From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from firstgate.proxmox.com (firstgate.proxmox.com [212.224.123.68]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by lists.proxmox.com (Postfix) with ESMTPS id B0800B18F for ; Thu, 29 Jun 2023 13:46:55 +0200 (CEST) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id 8AE563F845 for ; Thu, 29 Jun 2023 13:46:25 +0200 (CEST) Received: from proxmox-new.maurer-it.com (proxmox-new.maurer-it.com [94.136.29.106]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by firstgate.proxmox.com (Proxmox) with ESMTPS for ; Thu, 29 Jun 2023 13:46:24 +0200 (CEST) Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id 92D11421DF; Thu, 29 Jun 2023 13:46:24 +0200 (CEST) Message-ID: <15a22deb-baea-6940-7d96-94c27da578d1@proxmox.com> Date: Thu, 29 Jun 2023 13:46:23 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Content-Language: en-US To: =?UTF-8?Q?Fabian_Gr=C3=BCnbichler?= , Proxmox Backup Server development discussion References: <20230629103213.1041236-1-f.gruenbichler@proxmox.com> <08228309-cc0a-2e76-1038-215eee1217d6@proxmox.com> <1688038237.3xn9d6donm.astroid@yuna.none> From: Dominik Csapak In-Reply-To: <1688038237.3xn9d6donm.astroid@yuna.none> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-SPAM-LEVEL: Spam detection results: 0 AWL 0.016 Adjusted score from AWL reputation of From: address BAYES_00 -1.9 Bayes spam probability is 0 to 1% DMARC_MISSING 0.1 Missing DMARC policy KAM_DMARC_STATUS 0.01 Test Rule for DKIM or SPF Failure with Strict Alignment SPF_HELO_NONE 0.001 SPF: HELO does not publish an SPF Record SPF_PASS -0.001 SPF: sender matches SPF record T_SCC_BODY_TEXT_LINE -0.01 - Subject: Re: [pbs-devel] [PATCH proxmox-backup] mapped loop device: use read loop instead of read_exact X-BeenThere: pbs-devel@lists.proxmox.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: Proxmox Backup Server development discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 29 Jun 2023 11:46:55 -0000 On 6/29/23 13:35, Fabian Grünbichler wrote: > On June 29, 2023 1:03 pm, Dominik Csapak wrote: >> On 6/29/23 12:32, Fabian Grünbichler wrote: >>> since read_exact does not support short reads, which can easily happen if the >>> mapped image's EOF is not aligned with the request size. >>> >>> Signed-off-by: Fabian Grünbichler >>> --- >>> >>> Notes: >>> reported on the forum: >>> >>> https://forum.proxmox.com/threads/problem-backing-up-using-backup-client.129347 >>> >>> did a quick test reading from a mapped image full of random data, observed >>> no performance difference.. >>> >>> pbs-fuse-loop/src/fuse_loop.rs | 19 +++++++++++++------ >>> 1 file changed, 13 insertions(+), 6 deletions(-) >>> >>> diff --git a/pbs-fuse-loop/src/fuse_loop.rs b/pbs-fuse-loop/src/fuse_loop.rs >>> index 3d0ef123..7e780799 100644 >>> --- a/pbs-fuse-loop/src/fuse_loop.rs >>> +++ b/pbs-fuse-loop/src/fuse_loop.rs >>> @@ -188,13 +188,20 @@ impl FuseLoopSession { >>> match self.reader.seek(SeekFrom::Start(req.offset)).await { >>> Ok(_) => { >>> let mut buf = vec![0u8; req.size]; >>> - match self.reader.read_exact(&mut buf).await { >>> - Ok(_) => { >>> - req.reply(&buf) >>> - }, >>> - Err(e) => { >>> - req.io_fail(e) >>> + let mut read = 0; >>> + let mut res = Ok(()); >>> + while read < req.size && res.is_ok() { >>> + match self.reader.read(&mut buf).await { >>> + Ok(0) => { break; }, >>> + Ok(n) => { read += n; }, >>> + Err(e) => { res = Err(e); }, >>> } >> >> according to https://doc.rust-lang.org/std/io/trait.Read.html the error >> with errorkind 'Interrupted' should be retried so imho we should do that here? > > this is tokio's AsyncRead(Ext), which doesn't have that remark (and > AFAICT, we don't handle that error when using it anywhere).. if it > were std::io::Read I'd have used our ReadExt's read_exact_or_eof :) yes, you're right ofc. sorry for the noise then > >> >>> + }; >>> + if let Err(e) = res { >>> + req.io_fail(e) >>> + } else { >>> + buf.truncate(read); >>> + req.reply(&buf) >>> } >>> }, >>> Err(e) => { >> >> >>