From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.3xo.fr (mail.3xo.fr [212.129.21.66]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9EDBC1DC9B8; Mon, 6 Jan 2025 12:07:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=212.129.21.66 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736165281; cv=none; b=tYpf6QUBXYLUyjMVZyZhAjVHzXekdHimkFY7zXRrmTVjxs1WqwA+pXQHqTdlCHOQ/Oi48HtasLOOul302NAeWCxuuJHqa3mUXjaN28vKTpHxJwpD3Adxjrk5/M/+xBiagdrvQoIMPPCSnQ1NKnailokyYBZ632CMpHZGgZEyEos= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736165281; c=relaxed/simple; bh=n+eqCzLhYHG7tuw4O6CIzecns+zELJBTFr3/HlBdqhg=; h=MIME-Version:Date:From:To:Cc:Subject:In-Reply-To:References: Message-ID:Content-Type; b=tUueGVqmz9fHHcZahZVK8/87xq6zIl+MR1+JB/gwfKnH/k30eLkiKMQSETwPs8pucx8QFsArhCSsR/225/rQb4gIeX/P4PVhkpyb2lLZlntixxaD+1ZjufUzN4Wx0ztxo3jwB3QbNc1/aUWq3JkZNTc81sA8857hkWo7YTD3g+4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=3xo.fr; spf=pass smtp.mailfrom=3xo.fr; dkim=pass (2048-bit key) header.d=3xo.fr header.i=@3xo.fr header.b=ii3eaTUz; arc=none smtp.client-ip=212.129.21.66 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=3xo.fr Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=3xo.fr Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=3xo.fr header.i=@3xo.fr header.b="ii3eaTUz" Received: from localhost (mail.3xo.fr [212.129.21.66]) by mail.3xo.fr (Postfix) with ESMTP id EFA89C6; Mon, 6 Jan 2025 13:07:49 +0100 (CET) X-Virus-Scanned: Debian amavis at nxo2.3xo.fr Received: from mail.3xo.fr ([212.129.21.66]) by localhost (mail.3xo.fr [212.129.21.66]) (amavis, port 10024) with ESMTP id yelSwzv8orKl; Mon, 6 Jan 2025 13:07:45 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 mail.3xo.fr D5D0DC1 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=3xo.fr; s=3xo; t=1736165264; bh=UpXQpAdzuVWioOzu9/NdHU8wrAjhGB8vN3JBxloLtNA=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=ii3eaTUzz0XJhouEH2C8MxeCAo1boJMMOyRMmxIKu/sDICAC5IIESPnKRrrg7XbZX aXEJQX5Ea+EST5ZvEfrV07vsce7M+WimXFPPDoV1WeZxk/hud57EFA14qTPt2R8jXQ XiCBOoApIkg73bpEfms5UFv0GAWS5vJxZ55twOMQMO35mbiYyZCo/9ugylv9QdcvLA 2+wio020eNt0pi55OWLHex1rHZQQsWb0NiuGOcuZS83B/+GeC3uFhXZPRWopQV85aB Y0Faoe+zMABvuFysCi/80dcURH6OXN+iGg4yiOQC7Fw9/1hzdMJ+QK8iPGJXVnWGMt +qCGWfhTzxWOw== Received: from mail.3xo.fr (mail.3xo.fr [212.129.21.66]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mail.3xo.fr (Postfix) with ESMTPSA id D5D0DC1; Mon, 6 Jan 2025 13:07:44 +0100 (CET) Precedence: bulk X-Mailing-List: linux-cifs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Date: Mon, 06 Jan 2025 13:07:44 +0100 From: nicolas.baranger@3xo.fr To: David Howells Cc: Steve French , Christoph Hellwig , Jeff Layton , Christian Brauner , netfs@lists.linux.dev, linux-cifs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] netfs: Fix kernel async DIO In-Reply-To: <286638.1736163444@warthog.procyon.org.uk> References: <669f22fc89e45dd4e56d75876dc8f2bf@3xo.fr> <286638.1736163444@warthog.procyon.org.uk> Message-ID: X-Sender: nicolas.baranger@3xo.fr Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Hi David Thanks for the job ! I will buid Linux 6.10 and mainline with the provided change and I'm comming here as soon as I get results from tests (CET working time). Thanks again for help in this issue Nicolas Le 2025-01-06 12:37, David Howells a écrit : > Hi Nicolas, > > Does the attached fix your problem? > > David > --- > netfs: Fix kernel async DIO > > Netfslib needs to be able to handle kernel-initiated asynchronous DIO > that > is supplied with a bio_vec[] array. Currently, because of the async > flag, > this gets passed to netfs_extract_user_iter() which throws a warning > and > fails because it only handles IOVEC and UBUF iterators. This can be > triggered through a combination of cifs and a loopback blockdev with > something like: > > mount //my/cifs/share /foo > dd if=/dev/zero of=/foo/m0 bs=4K count=1K > losetup --sector-size 4096 --direct-io=on /dev/loop2046 /foo/m0 > echo hello >/dev/loop2046 > > This causes the following to appear in syslog: > > WARNING: CPU: 2 PID: 109 at fs/netfs/iterator.c:50 > netfs_extract_user_iter+0x170/0x250 [netfs] > > and the write to fail. > > Fix this by removing the check in netfs_unbuffered_write_iter_locked() > that > causes async kernel DIO writes to be handled as userspace writes. Note > that this change relies on the kernel caller maintaining the existence > of > the bio_vec array (or kvec[] or folio_queue) until the op is complete. > > Fixes: 153a9961b551 ("netfs: Implement unbuffered/DIO write support") > Reported by: Nicolas Baranger > Closes: > https://lore.kernel.org/r/fedd8a40d54b2969097ffa4507979858@3xo.fr/ > Signed-off-by: David Howells > cc: Steve French > cc: Jeff Layton > cc: netfs@lists.linux.dev > cc: linux-cifs@vger.kernel.org > cc: linux-fsdevel@vger.kernel.org > --- > fs/netfs/direct_write.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/fs/netfs/direct_write.c b/fs/netfs/direct_write.c > index eded8afaa60b..42ce53cc216e 100644 > --- a/fs/netfs/direct_write.c > +++ b/fs/netfs/direct_write.c > @@ -67,7 +67,7 @@ ssize_t netfs_unbuffered_write_iter_locked(struct > kiocb *iocb, struct iov_iter * > * allocate a sufficiently large bvec array and may shorten the > * request. > */ > - if (async || user_backed_iter(iter)) { > + if (user_backed_iter(iter)) { > n = netfs_extract_user_iter(iter, len, &wreq->buffer.iter, 0); > if (n < 0) { > ret = n; > @@ -77,6 +77,11 @@ ssize_t netfs_unbuffered_write_iter_locked(struct > kiocb *iocb, struct iov_iter * > wreq->direct_bv_count = n; > wreq->direct_bv_unpin = iov_iter_extract_will_pin(iter); > } else { > + /* If this is a kernel-generated async DIO request, > + * assume that any resources the iterator points to > + * (eg. a bio_vec array) will persist till the end of > + * the op. > + */ > wreq->buffer.iter = *iter; > } > }