vfs: make follow_link check RCU safe
This will allow this code to be used in RCU mode.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/namei.c b/fs/namei.c
index 3a85ced..e7b4506 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2307,6 +2307,7 @@
int acc_mode = op->acc_mode;
struct file *filp;
struct inode *inode;
+ int symlink_ok = 0;
int error;
nd->flags &= ~LOOKUP_PARENT;
@@ -2338,7 +2339,6 @@
}
if (!(open_flag & O_CREAT)) {
- int symlink_ok = 0;
if (nd->last.name[nd->last.len])
nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW))
@@ -2470,8 +2470,16 @@
if (!inode)
goto exit_dput;
- if (inode->i_op->follow_link)
+ if (should_follow_link(inode, !symlink_ok)) {
+ if (nd->flags & LOOKUP_RCU) {
+ if (unlikely(unlazy_walk(nd, path->dentry))) {
+ error = -ECHILD;
+ goto exit;
+ }
+ }
+ BUG_ON(inode != path->dentry->d_inode);
return NULL;
+ }
path_to_nameidata(path, nd);
nd->inode = inode;