[LTP] [PATCH v2] syscalls: avoid creating whiteout device in tests

[Jan Stancek <jstancek@redhat.com>]

----- Original Message -----
> From: "Eryu Guan" <eguan@redhat.com>
> To: ltp@lists.linux.it
> Sent: Friday, 11 December, 2015 2:24:23 PM
> Subject: [LTP] [PATCH v2] syscalls: avoid creating whiteout device in tests
> 
> A char device with major 0 and minor 0 is known as whiteout device, and
> overlayfs refuses to create such device. mknod01 and mount02 fail on
> overlayfs because of this restriction.
> 
> Fix it by creating null device instead.
> 
> Signed-off-by: Eryu Guan <eguan@redhat.com>
> ---
> 
> v2:
> - update the arg in mknod syscall to really use variable "dev", which is the
>   whole point of this patch

Pushed with reference to Documentation about whiteout device.

Regards,
Jan

> 
>  testcases/kernel/syscalls/mknod/mknod01.c | 19 ++++++++++++++-----
>  testcases/kernel/syscalls/mount/mount02.c |  8 ++++++--
>  2 files changed, 20 insertions(+), 7 deletions(-)
> 
> diff --git a/testcases/kernel/syscalls/mknod/mknod01.c
> b/testcases/kernel/syscalls/mknod/mknod01.c
> index 863d02d..c4da3a2 100644
> --- a/testcases/kernel/syscalls/mknod/mknod01.c
> +++ b/testcases/kernel/syscalls/mknod/mknod01.c
> @@ -66,6 +66,7 @@ int TST_TOTAL = ARRAY_SIZE(tcases);
>  int main(int ac, char **av)
>  {
>  	int lc, i;
> +	dev_t dev;
>  
>  	tst_parse_opts(ac, av, NULL, NULL);
>  
> @@ -75,17 +76,25 @@ int main(int ac, char **av)
>  		tst_count = 0;
>  
>  		for (i = 0; i < TST_TOTAL; i++) {
> -			TEST(mknod(PATH, tcases[i], 0));
> +			/*
> +			 * overlayfs doesn't support mknod char device with
> +			 * major 0 and minor 0, which is known as whiteout_dev
> +			 */
> +			if (S_ISCHR(tcases[i]))
> +				dev = makedev(1, 3);
> +			else
> +				dev = 0;
> +			TEST(mknod(PATH, tcases[i], dev));
>  
>  			if (TEST_RETURN == -1) {
>  				tst_resm(TFAIL,
> -					 "mknod(%s, %#o, 0) failed, errno=%d : %s",
> -					 PATH, tcases[i], TEST_ERRNO,
> +					 "mknod(%s, %#o, %lu) failed, errno=%d : %s",
> +					 PATH, tcases[i], dev, TEST_ERRNO,
>  					 strerror(TEST_ERRNO));
>  			} else {
>  				tst_resm(TPASS,
> -					 "mknod(%s, %#o, 0) returned %ld",
> -					 PATH, tcases[i], TEST_RETURN);
> +					 "mknod(%s, %#o, %lu) returned %ld",
> +					 PATH, tcases[i], dev, TEST_RETURN);
>  			}
>  
>  			SAFE_UNLINK(cleanup, PATH);
> diff --git a/testcases/kernel/syscalls/mount/mount02.c
> b/testcases/kernel/syscalls/mount/mount02.c
> index 85c050d..916c35e 100644
> --- a/testcases/kernel/syscalls/mount/mount02.c
> +++ b/testcases/kernel/syscalls/mount/mount02.c
> @@ -170,6 +170,8 @@ static void do_umount(void)
>  
>  static void setup(void)
>  {
> +	dev_t dev;
> +
>  	tst_sig(FORK, DEF_HANDLER, cleanup);
>  
>  	tst_require_root();
> @@ -190,9 +192,11 @@ static void setup(void)
>  
>  	memset(path, 'a', PATH_MAX + 1);
>  
> -	if (mknod(char_dev, S_IFCHR | FILE_MODE, 0)) {
> +	dev = makedev(1, 3);
> +	if (mknod(char_dev, S_IFCHR | FILE_MODE, dev)) {
>  		tst_brkm(TBROK | TERRNO, cleanup,
> -		         "failed to mknod(char_dev, S_IFCHR | FILE_MODE, 0)");
> +			 "failed to mknod(char_dev, S_IFCHR | FILE_MODE, %lu)",
> +			 dev);
>  	}
>  
>  	TEST_PAUSE;
> --
> 2.5.0
> 
> 
> --
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>