NFSv4: Fix lookup revalidate of regular files

If we're revalidating an existing dentry in order to open a file, we need
to ensure that we check the directory has not changed before we optimise
away the lookup.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

1 files changed, 39 insertions, 40 deletions

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 2e6a253e4104..71b2e390becf 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1231,7 +1231,8 @@ out_bad:
 }
 
 static int
-nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
+__nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags,
+                        int (*reval)(struct inode *, struct dentry *, unsigned int))
 {
         struct dentry *parent;
         struct inode *dir;
@@ -1242,17 +1243,22 @@ nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
                 dir = d_inode_rcu(parent);
                 if (!dir)
                         return -ECHILD;
-                ret = nfs_do_lookup_revalidate(dir, dentry, flags);
+                ret = reval(dir, dentry, flags);
                 if (parent != READ_ONCE(dentry->d_parent))
                         return -ECHILD;
         } else {
                 parent = dget_parent(dentry);
-                ret = nfs_do_lookup_revalidate(d_inode(parent), dentry, flags);
+                ret = reval(d_inode(parent), dentry, flags);
                 dput(parent);
         }
         return ret;
 }
 
+static int nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
+{
+        return __nfs_lookup_revalidate(dentry, flags, nfs_do_lookup_revalidate);
+}
+
 /*
  * A weaker form of d_revalidate for revalidating just the d_inode(dentry)
  * when we don't really care about the dentry name. This is called when a
@@ -1609,62 +1615,55 @@ no_open:
 }
 EXPORT_SYMBOL_GPL(nfs_atomic_open);
 
-static int nfs4_lookup_revalidate(struct dentry *dentry, unsigned int flags)
+static int
+nfs4_do_lookup_revalidate(struct inode *dir, struct dentry *dentry,
+                          unsigned int flags)
 {
         struct inode *inode;
-        int ret = 0;
 
         if (!(flags & LOOKUP_OPEN) || (flags & LOOKUP_DIRECTORY))
-                goto no_open;
+                goto full_reval;
         if (d_mountpoint(dentry))
-                goto no_open;
-        if (NFS_SB(dentry->d_sb)->caps & NFS_CAP_ATOMIC_OPEN_V1)
-                goto no_open;
+                goto full_reval;
 
         inode = d_inode(dentry);
 
         /* We can't create new files in nfs_open_revalidate(), so we
          * optimize away revalidation of negative dentries.
          */
-        if (inode == NULL) {
-                struct dentry *parent;
-                struct inode *dir;
-
-                if (flags & LOOKUP_RCU) {
-                        parent = READ_ONCE(dentry->d_parent);
-                        dir = d_inode_rcu(parent);
-                        if (!dir)
-                                return -ECHILD;
-                } else {
-                        parent = dget_parent(dentry);
-                        dir = d_inode(parent);
-                }
-                if (!nfs_neg_need_reval(dir, dentry, flags))
-                        ret = 1;
-                else if (flags & LOOKUP_RCU)
-                        ret = -ECHILD;
-                if (!(flags & LOOKUP_RCU))
-                        dput(parent);
-                else if (parent != READ_ONCE(dentry->d_parent))
-                        return -ECHILD;
-                goto out;
-        }
+        if (inode == NULL)
+                goto full_reval;
+
+        if (NFS_PROTO(dir)->have_delegation(inode, FMODE_READ))
+                return nfs_lookup_revalidate_delegated(dir, dentry, inode);
 
         /* NFS only supports OPEN on regular files */
         if (!S_ISREG(inode->i_mode))
-                goto no_open;
+                goto full_reval;
+
         /* We cannot do exclusive creation on a positive dentry */
-        if (flags & LOOKUP_EXCL)
-                goto no_open;
+        if (flags & (LOOKUP_EXCL | LOOKUP_REVAL))
+                goto reval_dentry;
+
+        /* Check if the directory changed */
+        if (!nfs_check_verifier(dir, dentry, flags & LOOKUP_RCU))
+                goto reval_dentry;
 
         /* Let f_op->open() actually open (and revalidate) the file */
-        ret = 1;
+        return 1;
+reval_dentry:
+        if (flags & LOOKUP_RCU)
+                return -ECHILD;
+        return nfs_lookup_revalidate_dentry(dir, dentry, inode);;
 
-out:
-        return ret;
+full_reval:
+        return nfs_do_lookup_revalidate(dir, dentry, flags);
+}
 
-no_open:
-        return nfs_lookup_revalidate(dentry, flags);
+static int nfs4_lookup_revalidate(struct dentry *dentry, unsigned int flags)
+{
+        return __nfs_lookup_revalidate(dentry, flags,
+                        nfs4_do_lookup_revalidate);
 }
 
 #endif /* CONFIG_NFSV4 */