Return-Path: linux-nfs-owner@vger.kernel.org Received: from fieldses.org ([174.143.236.118]:56281 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751140AbaFEQMX (ORCPT ); Thu, 5 Jun 2014 12:12:23 -0400 Date: Thu, 5 Jun 2014 12:12:23 -0400 From: "J. Bruce Fields" To: Jeff Layton Cc: trond.myklebust@primarydata.com, bhalevy@primarydata.com, linux-nfs@vger.kernel.org Subject: Re: [PATCH 8/9] NFSd: Protect addition to the file_hashtbl Message-ID: <20140605161222.GG8362@fieldses.org> References: <1401455373-18207-1-git-send-email-jlayton@primarydata.com> <1401455373-18207-9-git-send-email-jlayton@primarydata.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1401455373-18207-9-git-send-email-jlayton@primarydata.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Fri, May 30, 2014 at 09:09:32AM -0400, Jeff Layton wrote: > From: Trond Myklebust > > Ensure that we only can have a single struct nfs4_file per inode > in the file_hashtbl and make addition atomic with respect to lookup. > > Signed-off-by: Trond Myklebust > --- > fs/nfsd/nfs4state.c | 46 +++++++++++++++++++++++++++++++++++----------- > 1 file changed, 35 insertions(+), 11 deletions(-) > > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c > index a500033a2f87..553c2d6d48dc 100644 > --- a/fs/nfsd/nfs4state.c > +++ b/fs/nfsd/nfs4state.c > @@ -2519,6 +2519,8 @@ static void nfsd4_init_file(struct nfs4_file *fp, struct inode *ino) > { > unsigned int hashval = file_hashval(ino); > > + lockdep_assert_held(&state_lock); > + Oops, lockdep points out we overlooked a deadlock here: this function also calls igrab(), which takes the i_lock, the reverse ordering from what we take in the delegation-break case. Dropping this patch for now. --b. > atomic_set(&fp->fi_ref, 1); > INIT_LIST_HEAD(&fp->fi_stateids); > INIT_LIST_HEAD(&fp->fi_delegations); > @@ -2527,9 +2529,7 @@ static void nfsd4_init_file(struct nfs4_file *fp, struct inode *ino) > fp->fi_lease = NULL; > memset(fp->fi_fds, 0, sizeof(fp->fi_fds)); > memset(fp->fi_access, 0, sizeof(fp->fi_access)); > - spin_lock(&state_lock); > hlist_add_head(&fp->fi_hash, &file_hashtbl[hashval]); > - spin_unlock(&state_lock); > } > > void > @@ -2695,23 +2695,49 @@ find_openstateowner_str(unsigned int hashval, struct nfsd4_open *open, > > /* search file_hashtbl[] for file */ > static struct nfs4_file * > -find_file(struct inode *ino) > +find_file_locked(struct inode *ino) > { > unsigned int hashval = file_hashval(ino); > struct nfs4_file *fp; > > - spin_lock(&state_lock); > + lockdep_assert_held(&state_lock); > + > hlist_for_each_entry(fp, &file_hashtbl[hashval], fi_hash) { > if (fp->fi_inode == ino) { > get_nfs4_file(fp); > - spin_unlock(&state_lock); > return fp; > } > } > - spin_unlock(&state_lock); > return NULL; > } > > +static struct nfs4_file * > +find_file(struct inode *ino) > +{ > + struct nfs4_file *fp; > + > + spin_lock(&state_lock); > + fp = find_file_locked(ino); > + spin_unlock(&state_lock); > + return fp; > +} > + > +static struct nfs4_file * > +find_or_add_file(struct inode *ino, struct nfs4_file *new) > +{ > + struct nfs4_file *fp; > + > + spin_lock(&state_lock); > + fp = find_file_locked(ino); > + if (fp == NULL) { > + nfsd4_init_file(new, ino); > + fp = new; > + } > + spin_unlock(&state_lock); > + > + return fp; > +} > + > /* > * Called to check deny when READ with all zero stateid or > * WRITE with all zero or all one stateid > @@ -3230,21 +3256,19 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf > * and check for delegations in the process of being recalled. > * If not found, create the nfs4_file struct > */ > - fp = find_file(ino); > - if (fp) { > + fp = find_or_add_file(ino, open->op_file); > + if (fp != open->op_file) { > if ((status = nfs4_check_open(fp, open, &stp))) > goto out; > status = nfs4_check_deleg(cl, open, &dp); > if (status) > goto out; > } else { > + open->op_file = NULL; > status = nfserr_bad_stateid; > if (nfsd4_is_deleg_cur(open)) > goto out; > status = nfserr_jukebox; > - fp = open->op_file; > - open->op_file = NULL; > - nfsd4_init_file(fp, ino); > } > > /* > -- > 1.9.3 >