namei.c: take "jump to root" into a new helper

... and use it both in path_init() (for absolute pathnames) and
get_link() (for absolute symlinks).

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

diff --git a/fs/namei.c b/fs/namei.c
index a08018b..0baf64b 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -841,6 +841,26 @@ static inline void path_to_nameidata(const struct path *path,
        nd->path.dentry = path->dentry;
 }
 
+static int nd_jump_root(struct nameidata *nd)
+{
+       if (nd->flags & LOOKUP_RCU) {
+               struct dentry *d;
+               nd->path = nd->root;
+               d = nd->path.dentry;
+               nd->inode = d->d_inode;
+               nd->seq = nd->root_seq;
+               if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq)))
+                       return -ECHILD;
+       } else {
+               path_put(&nd->path);
+               nd->path = nd->root;
+               path_get(&nd->path);
+               nd->inode = nd->path.dentry->d_inode;
+       }
+       nd->flags |= LOOKUP_JUMPED;
+       return 0;
+}
+
 /*
  * Helper to directly jump to a known parsed path from ->follow_link,
  * caller must have taken a reference to path beforehand.
@@ -1017,21 +1037,8 @@ const char *get_link(struct nameidata *nd)
        if (*res == '/') {
                if (!nd->root.mnt)
                        set_root(nd);
-               if (nd->flags & LOOKUP_RCU) {
-                       struct dentry *d;
-                       nd->path = nd->root;
-                       d = nd->path.dentry;
-                       nd->inode = d->d_inode;
-                       nd->seq = nd->root_seq;
-                       if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq)))
-                               return ERR_PTR(-ECHILD);
-               } else {
-                       path_put(&nd->path);
-                       nd->path = nd->root;
-                       path_get(&nd->root);
-                       nd->inode = nd->path.dentry->d_inode;
-               }
-               nd->flags |= LOOKUP_JUMPED;
+               if (unlikely(nd_jump_root(nd)))
+                       return ERR_PTR(-ECHILD);
                while (unlikely(*++res == '/'))
                        ;
        }
@@ -2015,26 +2022,17 @@ static const char *path_init(struct nameidata *nd, unsigned flags)
        }
 
        nd->root.mnt = NULL;
+       nd->path.mnt = NULL;
+       nd->path.dentry = NULL;
 
        nd->m_seq = read_seqbegin(&mount_lock);
        if (*s == '/') {
                if (flags & LOOKUP_RCU)
                        rcu_read_lock();
                set_root(nd);
-               if (flags & LOOKUP_RCU) {
-                       nd->seq = nd->root_seq;
-                       nd->path = nd->root;
-               } else {
-                       path_get(&nd->root);
-                       nd->path = nd->root;
-               }
-               nd->inode = nd->path.dentry->d_inode;
-               if (!(flags & LOOKUP_RCU))
-                       return s;
-               if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq)))
+               if (likely(!nd_jump_root(nd)))
                        return s;
-               if (!(nd->flags & LOOKUP_ROOT))
-                       nd->root.mnt = NULL;
+               nd->root.mnt = NULL;
                rcu_read_unlock();
                return ERR_PTR(-ECHILD);
        } else if (nd->dfd == AT_FDCWD) {