From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: linux-nfs-owner@vger.kernel.org Received: from cantor2.suse.de ([195.135.220.15]:55196 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753619Ab2DPNo3 (ORCPT ); Mon, 16 Apr 2012 09:44:29 -0400 Date: Mon, 16 Apr 2012 14:44:22 +0100 From: Mel Gorman To: Fred Isaman Cc: Andrew Morton , Linux-MM , Linux-Netdev , Linux-NFS , LKML , David Miller , Trond Myklebust , Neil Brown , Christoph Hellwig , Peter Zijlstra , Mike Christie , Eric B Munson Subject: Re: [PATCH 08/11] nfs: disable data cache revalidation for swapfiles Message-ID: <20120416134422.GC2359@suse.de> References: <1334578675-23445-1-git-send-email-mgorman@suse.de> <1334578675-23445-9-git-send-email-mgorman@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 In-Reply-To: Sender: linux-nfs-owner@vger.kernel.org List-ID: On Mon, Apr 16, 2012 at 09:10:04AM -0400, Fred Isaman wrote: > > > > -static struct nfs_page *nfs_page_find_request_locked(struct page *page) > > +static struct nfs_page * > > +nfs_page_find_request_locked(struct nfs_inode *nfsi, struct page *page) > >  { > >        struct nfs_page *req = NULL; > > > > -       if (PagePrivate(page)) { > > +       if (PagePrivate(page)) > >                req = (struct nfs_page *)page_private(page); > > -               if (req != NULL) > > -                       kref_get(&req->wb_kref); > > +       else if (unlikely(PageSwapCache(page))) { > > +               struct nfs_page *freq, *t; > > + > > +               /* Linearly search the commit list for the correct req */ > > +               list_for_each_entry_safe(freq, t, &nfsi->commit_list, wb_list) { > > +                       if (freq->wb_page == page) { > > +                               req = freq; > > +                               break; > > +                       } > > +               } > > + > > +               BUG_ON(req == NULL); > > I suspect I am missing something, but why is it guaranteed that the > req is on the commit list? > It's a fair question and a statement about what I expected to happen. The commit list replaces the nfs_page_tree radix tree that used to exist and my understanding was that the req would exist in the radix tree until the swap IO was completed. I expected it to be the same for the commit list and the BUG_ON was based on that expectation. Are there cases where the req would not be found? Thanks. -- Mel Gorman SUSE Labs From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx161.postini.com [74.125.245.161]) by kanga.kvack.org (Postfix) with SMTP id 104616B00EC for ; Mon, 16 Apr 2012 09:44:30 -0400 (EDT) Date: Mon, 16 Apr 2012 14:44:22 +0100 From: Mel Gorman Subject: Re: [PATCH 08/11] nfs: disable data cache revalidation for swapfiles Message-ID: <20120416134422.GC2359@suse.de> References: <1334578675-23445-1-git-send-email-mgorman@suse.de> <1334578675-23445-9-git-send-email-mgorman@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Fred Isaman Cc: Andrew Morton , Linux-MM , Linux-Netdev , Linux-NFS , LKML , David Miller , Trond Myklebust , Neil Brown , Christoph Hellwig , Peter Zijlstra , Mike Christie , Eric B Munson On Mon, Apr 16, 2012 at 09:10:04AM -0400, Fred Isaman wrote: > > > > -static struct nfs_page *nfs_page_find_request_locked(struct page *page) > > +static struct nfs_page * > > +nfs_page_find_request_locked(struct nfs_inode *nfsi, struct page *page) > > { > > struct nfs_page *req = NULL; > > > > - if (PagePrivate(page)) { > > + if (PagePrivate(page)) > > req = (struct nfs_page *)page_private(page); > > - if (req != NULL) > > - kref_get(&req->wb_kref); > > + else if (unlikely(PageSwapCache(page))) { > > + struct nfs_page *freq, *t; > > + > > + /* Linearly search the commit list for the correct req */ > > + list_for_each_entry_safe(freq, t, &nfsi->commit_list, wb_list) { > > + if (freq->wb_page == page) { > > + req = freq; > > + break; > > + } > > + } > > + > > + BUG_ON(req == NULL); > > I suspect I am missing something, but why is it guaranteed that the > req is on the commit list? > It's a fair question and a statement about what I expected to happen. The commit list replaces the nfs_page_tree radix tree that used to exist and my understanding was that the req would exist in the radix tree until the swap IO was completed. I expected it to be the same for the commit list and the BUG_ON was based on that expectation. Are there cases where the req would not be found? Thanks. -- Mel Gorman SUSE Labs -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mel Gorman Subject: Re: [PATCH 08/11] nfs: disable data cache revalidation for swapfiles Date: Mon, 16 Apr 2012 14:44:22 +0100 Message-ID: <20120416134422.GC2359@suse.de> References: <1334578675-23445-1-git-send-email-mgorman@suse.de> <1334578675-23445-9-git-send-email-mgorman@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Andrew Morton , Linux-MM , Linux-Netdev , Linux-NFS , LKML , David Miller , Trond Myklebust , Neil Brown , Christoph Hellwig , Peter Zijlstra , Mike Christie , Eric B Munson To: Fred Isaman Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-nfs-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: netdev.vger.kernel.org On Mon, Apr 16, 2012 at 09:10:04AM -0400, Fred Isaman wrote: > > > > -static struct nfs_page *nfs_page_find_request_locked(struct page *= page) > > +static struct nfs_page * > > +nfs_page_find_request_locked(struct nfs_inode *nfsi, struct page *= page) > > =A0{ > > =A0 =A0 =A0 =A0struct nfs_page *req =3D NULL; > > > > - =A0 =A0 =A0 if (PagePrivate(page)) { > > + =A0 =A0 =A0 if (PagePrivate(page)) > > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0req =3D (struct nfs_page *)page_priv= ate(page); > > - =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (req !=3D NULL) > > - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 kref_get(&req->wb_kre= f); > > + =A0 =A0 =A0 else if (unlikely(PageSwapCache(page))) { > > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 struct nfs_page *freq, *t; > > + > > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 /* Linearly search the commit list fo= r the correct req */ > > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 list_for_each_entry_safe(freq, t, &nf= si->commit_list, wb_list) { > > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (freq->wb_page =3D= =3D page) { > > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 req =3D= freq; > > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 break= ; > > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 } > > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 } > > + > > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 BUG_ON(req =3D=3D NULL); >=20 > I suspect I am missing something, but why is it guaranteed that the > req is on the commit list? >=20 It's a fair question and a statement about what I expected to happen. The commit list replaces the nfs_page_tree radix tree that used to exis= t and my understanding was that the req would exist in the radix tree unt= il the swap IO was completed. I expected it to be the same for the commit list and the BUG_ON was based on that expectation. Are there cases wher= e the req would not be found? Thanks. --=20 Mel Gorman SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html