Return-Path: linux-nfs-owner@vger.kernel.org Received: from cantor2.suse.de ([195.135.220.15]:52103 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755165AbaCEDCC (ORCPT ); Tue, 4 Mar 2014 22:02:02 -0500 From: NeilBrown To: Trond Myklebust Date: Wed, 05 Mar 2014 14:00:28 +1100 Subject: [PATCH 6/8] NFS: teach nfs_neg_need_reval to understand LOOKUP_RCU Cc: linux-nfs@vger.kernel.org Message-ID: <20140305030028.27421.49580.stgit@notabene.brown> In-Reply-To: <20140305025813.27421.23871.stgit@notabene.brown> References: <20140305025813.27421.23871.stgit@notabene.brown> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Sender: linux-nfs-owner@vger.kernel.org List-ID: This requires nfs_check_verifier to take an rcu_walk flag, and requires an rcu version of nfs_revalidate_inode which returns -ECHILD rather than making an RPC call. With this, nfs_lookup_revalidate can call nfs_neg_need_reval in RCU-walk mode. We can also move the LOOKUP_RCU check past the nfs_check_verifier() call in nfs_lookup_revalidate. Signed-off-by: NeilBrown --- fs/nfs/dir.c | 47 ++++++++++++++++++++++++++++++++--------------- fs/nfs/inode.c | 9 +++++++++ include/linux/nfs_fs.h | 1 + 3 files changed, 42 insertions(+), 15 deletions(-) diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index f3895325ac6a..76b5f40c8587 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -956,8 +956,11 @@ EXPORT_SYMBOL_GPL(nfs_force_lookup_revalidate); * In the case it has, we assume that the dentries are untrustworthy * and may need to be looked up again. */ -static int nfs_check_verifier(struct inode *dir, struct dentry *dentry) +static int nfs_check_verifier(struct inode *dir, struct dentry *dentry, + int rcu_walk) { + int ret; + if (IS_ROOT(dentry)) return 1; if (NFS_SERVER(dir)->flags & NFS_MOUNT_LOOKUP_CACHE_NONE) @@ -965,7 +968,13 @@ static int nfs_check_verifier(struct inode *dir, struct dentry *dentry) if (!nfs_verify_change_attribute(dir, dentry->d_time)) return 0; /* Revalidate nfsi->cache_change_attribute before we declare a match */ - if (nfs_revalidate_inode(NFS_SERVER(dir), dir) < 0) + if (rcu_walk) + ret = nfs_revalidate_inode_rcu(NFS_SERVER(dir), dir); + else + ret = nfs_revalidate_inode(NFS_SERVER(dir), dir); + if (ret == -ECHILD) + return -ECHILD; + if (ret < 0) return 0; if (!nfs_verify_change_attribute(dir, dentry->d_time)) return 0; @@ -1031,7 +1040,7 @@ int nfs_neg_need_reval(struct inode *dir, struct dentry *dentry, return 0; if (NFS_SERVER(dir)->flags & NFS_MOUNT_LOOKUP_CACHE_NONEG) return 1; - return !nfs_check_verifier(dir, dentry); + return !nfs_check_verifier(dir, dentry, flags & LOOKUP_RCU); } /* @@ -1064,11 +1073,11 @@ static int nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags) inode = dentry->d_inode; if (!inode) { - if (flags & LOOKUP_RCU) - return -ECHILD; - - if (nfs_neg_need_reval(dir, dentry, flags)) + if (nfs_neg_need_reval(dir, dentry, flags)) { + if (flags & LOOKUP_RCU) + return -ECHILD; goto out_bad; + } goto out_valid_noent; } @@ -1081,11 +1090,13 @@ static int nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags) if (NFS_PROTO(dir)->have_delegation(inode, FMODE_READ)) goto out_set_verifier; - if (flags & LOOKUP_RCU) - return -ECHILD; - /* Force a full look up iff the parent directory has changed */ - if (!nfs_is_exclusive_create(dir, flags) && nfs_check_verifier(dir, dentry)) { + if (!nfs_is_exclusive_create(dir, flags) && + nfs_check_verifier(dir, dentry, flags & LOOKUP_RCU)) { + + if (flags & LOOKUP_RCU) + return -ECHILD; + if (nfs_lookup_verify_inode(inode, flags)) goto out_zap_parent; goto out_valid; @@ -1094,6 +1105,9 @@ static int nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags) if (NFS_STALE(inode)) goto out_bad; + if (flags & LOOKUP_RCU) + return -ECHILD; + error = -ENOMEM; fhandle = nfs_alloc_fhandle(); fattr = nfs_alloc_fattr(); @@ -1525,13 +1539,16 @@ static int nfs4_lookup_revalidate(struct dentry *dentry, unsigned int flags) struct inode *dir; if (flags & LOOKUP_RCU) - return -ECHILD; - - parent = dget_parent(dentry); + parent = rcu_dereference(dentry); + else + parent = dget_parent(dentry); dir = parent->d_inode; if (!nfs_neg_need_reval(dir, dentry, flags)) ret = 1; - dput(parent); + else if (flags & LOOKUP_RCU) + ret = -ECHILD; + if (!(flags & LOOKUP_RCU)) + dput(parent); goto out; } diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c index 59e57cceeab5..6f39cadfad8c 100644 --- a/fs/nfs/inode.c +++ b/fs/nfs/inode.c @@ -962,6 +962,15 @@ int nfs_revalidate_inode(struct nfs_server *server, struct inode *inode) } EXPORT_SYMBOL_GPL(nfs_revalidate_inode); +int nfs_revalidate_inode_rcu(struct nfs_server *server, struct inode *inode) +{ + if (!(NFS_I(inode)->cache_validity & + (NFS_INO_INVALID_ATTR|NFS_INO_INVALID_LABEL)) + && !nfs_attribute_cache_expired(inode)) + return NFS_STALE(inode) ? -ESTALE : 0; + return -ECHILD; +} + static int nfs_invalidate_mapping(struct inode *inode, struct address_space *mapping) { struct nfs_inode *nfsi = NFS_I(inode); diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h index 0ae5807480f4..9e91f2cfcd01 100644 --- a/include/linux/nfs_fs.h +++ b/include/linux/nfs_fs.h @@ -351,6 +351,7 @@ extern int nfs_release(struct inode *, struct file *); extern int nfs_attribute_timeout(struct inode *inode); extern int nfs_attribute_cache_expired(struct inode *inode); extern int nfs_revalidate_inode(struct nfs_server *server, struct inode *inode); +extern int nfs_revalidate_inode_rcu(struct nfs_server *server, struct inode *inode); extern int __nfs_revalidate_inode(struct nfs_server *, struct inode *); extern int nfs_revalidate_mapping(struct inode *inode, struct address_space *mapping); extern int nfs_setattr(struct dentry *, struct iattr *);