From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from submarine.notk.org (submarine.notk.org [62.210.214.84]) by smtp.subspace.kernel.org (Postfix) with ESMTP id E334B2BE62C for ; Mon, 3 Nov 2025 07:34:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=62.210.214.84 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762155283; cv=none; b=DPpKVnSGq5c9bP+0009pDDjl+nlu7dN0Kk7f2Ocx0AhFxqIhoz0OZoyXgL+ZDDxxknsEOPu7J7l2kchceHptIkbuskDZBm3+k2tbt2erL3c6SANz37vv0X7/MzWe7NPC3mR0G4IVVyAZrGiDrG8IpbclwdAxO1O9LBqMvKEJlBE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762155283; c=relaxed/simple; bh=OaIrQuLa4Fc/nUWN+i36v0NLFWmb/7dXjMkFBh6t7HQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=O5KxhlXEznf6bArFUw98svqMDV4dxPTwBo5ASTb+KxKRADO40WiVS+bSDhPYgyVnNee/i8xh7UbfPTyEgn73ThVDbHBscVvvNxrusZ9FP4UiMEsTIBj6eBhKyrO9UOScmNHXUH6a6j+rEcOzpgBZyLXuuU+j1RedeoHKQfkJgbc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=codewreck.org; spf=pass smtp.mailfrom=codewreck.org; dkim=pass (2048-bit key) header.d=codewreck.org header.i=@codewreck.org header.b=Q5155Gp8; arc=none smtp.client-ip=62.210.214.84 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=codewreck.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=codewreck.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=codewreck.org header.i=@codewreck.org header.b="Q5155Gp8" Received: from gaia.codewreck.org (localhost [127.0.0.1]) by submarine.notk.org (Postfix) with ESMTPS id 5ED9014C2D3; Mon, 3 Nov 2025 08:34:36 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=codewreck.org; s=2; t=1762155277; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=yQrtrx4bqMFJsQe0FEzhHJ9535jhbktObZu6e5hp1Hw=; b=Q5155Gp8XBV8wrqnW7AmSnBBTyLdLM+Pext9G/hNgUyJmWEYI4tVax6dZe1b02SLnWba7W NNtD4srNvbh2BwyaewUZIoofXsXLDQH4IVBdPAmrlmZ61tNqMzK6mttrfaI73hvG+AuJpY UaWoXebY0HSZDDtwvQRc7UEeRUCoL9A6Lq9SAswb9JwZFMbQlOZiMqpUQa8gazGta//OtT yA9PxowqL2lPS0PhKViSQuZUAEMHqQVEPFUipLlvSqnqb/7Ah/+qbiORjrmgJNUqt5/Gcp keja4xlWVDLIGFe49bhjQ6kA5W+tsfS71qJBp97N607ZnAiJPreMGpkFO3v7OA== Received: from localhost (gaia.codewreck.org [local]) by gaia.codewreck.org (OpenSMTPD) with ESMTPA id 1231a4a8; Mon, 3 Nov 2025 07:34:34 +0000 (UTC) Date: Mon, 3 Nov 2025 16:34:19 +0900 From: Dominique Martinet To: Tingmao Wang Cc: Christian Schoenebeck , Eric Van Hensbergen , Latchesar Ionkov , v9fs@lists.linux.dev Subject: Re: [PATCH v2] fs/9p: Don't open remote file with APPEND mode when writeback cache is used Message-ID: References: <20251102235631.8724-1-m@maowtm.org> Precedence: bulk X-Mailing-List: v9fs@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20251102235631.8724-1-m@maowtm.org> Thanks for the v2 Tingmao Wang wrote on Sun, Nov 02, 2025 at 11:56:30PM +0000: > I haven't done a bisect to figure out if this regression was introduced by > a change or was this behaviour always present - 6.14 has the same problem > and 6.13 did not compile for me due to some problem with bool / true / > false being a keyword in c23, and it could not compile with c17 either. Ok so you got me at the "it happens in cache=loose too", so I went ahead with bisect... I had the same problem with newer gcc being c23 and older kernels being silly, you'd think `KCFLAGS=-std=gnu11` is enough but some arch makefiles ignore that so I went in heavy patching arch/x86/boot/Makefile and arch/x86/boot/compressed/Makefile . . . ... Anyway, it certainly didn't break recently, but it's not ages ago either: the repro you made (thank you!!) starts failing in 6.4 cache rework: the first bad commit is actually 21e26d5e54ab ("fs/9p: Fix bit operation logic error"), but that's just a fixup of the previous commit so 4eb3117888a9 ("fs/9p: Rework cache modes and add new options to Documentation") is the cluprit... and... I'm not quite sure I get why without digging deeper... (But at least that made me realize the commit just before, 1543b4c5071c ("fs/9p: remove writeback fid and fix per-file modes"), removed the writeback fid I was talking about... But that commit was working (with a sane ~P9_OWRITE mask), so it's not directly that removal that broke things, but something else in the rework) Anyway, I think this commit is a strict improvement over the current situation, I'll just slap a Fixes tag and push to -next for now, and if time allows I'll try to have a closer look... Thanks, -- Dominique