From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f179.google.com ([209.85.192.179]:36229 "EHLO mail-pf0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932600AbcKWEjU (ORCPT ); Tue, 22 Nov 2016 23:39:20 -0500 Received: by mail-pf0-f179.google.com with SMTP id 189so764510pfz.3 for ; Tue, 22 Nov 2016 20:39:20 -0800 (PST) Date: Tue, 22 Nov 2016 20:39:18 -0800 From: Omar Sandoval To: "Darrick J. Wong" Cc: mtk.manpages@gmail.com, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, linux-xfs@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-man@vger.kernel.org Subject: Re: [PATCH] fideduperange.2: fix the discussion of maximum sizes Message-ID: <20161123043918.GD29697@mew> References: <20161123042222.GA30324@birch.djwong.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161123042222.GA30324@birch.djwong.org> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Tue, Nov 22, 2016 at 08:22:22PM -0800, Darrick J. Wong wrote: > Fix the discussion of the limitations on the dest_count and src_length > parameters to the fideduperange ioctl to reflect what's actually in the > kernel. > > Signed-off-by: Darrick J. Wong > --- > man2/ioctl_fideduperange.2 | 12 +++++++++--- > 1 file changed, 9 insertions(+), 3 deletions(-) > > diff --git a/man2/ioctl_fideduperange.2 b/man2/ioctl_fideduperange.2 > index 2112d10..59f0ea9 100644 > --- a/man2/ioctl_fideduperange.2 > +++ b/man2/ioctl_fideduperange.2 > @@ -95,7 +95,7 @@ struct file_dedupe_range_info { > .in > > Each deduplication operation targets > -.IR length > +.IR src_length > bytes in file descriptor > .IR dest_fd > at offset > @@ -108,8 +108,14 @@ During the call, > must be open for reading and > .IR dest_fd > must be open for writing. > -For any call to this ioctl, there may not be more than 65,536 > -requests attached; each request may not exceed 16MiB. > +The combined size of the struct > +.IR file_dedupe_range > +and the struct > +.IR file_dedupe_range_info > +array must not exceed the system page size. > +The maximum size of > +.IR src_length > +is filesystem dependent and is typically 16MiB. > By convention, the storage used by > .IR src_fd > is mapped into Might be worth it to clarify that the file_dedupe_range_info limit is a hard limit that will result in an error if exceeded and that the src_length limit is silently enforced. These semantics suck... -- Omar