Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932584AbZJAOJF (ORCPT ); Thu, 1 Oct 2009 10:09:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932560AbZJAOI4 (ORCPT ); Thu, 1 Oct 2009 10:08:56 -0400 Received: from victor.provo.novell.com ([137.65.250.26]:45183 "EHLO victor.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932549AbZJAOIy (ORCPT ); Thu, 1 Oct 2009 10:08:54 -0400 From: Suresh Jayaraman To: Linus Torvalds , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: netdev@vger.kernel.org, Neil Brown , Miklos Szeredi , Wouter Verhelst , Peter Zijlstra , trond.myklebust@fys.uio.no, Suresh Jayaraman Subject: [PATCH 26/31] nfs: disable data cache revalidation for swapfiles Date: Thu, 1 Oct 2009 19:40:09 +0530 Message-Id: <1254406209-16591-1-git-send-email-sjayaraman@suse.de> X-Mailer: git-send-email 1.6.0.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5339 Lines: 176 From: Peter Zijlstra Do as Trond suggested: http://lkml.org/lkml/2006/8/25/348 Disable NFS data cache revalidation on swap files since it doesn't really make sense to have other clients change the file while you are using it. Thereby we can stop setting PG_private on swap pages, since there ought to be no further races with invalidate_inode_pages2() to deal with. And since we cannot set PG_private we cannot use page->private (which is already used by PG_swapcache pages anyway) to store the nfs_page. Thus augment the new nfs_page_find_request logic. Signed-off-by: Peter Zijlstra Signed-off-by: Suresh Jayaraman --- fs/nfs/inode.c | 6 ++++ fs/nfs/write.c | 73 ++++++++++++++++++++++++++++++++++++++++++++++----------- 2 files changed, 66 insertions(+), 13 deletions(-) Index: mmotm/fs/nfs/inode.c =================================================================== --- mmotm.orig/fs/nfs/inode.c +++ mmotm/fs/nfs/inode.c @@ -820,6 +820,12 @@ int nfs_revalidate_mapping_nolock(struct struct nfs_inode *nfsi = NFS_I(inode); int ret = 0; + /* + * swapfiles are not supposed to be shared. + */ + if (IS_SWAPFILE(inode)) + goto out; + if ((nfsi->cache_validity & NFS_INO_REVAL_PAGECACHE) || nfs_attribute_timeout(inode) || NFS_STALE(inode)) { ret = __nfs_revalidate_inode(NFS_SERVER(inode), inode); Index: mmotm/fs/nfs/write.c =================================================================== --- mmotm.orig/fs/nfs/write.c +++ mmotm/fs/nfs/write.c @@ -107,25 +107,64 @@ static void nfs_context_set_write_error( set_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags); } -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, + int get) { 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))) + req = radix_tree_lookup(&nfsi->nfs_page_tree, + page_file_index(page)); + + if (get && req) + kref_get(&req->wb_kref); + return req; } +static inline struct nfs_page * +nfs_page_find_request_locked(struct nfs_inode *nfsi, struct page *page) +{ + return __nfs_page_find_request_locked(nfsi, page, 1); +} + +static int __nfs_page_has_request(struct page *page) +{ + struct inode *inode = page_file_mapping(page)->host; + struct nfs_page *req = NULL; + + spin_lock(&inode->i_lock); + req = __nfs_page_find_request_locked(NFS_I(inode), page, 0); + spin_unlock(&inode->i_lock); + + /* + * hole here plugged by the caller holding onto PG_locked + */ + + return req != NULL; +} + +static inline int nfs_page_has_request(struct page *page) +{ + if (PagePrivate(page)) + return 1; + + if (unlikely(PageSwapCache(page))) + return __nfs_page_has_request(page); + + return 0; +} + static struct nfs_page *nfs_page_find_request(struct page *page) { struct inode *inode = page_file_mapping(page)->host; struct nfs_page *req = NULL; spin_lock(&inode->i_lock); - req = nfs_page_find_request_locked(page); + req = nfs_page_find_request_locked(NFS_I(inode), page); spin_unlock(&inode->i_lock); return req; } @@ -231,7 +270,7 @@ static int nfs_page_async_flush(struct n spin_lock(&inode->i_lock); for(;;) { - req = nfs_page_find_request_locked(page); + req = nfs_page_find_request_locked(NFS_I(inode), page); if (req == NULL) { spin_unlock(&inode->i_lock); return 0; @@ -370,8 +409,14 @@ static int nfs_inode_add_request(struct if (nfs_have_delegation(inode, FMODE_WRITE)) nfsi->change_attr++; } - SetPagePrivate(req->wb_page); - set_page_private(req->wb_page, (unsigned long)req); + /* + * Swap-space should not get truncated. Hence no need to plug the race + * with invalidate/truncate. + */ + if (likely(!PageSwapCache(req->wb_page))) { + SetPagePrivate(req->wb_page); + set_page_private(req->wb_page, (unsigned long)req); + } nfsi->npages++; kref_get(&req->wb_kref); radix_tree_tag_set(&nfsi->nfs_page_tree, req->wb_index, @@ -393,8 +438,10 @@ static void nfs_inode_remove_request(str BUG_ON (!NFS_WBACK_BUSY(req)); spin_lock(&inode->i_lock); - set_page_private(req->wb_page, 0); - ClearPagePrivate(req->wb_page); + if (likely(!PageSwapCache(req->wb_page))) { + set_page_private(req->wb_page, 0); + ClearPagePrivate(req->wb_page); + } radix_tree_delete(&nfsi->nfs_page_tree, req->wb_index); nfsi->npages--; if (!nfsi->npages) { @@ -606,7 +653,7 @@ static struct nfs_page *nfs_try_to_updat spin_lock(&inode->i_lock); for (;;) { - req = nfs_page_find_request_locked(page); + req = nfs_page_find_request_locked(NFS_I(inode), page); if (req == NULL) goto out_unlock; @@ -1537,7 +1584,7 @@ int nfs_wb_page_cancel(struct inode *ino if (ret < 0) goto out; } - if (!PagePrivate(page)) + if (!nfs_page_has_request(page)) return 0; ret = nfs_sync_mapping_wait(page_file_mapping(page), &wbc, FLUSH_INVALIDATE); -- 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/