From f84f62e69963d7742acec4340ec1c4c7ef22b887 Mon Sep 17 00:00:00 2001 From: Andre Przywara Date: Mon, 21 Aug 2023 17:05:34 +0100 Subject: [PATCH] selftests: cachestat: catch failing fsync test on tmpfs The cachestat kselftest runs a test on a normal file, which is created temporarily in the current directory. Among the tests it runs there is a call to fsync(), which is expected to clean all dirty pages used by the file. However the tmpfs filesystem implements fsync() as noop_fsync(), so the call will not even attempt to clean anything when this test file happens to live on a tmpfs instance. This happens in an initramfs, or when the current directory is in /dev/shm or sometimes /tmp. To avoid this test failing wrongly, use statfs() to check which filesystem the test file lives on. If that is "tmpfs", we skip the fsync() test. Since the fsync test is only one part of the "normal file" test, we now execute this twice, skipping the fsync part on the first call. This way only the second test, including the fsync part, would be skipped. Link: https://lkml.kernel.org/r/20230821160534.3414911-3-andre.przywara@arm.com Signed-off-by: Andre Przywara Cc: Johannes Weiner Cc: Nhat Pham Cc: Shuah Khan Signed-off-by: Andrew Morton --- tools/testing/selftests/cachestat/test_cachestat.c | 62 ++++++++++++++++------ 1 file changed, 47 insertions(+), 15 deletions(-) diff --git a/tools/testing/selftests/cachestat/test_cachestat.c b/tools/testing/selftests/cachestat/test_cachestat.c index b0c06393bcad..c037553cfd92 100644 --- a/tools/testing/selftests/cachestat/test_cachestat.c +++ b/tools/testing/selftests/cachestat/test_cachestat.c @@ -4,10 +4,12 @@ #include #include #include +#include #include #include #include #include +#include #include #include #include @@ -15,7 +17,7 @@ #include "../kselftest.h" -#define NR_TESTS 8 +#define NR_TESTS 9 static const char * const dev_files[] = { "/dev/zero", "/dev/null", "/dev/urandom", @@ -93,19 +95,33 @@ out: } /* + * fsync() is implemented via noop_fsync() on tmpfs. This makes the fsync() + * test fail below, so we need to check for test file living on a tmpfs. + */ +static bool is_on_tmpfs(int fd) +{ + struct statfs statfs_buf; + + if (fstatfs(fd, &statfs_buf)) + return false; + + return statfs_buf.f_type == TMPFS_MAGIC; +} + +/* * Open/create the file at filename, (optionally) write random data to it * (exactly num_pages), then test the cachestat syscall on this file. * * If test_fsync == true, fsync the file, then check the number of dirty * pages. */ -bool test_cachestat(const char *filename, bool write_random, bool create, - bool test_fsync, unsigned long num_pages, int open_flags, - mode_t open_mode) +static int test_cachestat(const char *filename, bool write_random, bool create, + bool test_fsync, unsigned long num_pages, + int open_flags, mode_t open_mode) { size_t PS = sysconf(_SC_PAGESIZE); int filesize = num_pages * PS; - bool ret = true; + int ret = KSFT_PASS; long syscall_ret; struct cachestat cs; struct cachestat_range cs_range = { 0, filesize }; @@ -114,7 +130,7 @@ bool test_cachestat(const char *filename, bool write_random, bool create, if (fd == -1) { ksft_print_msg("Unable to create/open file.\n"); - ret = false; + ret = KSFT_FAIL; goto out; } else { ksft_print_msg("Create/open %s\n", filename); @@ -123,7 +139,7 @@ bool test_cachestat(const char *filename, bool write_random, bool create, if (write_random) { if (!write_exactly(fd, filesize)) { ksft_print_msg("Unable to access urandom.\n"); - ret = false; + ret = KSFT_FAIL; goto out1; } } @@ -134,7 +150,7 @@ bool test_cachestat(const char *filename, bool write_random, bool create, if (syscall_ret) { ksft_print_msg("Cachestat returned non-zero.\n"); - ret = false; + ret = KSFT_FAIL; goto out1; } else { @@ -144,15 +160,17 @@ bool test_cachestat(const char *filename, bool write_random, bool create, if (cs.nr_cache + cs.nr_evicted != num_pages) { ksft_print_msg( "Total number of cached and evicted pages is off.\n"); - ret = false; + ret = KSFT_FAIL; } } } if (test_fsync) { - if (fsync(fd)) { + if (is_on_tmpfs(fd)) { + ret = KSFT_SKIP; + } else if (fsync(fd)) { ksft_print_msg("fsync fails.\n"); - ret = false; + ret = KSFT_FAIL; } else { syscall_ret = syscall(cachestat_nr, fd, &cs_range, &cs, 0); @@ -163,13 +181,13 @@ bool test_cachestat(const char *filename, bool write_random, bool create, print_cachestat(&cs); if (cs.nr_dirty) { - ret = false; + ret = KSFT_FAIL; ksft_print_msg( "Number of dirty should be zero after fsync.\n"); } } else { ksft_print_msg("Cachestat (after fsync) returned non-zero.\n"); - ret = false; + ret = KSFT_FAIL; goto out1; } } @@ -260,7 +278,7 @@ int main(void) const char *dev_filename = dev_files[i]; if (test_cachestat(dev_filename, false, false, false, - 4, O_RDONLY, 0400)) + 4, O_RDONLY, 0400) == KSFT_PASS) ksft_test_result_pass("cachestat works with %s\n", dev_filename); else { ksft_test_result_fail("cachestat fails with %s\n", dev_filename); @@ -269,13 +287,27 @@ int main(void) } if (test_cachestat("tmpfilecachestat", true, true, - true, 4, O_CREAT | O_RDWR, 0400 | 0600)) + false, 4, O_CREAT | O_RDWR, 0600) == KSFT_PASS) ksft_test_result_pass("cachestat works with a normal file\n"); else { ksft_test_result_fail("cachestat fails with normal file\n"); ret = 1; } + switch (test_cachestat("tmpfilecachestat", true, true, + true, 4, O_CREAT | O_RDWR, 0600)) { + case KSFT_FAIL: + ksft_test_result_fail("cachestat fsync fails with normal file\n"); + ret = KSFT_FAIL; + break; + case KSFT_PASS: + ksft_test_result_pass("cachestat fsync works with a normal file\n"); + break; + case KSFT_SKIP: + ksft_test_result_skip("tmpfilecachestat is on tmpfs\n"); + break; + } + if (test_cachestat_shmem()) ksft_test_result_pass("cachestat works with a shmem file\n"); else { -- 2.11.0