Merge tag 'exynos-drm-fixes-for-v4.12' of git://git.kernel.org/pub/scm/linux/kernel...

[linux.git] / fs / namei.c

diff --git a/fs/namei.c b/fs/namei.c
index 7286f87ce863568bbe1b84f8e432b809118146b5..6571a5f5112ed82894fdbec1c9b6dfaf557d93b1 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2142,7 +2142,6 @@ OK:
 
 static const char *path_init(struct nameidata *nd, unsigned flags)
 {
-       int retval = 0;
        const char *s = nd->name->name;
 
        if (!*s)
@@ -2154,13 +2153,8 @@ static const char *path_init(struct nameidata *nd, unsigned flags)
        if (flags & LOOKUP_ROOT) {
                struct dentry *root = nd->root.dentry;
                struct inode *inode = root->d_inode;
-               if (*s) {
-                       if (!d_can_lookup(root))
-                               return ERR_PTR(-ENOTDIR);
-                       retval = inode_permission(inode, MAY_EXEC);
-                       if (retval)
-                               return ERR_PTR(retval);
-               }
+               if (*s && unlikely(!d_can_lookup(root)))
+                       return ERR_PTR(-ENOTDIR);
                nd->path = nd->root;
                nd->inode = inode;
                if (flags & LOOKUP_RCU) {
@@ -2258,6 +2252,35 @@ static inline int lookup_last(struct nameidata *nd)
        return walk_component(nd, 0);
 }
 
+static int handle_lookup_down(struct nameidata *nd)
+{
+       struct path path = nd->path;
+       struct inode *inode = nd->inode;
+       unsigned seq = nd->seq;
+       int err;
+
+       if (nd->flags & LOOKUP_RCU) {
+               /*
+                * don't bother with unlazy_walk on failure - we are
+                * at the very beginning of walk, so we lose nothing
+                * if we simply redo everything in non-RCU mode
+                */
+               if (unlikely(!__follow_mount_rcu(nd, &path, &inode, &seq)))
+                       return -ECHILD;
+       } else {
+               dget(path.dentry);
+               err = follow_managed(&path, nd);
+               if (unlikely(err < 0))
+                       return err;
+               inode = d_backing_inode(path.dentry);
+               seq = 0;
+       }
+       path_to_nameidata(&path, nd);
+       nd->inode = inode;
+       nd->seq = seq;
+       return 0;
+}
+
 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
 static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path)
 {
@@ -2266,6 +2289,15 @@ static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path
 
        if (IS_ERR(s))
                return PTR_ERR(s);
+
+       if (unlikely(flags & LOOKUP_DOWN)) {
+               err = handle_lookup_down(nd);
+               if (unlikely(err < 0)) {
+                       terminate_walk(nd);
+                       return err;
+               }
+       }
+
        while (!(err = link_path_walk(s, nd))
                && ((err = lookup_last(nd)) > 0)) {
                s = trailing_symlink(nd);