namei: make should_follow_link() store the link in nd->link

... if it decides to follow, that is.

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

diff --git a/fs/namei.c b/fs/namei.c
index 1c9af92..1b4bc1b 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1566,15 +1566,31 @@ static void terminate_walk(struct nameidata *nd)
                put_link(nd);
 }
 
+static int pick_link(struct nameidata *nd, struct path *link)
+{
+       if (nd->flags & LOOKUP_RCU) {
+               if (unlikely(nd->path.mnt != link->mnt ||
+                            unlazy_walk(nd, link->dentry))) {
+                       return -ECHILD;
+               }
+       }
+       nd->link = *link;
+       return 1;
+}
+
 /*
  * Do we need to follow links? We _really_ want to be able
  * to do this check without having to look at inode->i_op,
  * so we keep a cache of "no, this doesn't need follow_link"
  * for the common case.
  */
-static inline int should_follow_link(struct dentry *dentry, int follow)
+static inline int should_follow_link(struct nameidata *nd, struct path *link, int follow)
 {
-       return unlikely(d_is_symlink(dentry)) ? follow : 0;
+       if (likely(!d_is_symlink(link->dentry)))
+               return 0;
+       if (!follow)
+               return 0;
+       return pick_link(nd, link);
 }
 
 enum {WALK_GET = 1, WALK_PUT = 2};
@@ -1612,17 +1628,9 @@ static int walk_component(struct nameidata *nd, int flags)
 
        if (flags & WALK_PUT)
                put_link(nd);
-       if (should_follow_link(path.dentry, flags & WALK_GET)) {
-               if (nd->flags & LOOKUP_RCU) {
-                       if (unlikely(nd->path.mnt != path.mnt ||
-                                    unlazy_walk(nd, path.dentry))) {
-                               return -ECHILD;
-                       }
-               }
-               BUG_ON(inode != path.dentry->d_inode);
-               nd->link = path;
-               return 1;
-       }
+       err = should_follow_link(nd, &path, flags & WALK_GET);
+       if (unlikely(err))
+               return err;
        path_to_nameidata(&path, nd);
        nd->inode = inode;
        return 0;
@@ -2375,9 +2383,11 @@ done:
                put_link(nd);
        path->dentry = dentry;
        path->mnt = nd->path.mnt;
-       if (should_follow_link(dentry, nd->flags & LOOKUP_FOLLOW)) {
-               nd->link = *path;
-               return 1;
+       error = should_follow_link(nd, path, nd->flags & LOOKUP_FOLLOW);
+       if (unlikely(error)) {
+               if (error < 0)
+                       goto out;
+               return error;
        }
        mntget(path->mnt);
        follow_mount(path);
@@ -3095,19 +3105,13 @@ retry_lookup:
                goto out;
        }
 finish_lookup:
-       if (should_follow_link(path.dentry, nd->flags & LOOKUP_FOLLOW)) {
-               if (nd->flags & LOOKUP_RCU) {
-                       if (unlikely(nd->path.mnt != path.mnt ||
-                                    unlazy_walk(nd, path.dentry))) {
-                               error = -ECHILD;
-                               goto out;
-                       }
-               }
-               BUG_ON(inode != path.dentry->d_inode);
-               if (nd->depth)
-                       put_link(nd);
-               nd->link = path;
-               return 1;
+       if (nd->depth)
+               put_link(nd);
+       error = should_follow_link(nd, &path, nd->flags & LOOKUP_FOLLOW);
+       if (unlikely(error)) {
+               if (error < 0)
+                       goto out;
+               return error;
        }
 
        if (unlikely(d_is_symlink(path.dentry)) && !(open_flag & O_PATH)) {