[LTP] [RFC PATCH v1 1/2] safe_macros.c: Fix missing ro flag for FUSE NTFS mounts

[Petr Vorel]

Hi Jan,

> The test incorrectly assumes that NTFS mounts are read-only, but the mount
> command does not explicitly set the read-only flag. As a result, the test fails
> when checking `sb_flags` against `MS_RDONLY`.

> Old behavior:

Reviewed-by: Petr Vorel <pvorel@suse.cz>
IMHO candidate for a release. Li, Cyril WDYT?

> 	sudo LTP_SINGLE_FS_TYPE=ntfs strace -e trace=mount,statmount -o log.log -s 128 -f ./statmount02
FYI the problem is currently LTP_SINGLE_FS_TYPE is still meant only for testing
one of the filesystems among .all_filesystems => these in fs_type_whitelist[]
(see lib/tst_supported_fs_types.c).

BTW that's similar to use case we haven't even formulated in issue:
https://lore.kernel.org/ltp/Z066Fj9VQVlTOMp_@rei.lan/
https://lore.kernel.org/ltp/Z1mA2wzjW0hpQxUH@yuki.lan/
(The only difference is that this requires to use filesystem not in
fs_type_whitelist[], therefore minor bug for it was found).

Kind regards,
Petr

> 	...
> 	statmount02.c:47: TFAIL: st_mount->sb_flags (0) != MS_RDONLY (1)
> 	...

> Relevant log excerpt:

> 	3890601 mount("/dev/zero", "/tmp/mountBDSEqk", "ntfs", 0, NULL) = -1 ENOTBLK (Block device required)
> 	3890608 mount("/dev/loop0", "/tmp/LTP_staTPRruR/mntpoint", "fuseblk", 0, "allow_other,blksize=4096,fd=4,rootmode=40000,user_id=0,group_id=0") = 0
> 	3890607 statmount({size=24, mnt_id=0x80010957, param=STATMOUNT_SB_BASIC}, {size=512, mask=STATMOUNT_SB_BASIC, sb_dev_major=7, sb_dev_minor=0, sb_magic=FUSE_SUPER_MAGIC, sb_flags=0}, 512, 0) = 0

> Signed-off-by: Jan Polensky <japo@linux.ibm.com>
> ---
>  lib/safe_macros.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)

> diff --git a/lib/safe_macros.c b/lib/safe_macros.c
> index 6946cc5bcb94..1270b17af8f4 100644
> --- a/lib/safe_macros.c
> +++ b/lib/safe_macros.c
> @@ -942,10 +942,15 @@ int safe_mount(const char *file, const int lineno, void (*cleanup_fn)(void),
>  	 */
>  	if (possibly_fuse(filesystemtype)) {
>  		char buf[1024];
> +		const char* mount_fmt;

>  		tst_resm_(file, lineno, TINFO, "Trying FUSE...");
> -		snprintf(buf, sizeof(buf), "mount.%s '%s' '%s'",
> -			filesystemtype, source, target);
> +		if (!strcmp(filesystemtype, "ntfs") && mountflags & MS_RDONLY)
> +			mount_fmt = "mount.%s -o ro '%s' '%s'";
> +		else
> +			mount_fmt = "mount.%s '%s' '%s'";
> +		snprintf(buf, sizeof(buf), mount_fmt, filesystemtype,
> +				source, target);

>  		rval = tst_system(buf);
>  		if (WIFEXITED(rval) && WEXITSTATUS(rval) == 0)