Re: [PATCH 3/3] selftests: add OFD lock tests

[Jeff Layton]

On Tue, 2023-06-20 at 14:55 +0500, Stas Sergeev wrote:
> Test the basic locking stuff on 2 fds: multiple read locks,
> conflicts between read and write locks, use of len==0 for queries.
> Also test for pid and F_UNLCK F_OFD_GETLK extensions.
> 
> Signed-off-by: Stas Sergeev <stsp2@xxxxxxxxx>
> 
> CC: Shuah Khan <shuah@xxxxxxxxxx>
> CC: linux-kernel@xxxxxxxxxxxxxxx
> CC: linux-kselftest@xxxxxxxxxxxxxxx
> CC: Jeff Layton <jlayton@xxxxxxxxxx>
> CC: Chuck Lever <chuck.lever@xxxxxxxxxx>
> CC: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
> CC: Christian Brauner <brauner@xxxxxxxxxx>
> CC: linux-fsdevel@xxxxxxxxxxxxxxx
> 
> ---
>  tools/testing/selftests/locking/Makefile   |   2 +
>  tools/testing/selftests/locking/ofdlocks.c | 138 +++++++++++++++++++++
>  2 files changed, 140 insertions(+)
>  create mode 100644 tools/testing/selftests/locking/ofdlocks.c
> 
> diff --git a/tools/testing/selftests/locking/Makefile b/tools/testing/selftests/locking/Makefile
> index 6e7761ab3536..a83ced1626de 100644
> --- a/tools/testing/selftests/locking/Makefile
> +++ b/tools/testing/selftests/locking/Makefile
> @@ -7,4 +7,6 @@ all:
>  
>  TEST_PROGS := ww_mutex.sh
>  
> +TEST_GEN_PROGS := ofdlocks
> +
>  include ../lib.mk
> diff --git a/tools/testing/selftests/locking/ofdlocks.c b/tools/testing/selftests/locking/ofdlocks.c
> new file mode 100644
> index 000000000000..1cff350e2c81
> --- /dev/null
> +++ b/tools/testing/selftests/locking/ofdlocks.c
> @@ -0,0 +1,138 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#define _GNU_SOURCE
> +#include <fcntl.h>
> +#include <assert.h>
> +#include <stdio.h>
> +#include <unistd.h>
> +#include <string.h>
> +#include "../kselftest.h"
> +
> +static int lock_set(int fd, struct flock *fl)
> +{
> +	int ret;
> +
> +	fl->l_pid = 0;		// needed for OFD locks
> +	fl->l_whence = SEEK_SET;
> +	ret = fcntl(fd, F_OFD_SETLK, fl);
> +	if (ret)
> +		perror("fcntl()");
> +	return ret;
> +}
> +
> +static int lock_get(int fd, struct flock *fl)
> +{
> +	int ret;
> +
> +	fl->l_pid = 0;		// needed for OFD locks
> +	fl->l_whence = SEEK_SET;
> +	ret = fcntl(fd, F_OFD_GETLK, fl);
> +	if (ret)
> +		perror("fcntl()");
> +	return ret;
> +}
> +
> +int main(void)
> +{
> +	int rc;
> +	struct flock fl, fl2;
> +	int fd = open("/tmp/aa", O_RDWR | O_CREAT | O_EXCL, 0600);
> +	int fd2 = open("/tmp/aa", O_RDONLY);
> +
> +	unlink("aa");
> +	assert(fd != -1);
> +	assert(fd2 != -1);
> +	ksft_print_msg("[INFO] opened fds %i %i\n", fd, fd2);
> +
> +	/* Set some read lock */
> +	fl.l_type = F_RDLCK;
> +	fl.l_start = 5;
> +	fl.l_len = 3;
> +	rc = lock_set(fd, &fl);
> +	if (rc == 0) {
> +		ksft_print_msg
> +		    ("[SUCCESS] set OFD read lock on first fd\n");
> +	} else {
> +		ksft_print_msg("[FAIL] to set OFD read lock on first fd\n");
> +		return -1;
> +	}
> +	/* Make sure read locks do not conflict on different fds. */
> +	fl.l_type = F_RDLCK;
> +	fl.l_start = 5;
> +	fl.l_len = 1;
> +	rc = lock_get(fd2, &fl);
> +	if (rc != 0)
> +		return -1;
> +	if (fl.l_type != F_UNLCK) {
> +		ksft_print_msg("[FAIL] read locks conflicted\n");
> +		return -1;
> +	}
> +	/* Make sure read/write locks do conflict on different fds. */
> +	fl.l_type = F_WRLCK;
> +	fl.l_start = 5;
> +	fl.l_len = 1;
> +	rc = lock_get(fd2, &fl);
> +	if (rc != 0)
> +		return -1;
> +	if (fl.l_type != F_UNLCK) {
> +		ksft_print_msg
> +		    ("[SUCCESS] read and write locks conflicted\n");
> +	} else {
> +		ksft_print_msg
> +		    ("[SUCCESS] read and write locks not conflicted\n");
> +		return -1;
> +	}
> +	/* Get info about the lock on first fd. */
> +	fl.l_type = F_UNLCK;
> +	fl.l_start = 5;
> +	fl.l_len = 1;
> +	rc = lock_get(fd, &fl);
> +	if (rc != 0) {
> +		ksft_print_msg
> +		    ("[FAIL] F_OFD_GETLK with F_UNLCK not supported\n");
> +		return -1;
> +	}
> +	if (fl.l_type != F_UNLCK) {
> +		if (fl.l_pid != getpid()) {
> +			ksft_print_msg
> +			    ("[FAIL] F_OFD_GETLK does not return pid, %i\n",
> +			    fl.l_pid);
> +			return -1;
> +		}

A selftest seems like a reasonable thing to add. The above check will
need to be fixed to not expect a real pid on a OFD lock, of course.

> +		ksft_print_msg
> +		    ("[SUCCESS] F_UNLCK test returns: locked, type %i pid %i len %zi\n",
> +		     fl.l_type, fl.l_pid, fl.l_len);
> +	} else {
> +		ksft_print_msg
> +		    ("[FAIL] F_OFD_GETLK with F_UNLCK did not return lock info\n");
> +		return -1;
> +	}
> +	/* Try the same but by locking everything by len==0. */
> +	fl2.l_type = F_UNLCK;
> +	fl2.l_start = 0;
> +	fl2.l_len = 0;
> +	rc = lock_get(fd, &fl2);
> +	if (rc != 0) {
> +		ksft_print_msg
> +		    ("[FAIL] F_OFD_GETLK with F_UNLCK not supported\n");
> +		return -1;
> +	}
> +	if (memcmp(&fl, &fl2, sizeof(fl))) {
> +		ksft_print_msg
> +		    ("[FAIL] F_UNLCK test returns: locked, type %i pid %i len %zi\n",
> +		     fl.l_type, fl.l_pid, fl.l_len);
> +		return -1;
> +	}
> +	ksft_print_msg("[SUCCESS] F_UNLCK with len==0 returned the same\n");
> +	/* Get info about the lock on second fd - no locks on it. */
> +	fl.l_type = F_UNLCK;
> +	fl.l_start = 0;
> +	fl.l_len = 0;
> +	lock_get(fd2, &fl);
> +	if (fl.l_type != F_UNLCK) {
> +		ksft_print_msg
> +		    ("[FAIL] F_OFD_GETLK with F_UNLCK return lock info from another fd\n");
> +		return -1;
> +	}
> +	return 0;
> +}

-- 
Jeff Layton <jlayton@xxxxxxxxxx>