Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756235Ab3JQNy0 (ORCPT ); Thu, 17 Oct 2013 09:54:26 -0400 Received: from e23smtp01.au.ibm.com ([202.81.31.143]:33788 "EHLO e23smtp01.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755659Ab3JQNyY (ORCPT ); Thu, 17 Oct 2013 09:54:24 -0400 Date: Thu, 17 Oct 2013 08:54:17 -0500 From: Robert Jennings To: Dave Hansen Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Alexander Viro , Rik van Riel , Andrea Arcangeli , Matt Helsley , Anthony Liguori , Michael Roth , Lei Li , Leonardo Garcia , Vlastimil Babka Subject: Re: [PATCH 1/2] vmsplice: unmap gifted pages for recipient Message-ID: <20131017135417.GC19741@linux.vnet.ibm.com> Mail-Followup-To: Dave Hansen , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Alexander Viro , Rik van Riel , Andrea Arcangeli , Matt Helsley , Anthony Liguori , Michael Roth , Lei Li , Leonardo Garcia , Vlastimil Babka References: <1381177293-27125-1-git-send-email-rcj@linux.vnet.ibm.com> <1381177293-27125-2-git-send-email-rcj@linux.vnet.ibm.com> <52543185.3060705@sr71.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <52543185.3060705@sr71.net> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13101713-1618-0000-0000-000004D19273 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2383 Lines: 60 * Dave Hansen (dave@sr71.net) wrote: > On 10/07/2013 01:21 PM, Robert C Jennings wrote: > > spd.partial[page_nr].offset = loff; > > spd.partial[page_nr].len = this_len; > > + spd.partial[page_nr].useraddr = index << PAGE_CACHE_SHIFT; > > len -= this_len; > > loff = 0; > > spd.nr_pages++; > > @@ -656,6 +702,7 @@ ssize_t default_file_splice_read(struct file *in, loff_t *ppos, > > this_len = min_t(size_t, vec[i].iov_len, res); > > spd.partial[i].offset = 0; > > spd.partial[i].len = this_len; > > + spd.partial[i].useraddr = (unsigned long)vec[i].iov_base; > > if (!this_len) { > > __free_page(spd.pages[i]); > > spd.pages[i] = NULL; > > @@ -1475,6 +1522,8 @@ static int get_iovec_page_array(const struct iovec __user *iov, > > > > partial[buffers].offset = off; > > partial[buffers].len = plen; > > + partial[buffers].useraddr = (unsigned long)base; > > + base = (void*)((unsigned long)base + PAGE_SIZE); > > > > off = 0; > > len -= plen; > > diff --git a/include/linux/splice.h b/include/linux/splice.h > > index 74575cb..56661e3 100644 > > --- a/include/linux/splice.h > > +++ b/include/linux/splice.h > > @@ -44,6 +44,7 @@ struct partial_page { > > unsigned int offset; > > unsigned int len; > > unsigned long private; > > + unsigned long useraddr; > > }; > > "useraddr" confuses me. You make it an 'unsigned long', yet two of the > three assignments are from "void __user *". The other assignment: > > spd.partial[page_nr].useraddr = index << PAGE_CACHE_SHIFT; > > 'index' looks to be the offset inside the file, not a user address, so > I'm confused what that is doing. > > Could you elaborate a little more on why 'useraddr' is suddenly needed > in these patches? How is "index << PAGE_CACHE_SHIFT" a virtual address? > Also, are we losing any of the advantages of sparse checking since > 'useraddr' is without the __user annotation? > I'm working on cleaning this up. Trying to remove useraddr altogher through the use of the existing 'private' field just for the splice_to_user/pipe_to_user flow without upsetting other uses of the private field. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/