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From:   Miklos Szeredi <miklos@szeredi.hu>
Date:   Wed, 7 Nov 2018 14:16:30 +0100
Message-ID: <CAJfpegttTpU0=yF_7QNx_PCOELetG0eGoEtmRyv0m4czK9EGNQ@mail.gmail.com>
Subject: Re: [PATCH 4/6] fuse: Check for FR_SENT bit in fuse_dev_do_write()
To:     Kirill Tkhai <ktkhai@virtuozzo.com>
Cc:     linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
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On Tue, Nov 6, 2018 at 10:30 AM, Kirill Tkhai <ktkhai@virtuozzo.com> wrote:
> It's not possible to have answer to a request,
> before the request is actually sent. Add sanity
> check for that.

It's checking for the impossible.  That sometimes makes sense as a
WARN_ON() or in special cases a BUG_ON().


>
> Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
> ---
>  fs/fuse/dev.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
> index 739968ee8b0c..c603f1ebf0fd 100644
> --- a/fs/fuse/dev.c
> +++ b/fs/fuse/dev.c
> @@ -1947,7 +1947,7 @@ static ssize_t fuse_dev_do_write(struct fuse_dev *fud,
>                 goto err_unlock_pq;
>
>         req = request_find(fpq, oh.unique & ~FUSE_INT_REQ_BIT);
> -       if (!req)
> +       if (!req || !test_bit(FR_SENT, &req->flags))
>                 goto err_unlock_pq;
>
>         /* Is it an interrupt reply ID? */
>