If LOOKUP_RCU is set, follow_link will not take/drop reference counts.

Replace cond_resched() with _cond_resched() as the latter
is a no-op if rcu_read_lock() is held while the former will
give a warning in that case.

Signed-off-by: NeilBrown <ne...@suse.de>
---
 fs/namei.c |   19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 1663d21a3eb4..536e0254f5f1 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -906,7 +906,8 @@ follow_link(struct path *link, struct nameidata *nd, void 
**p)
        if (unlikely(current->nameidata->total_link_count >= 40))
                goto out_put_nd_path;
 
-       cond_resched();
+       /* If rcu_read_locked(), this will not resched, and will not warn */
+       _cond_resched();
        current->nameidata->total_link_count++;
 
        if (nd->flags & LOOKUP_RCU) {
@@ -936,11 +937,17 @@ follow_link(struct path *link, struct nameidata *nd, void 
**p)
                        return PTR_ERR(s);
                }
                if (*s == '/') {
-                       if (!nd->root.mnt)
-                               set_root(nd);
-                       path_put(&nd->path);
-                       nd->path = nd->root;
-                       path_get(&nd->root);
+                       if (nd->flags & LOOKUP_RCU) {
+                               if (!nd->root.mnt)
+                                       set_root_rcu(nd);
+                               nd->path = nd->root;
+                       } else {
+                               if (!nd->root.mnt)
+                                       set_root(nd);
+                               path_put(&nd->path);
+                               nd->path = nd->root;
+                               path_get(&nd->root);
+                       }
                        nd->flags |= LOOKUP_JUMPED;
                }
                nd->inode = nd->path.dentry->d_inode;


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