From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:41202 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754515AbdARLIb (ORCPT ); Wed, 18 Jan 2017 06:08:31 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Benjamin Coddington , Trond Myklebust Subject: [PATCH 4.9 090/120] NFS: Fix a performance regression in readdir Date: Wed, 18 Jan 2017 11:46:48 +0100 Message-Id: <20170118104651.798685114@linuxfoundation.org> In-Reply-To: <20170118104648.120216880@linuxfoundation.org> References: <20170118104648.120216880@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Trond Myklebust commit 79f687a3de9e3ba2518b4ea33f38ca6cbe9133eb upstream. Ben Coddington reports that commit 311324ad1713, by adding the function nfs_dir_mapping_need_revalidate() that checks page cache validity on each call to nfs_readdir() causes a performance regression when the directory is being modified. If the directory is changing while we're iterating through the directory, POSIX does not require us to invalidate the page cache unless the user calls rewinddir(). However, we still do want to ensure that we use readdirplus in order to avoid a load of stat() calls when the user is doing an 'ls -l' workload. The fix should be to invalidate the page cache immediately when we're setting the NFS_INO_ADVISE_RDPLUS bit. Reported-by: Benjamin Coddington Fixes: 311324ad1713 ("NFS: Be more aggressive in using readdirplus...") Reviewed-by: Benjamin Coddington Tested-by: Benjamin Coddington Signed-off-by: Trond Myklebust Signed-off-by: Greg Kroah-Hartman --- fs/nfs/dir.c | 15 ++------------- 1 file changed, 2 insertions(+), 13 deletions(-) --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -477,7 +477,7 @@ void nfs_force_use_readdirplus(struct in { if (!list_empty(&NFS_I(dir)->open_files)) { nfs_advise_use_readdirplus(dir); - nfs_zap_mapping(dir, dir->i_mapping); + invalidate_mapping_pages(dir->i_mapping, 0, -1); } } @@ -886,17 +886,6 @@ int uncached_readdir(nfs_readdir_descrip goto out; } -static bool nfs_dir_mapping_need_revalidate(struct inode *dir) -{ - struct nfs_inode *nfsi = NFS_I(dir); - - if (nfs_attribute_cache_expired(dir)) - return true; - if (nfsi->cache_validity & NFS_INO_INVALID_DATA) - return true; - return false; -} - /* The file offset position represents the dirent entry number. A last cookie cache takes care of the common case of reading the whole directory. @@ -928,7 +917,7 @@ static int nfs_readdir(struct file *file desc->decode = NFS_PROTO(inode)->decode_dirent; desc->plus = nfs_use_readdirplus(inode, ctx) ? 1 : 0; - if (ctx->pos == 0 || nfs_dir_mapping_need_revalidate(inode)) + if (ctx->pos == 0 || nfs_attribute_cache_expired(inode)) res = nfs_revalidate_mapping(inode, file->f_mapping); if (res < 0) goto out;