generic/530, xfs/501: pass fs shutdown handle to t_open_tmpfiles

So it turns out that overlayfs can't pass FS_IOC_SHUTDOWN to the lower
filesystems and so xfstests works around this by creating shutdown
helpers for the scratch fs to direct the shutdown ioctl to wherever it
needs to go to shut down the filesystem -- SCRATCH_MNT on normal
filesystems and OVL_BASE_SCRATCH_MNT when -overlay is enabled.  This
means that t_open_tmpfiles cannot simply use one of the open tempfiles
to shut down the filesystem.

Commit f8f5774722 tried to "fix" this by ripping the shutdown code out,
but this made the tests useless.  Fix this instead by creating a
xfstests helper to return a path that can be used to shut down the
filesystem and then pass that path to t_open_tmpfiles so that we can
shut down the filesystem when overlayfs is enabled.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>

common/rc

@@ -393,6 +393,17 @@ _scratch_shutdown()
 	fi
 }
 
+# Return a file path that can be used to shut down the scratch filesystem.
+# Caller should _require_scratch_shutdown before using this.
+_scratch_shutdown_handle()
+{
+	if [ $FSTYP = "overlay" ]; then
+		echo $OVL_BASE_SCRATCH_MNT
+	else
+		echo $SCRATCH_MNT
+	fi
+}
+
 _test_mount()
 {
     if [ "$FSTYP" == "overlay" ]; then

src/t_open_tmpfiles.c

@@ -24,7 +24,7 @@ static int min_fd = -1;
 static int max_fd = -1;
 static unsigned int nr_opened = 0;
 static float start_time;
-static int shutdown_fs = 0;
+static int shutdown_fd = -1;
 
 void clock_time(float *time)
 {
@@ -69,7 +69,7 @@ void die(void)
 				end_time - start_time);
 		fflush(stdout);
 
-		if (shutdown_fs) {
+		if (shutdown_fd >= 0) {
 			/*
 			 * Flush the log so that we have to process the
 			 * unlinked inodes the next time we mount.
@@ -77,7 +77,7 @@ void die(void)
 			int flag = XFS_FSOP_GOING_FLAGS_LOGFLUSH;
 			int ret;
 
-			ret = ioctl(min_fd, XFS_IOC_GOINGDOWN, &flag);
+			ret = ioctl(shutdown_fd, XFS_IOC_GOINGDOWN, &flag);
 			if (ret) {
 				perror("shutdown");
 				exit(2);
@@ -148,8 +148,9 @@ void leak_tmpfile(void)
 
 /*
  * Try to put as many files on the unlinked list and then kill them.
- * The first argument is a directory to chdir into; passing any second arg
- * will shut down the fs instead of closing files.
+ * The first argument is a directory to chdir into; the second argumennt (if
+ * provided) is a file path that will be opened and then used to shut down the
+ * fs before the program exits.
  */
 int main(int argc, char *argv[])
 {
@@ -160,8 +161,13 @@ int main(int argc, char *argv[])
 		if (ret)
 			perror(argv[1]);
 	}
-	if (argc > 2 && !strcmp(argv[2], "shutdown"))
-		shutdown_fs = 1;
+	if (argc > 2) {
+		shutdown_fd = open(argv[2], O_RDONLY);
+		if (shutdown_fd < 0) {
+			perror(argv[2]);
+			return 1;
+		}
+	}
 
 	clock_time(&start_time);
 	while (1)

tests/generic/530

@@ -49,7 +49,7 @@ ulimit -n $max_files
 
 # Open a lot of unlinked files
 echo create >> $seqres.full
-$here/src/t_open_tmpfiles $SCRATCH_MNT shutdown >> $seqres.full
+$here/src/t_open_tmpfiles $SCRATCH_MNT $(_scratch_shutdown_handle) >> $seqres.full
 
 # Unmount to prove that we can clean it all
 echo umount >> $seqres.full

tests/xfs/501

@@ -54,7 +54,7 @@ ulimit -n $max_files
 
 # Open a lot of unlinked files
 echo create >> $seqres.full
-$here/src/t_open_tmpfiles $SCRATCH_MNT shutdown >> $seqres.full
+$here/src/t_open_tmpfiles $SCRATCH_MNT $(_scratch_shutdown_handle) >> $seqres.full
 
 # Unmount to prove that we can clean it all
 echo umount >> $seqres.full