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 054B720DF4; Fri, 23 Aug 2024 04:12:54 +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=1724386376; cv=none; b=L66y7hun2GekTF52ogDHeh8QsarXaskbrULtzeKVbNy+l3/vYfXsC3RNdgSDFxziCJv1L4JLyTczKQZm5HynyxkqwasgAeYxQ5YxHryfTqQjm90vybOjk3JZx9JZjiNYSQB28yZ+kKA3wHcvlnI+8qpTq7Ig3/cQqjrz/0yYztU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724386376; c=relaxed/simple; bh=orG3i4aC50Y2+w24ZR54cn8YeKGYgkrgemAFcdwKaA4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=gZPt3LoAEFS1Hus73bt7+tA9tZG4kdUQc+9trbQ8WLcQryUCtzimsvBKp2eGldQPqtQv/oZrWEoSOtQMREEiCSvEjLydldeIX3FL6CtcTUmKkP57JxbHT4zSwIhZdmT1YSNCNdQ/8FW18+y+zPjv5+i6FCoHBiJrsbSsBhEfJnk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (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=CcEXuaVB; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (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="CcEXuaVB" 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=+2tuBUHgyGGUFpDJLqCfcZl9Dehbaq5TnacgaFILWGc=; b=CcEXuaVBC8jwyxcUuZAepnBzrW iSkce6/tu1rFt+PaNG/H1eUSgn/U976HzEGJXB/UOkZgR3zW8cr5b/z1CKj6UDZS7UBMGXziI91ct Mp63Juo2nnCpVpj39pXEk1nJf08j0sa2f+rn1SlN5agNqU58tsn2mBFMIirnEecrDy1ypDyKKD30C bwpW3p0k/ps6nllqore/Dg+mViWN39yvfB9xFQOOpfQTpKlMkozcaUyiKZIGAO6zhonUo5JbQMCYv P2B8YZdriLDR5bHus71yYZ28J1LeHJP+Bg/RA78uAuzHhiL+UjK1a4KR+6vgKmiUitKM1dWk6hRVW nAZ1f6/A==; Received: from hch by bombadil.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1shLfS-0000000F9ec-2kce; Fri, 23 Aug 2024 04:12:54 +0000 Date: Thu, 22 Aug 2024 21:12:54 -0700 From: Christoph Hellwig To: "Darrick J. Wong" Cc: hch@lst.de, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, Jeff Layton Subject: Re: [PATCH 1/1] xfs: introduce new file range commit ioctls Message-ID: References: <172437084258.57211.13522832162579952916.stgit@frogsfrogsfrogs> <172437084278.57211.4355071581143024290.stgit@frogsfrogsfrogs> Precedence: bulk X-Mailing-List: linux-fsdevel@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: <172437084278.57211.4355071581143024290.stgit@frogsfrogsfrogs> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Thu, Aug 22, 2024 at 05:01:22PM -0700, Darrick J. Wong wrote: > From: Darrick J. Wong > > This patch introduces two more new ioctls to manage atomic updates to > file contents -- XFS_IOC_START_COMMIT and XFS_IOC_COMMIT_RANGE. The > commit mechanism here is exactly the same as what XFS_IOC_EXCHANGE_RANGE > does, but with the additional requirement that file2 cannot have changed > since some sampling point. The start-commit ioctl performs the sampling > of file attributes. The code itself looks simply enough now, but how do we guarantee that ctime actually works as a full change count and not just by chance here?