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>

1 files changed, 26 insertions, 28 deletions

diff --git a/fs/namei.c b/fs/namei.c
index a08018b1485c..0baf64b116bd 100644
--- 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) {