From: Tao Ma Subject: Re: [PATCH 1/2] fs: Do not dispatch FITRIM through separate super_operation Date: Thu, 18 Nov 2010 22:36:24 +0800 Message-ID: <4CE539E8.2040107@oracle.com> References: <1290065809-3976-1-git-send-email-lczerner@redhat.com> <20101118130630.GJ6178@parisc-linux.org> <20101118134804.GN5618@dhcp231-156.rdu.redhat.com> <20101118141957.GK6178@parisc-linux.org> <20101118143101.GO5618@dhcp231-156.rdu.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Matthew Wilcox , Lukas Czerner , tytso@mit.edu, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, hch@infradead.org, sandeen@redhat.com To: Josef Bacik Return-path: In-Reply-To: <20101118143101.GO5618@dhcp231-156.rdu.redhat.com> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On 11/18/2010 10:31 PM, Josef Bacik wrote: > On Thu, Nov 18, 2010 at 07:19:58AM -0700, Matthew Wilcox wrote: >> On Thu, Nov 18, 2010 at 08:48:04AM -0500, Josef Bacik wrote: >>> On Thu, Nov 18, 2010 at 06:06:30AM -0700, Matthew Wilcox wrote: >>>> On Thu, Nov 18, 2010 at 08:36:48AM +0100, Lukas Czerner wrote: >>>>> There was concern that FITRIM ioctl is not common enough to be included >>>>> in core vfs ioctl, as Christoph Hellwig pointed out there's no real point >>>>> in dispatching this out to a separate vector instead of just through >>>>> ->ioctl. >>>> >>>> Um, are you and Josef working independently of each other? You don't >>>> seem to be cc'ing each other on your patches, and you're basically doing >>>> the same thing. >>>> >>> >>> I guess they are the same thing in that we're both dealing with free'ing up >>> space, but thats about where the similarities end. Lukas' work is in TRIM'ing >>> already free'd space, mine is in creating free'd space. Plus I don't know >>> anything nor wish to ever know anything about TRIM ;). Thanks, >> >> I guess I was assuming that, on receiving a FALLOC_FL_PUNCH_HOLE, a >> filesystem that was TRIM-aware would pass that information down to the >> block device that it's mounted on. I strongly feel that we shouldn't >> have two interfaces to do essentially the same thing. > > But they aren't doing the same thing, his is discarding already free'd space, > I'm enabling people to de-allocate space in the middle of files, they are two > seperate things. Of course if the filesystem is TRIM aware the de-allocation > would lead to a TRIM, but not if the filesystem isn't mounted with -o discard. > Hole punching is useful independantly of the ability to do TRIM. Thanks, yeah, actually, ocfs2 has implemented punching holes while we don't have TRIM support enabled yet. Regards, Tao