Message-ID: <4db7c65bee0739fe7983059296cfc95f20647fa3.camel@kernel.org>
Date:   Thu, 22 Jun 2023 07:48:34 -0400
From:   Jeff Layton <jlayton@...nel.org>
To:     Stas Sergeev <stsp2@...dex.ru>, linux-kernel@...r.kernel.org
Cc:     Chuck Lever <chuck.lever@...cle.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Christian Brauner <brauner@...nel.org>,
        linux-fsdevel@...r.kernel.org, Shuah Khan <shuah@...nel.org>,
        linux-kselftest@...r.kernel.org, linux-api@...r.kernel.org
Subject: Re: [PATCH 2/2] selftests: add OFD lock tests

On Wed, 2023-06-21 at 20:22 +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 tests for F_UNLCK F_OFD_GETLK extension.
> 
> Signed-off-by: Stas Sergeev <stsp2@...dex.ru>
> 
> CC: Jeff Layton <jlayton@...nel.org>
> CC: Chuck Lever <chuck.lever@...cle.com>
> CC: Alexander Viro <viro@...iv.linux.org.uk>
> CC: Christian Brauner <brauner@...nel.org>
> CC: linux-fsdevel@...r.kernel.org
> CC: linux-kernel@...r.kernel.org
> CC: Shuah Khan <shuah@...nel.org>
> CC: linux-kselftest@...r.kernel.org
> CC: linux-api@...r.kernel.org
> 
> ---
>  tools/testing/selftests/locking/Makefile   |   2 +
>  tools/testing/selftests/locking/ofdlocks.c | 132 +++++++++++++++++++++
>  2 files changed, 134 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

I'm not sure this really belongs in the "locking" directory. Given that
there is only the ww_mutex test in there, that's more for internal
synchronization mechanisms, I think.

Can you create a new "filelock" directory and drop this into there
instead?


> diff --git a/tools/testing/selftests/locking/ofdlocks.c b/tools/testing/selftests/locking/ofdlocks.c
> new file mode 100644
> index 000000000000..1ccb2b9b5ead
> --- /dev/null
> +++ b/tools/testing/selftests/locking/ofdlocks.c
> @@ -0,0 +1,132 @@
> +// 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) {
> +		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;
> +}

I'm not opposed to adding a selftest here, but most filesystem testing
is done via xfstests:

    https://git.kernel.org/pub/scm/fs/xfs/xfstests-dev.git/

It would be better to add this test to the existing generic/478 test
that tests OFD locks. Can you patch that to add a test for the new
functionality?

Thanks,
-- 
Jeff Layton <jlayton@...nel.org>

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