namei.c: separate the parts of follow_link() that find the link body

Split a piece of fs/namei.c:follow_link() that does obtaining the link
body into a separate function.  follow_link() itself is converted to
calling get_link() and then doing the body traversal (if any).

The next step will expand follow_link() call in link_path_walk()
and this helps to keep the size down...

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

diff --git a/fs/namei.c b/fs/namei.c
index aeca448..a1ba556 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -836,21 +836,22 @@ static int may_linkat(struct path *link)
        return -EPERM;
 }
 
-static __always_inline int
-follow_link(struct path *link, struct nameidata *nd, void **p)
+static __always_inline const char *
+get_link(struct path *link, struct nameidata *nd, void **p)
 {
        struct dentry *dentry = link->dentry;
+       struct inode *inode = dentry->d_inode;
        int error;
-       const char *s;
+       const char *res;
 
        BUG_ON(nd->flags & LOOKUP_RCU);
 
        if (link->mnt == nd->path.mnt)
                mntget(link->mnt);
 
-       error = -ELOOP;
+       res = ERR_PTR(-ELOOP);
        if (unlikely(current->total_link_count >= 40))
-               goto out_put_nd_path;
+               goto out;
 
        cond_resched();
        current->total_link_count++;
@@ -858,37 +859,43 @@ follow_link(struct path *link, struct nameidata *nd, void **p)
        touch_atime(link);
 
        error = security_inode_follow_link(dentry);
+       res = ERR_PTR(error);
        if (error)
-               goto out_put_nd_path;
+               goto out;
 
        nd->last_type = LAST_BIND;
        *p = NULL;
-       s = dentry->d_inode->i_op->follow_link(dentry, p, nd);
-       error = PTR_ERR(s);
-       if (IS_ERR(s))
-               goto out_put_nd_path;
-
-       error = 0;
-       if (s) {
-               if (*s == '/') {
-                       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;
-               error = link_path_walk(s, nd);
-               if (unlikely(error))
-                       put_link(nd, link, *p);
+       res = inode->i_op->follow_link(dentry, p, nd);
+       if (IS_ERR(res)) {
+out:
+               path_put(&nd->path);
+               path_put(link);
        }
+       return res;
+}
 
-       return error;
+static __always_inline int
+follow_link(struct path *link, struct nameidata *nd, void **p)
+{
+       const char *s = get_link(link, nd, p);
+       int error;
 
-out_put_nd_path:
-       path_put(&nd->path);
-       path_put(link);
+       if (unlikely(IS_ERR(s)))
+               return PTR_ERR(s);
+       if (unlikely(!s))
+               return 0;
+       if (*s == '/') {
+               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;
+       error = link_path_walk(s, nd);
+       if (unlikely(error))
+               put_link(nd, link, *p);
        return error;
 }