From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 76228248BDE; Wed, 15 Jan 2025 10:48:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736938096; cv=none; b=XtMZqL1TrxwwcSThppHNVPpQiBie1QxNVas4LzAI3GotEwfrZfWW6aLIHdy+fWX4JlA9mBeugNYWTOyEXNO4KyCN062Gk7YOOBP/GJqQdOfyC1GN/9U3wrWyOcvV3xk4GVMaVu4hURC2hjBBCbJpDFKIzHHqdRgo+EggrHLH98M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736938096; c=relaxed/simple; bh=DBvTNx5WZ00FXWc9brltJLXVau2q4RNCLcI8SZa5Qr0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=mTPiGHGBckGU7bIYPkyTQtuaZgQoSbsCTaO5lR9kg+tF9S03c0C/AHHWLJFNMgGbdpFHv2jQRAaVRaGdpv7rAeaXUXqvEhgZCjys2ggnM6rQEsW4kqqQyaUfDAaHiFCEngANg6mYarm/LXedBME36rh/mvdvdEi87Q3YJ+xCuz8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=uHdCCXl8; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="uHdCCXl8" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A70D5C4CEDF; Wed, 15 Jan 2025 10:48:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1736938096; bh=DBvTNx5WZ00FXWc9brltJLXVau2q4RNCLcI8SZa5Qr0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uHdCCXl83FVzNp7SO/AWWJBLB9tYjocOMrmu5G6n+qZkkrgn6pig5VdRQBfu9jcVB 7PtwjxPesdpxs5Ca9Fn/8FLUcj3YO1ZshPejya6QGclHWGvK0aWhnEey5EcEOyaDnH xOcllnN4lT4G/Q46TXkRdLi3pPv58aJY9QZO3j8w= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Nicolas Baranger , David Howells , "Paulo Alcantara (Red Hat)" , Steve French , Jeff Layton , netfs@lists.linux.dev, linux-cifs@vger.kernel.org, linux-fsdevel@vger.kernel.org, Christian Brauner , Sasha Levin Subject: [PATCH 6.12 081/189] netfs: Fix kernel async DIO Date: Wed, 15 Jan 2025 11:36:17 +0100 Message-ID: <20250115103609.579059069@linuxfoundation.org> X-Mailer: git-send-email 2.48.0 In-Reply-To: <20250115103606.357764746@linuxfoundation.org> References: <20250115103606.357764746@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: linux-cifs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Howells [ Upstream commit 3f6bc9e3ab9b127171d39f9ac6eca1abb693b731 ] 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 Link: https://lore.kernel.org/r/608725.1736275167@warthog.procyon.org.uk Tested-by: Nicolas Baranger Acked-by: Paulo Alcantara (Red Hat) cc: Steve French cc: Jeff Layton cc: netfs@lists.linux.dev cc: linux-cifs@vger.kernel.org cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin --- 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 88f2adfab75e..26cf9c94deeb 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->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->iter = *iter; } -- 2.39.5