From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 9AEE83B2FE4; Thu, 9 Jul 2026 06:24:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783578269; cv=none; b=agX1xClWWuc4KpLF6FWT9f16WPphL7fS7OqcvTBcm/4P5Z0GuQlukXLagTQXTqYNfsEmCoNfdx+iMqDO41/tEfODIsF0XDU69Qu0GkTP5nChathPIqIdv9cgANtgE3meS+MRXPt/dYJegRsYxRaMKsleTJSBLENUAj5nGpFInzk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783578269; c=relaxed/simple; bh=0Q6aCgZD5NZhEbbekRWxpDEd0tHlsaeYptMJJPzDoXQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=cUf4FeQeb8i83UZozh811j0UmLHpUHv1ios2FOg6dPaEaTi3wSVslcnmXD8eLmpqBYP8AylsLO5O4XwIPnkVlVAZ1wkItcE8YzxEiOKUYnxw5MPVwIPjwlwjQ3XaR1eGJA8bV8qWkvDgyo1bP9tT/XbbcpJ9hPrm7D0+EOrgMSI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=W+qXhSiu; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="W+qXhSiu" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=AkuTJKyJs6+w/jmQ1TO2HwS3psOFgANSyhhhMRiZBaI=; b=W+qXhSiuOFm3XZJ53iGpdaQfIt 1FfggNE0aNtM/4NvEylrbcQZ6inXv7BrLVUGQCsuWO2zrxxamwtrGleWeJeSwrGqj2OZAHGuCKCuc 0SEZzX79JWaehyHxJ3ZFalnowI2sTGAobTlt1qgESoIl9OMbnUcKfqOugozhkQkp0kIc0MDI7p3mD gF878BQ/7CXA5AI9RXUXRd4pC1+rsyQaYoAWmUgOYalNEHeFkWWWXvGgaDJCghIrVwZZ3xQozrj7n knH8dFXVDcxKIyDC/c7zwdO2yVVQP0KIKZrUi9wteBdG6CV6t/4o1YOY60LO/Pg/BpE6cKk9FgS/v 9lGT9FJg==; Received: from hch by bombadil.infradead.org with local (Exim 4.99.1 #2 (Red Hat Linux)) id 1whiBJ-000000018xG-49Sj; Thu, 09 Jul 2026 06:24:22 +0000 Date: Wed, 8 Jul 2026 23:24:21 -0700 From: Christoph Hellwig To: Pedro Falcato Cc: Jori Koolstra , Aleksa Sarai , Jeff Layton , Christian Brauner , Al Viro , NeilBrown , Amir Goldstein , Jan Kara , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 09/14] vfs: add O_CREAT|O_DIRECTORY to open*(2) Message-ID: References: <20260704164149.3480051-1-jkoolstra@xs4all.nl> <20260704164149.3480051-10-jkoolstra@xs4all.nl> <1464441345.181098.1783418805206@kpc.webmail.kpnmail.nl> <1400609680.217714.1783433931054@kpc.webmail.kpnmail.nl> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Wed, Jul 08, 2026 at 04:39:54PM +0100, Pedro Falcato wrote: > Because it's a black box: > - Maybe this feature lands in 7.3 or 7.4 and enterprise kernels (and Android) > backport it to older releases on request (as a random example, XFS atomic > writes were added in 6.16, but were backported to 6.12 in SLES, and UEK 8, > and possibly RHEL/Ubuntu too) > - Maybe the feature is posteriously reverted, disabled, changed > - Upstream LTS also does its backports, so the O_CREAT | O_DIRECTORY EINVAL > only landed in 6.4, but was backported to 6.1, but not to 6.2 or 6.3, and > not to 5.15 or 5.10, and the behavior will again change as soon as this > lands > - Sometimes the kernel perfectly supports a feature but you're running under > a tight seccomp filter that rejects unknown syscalls (or ones that it can't > filter, like SYS_clone3), so you get a mysterious -ENOSYS that uname() will > not be able to explain. > - You can technically even be running under the uname26 personality and now > your uname() is completely nonsensical Exactly. NEw features need to be discoverable, and O_ flags that get ignored by old kernel are not.