OS-2271 'tail -F ...' not resetting the offset of file rotation properly

2 files changed, 87 insertions, 9 deletions

diff --git a/usr/src/cmd/tail/tests/tailtests.sh b/usr/src/cmd/tail/tests/tailtests.sh
index 1ce5f5df02..c0ae3afcc4 100644
--- a/usr/src/cmd/tail/tests/tailtests.sh
+++ b/usr/src/cmd/tail/tests/tailtests.sh
@@ -13,7 +13,7 @@
 
 #
 # Copyright 2010 Chris Love.  All rights reserved.
-# Copyright (c) 2012, Joyent, Inc. All rights reserved.
+# Copyright (c) 2013, Joyent, Inc. All rights reserved.
 #
 
 checktest()
@@ -312,8 +312,14 @@ sleep 2
 mv $follow $moved
 
 echo -e "x\ny\nz" >> $moved
+
+#
+# At this point, tail is polling on stat'ing the missing file; we need to
+# be sure to sleep long enough after recreating it to know that it will pick
+# it up.
+#
 echo -e "d\ne\nf" > $follow
-sleep 1
+sleep 5
 kill $child
 sleep 1
 
@@ -361,6 +367,75 @@ a=`cat $out`
 checktest "$a" "$o" 27
 rm $follow $moved
 
+if [[ `uname -s` == "SunOS" ]]; then
+	#
+	# Use DTrace to truncate the file between the return from port_get()
+	# and the reassociation of the file object with the port, exposing
+	# any race conditions whereby FILE_TRUNC events are lost.
+	#
+	cat /dev/null > $follow
+	dtrace -c "$PROG -f $follow" -s /dev/stdin > $out <<EOF
+		#pragma D option destructive
+		#pragma D option quiet 
+
+		pid\$target::port_get:return
+		/++i == 5/
+		{
+			stop();
+			system("cat /dev/null > $follow");
+			system("prun %d", pid);
+		}
+
+		tick-1sec
+		{
+			system("echo %d >> $follow", j++);
+		}
+
+		tick-1sec
+		/j == 10/
+		{
+			exit(0);
+		}
+EOF
+
+	o=`echo -e "0\n1\n2\n3\n5\n6\n7\n8\n9\n"`
+	a=`cat $out`
+	checktest "$a" "$o" 27a
+	rm $follow
+
+	cat /dev/null > $follow
+	dtrace -c "$PROG -f $follow" -s /dev/stdin > $out <<EOF
+		#pragma D option destructive
+		#pragma D option quiet 
+
+		pid\$target::port_get:return
+		/++i == 5/
+		{
+			stop();
+			system("mv $follow $moved");
+			system("cat /dev/null > $moved");
+			system("prun %d", pid);
+		}
+
+		tick-1sec
+		{
+			system("echo %d >> %s", j++,
+			    i < 5 ? "$follow" : "$moved");
+		}
+
+		tick-1sec
+		/j == 10/
+		{
+			exit(0);
+		}
+EOF
+
+	o=`echo -e "0\n1\n2\n3\n5\n6\n7\n8\n9\n"`
+	a=`cat $out`
+	checktest "$a" "$o" 27b
+	rm $moved
+fi
+
 echo "$CMD: completed"
 
 exit $errs
diff --git a/usr/src/uts/common/fs/portfs/port_fop.c b/usr/src/uts/common/fs/portfs/port_fop.c
index 48792394a5..1094dc160c 100644
--- a/usr/src/uts/common/fs/portfs/port_fop.c
+++ b/usr/src/uts/common/fs/portfs/port_fop.c
@@ -24,7 +24,7 @@
  */
 
 /*
- * Copyright (c) 2012, Joyent, Inc. All rights reserved.
+ * Copyright (c) 2013, Joyent, Inc. All rights reserved.
  */
 
 /*
@@ -1259,7 +1259,7 @@ port_associate_fop(port_t *pp, int source, uintptr_t object, int events,
     void *user)
 {
 	portfop_cache_t	*pfcp;
-	vnode_t		*vp, *dvp, *oldvp = NULL, *olddvp = NULL;
+	vnode_t		*vp, *dvp, *oldvp = NULL, *olddvp = NULL, *orig;
 	portfop_t	*pfp;
 	int		error = 0;
 	file_obj_t	fobj;
@@ -1316,8 +1316,7 @@ port_associate_fop(port_t *pp, int source, uintptr_t object, int events,
 		goto errout;
 	}
 
-	vp = port_resolve_vp(vp);
-
+	vp = port_resolve_vp(orig = vp);
 
 	if (vp != NULL && vnevent_support(vp, NULL)) {
 		error = ENOTSUP;
@@ -1325,10 +1324,14 @@ port_associate_fop(port_t *pp, int source, uintptr_t object, int events,
 	}
 
 	/*
-	 * If dvp belongs to a different filesystem just ignore it.
-	 * Hardlinks cannot exist across filesystems.
+	 * If dvp belongs to a different filesystem just ignore it, as hard
+	 * links cannot exist across filesystems.  We make an exception for
+	 * procfs, however, the magic of which we treat semantically as a hard
+	 * link, allowing one to use /proc/[pid]/fd/[fd] for PORT_SOURCE_FILE
+	 * and avoid spurious FILE_RENAME_FROM/FILE_RENAME_TO events.
 	 */
-	if (dvp != NULL && dvp->v_vfsp != vp->v_vfsp) {
+	if (dvp != NULL && dvp->v_vfsp != vp->v_vfsp &&
+	    !(orig->v_type == VPROC && vp != NULL && vp->v_type != VPROC)) {
 		VN_RELE(dvp);
 		dvp = NULL;
 	}