Return-Path: linux-nfs-owner@vger.kernel.org Received: from mail-qa0-f47.google.com ([209.85.216.47]:60952 "EHLO mail-qa0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751152AbaFFNHU (ORCPT ); Fri, 6 Jun 2014 09:07:20 -0400 Received: by mail-qa0-f47.google.com with SMTP id s7so3683894qap.34 for ; Fri, 06 Jun 2014 06:07:19 -0700 (PDT) From: Jeff Layton To: bfields@fieldses.org Cc: linux-nfs@vger.kernel.org, trond.myklebust@primarydata.com, hch@infradead.org Subject: [PATCH v2 1/2] nfsd: Protect addition to the file_hashtbl Date: Fri, 6 Jun 2014 09:07:05 -0400 Message-Id: <1402060026-26511-2-git-send-email-jlayton@primarydata.com> In-Reply-To: <1402060026-26511-1-git-send-email-jlayton@primarydata.com> References: <1402060026-26511-1-git-send-email-jlayton@primarydata.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: 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. To prevent an i_lock/state_lock inversion, change nfsd4_init_file to use ihold instead if igrab. That's also more efficient anyway as we definitely hold a reference to the inode at that point. Signed-off-by: Trond Myklebust Signed-off-by: Jeff Layton --- fs/nfsd/nfs4state.c | 49 +++++++++++++++++++++++++++++++++++++------------ 1 file changed, 37 insertions(+), 12 deletions(-) diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index a500033a2f87..cbec573e9445 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -2519,17 +2519,18 @@ static void nfsd4_init_file(struct nfs4_file *fp, struct inode *ino) { unsigned int hashval = file_hashval(ino); + lockdep_assert_held(&state_lock); + atomic_set(&fp->fi_ref, 1); INIT_LIST_HEAD(&fp->fi_stateids); INIT_LIST_HEAD(&fp->fi_delegations); - fp->fi_inode = igrab(ino); + ihold(ino); + fp->fi_inode = ino; fp->fi_had_conflict = false; 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 +2696,49 @@ 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 +3257,19 @@ 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