From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Hansen Subject: Re: [PATCHv4 20/39] thp, mm: naive support of thp in generic read/write routines Date: Fri, 07 Jun 2013 08:29:19 -0700 Message-ID: <51B1FC4F.2020700@sr71.net> References: <1368321816-17719-1-git-send-email-kirill.shutemov@linux.intel.com> <1368321816-17719-21-git-send-email-kirill.shutemov@linux.intel.com> <519BE6ED.8030202@sr71.net> <20130607151718.E126AE0090@blue.fi.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Andrea Arcangeli , Andrew Morton , Al Viro , Hugh Dickins , Wu Fengguang , Jan Kara , Mel Gorman , linux-mm@kvack.org, Andi Kleen , Matthew Wilcox , "Kirill A. Shutemov" , Hillf Danton , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: "Kirill A. Shutemov" Return-path: In-Reply-To: <20130607151718.E126AE0090@blue.fi.intel.com> Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org On 06/07/2013 08:17 AM, Kirill A. Shutemov wrote: > I guess this way is better, right? > > @@ -2382,6 +2393,7 @@ static ssize_t generic_perform_write(struct file *file, > unsigned long bytes; /* Bytes to write to page */ > size_t copied; /* Bytes copied from user */ > void *fsdata; > + int subpage_nr = 0; > > offset = (pos & (PAGE_CACHE_SIZE - 1)); > bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset, > @@ -2411,8 +2423,14 @@ again: > if (mapping_writably_mapped(mapping)) > flush_dcache_page(page); > > + if (PageTransHuge(page)) { > + off_t huge_offset = pos & ~HPAGE_PMD_MASK; > + subpage_nr = huge_offset >> PAGE_CACHE_SHIFT; > + } > + > pagefault_disable(); > - copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes); > + copied = iov_iter_copy_from_user_atomic(page + subpage_nr, i, > + offset, bytes); > pagefault_enable(); > flush_dcache_page(page); That looks substantially easier to understand to me. Nice. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756193Ab3FGP3X (ORCPT ); Fri, 7 Jun 2013 11:29:23 -0400 Received: from www.sr71.net ([198.145.64.142]:43758 "EHLO blackbird.sr71.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753453Ab3FGP3V (ORCPT ); Fri, 7 Jun 2013 11:29:21 -0400 Message-ID: <51B1FC4F.2020700@sr71.net> Date: Fri, 07 Jun 2013 08:29:19 -0700 From: Dave Hansen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130510 Thunderbird/17.0.6 MIME-Version: 1.0 To: "Kirill A. Shutemov" CC: Andrea Arcangeli , Andrew Morton , Al Viro , Hugh Dickins , Wu Fengguang , Jan Kara , Mel Gorman , linux-mm@kvack.org, Andi Kleen , Matthew Wilcox , "Kirill A. Shutemov" , Hillf Danton , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCHv4 20/39] thp, mm: naive support of thp in generic read/write routines References: <1368321816-17719-1-git-send-email-kirill.shutemov@linux.intel.com> <1368321816-17719-21-git-send-email-kirill.shutemov@linux.intel.com> <519BE6ED.8030202@sr71.net> <20130607151718.E126AE0090@blue.fi.intel.com> In-Reply-To: <20130607151718.E126AE0090@blue.fi.intel.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/07/2013 08:17 AM, Kirill A. Shutemov wrote: > I guess this way is better, right? > > @@ -2382,6 +2393,7 @@ static ssize_t generic_perform_write(struct file *file, > unsigned long bytes; /* Bytes to write to page */ > size_t copied; /* Bytes copied from user */ > void *fsdata; > + int subpage_nr = 0; > > offset = (pos & (PAGE_CACHE_SIZE - 1)); > bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset, > @@ -2411,8 +2423,14 @@ again: > if (mapping_writably_mapped(mapping)) > flush_dcache_page(page); > > + if (PageTransHuge(page)) { > + off_t huge_offset = pos & ~HPAGE_PMD_MASK; > + subpage_nr = huge_offset >> PAGE_CACHE_SHIFT; > + } > + > pagefault_disable(); > - copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes); > + copied = iov_iter_copy_from_user_atomic(page + subpage_nr, i, > + offset, bytes); > pagefault_enable(); > flush_dcache_page(page); That looks substantially easier to understand to me. Nice.