[LTP] [PATCH] fanotify: Fix broken tests due to fanotify_events_supported_by_kernel()

[Petr Vorel]

Hi Jan,

> When LTP test is run with CWD in btrfs subvolume, tests like fanotify16
> fail with:

> fanotify.h:169: TBROK: fanotify_mark (3, FAN_MARK_ADD, ..., AT_FDCWD, ".") failed: EXDEV (18)

I'll have a deeper look tomorrow, but actually with this patch it fails

LTP_SINGLE_FS_TYPE=btrfs ./fanotify16
...
fanotify.h:168: TBROK: fanotify_mark (3, FAN_MARK_ADD | 0, 10000000, AT_FDCWD, ".") failed: EXDEV (18)

And it works without it. What am I missing?

Tested on 6.7.0-rc1-2.g86e46c2-default

> This is because fanotify_events_supported_by_kernel() try to place a
> mark onto CWD and that is forbidden for btrfs subvolumes. Change
> fanotify_events_supported_by_kernel() to use "/" instead of "." which
> has higher chances of working for btrfs.

> Also update the error message to provide a bit more info.

> Signed-off-by: Jan Kara <jack@suse.cz>
> ---
>  testcases/kernel/syscalls/fanotify/fanotify.h | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)

> diff --git a/testcases/kernel/syscalls/fanotify/fanotify.h b/testcases/kernel/syscalls/fanotify/fanotify.h
> index 32b510cdc178..f2fe0c05b449 100644
> --- a/testcases/kernel/syscalls/fanotify/fanotify.h
> +++ b/testcases/kernel/syscalls/fanotify/fanotify.h
> @@ -161,12 +161,13 @@ static inline int fanotify_events_supported_by_kernel(uint64_t mask,

>  	fd = SAFE_FANOTIFY_INIT(init_flags, O_RDONLY);

> -	if (fanotify_mark(fd, FAN_MARK_ADD | mark_flags, mask, AT_FDCWD, ".") < 0) {
> +	if (fanotify_mark(fd, FAN_MARK_ADD | mark_flags, mask, AT_FDCWD, "/") < 0) {
>  		if (errno == EINVAL) {
>  			rval = -1;
>  		} else {
>  			tst_brk(TBROK | TERRNO,
> -				"fanotify_mark (%d, FAN_MARK_ADD, ..., AT_FDCWD, \".\") failed", fd);
> +				"fanotify_mark (%d, FAN_MARK_ADD | %x, %llx, AT_FDCWD, \".\") failed",
				"fanotify_mark (%d, FAN_MARK_ADD | %x, %llx, AT_FDCWD, \"/\") failed",

(You changed directory . to /, thus error message should be updated as well)

Kind regards,
Petr

> +				fd, mark_flags, (unsigned long long)mask);
>  		}
>  	}