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// SPDX-License-Identifier: GPL-2.0
/*
* Reading the root of an empty mount namespace holds nothing that anybody
* else waits for: the directory never has an entry, so a readdir stuck in
* the page fault of its buffer stalls neither a create nor a lookup in it.
*/
#define _GNU_SOURCE
#include <errno.h>
#include <fcntl.h>
#include <sched.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "../../kselftest_harness.h"
#include "../readdir_hold.h"
#include "empty_mntns.h"
TEST(readdir_blocks_nobody)
{
struct readdir_hold hold;
bool stalled;
int dfd;
if (geteuid())
SKIP(return, "test requires root");
if (readdir_hold_init(&hold))
SKIP(return, "test requires userfaultfd");
if (unshare(UNSHARE_EMPTY_MNTNS)) {
readdir_hold_destroy(&hold);
if (errno == EINVAL)
SKIP(return, "UNSHARE_EMPTY_MNTNS not supported");
ASSERT_TRUE(false)
TH_LOG("unshare(UNSHARE_EMPTY_MNTNS): %m");
}
dfd = open("/", O_RDONLY | O_DIRECTORY | O_CLOEXEC);
ASSERT_GE(dfd, 0);
ASSERT_EQ(readdir_hold_check(&hold, dfd, &stalled), 0);
/* the lookup came back while the readdir was stuck in its fault */
EXPECT_FALSE(stalled);
close(dfd);
readdir_hold_destroy(&hold);
}
TEST_HARNESS_MAIN
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