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>

diff --git a/fs/namei.c b/fs/namei.c
index a9b94c62c303807434e18374eb85b6ffee7b5675..0e1b9c3eb36d4812132239d345559a6361a8c0c5 100644 (file)
--- 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;
 

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 3bd5ac1ff0181147a6c4c59380eb0963aec6f1d4..2772208338f811c6b5d5bc067c490fe8725ba3cb 100644 (file)
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1438,8 +1438,7 @@ static void *proc_pid_follow_link(struct dentry *dentry, struct nameidata *nd)
        if (error)
                goto out;
 
-       path_put(&nd->path);
-       nd->path = path;
+       nd_jump_link(nd, &path);
        return NULL;
 out:
        return ERR_PTR(error);

diff --git a/include/linux/namei.h b/include/linux/namei.h
index f5931489e150431bda9cef57e14b5cca31784927..d2ef8b34b96722078c5ab7a3914579d5b50a8ca6 100644 (file)
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -80,6 +80,8 @@ extern int follow_up(struct path *);
 extern struct dentry *lock_rename(struct dentry *, struct dentry *);
 extern void unlock_rename(struct dentry *, struct dentry *);
 
+extern void nd_jump_link(struct nameidata *nd, struct path *path);
+
 static inline void nd_set_link(struct nameidata *nd, char *path)
 {
        nd->saved_names[nd->depth] = path;