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 17EAC16EB7C; Fri, 28 Feb 2025 15:39:22 +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=1740757163; cv=none; b=G0uTRySy4K+Ilnwlvch7HRijpKZe+Y3zZHmHdau7jZ+bcWwZkgIisVCuGT0HcEecB842/t/WLbLiChkVMdmjyUcXX1vV7ZPf/Paeu7L8l2haV/n711Bo3lZaFP8w6F8dGxbT6I/L8t55pSM2RakYf2CM0M1u2muRb2rseK71OLU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740757163; c=relaxed/simple; bh=B8f9YoA217D5MfhZBuAP3T/3FZZ+EJYwQ1Da0jiEJVw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=H3HCNfByGuyWVf+LD/Sbltvl20cG6z3d8hBNQJw7ZqloKMIy/n54+a2nDpwhiAnXhnKNoEqnmD4BMJfD3Pn/jN9V82pq0/rAUesVmM6MqI2E7EIfVBWoeGA1zNlXwkIt5L1bEG69G/NYBkEFYNlUOlXAikOxo4Y2itW/7MAJnS0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=oqsGOGVy; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="oqsGOGVy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 850A9C4CED6; Fri, 28 Feb 2025 15:39:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1740757162; bh=B8f9YoA217D5MfhZBuAP3T/3FZZ+EJYwQ1Da0jiEJVw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=oqsGOGVyOu9yYSdB2GX0A4lXGa3nLORJjJrhnVDHUg9fMvH5+bNb6fAjKnFGEY+kD JrilKnDRUC9PpZvl1kHG4Az4lbPkMn04JxMpwaeF+2XZxHo2aNXHCTfUoAKt+lOPPG x+oUWMiTV7/or3OkvMl5jg3XYKk1myk4iI/eqwiFqpeHhcPnA/EYFHuarZB1XFglSs aNGJ0fRG/q6jghFyjEPeMH3K/8b6Xjam4rC2IMtq2b+sC5l4r3taDPWysMXQE6Z4tl Ik4bKy9B+qQ8sdjD0NdYMLuZ9EOrMq+lIWd9EaHhq8SrhYJTW5hcpTYTnobweKp7mG iwWLmLwE1SE/g== Date: Fri, 28 Feb 2025 07:39:22 -0800 From: "Darrick J. Wong" To: John Garry Cc: brauner@kernel.org, cem@kernel.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, ojaswin@linux.ibm.com, ritesh.list@gmail.com, martin.petersen@oracle.com, tytso@mit.edu, linux-ext4@vger.kernel.org Subject: Re: [PATCH v3 09/12] xfs: Add xfs_file_dio_write_atomic() Message-ID: <20250228153922.GY6242@frogsfrogsfrogs> References: <20250227180813.1553404-1-john.g.garry@oracle.com> <20250227180813.1553404-10-john.g.garry@oracle.com> <20250228011913.GD1124788@frogsfrogsfrogs> <903c3d2d-8f31-457c-b29d-45cc14a2b851@oracle.com> Precedence: bulk X-Mailing-List: linux-xfs@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: <903c3d2d-8f31-457c-b29d-45cc14a2b851@oracle.com> On Fri, Feb 28, 2025 at 07:45:59AM +0000, John Garry wrote: > On 28/02/2025 01:19, Darrick J. Wong wrote: > > > + if (ret == -EAGAIN && !(iocb->ki_flags & IOCB_NOWAIT) && > > > + !(dio_flags & IOMAP_DIO_ATOMIC_SW)) { > > > + xfs_iunlock(ip, iolock); > > > + dio_flags = IOMAP_DIO_ATOMIC_SW | IOMAP_DIO_FORCE_WAIT; > > One last little nit here: if the filesystem doesn't have reflink, you > > can't use copy on write as a fallback. > > > > /* > > * The atomic write fallback uses out of place writes > > * implemented with the COW code, so we must fail the > > * atomic write if that is not supported. > > */ > > if (!xfs_has_reflink(ip->i_mount)) > > return -EOPNOTSUPP; > > dio_flags = IOMAP_DIO_ATOMIC_SW | IOMAP_DIO_FORCE_WAIT; > > > > Currently the awu max is limited to 1x FS block if no reflink, and then we > check the write length against awu max in xfs_file_write_iter() for > IOCB_ATOMIC. And the xfs iomap would not request a SW-based atomic write for > 1x FS block. So in a around-about way we are checking it. > > So let me know if you would still like that additional check - it seems > sensible to add it. Yes, please. The more guardrails the better, particularly when someone gets around to enabling software-only RWF_ATOMIC. --D > Cheers, > John > >