Mount an overlayfs, create and write a file in the merged directory, and run cachestat() on it, reusing the existing test_cachestat() helper.
Also bump NR_TESTS to the actual number of tests run: it was 9 while ten tests were already executed, and this adds an eleventh. Signed-off-by: Pavel Tikhomirov <[email protected]> --- .../selftests/cachestat/test_cachestat.c | 75 ++++++++++++++++++- 1 file changed, 74 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/cachestat/test_cachestat.c b/tools/testing/selftests/cachestat/test_cachestat.c index 542cd09cb4434..1662d9817c50b 100644 --- a/tools/testing/selftests/cachestat/test_cachestat.c +++ b/tools/testing/selftests/cachestat/test_cachestat.c @@ -4,21 +4,25 @@ #include <stdio.h> #include <stdbool.h> +#include <stdlib.h> #include <linux/kernel.h> #include <linux/magic.h> #include <linux/mman.h> #include <sys/mman.h> +#include <sys/mount.h> #include <sys/shm.h> +#include <sys/stat.h> #include <sys/syscall.h> #include <sys/vfs.h> #include <unistd.h> #include <string.h> #include <fcntl.h> #include <errno.h> +#include <limits.h> #include "kselftest.h" -#define NR_TESTS 9 +#define NR_TESTS 11 static const char * const dev_files[] = { "/dev/zero", "/dev/null", "/dev/urandom", @@ -294,6 +298,62 @@ bool run_cachestat_test(enum file_type type) return ret; } +/* + * Set up an overlayfs mount and run cachestat on a freshly created file in the + * merged directory. Overlayfs forwards data I/O to the underlying (upper) + * inode, so the page cache lives there and not in the overlay inode's mapping. + * This is a regression test for cachestat returning all zeroes on overlayfs. + */ +static int run_cachestat_overlayfs_test(void) +{ + char tmpl[] = "/tmp/cachestat_ovl.XXXXXX"; + char lower[PATH_MAX], upper[PATH_MAX], work[PATH_MAX]; + char merged[PATH_MAX], opts[4 * PATH_MAX], file[PATH_MAX]; + char *base; + int ret; + + base = mkdtemp(tmpl); + if (!base) { + ksft_print_msg("Unable to create overlayfs base dir: %s\n", + strerror(errno)); + return KSFT_FAIL; + } + + snprintf(lower, sizeof(lower), "%s/lower", base); + snprintf(upper, sizeof(upper), "%s/upper", base); + snprintf(work, sizeof(work), "%s/work", base); + snprintf(merged, sizeof(merged), "%s/merged", base); + + if (mkdir(lower, 0755) || mkdir(upper, 0755) || + mkdir(work, 0755) || mkdir(merged, 0755)) { + ksft_print_msg("Unable to create overlayfs dirs: %s\n", + strerror(errno)); + ret = KSFT_FAIL; + goto cleanup; + } + + snprintf(opts, sizeof(opts), "lowerdir=%s,upperdir=%s,workdir=%s", + lower, upper, work); + + if (mount("overlay", merged, "overlay", 0, opts)) { + ksft_print_msg("Unable to mount overlayfs (need root?): %s\n", + strerror(errno)); + ret = KSFT_SKIP; + goto cleanup; + } + + snprintf(file, sizeof(file), "%s/merged/cachestat", base); + ret = test_cachestat(file, true, true, false, 4, O_CREAT | O_RDWR, 0600); + + umount(merged); +cleanup: + /* Best-effort recursive cleanup of the temporary tree. */ + snprintf(opts, sizeof(opts), "rm -rf %s", base); + if (system(opts)) + ksft_print_msg("Unable to clean up %s\n", base); + return ret; +} + int main(void) { int ret; @@ -361,5 +421,18 @@ int main(void) ksft_test_result_fail("cachestat fails with a mmap file\n"); ret = 1; } + + switch (run_cachestat_overlayfs_test()) { + case KSFT_FAIL: + ksft_test_result_fail("cachestat fails with an overlayfs file\n"); + ret = 1; + break; + case KSFT_PASS: + ksft_test_result_pass("cachestat works with an overlayfs file\n"); + break; + case KSFT_SKIP: + ksft_test_result_skip("overlayfs not available\n"); + break; + } return ret; } -- 2.54.0
