_log_init (char *p);
 void diod_log_fini (void);
 void diod_log_set_dest (char *dest);
 char *diod_log_get_dest (void);
-void diod_log_msg (const char *fmt, va_list ap);
+void diod_log_buf (const char *buf);
 
 void err_exit (const char *fmt, ...)
         __attribute__ ((format (printf, 1, 2), noreturn));
diff --git a/src/libdiod/diod_ops.c b/src/libdiod/diod_ops.c
index daa19724..d1336d08 100644
--- a/src/libdiod/diod_ops.c
+++ b/src/libdiod/diod_ops.c
@@ -159,7 +159,7 @@ diod_init (Npsrv *srv)
 {
     srv->msize = DIOD_SRV_MAX_MSIZE;
     srv->fiddestroy = diod_fiddestroy;
-    srv->logmsg = diod_log_msg;
+    srv->logmsg = diod_log_buf;
     srv->remapuser = diod_remapuser;
     srv->exportok = diod_exportok;
     srv->auth_required = diod_auth_required;
@@ -218,11 +218,12 @@ diod_ustat2qid (struct stat *st, Npqid *qid)
     qid->path = st->st_ino;
     //qid->version = st->st_mtime ^ (st->st_size << 8);
     qid->version = 0;
-    qid->type = 0;
     if (S_ISDIR(st->st_mode))
-        qid->type |= Qtdir;
-    if (S_ISLNK(st->st_mode))
-        qid->type |= Qtsymlink;
+        qid->type = Qtdir;
+    else if (S_ISLNK(st->st_mode))
+        qid->type = Qtsymlink;
+    else
+        qid->type = Qtfile;
 }
 
 static void
@@ -231,11 +232,12 @@ _dirent2qid (struct dirent *d, Npqid *qid)
     NP_ASSERT (d->d_type != DT_UNKNOWN);
     qid->path = d->d_ino;
     qid->version = 0;
-    qid->type = 0;
     if (d->d_type == DT_DIR)
-        qid->type |= Qtdir;
-    if (d->d_type == DT_LNK)
-        qid->type |= Qtsymlink;
+        qid->type = Qtdir;
+    else if (d->d_type == DT_LNK)
+        qid->type = Qtsymlink;
+    else
+        qid->type = Qtfile;
 }
 
 int
diff --git a/src/libnpclient/test/simple.c b/src/libnpclient/test/simple.c
index b44f4558..6fd8fd08 100644
--- a/src/libnpclient/test/simple.c
+++ b/src/libnpclient/test/simple.c
@@ -29,11 +29,11 @@
 
 #define TEST_MSIZE 8192
 
-static void diag_logger (const char *fmt, va_list ap)
+static void diag_logger (const char *buf)
 {
-    char buf[1024]; /* make it large enough for protocol debug output */
-    vsnprintf (buf, sizeof (buf), fmt, ap);  /* ignore overflow */
-    fprintf (stderr, "# %s\n", buf);
+    fputs ("# ", stderr);
+    fputs (buf, stderr);
+    fputc ('\n', stderr);
 }
 
 static void check_data_trimmed (const char *name, const char *s, const char *expect)
diff --git a/src/libnpfs/conn.c b/src/libnpfs/conn.c
index c678b244..dc6ef5a5 100644
--- a/src/libnpfs/conn.c
+++ b/src/libnpfs/conn.c
@@ -122,21 +122,34 @@ np_conn_destroy(Npconn *conn)
 static void
 _debug_trace (Npsrv *srv, Npfcall *fc)
 {
-	if ((srv->flags & SRV_FLAGS_DEBUG_9PTRACE)) {
-		char s[512];
-		static struct timeval b = { 0, 0 };
-		struct timeval a, c;
+	if ((srv->flags & SRV_FLAGS_DEBUG_9PTRACE) && srv->logmsg) {
+		xpthread_mutex_lock (&srv->tracebuf_lock);
+
+		char *buf = srv->tracebuf;
+		size_t size = srv->tracebuf_size;
 
-		np_snprintfcall(s, sizeof (s), fc);
 		if ((srv->flags & SRV_FLAGS_DEBUG_TIMES)) {
+			static struct timeval b = { 0, 0 };
+			struct timeval a, c;
+			int n;
+
 			if (b.tv_sec == 0)
 				(void)gettimeofday(&b, NULL);
-			(void)gettimeofday(&a, NULL);
-			timersub(&a, &b, &c);
-			np_logmsg(srv, "[%"PRIdMAX".%-3"PRIdMAX"] %s",
-				  (intmax_t)c.tv_sec, (intmax_t)c.tv_usec/1000, s);
-		} else
-			np_logmsg(srv, "%s", s);
+			(void)gettimeofday (&a, NULL);
+			timersub (&a, &b, &c);
+			n = snprintf (buf, size, "[%"PRIdMAX".%-3"PRIdMAX"] ",
+					(intmax_t)c.tv_sec,
+					(intmax_t)c.tv_usec/1000);
+			if (n < size) {
+				buf += n;
+				size -= n;
+			}
+		}
+		np_snprintfcall (buf, size, fc);
+
+		srv->logmsg (srv->tracebuf);
+
+		xpthread_mutex_unlock (&srv->tracebuf_lock);
 	}
 }
 
diff --git a/src/libnpfs/fmt.c b/src/libnpfs/fmt.c
index ea61d1d9..d2b550f0 100644
--- a/src/libnpfs/fmt.c
+++ b/src/libnpfs/fmt.c
@@ -11,6 +11,7 @@
 #if HAVE_CONFIG_H
 #include "config.h"
 #endif
+#include <sys/param.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
@@ -33,16 +34,21 @@ np_printqid(char *s, int len, Npqid *q)
 
 	if (q->type & Qtdir)
 		buf[n++] = 'd';
+	else if (q->type & Qtauth)
+		buf[n++] = 'A';
+	else if (q->type & Qtsymlink)
+		buf[n++] = 'L';
+	else if (q->type & Qtlink)
+		buf[n++] = 'l';
+	else /* Qtfile = 0 */
+		buf[n++] = 'f';
+
 	if (q->type & Qtappend)
 		buf[n++] = 'a';
-	if (q->type & Qtauth)
-		buf[n++] = 'A';
 	if (q->type & Qtexcl)
-		buf[n++] = 'l';
+		buf[n++] = 'x';
 	if (q->type & Qttmp)
 		buf[n++] = 't';
-	if (q->type & Qtsymlink)
-		buf[n++] = 'L';
 	buf[n] = '\0';
 
 	spf (s, len, "(%.16"PRIx64" %x '%s')", q->path, q->version, buf);
@@ -84,13 +90,33 @@ np_timestr(const u64 sec, const u64 nsec)
 	return s;
 }
 
+static void
+np_printdentry(char *s, int len, Npqid *qid, char *dname, u8 type, u64 off)
+{
+	spf (s, len, "\n");
+	np_printqid (s, len, qid);
+	spf (s, len, " %u %-21ju %s", type, (uintmax_t)off, dname);
+}
+
 static void
 np_printdents(char *s, int len, u8 *buf, int buflen)
 {
-	if (buflen > 0)
-		spf (s, len, "\n");
-	/* FIXME: decode directory entries here */
-	np_sndump(s, len, buf, buflen < 64 ? buflen : 64);
+	int res;
+
+	do {
+		Npqid qid;
+		char dname[PATH_MAX + 1];
+		u64 offset;
+		u8 type;
+
+		res = np_deserialize_p9dirent (&qid, &offset, &type, dname,
+						sizeof (dname), buf, buflen);
+		if (res > 0) {
+			np_printdentry (s, len, &qid, dname, type, offset);
+			buf += res;
+			buflen -= res;
+		}
+	} while (res > 0);
 }
 
 static void
diff --git a/src/libnpfs/npfs.h b/src/libnpfs/npfs.h
index 4035d89c..dbc5d8f4 100644
--- a/src/libnpfs/npfs.h
+++ b/src/libnpfs/npfs.h
@@ -270,7 +270,7 @@ struct Npsrv {
 	void*		srvaux;
 	Npfile*		ctlroot;
 	void*		usercache;
-	void		(*logmsg)(const char *, va_list);
+	void		(*logmsg)(const char *buf);
 	int		(*remapuser)(Npfid *fid);
 	int		(*auth_required)(Npstr *, u32, Npstr *);
 	int		(*exportok)(Npfid *fid);
@@ -278,6 +278,10 @@ struct Npsrv {
 	Npauth*		auth;
 	int		flags;
 
+	char		*tracebuf;
+	size_t		tracebuf_size;
+	pthread_mutex_t	tracebuf_lock;
+
 	void		(*fiddestroy)(Npfid *);
 
 	Npfcall*	(*version)(Npconn *conn, u32 msize, Npstr *version);
diff --git a/src/libnpfs/npstring.c b/src/libnpfs/npstring.c
index 896250f0..6ed093eb 100644
--- a/src/libnpfs/npstring.c
+++ b/src/libnpfs/npstring.c
@@ -110,12 +110,12 @@ vaspf (char **sp, int *lp, const char *fmt, va_list ap)
 int
 aspf (char **sp, int *lp, const char *fmt, ...)
 {
-        va_list ap;
-        int n;
+	va_list ap;
+	int n;
 
-        va_start (ap, fmt);
-        n = vaspf (sp, lp, fmt, ap);
-        va_end (ap);
+	va_start (ap, fmt);
+	n = vaspf (sp, lp, fmt, ap);
+	va_end (ap);
 
 	return n;
 }
@@ -123,16 +123,17 @@ aspf (char **sp, int *lp, const char *fmt, ...)
 void
 spf (char *s, int len, const char *fmt, ...)
 {
-        va_list ap;
-        int n = strlen (s);
+	va_list ap;
+	int n = strlen (s);
 
-        len -= n;
-        s += n;
-        NP_ASSERT (len > 0);
+	len -= n;
+	s += n;
+	NP_ASSERT (len > 0);
 
-        va_start (ap, fmt);
-        vsnprintf (s, len, fmt, ap); /* ignore overflow */
-        va_end (ap);
+	va_start (ap, fmt);
+	if (vsnprintf (s, len, fmt, ap) >= len)
+		strncpy (&s[len - 4], "...", 4);
+	va_end (ap);
 }
 
 #if NPSTATS_RWCOUNT_BINS != 12
diff --git a/src/libnpfs/srv.c b/src/libnpfs/srv.c
index 14ab5e21..6a809232 100644
--- a/src/libnpfs/srv.c
+++ b/src/libnpfs/srv.c
@@ -70,6 +70,12 @@ np_srv_create(int nwthread, int flags)
 		goto error;
 	np_tpool_incref (srv->tpool);
 	np_assert_srv = srv;
+	if ((flags & SRV_FLAGS_DEBUG_9PTRACE)) {
+		pthread_mutex_init (&srv->tracebuf_lock, NULL);
+		srv->tracebuf_size = 1048576;
+		if (!(srv->tracebuf = calloc (1, srv->tracebuf_size)))
+			goto error;
+	}
 	return srv;
 error:
 	if (srv)
@@ -102,6 +108,7 @@ np_srv_destroy(Npsrv *srv)
 	np_usercache_destroy (srv);
 	np_ctl_finalize (srv);
 	np_assert_srv = NULL;
+	free (srv->tracebuf);
 	free (srv);
 }
 
@@ -869,10 +876,13 @@ void
 np_logmsg(Npsrv *srv, const char *fmt, ...)
 {
 	va_list ap;
+	char buf[1024];
 
 	va_start (ap, fmt);
-	if (srv->logmsg)
-		srv->logmsg (fmt, ap);
+	if (srv->logmsg) {
+		(void)vsnprintf (buf, sizeof (buf), fmt, ap);
+		srv->logmsg (buf);
+	}
 	va_end (ap);
 }
 
diff --git a/src/libnpfs/test/fidpool.c b/src/libnpfs/test/fidpool.c
index 40870a67..22cfd880 100644
--- a/src/libnpfs/test/fidpool.c
+++ b/src/libnpfs/test/fidpool.c
@@ -16,11 +16,11 @@
 #include "src/libtap/tap.h"
 
 
-void diag_logger (const char *fmt, va_list ap)
+void diag_logger (const char *buf)
 {
-    char buf[1024]; /* make it large enough for protocol debug output */
-    vsnprintf (buf, sizeof (buf), fmt, ap);  /* ignore overflow */
-    fprintf (stderr, "# %s\n", buf);
+    fputs ("# ", stderr);
+    fputs (buf, stderr);
+    fputc ('\n', stderr);
 }