NFSv4: Fix lookup revalidate of regular files

commit c7944ebb9ce9461079659e9e6ec5baaf73724b3b upstream.

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>
Signed-off-by: Qian Lu <luqia@amazon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 2e6a253..71b2e39 100644 (file)
--- 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 */