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 E03B0317165; Wed, 4 Mar 2026 14:06:55 +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=1772633218; cv=none; b=I6UNCA2rSgr9ALxTf7UvyId0cT1KewFgpzcjuCVopDFXfnr1RJF6+0OLidnoccIuk/T4lnQwr9fJ/yfkDCGxAh54boEqt6pwU6QXlu/hZn2jDETLkQmnqVJHbKgt70558GgpzeVoXmV2U3K0aUoqezyQXjiRbq4Xu+Frn4I/zu4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772633218; c=relaxed/simple; bh=VUkKOHHwR4DUqNl7CIoYkjEs34HKeKA+DvhqCHfXda8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=XR2nXniE405tfhWF166h4hgkf4mJNJ6BJnI6aqtluAlnklnxVDwyVlbkYdZTUH2bAo2lvko4rekc108+vJJ93IF61ksH0cJccgV8trqSyFoB52/eDpaIRWJx0SOX5WJgyjMy51TKELkkU0uy6zzaYjVq+arkXQAds0novjiBTlc= 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=itEE5yL7; 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="itEE5yL7" 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=xqxwF+gq0vpYABTAm5oTRzQyr7fLwLpJQ2d9FH5PKsY=; b=itEE5yL74fTzhgAjiXSjzWrWxa tkS0tph6z/o24xtAwqxinzTa3LTdHa4hLb5Yz9BZj80NDy4k+VdepgO0JgJAI9zACjWGPvmhXFyL1 AARQPMlrorYLcUnvXfHqHVxTQmSqqpYSYVVjFgnEajMdVwraIxdiBOgSRBxQgs5FF9njsK65W4UB1 ywjq1fZFcIbt4xN+SEqb2suW0+wRtyX9uSzRfxjysfy0QSV7k57nH7IGtNColVPOwukkaP34Q2xpm ukTRtBs9wzFDTxj+fVro4FCB82T9PDK+KIvMiWHFrYtLS2yGqGZSdQ+T77FJEAeVbZg6n0PXKeU/O cbpdSYcw==; Received: from hch by bombadil.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1vxmsG-0000000HKBE-09qn; Wed, 04 Mar 2026 14:06:52 +0000 Date: Wed, 4 Mar 2026 06:06:52 -0800 From: Christoph Hellwig To: David Howells Cc: Matthew Wilcox , Christoph Hellwig , Jens Axboe , Leon Romanovsky , Christian Brauner , Paulo Alcantara , netfs@lists.linux.dev, linux-afs@lists.infradead.org, linux-cifs@vger.kernel.org, linux-nfs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Paulo Alcantara , Steve French , Namjae Jeon , Tom Talpey , Chuck Lever Subject: Re: [RFC PATCH 02/17] vfs: Implement a FIEMAP callback Message-ID: References: <20260304140328.112636-1-dhowells@redhat.com> <20260304140328.112636-3-dhowells@redhat.com> 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: <20260304140328.112636-3-dhowells@redhat.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Wed, Mar 04, 2026 at 02:03:09PM +0000, David Howells wrote: > Implement a callback in the internal kernel FIEMAP API so that kernel users > can make use of it as the filler function expects to write to userspace. > This allows the FIEMAP data to be captured and parsed. This is useful for > cachefiles and also potentially for knfsd and ksmbd to implement their > equivalents of FIEMAP remotely rather than using SEEK_DATA/SEEK_HOLE. Hell no. FIEMAP is purely a debugging toool and must not get anywhere near a data path. NAK to all of this.