fs: add nd_jump_link

Add a helper that abstracts out the jump to an already parsed struct path
from ->follow_link operation from procfs.  Not only does this clean up
the code by moving the two sides of this game into a single helper, but
it also prepares for making struct nameidata private to namei.c

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 17 insertions, 10 deletions

diff --git a/fs/namei.c b/fs/namei.c
index a9b94c62c303..0e1b9c3eb36d 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -586,6 +586,21 @@ static inline void path_to_nameidata(const struct path *path,
         nd->path.dentry = path->dentry;
 }
 
+/*
+ * Helper to directly jump to a known parsed path from ->follow_link,
+ * caller must have taken a reference to path beforehand.
+ */
+void nd_jump_link(struct nameidata *nd, struct path *path)
+{
+        path_put(&nd->path);
+
+        nd->path = *path;
+        nd->inode = nd->path.dentry->d_inode;
+        nd->flags |= LOOKUP_JUMPED;
+
+        BUG_ON(nd->inode->i_op->follow_link);
+}
+
 static inline void put_link(struct nameidata *nd, struct path *link, void *cookie)
 {
         struct inode *inode = link->dentry->d_inode;
@@ -630,17 +645,9 @@ follow_link(struct path *link, struct nameidata *nd, void **p)
         s = nd_get_link(nd);
         if (s) {
                 error = __vfs_follow_link(nd, s);
-        } else if (nd->last_type == LAST_BIND) {
-                nd->flags |= LOOKUP_JUMPED;
-                nd->inode = nd->path.dentry->d_inode;
-                if (nd->inode->i_op->follow_link) {
-                        /* stepped on a _really_ weird one */
-                        path_put(&nd->path);
-                        error = -ELOOP;
-                }
+                if (unlikely(error))
+                        put_link(nd, link, *p);
         }
-        if (unlikely(error))
-                put_link(nd, link, *p);
 
         return error;