From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ej1-f49.google.com (mail-ej1-f49.google.com [209.85.218.49]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E2A20175A5 for ; Mon, 2 Sep 2024 11:11:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.218.49 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725275508; cv=none; b=oPtEN1wUI9SUEs7Njrm+DpS2VMcePi2DdAWEioWks24h5i0MgqzHGFcueEAJUxEj0XhqeYr6HuotA/rVjPzdlle/1i99OL8aSdHN1v4CXgdoFU0tGNGqhhuVqKsx1nZQhH6/zbjJVcx82uixsqTtLx2h0syvjOoqYV2OifE3NJk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725275508; c=relaxed/simple; bh=ACYti0hxKYVlzkz96GHvJe0UCYPSKaa4OxF8s/gep5I=; h=MIME-Version:References:In-Reply-To:From:Date:Message-ID:Subject: To:Cc:Content-Type; b=GHrP/LMGw7DiUyKKpS3eAB400V1xzDC1I9FMGE2Xq5fhaos2ELH7DN7YLgZHDuYk6O+1QyusGo28vmofbJ7dS+37m9hNfR3TZx+NJ8VeVz9ii7Vzv6DubkSmZxMl62aRBfrtlalXIfyXJUYpTEO+G5naEQidCN+hs/B1XqfrLDo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=szeredi.hu; spf=pass smtp.mailfrom=szeredi.hu; dkim=pass (1024-bit key) header.d=szeredi.hu header.i=@szeredi.hu header.b=OnCmY1mq; arc=none smtp.client-ip=209.85.218.49 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=szeredi.hu Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=szeredi.hu Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=szeredi.hu header.i=@szeredi.hu header.b="OnCmY1mq" Received: by mail-ej1-f49.google.com with SMTP id a640c23a62f3a-a869332c2c2so812961066b.0 for ; Mon, 02 Sep 2024 04:11:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=szeredi.hu; s=google; t=1725275504; x=1725880304; darn=vger.kernel.org; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=Kuph0+9o4A1RPBphrgMO3PL8jFdGA5zKpiVVErC0F/k=; b=OnCmY1mqmtxMVFTFjLXpy3zZigFu0OOki2+j5xPTGH0X0rEfdXSfa+MiNxF82m2xNB N/0AGia4jUlm07ScatBxnkXDeN/4ooekEEnc8Fn4ypZHwZG6H016TcixqxEjlv5qIpJd DmM0RG40rCJnbfXTatNOK37TeNw91gTvRInag= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1725275504; x=1725880304; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=Kuph0+9o4A1RPBphrgMO3PL8jFdGA5zKpiVVErC0F/k=; b=CtiFK/KipPwFTeYBJ7LDzQGCVV0lKwebCEXLjqS2vDMAvxOYNHXjyzyyzmMdn/gpwo BMOHbrK0XgHVjmphhTF2wwHFpqHMA2HPG2q8Jm1PITSwrIAAd5F1Quxy/DFb0w0EVbkU 1ofEQIrIpLorhtd42Jbsq0ULrwvHgmvW8c1hl8qPz4CominN9mxQcXGNJWAPuAUC+EfH 9mNnXNK6HPZo/uyL6p3GIoY8KXsKec6Is6wc9cERigZwqk05KE+W2jvGHKhv0WrPFcV2 hhqx+0woDAVn75fnEQz0yFehY9Yo0REEFzQ1ACrTEC2N07hYfm9SI6Mb+m2K//Ask0dZ 4bwQ== X-Forwarded-Encrypted: i=1; AJvYcCUY7LbLidmyCXRybpp7XVHkeDrJxWSbEWqV/Jv+BiDSK1ZBrBFrylyFfv0C0xzGF808bWAFTnNkD2rJaDAS@vger.kernel.org X-Gm-Message-State: AOJu0YxAvChY01FxV1a4DF5MNZ+clp/Y0Y4J32/I2OvacdLZ5xbVkI6y AaZaArN/ZPTlVAG4/I8LXzdtGoWJfroCWOFVTafMbYP1MVX7XM0bE51xbkxUvJwFOhHnHqLMSHn Z5B3XOjKNjbKVA1i0eLQchOkBCqUxonJklGd5d5RRdrgF4wSXkaA= X-Google-Smtp-Source: AGHT+IFBxYjxkpMm6qbV9fEsZkagQqPFpQha8XkxW51P/F5oJ/Yydy83LAC9tU2cSwhRYQpNxEurFqLkG3Jmy8LaC6g= X-Received: by 2002:a17:907:3da0:b0:a86:a6ee:7d92 with SMTP id a640c23a62f3a-a89825a4390mr1484060166b.18.1725275504209; Mon, 02 Sep 2024 04:11:44 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20240830162649.3849586-1-joannelkoong@gmail.com> <20240830162649.3849586-2-joannelkoong@gmail.com> <1c7c9f00-8e94-4a98-a3d4-a3610d35e744@fastmail.fm> In-Reply-To: <1c7c9f00-8e94-4a98-a3d4-a3610d35e744@fastmail.fm> From: Miklos Szeredi Date: Mon, 2 Sep 2024 13:11:31 +0200 Message-ID: Subject: Re: [PATCH v6 1/2] fuse: add optional kernel-enforced timeout for requests To: Bernd Schubert Cc: Joanne Koong , linux-fsdevel@vger.kernel.org, josef@toxicpanda.com, jefflexu@linux.alibaba.com, laoar.shao@gmail.com, kernel-team@meta.com Content-Type: text/plain; charset="UTF-8" On Mon, 2 Sept 2024 at 12:50, Bernd Schubert wrote: > In case of distributed servers, it can easily happen that one server has > an issue, while other servers still process requests. Especially when > these are just requests that read/getattr/etc and do not write, i.e. > accessing the stuck server is not needed by other servers. So in my > opinion not so unlikely. Although for such cases not difficult to > timeout within the fuse server. Exactly. Normally the kernel should not need to time out fuse requests, and it might be actively detrimental to do so. The main case this wants to solve is a deadlocked server due to programming error, AFAICS. And this would only work in environments where requests are guaranteed to complete within some time period. So if the server needs to handle request timeouts, then it should *not* rely on the kernel timeout. The kernel timeout should be a safeguard against broken or malicious servers, not an aid to implement request timeouts. Thanks, Miklos