Return-Path: linux-nfs-owner@vger.kernel.org Received: from mail-qa0-f41.google.com ([209.85.216.41]:39393 "EHLO mail-qa0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751283AbbBFCyj (ORCPT ); Thu, 5 Feb 2015 21:54:39 -0500 Received: by mail-qa0-f41.google.com with SMTP id bm13so8990896qab.0 for ; Thu, 05 Feb 2015 18:54:38 -0800 (PST) MIME-Version: 1.0 In-Reply-To: References: <1423175831-54558-1-git-send-email-trond.myklebust@primarydata.com> From: Peng Tao Date: Fri, 6 Feb 2015 10:54:18 +0800 Message-ID: Subject: Re: [PATCH 1/5] NFSv4: Ensure we reference the inode for return-on-close in delegreturn To: Trond Myklebust Cc: Linux NFS Mailing List Content-Type: text/plain; charset=UTF-8 Sender: linux-nfs-owner@vger.kernel.org List-ID: On Fri, Feb 6, 2015 at 9:57 AM, Peng Tao wrote: > On Fri, Feb 6, 2015 at 9:45 AM, Peng Tao wrote: >> On Fri, Feb 6, 2015 at 6:37 AM, Trond Myklebust >> wrote: >>> If we have to do a return-on-close in the delegreturn code, then >>> we must ensure that the inode and super block remain referenced. >>> > ah, a second thought. I looked for call sites of nfs_sb_active() and > it gets called at five places in current tree: > alloc_nfs_open_context, nfs4_opendata_alloc, nfs4_do_close, > nfs_do_call_unlink, nfs_do_call_unlink > > So it appears that sb is activated while any file keeps opened and > between unlink calls. Then it looks that we are allowed to keep > delegations after sb is released? Maybe the best way to fix the sb > reference part is to pin sb when getting the first delegation. > err, that cannot be working at all... by pinning super block, we prevent umount from happening. and we are returning delegations while shutting down nfs_server and evicting inode. I see your point that the patch actually intends to deal with race between async delegation return vs. nfs_server shutting down and inode eviction. oops! sorry for the noise... you patch is definitely the way we want to go. Cheers, Tao > Cheers, > Tao > >> looks good. One nit is that maybe it's better to reuse the two helpers >> in your 2ed patch. >> >> Reviewed-by: Peng Tao >>> Cc: Peng Tao >>> Cc: stable@vger.kernel.org # 3.17.x >>> Signed-off-by: Trond Myklebust >>> --- >>> fs/nfs/nfs4proc.c | 19 ++++++++++++++----- >>> 1 file changed, 14 insertions(+), 5 deletions(-) >>> >>> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c >>> index cd4295d84d54..b803c1d363e7 100644 >>> --- a/fs/nfs/nfs4proc.c >>> +++ b/fs/nfs/nfs4proc.c >>> @@ -5175,9 +5175,16 @@ static void nfs4_delegreturn_done(struct rpc_task *task, void *calldata) >>> static void nfs4_delegreturn_release(void *calldata) >>> { >>> struct nfs4_delegreturndata *data = calldata; >>> + struct inode *inode = data->inode; >>> + >>> + if (inode) { >>> + struct super_block *sb = inode->i_sb; >>> >>> - if (data->roc) >>> - pnfs_roc_release(data->inode); >>> + if (data->roc) >>> + pnfs_roc_release(inode); >>> + iput(inode); >>> + nfs_sb_deactive(sb); >>> + } >>> kfree(calldata); >>> } >>> >>> @@ -5234,9 +5241,11 @@ static int _nfs4_proc_delegreturn(struct inode *inode, struct rpc_cred *cred, co >>> nfs_fattr_init(data->res.fattr); >>> data->timestamp = jiffies; >>> data->rpc_status = 0; >>> - data->inode = inode; >>> - data->roc = list_empty(&NFS_I(inode)->open_files) ? >>> - pnfs_roc(inode) : false; >>> + data->inode = igrab(inode); >>> + if (data->inode) { >>> + nfs_sb_active(inode->i_sb); >>> + data->roc = nfs4_roc(inode); >>> + } >>> >>> task_setup_data.callback_data = data; >>> msg.rpc_argp = &data->args; >>> -- >>> 2.1.0 >>>