nfsd: filter lookup results in V4ROOT case

We treat every object as a mountpoint and pretend it doesn't exist if
it isn't exported.

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

1 files changed, 14 insertions, 1 deletions

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 7e2fdd50113f..eaf2f0dca12a 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -166,6 +166,19 @@ static int nfsd_lookup_parent(struct svc_rqst *rqstp, struct dentry *dparent, st
         return 0;
 }
 
+/*
+ * For nfsd purposes, we treat V4ROOT exports as though there was an
+ * export at *every* directory.
+ */
+static int nfsd_mountpoint(struct dentry *dentry, struct svc_export *exp)
+{
+        if (d_mountpoint(dentry))
+                return 1;
+        if (!(exp->ex_flags & NFSEXP_V4ROOT))
+                return 0;
+        return dentry->d_inode != NULL;
+}
+
 __be32
 nfsd_lookup_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp,
                    const char *name, unsigned int len,
@@ -211,7 +224,7 @@ nfsd_lookup_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp,
                 /*
                  * check if we have crossed a mount point ...
                  */
-                if (d_mountpoint(dentry)) {
+                if (nfsd_mountpoint(dentry, exp)) {
                         if ((host_err = nfsd_cross_mnt(rqstp, &dentry, &exp))) {
                                 dput(dentry);
                                 goto out_nfserr;