nothing in do_follow_link() is going to see RCU

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/namei.c b/fs/namei.c
index ec4b2d0190a8584db09b2252260bd6a8fb8771b2..9ce6d272f4f208efe013e76f466cc36f7b68f5be 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -668,9 +668,6 @@ force_reval_path(struct path *path, struct nameidata *nd)
                return 0;
 
        if (!status) {
-               /* Don't d_invalidate in rcu-walk mode */
-               if (nameidata_drop_rcu(nd))
-                       return -ECHILD;
                d_invalidate(dentry);
                status = -ESTALE;
        }
@@ -777,6 +774,8 @@ __do_follow_link(const struct path *link, struct nameidata *nd, void **p)
        int error;
        struct dentry *dentry = link->dentry;
 
+       BUG_ON(nd->flags & LOOKUP_RCU);
+
        touch_atime(link->mnt, dentry);
        nd_set_link(nd, NULL);
 
@@ -811,6 +810,11 @@ static inline int do_follow_link(struct path *path, struct nameidata *nd)
 {
        void *cookie;
        int err = -ELOOP;
+
+       /* We drop rcu-walk here */
+       if (nameidata_dentry_drop_rcu_maybe(nd, path->dentry))
+               return -ECHILD;
+
        if (current->link_count >= MAX_NESTED_LINKS)
                goto loop;
        if (current->total_link_count >= 40)
@@ -1419,9 +1423,6 @@ exec_again:
                        goto out_dput;
 
                if (inode->i_op->follow_link) {
-                       /* We commonly drop rcu-walk here */
-                       if (nameidata_dentry_drop_rcu_maybe(nd, next.dentry))
-                               return -ECHILD;
                        BUG_ON(inode != next.dentry->d_inode);
                        err = do_follow_link(&next, nd);
                        if (err)
@@ -1467,8 +1468,6 @@ last_component:
                        break;
                if (inode && unlikely(inode->i_op->follow_link) &&
                    (lookup_flags & LOOKUP_FOLLOW)) {
-                       if (nameidata_dentry_drop_rcu_maybe(nd, next.dentry))
-                               return -ECHILD;
                        BUG_ON(inode != next.dentry->d_inode);
                        err = do_follow_link(&next, nd);
                        if (err)