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 7DEDB28469A; Sat, 11 Oct 2025 19:40:40 +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=1760211644; cv=none; b=lrkXtmz3hTify99fKY8PAx97vyiiDcUV67xn43BBeqak+RJkAW9M0/1y1ETOOJXN1v1u0A4dO1hTKQskAlxVpmjaPhSCxtvqIgUMxC8toLJryr4Hx2x8o9ermgRHCHtQQ9noK3CHZCGTOmVTPE2Ot9sHJLHLtoUv0vdixPi35p8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760211644; c=relaxed/simple; bh=l6PfjANfUpBtaN0fS4GZaMfa9JZ+uJ9pMscD9Z98sNA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=kNnqpPAVzoZIscH0kLMRHlDL81fa8OXXnu/40/BCDtCWQ9eZFDJLZNc2Wn8hsKmtyM5ecN9eR2YzneCWxhToqagtarZ1RILm4ndrbEfR8XWId7qXf/UfzDJfVbCl0pT5Sc11Q051WAVdUTcOTnOz9ICdyel2afH2xlNwVUJ5wfk= 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=HQe5kHc1; 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="HQe5kHc1" Received: from gaia.codewreck.org (localhost [127.0.0.1]) by submarine.notk.org (Postfix) with ESMTPS id F0BA314C2D3; Sat, 11 Oct 2025 21:40:30 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=codewreck.org; s=2; t=1760211633; 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=SLEV4E8ZPaERjqSqpcXc1T1WbVXZeBg8LghWOpCBdv8=; b=HQe5kHc1ymePtuKmO36tA/3PYgqJ7bIeEonDAy0MLRVl2NaRDt+QA1vkx7axRnVkj78vJq AJEi1x8zKyeOmZe2X6LtW7DAR/A7G+ChRa16CrEr6w/EMb08shh156CkyE4s8zJbOqb1Ye DvVYZIV5hR6ffU2qmmG3BapQaMAA8wVYjNJA5UpaiyA/1b9QXwJK9P0SJW51bAXnAQlk9Y 2rUVOb0eT2sLeb1Lx7DqNv50qvQSGd4jsc950Hy1z4iOm1qcAtIgb8fVcjyiwgOa0ObekZ Tw91s8UKGNv5fdE4Oqy1fxMWD0jw8OKWIN+qSip4Nk7aPKauBywxSyt1hyV5yg== Received: from localhost (gaia.codewreck.org [local]) by gaia.codewreck.org (OpenSMTPD) with ESMTPA id 3e2783d9; Sat, 11 Oct 2025 19:40:29 +0000 (UTC) Date: Sun, 12 Oct 2025 04:40:14 +0900 From: Dominique Martinet To: Kent Overstreet , Tingmao Wang Cc: v9fs@lists.linux.dev, netfs@lists.linux.dev, linux-fsdevel@vger.kernel.org, David Howells , Eric Van Hensbergen , Latchesar Ionkov Subject: Re: -ENODATA from read syscall on 9p Message-ID: References: Precedence: bulk X-Mailing-List: netfs@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: Tingmao Wang wrote on Sat, Oct 11, 2025 at 03:35:00PM +0100: > Not a 9pfs maintainer here, but I think I have encountered this in the > past but I didn't think too much of it. Which kernel version are you > testing on? A while ago I sent a patch to fix some stale metadata > issue on uncached 9pfs, and one of the symptom was -ENODATA from a read: > https://lore.kernel.org/all/cover.1743956147.git.m@maowtm.org/ > > Basically, if some other process has a 9pfs file open, and the file > shrinks on the server side, the inode's i_size is not updated when another > process tries to read it, and the result is -ENODATA (instead of reporting > a normal EOF). > > Does this sound like it could be happening in your situation? This patch > series should land in 6.18, so if this was not reproduced on -next it > might be worth a try? It got merged in yesterday With that said I'm also curious if that's the reason 9p reads stopped progressing, but even with this patch I think there'd be a window for files to shrink while the read is happening so netfs needs to return a short read anyway -- if the file really is being modified under us it's possible to hit end of file early. OTOH I don't think that's what's happening here though, as Kent is likely just running xfstest on its own in a directory... You says these errors just started happening recently? How recently are you talking? I doubt it's been months but the only recent changes I see in this area would be the netfs i_size updating patches early July.. If it's more recent than that there's something else I didn't see anything obvious, having a rough range to look at would be welcome for closer inspection. -- Dominique Martinet | Asmadeus