[Devel] [PATCH 1/2] fs/fuse kio: add FUSE_S_FAIL_IMMEDIATELY check in pcs_fuse_submit()

[Kirill Tkhai]

On 24.01.2019 16:12, Pavel Butsykin wrote:
> Fuse file with FUSE_S_FAIL_IMMEDIATELY state should not allow to execute new
> requests. But in case of kio requests it doesn't work because the status check
> is located behind kio.op->req_send(). To fix this let's add the status check
> in pcs_fuse_submit().
> 
> Signed-off-by: Pavel Butsykin <pbutsykin at virtuozzo.com>
> ---
> Note:
> applies on top of "[PATCH v2] fs/fuse kio: invalidate files for kio"
> 
>  fs/fuse/kio/pcs/pcs_fuse_kdirect.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/fs/fuse/kio/pcs/pcs_fuse_kdirect.c b/fs/fuse/kio/pcs/pcs_fuse_kdirect.c
> index da4b5fba03fb..3ca1ce2d6bd5 100644
> --- a/fs/fuse/kio/pcs/pcs_fuse_kdirect.c
> +++ b/fs/fuse/kio/pcs/pcs_fuse_kdirect.c
> @@ -986,6 +986,11 @@ error:
>  
>  submit:
>  	spin_lock(&di->kq_lock);
> +	if (req->ff && test_bit(FUSE_S_FAIL_IMMEDIATELY, &req->ff->ff_state)) {

FUSE_S_FAIL_IMMEDIATELY is set under fc->lock, while it's checked under kq_lock.
How do you guarantee visibility?

> +		spin_unlock(&di->kq_lock);
> +		req->out.h.error = -EIO;
> +		goto error;
> +	}
>  	list_add_tail(&req->list, &di->kq);
>  	spin_unlock(&di->kq_lock);
>  
>