[LTP] [PATCH 6/7] syscalls/fanotify20: Test file event with broken inode

[Amir Goldstein]

On Tue, Aug 3, 2021 at 12:47 AM Gabriel Krisman Bertazi
<krisman@collabora.com> wrote:
>
> This test corrupts an inode entry with an invalid mode through debugfs
> and then tries to access it.  This should result in a ext4 error, which
> we monitor through the fanotify group.
>
> Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
> ---
>  .../kernel/syscalls/fanotify/fanotify20.c     | 38 +++++++++++++++++++
>  1 file changed, 38 insertions(+)
>
> diff --git a/testcases/kernel/syscalls/fanotify/fanotify20.c b/testcases/kernel/syscalls/fanotify/fanotify20.c
> index e7ced28eb61d..0c63e90edc3a 100644
> --- a/testcases/kernel/syscalls/fanotify/fanotify20.c
> +++ b/testcases/kernel/syscalls/fanotify/fanotify20.c
> @@ -76,6 +76,36 @@ static void trigger_fs_abort(void)
>                    MS_REMOUNT|MS_RDONLY, "abort");
>  }
>
> +#define TCASE2_BASEDIR "tcase2"
> +#define TCASE2_BAD_DIR TCASE2_BASEDIR"/bad_dir"
> +
> +static unsigned int tcase2_bad_ino;
> +static void tcase2_prepare_fs(void)
> +{
> +       struct stat stat;
> +
> +       SAFE_MKDIR(MOUNT_PATH"/"TCASE2_BASEDIR, 0777);
> +       SAFE_MKDIR(MOUNT_PATH"/"TCASE2_BAD_DIR, 0777);
> +
> +       SAFE_STAT(MOUNT_PATH"/"TCASE2_BAD_DIR, &stat);
> +       tcase2_bad_ino = stat.st_ino;
> +
> +       SAFE_UMOUNT(MOUNT_PATH);
> +       do_debugfs_request(tst_device->dev, "sif " TCASE2_BAD_DIR " mode 0xff");
> +       SAFE_MOUNT(tst_device->dev, MOUNT_PATH, tst_device->fs_type, 0, NULL);
> +}
> +
> +static void tcase2_trigger_lookup(void)
> +{
> +       int ret;
> +
> +       /* SAFE_OPEN cannot be used here because we expect it to fail. */
> +       ret = open(MOUNT_PATH"/"TCASE2_BAD_DIR, O_RDONLY, 0);
> +       if (ret != -1 && errno != EUCLEAN)
> +               tst_res(TFAIL, "Unexpected lookup result(%d) of %s (%d!=%d)",
> +                       ret, TCASE2_BAD_DIR, errno, EUCLEAN);
> +}
> +
>  static const struct test_case {
>         char *name;
>         int error;
> @@ -92,6 +122,14 @@ static const struct test_case {
>                 .error_count = 1,
>                 .error = EXT4_ERR_ESHUTDOWN,
>                 .inode = NULL
> +       },
> +       {
> +               .name = "Lookup of inode with invalid mode",
> +               .prepare_fs = tcase2_prepare_fs,
> +               .trigger_error = &tcase2_trigger_lookup,
> +               .error_count = 1,
> +               .error = 0,
> +               .inode = &tcase2_bad_ino,

Why is error 0?
What's the rationale?

Thanks,
Amir.