Merge tag 'nfsd-4.12' of git://linux-nfs.org/~bfields/linux

Pull nfsd updates from Bruce Fields:
 "Another RDMA update from Chuck Lever, and a bunch of miscellaneous
  bugfixes"

* tag 'nfsd-4.12' of git://linux-nfs.org/~bfields/linux: (26 commits)
  nfsd: Fix up the "supattr_exclcreat" attributes
  nfsd: encoders mustn't use unitialized values in error cases
  nfsd: fix undefined behavior in nfsd4_layout_verify
  lockd: fix lockd shutdown race
  NFSv4: Fix callback server shutdown
  SUNRPC: Refactor svc_set_num_threads()
  NFSv4.x/callback: Create the callback service through svc_create_pooled
  lockd: remove redundant check on block
  svcrdma: Clean out old XDR encoders
  svcrdma: Remove the req_map cache
  svcrdma: Remove unused RDMA Write completion handler
  svcrdma: Reduce size of sge array in struct svc_rdma_op_ctxt
  svcrdma: Clean up RPC-over-RDMA backchannel reply processing
  svcrdma: Report Write/Reply chunk overruns
  svcrdma: Clean up RDMA_ERROR path
  svcrdma: Use rdma_rw API in RPC reply path
  svcrdma: Introduce local rdma_rw API helpers
  svcrdma: Clean up svc_rdma_get_inv_rkey()
  svcrdma: Add helper to save pages under I/O
  svcrdma: Eliminate RPCRDMA_SQ_DEPTH_MULT
  ...

1 files changed, 20 insertions, 4 deletions

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 9aaf6ca77569..2be32955d7f2 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -94,6 +94,12 @@ nfsd_cross_mnt(struct svc_rqst *rqstp, struct dentry **dpp,
         err = follow_down(&path);
         if (err < 0)
                 goto out;
+        if (path.mnt == exp->ex_path.mnt && path.dentry == dentry &&
+            nfsd_mountpoint(dentry, exp) == 2) {
+                /* This is only a mountpoint in some other namespace */
+                path_put(&path);
+                goto out;
+        }
 
         exp2 = rqst_exp_get_by_name(rqstp, &path);
         if (IS_ERR(exp2)) {
@@ -167,16 +173,26 @@ static int nfsd_lookup_parent(struct svc_rqst *rqstp, struct dentry *dparent, st
 /*
  * For nfsd purposes, we treat V4ROOT exports as though there was an
  * export at *every* directory.
+ * We return:
+ * '1' if this dentry *must* be an export point,
+ * '2' if it might be, if there is really a mount here, and
+ * '0' if there is no chance of an export point here.
  */
 int nfsd_mountpoint(struct dentry *dentry, struct svc_export *exp)
 {
-        if (d_mountpoint(dentry))
+        if (!d_inode(dentry))
+                return 0;
+        if (exp->ex_flags & NFSEXP_V4ROOT)
                 return 1;
         if (nfsd4_is_junction(dentry))
                 return 1;
-        if (!(exp->ex_flags & NFSEXP_V4ROOT))
-                return 0;
-        return d_inode(dentry) != NULL;
+        if (d_mountpoint(dentry))
+                /*
+                 * Might only be a mountpoint in a different namespace,
+                 * but we need to check.
+                 */
+                return 2;
+        return 0;
 }
 
 __be32