ovl: Set redirect on metacopy files upon rename

Set redirect on metacopy files upon rename.  This will help find data
dentry in lower dirs.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index 4fa756c..ba59081 100644 (file)
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -874,13 +874,13 @@ static bool ovl_can_move(struct dentry *dentry)
                !d_is_dir(dentry) || !ovl_type_merge_or_lower(dentry);
 }
 
-static char *ovl_get_redirect(struct dentry *dentry, bool samedir)
+static char *ovl_get_redirect(struct dentry *dentry, bool abs_redirect)
 {
        char *buf, *ret;
        struct dentry *d, *tmp;
        int buflen = ovl_redirect_max + 1;
 
-       if (samedir) {
+       if (!abs_redirect) {
                ret = kstrndup(dentry->d_name.name, dentry->d_name.len,
                               GFP_KERNEL);
                goto out;
@@ -934,15 +934,43 @@ out:
        return ret ? ret : ERR_PTR(-ENOMEM);
 }
 
+static bool ovl_need_absolute_redirect(struct dentry *dentry, bool samedir)
+{
+       struct dentry *lowerdentry;
+
+       if (!samedir)
+               return true;
+
+       if (d_is_dir(dentry))
+               return false;
+
+       /*
+        * For non-dir hardlinked files, we need absolute redirects
+        * in general as two upper hardlinks could be in different
+        * dirs. We could put a relative redirect now and convert
+        * it to absolute redirect later. But when nlink > 1 and
+        * indexing is on, that means relative redirect needs to be
+        * converted to absolute during copy up of another lower
+        * hardllink as well.
+        *
+        * So without optimizing too much, just check if lower is
+        * a hard link or not. If lower is hard link, put absolute
+        * redirect.
+        */
+       lowerdentry = ovl_dentry_lower(dentry);
+       return (d_inode(lowerdentry)->i_nlink > 1);
+}
+
 static int ovl_set_redirect(struct dentry *dentry, bool samedir)
 {
        int err;
        const char *redirect = ovl_dentry_get_redirect(dentry);
+       bool absolute_redirect = ovl_need_absolute_redirect(dentry, samedir);
 
-       if (redirect && (samedir || redirect[0] == '/'))
+       if (redirect && (!absolute_redirect || redirect[0] == '/'))
                return 0;
 
-       redirect = ovl_get_redirect(dentry, samedir);
+       redirect = ovl_get_redirect(dentry, absolute_redirect);
        if (IS_ERR(redirect))
                return PTR_ERR(redirect);
 
@@ -1118,22 +1146,20 @@ static int ovl_rename(struct inode *olddir, struct dentry *old,
                goto out_dput;
 
        err = 0;
-       if (is_dir) {
-               if (ovl_type_merge_or_lower(old))
-                       err = ovl_set_redirect(old, samedir);
-               else if (!old_opaque && ovl_type_merge(new->d_parent))
-                       err = ovl_set_opaque_xerr(old, olddentry, -EXDEV);
-               if (err)
-                       goto out_dput;
-       }
-       if (!overwrite && new_is_dir) {
-               if (ovl_type_merge_or_lower(new))
-                       err = ovl_set_redirect(new, samedir);
-               else if (!new_opaque && ovl_type_merge(old->d_parent))
-                       err = ovl_set_opaque_xerr(new, newdentry, -EXDEV);
-               if (err)
-                       goto out_dput;
-       }
+       if (ovl_type_merge_or_lower(old))
+               err = ovl_set_redirect(old, samedir);
+       else if (is_dir && !old_opaque && ovl_type_merge(new->d_parent))
+               err = ovl_set_opaque_xerr(old, olddentry, -EXDEV);
+       if (err)
+               goto out_dput;
+
+       if (!overwrite && ovl_type_merge_or_lower(new))
+               err = ovl_set_redirect(new, samedir);
+       else if (!overwrite && new_is_dir && !new_opaque &&
+                ovl_type_merge(old->d_parent))
+               err = ovl_set_opaque_xerr(new, newdentry, -EXDEV);
+       if (err)
+               goto out_dput;
 
        err = ovl_do_rename(old_upperdir->d_inode, olddentry,
                            new_upperdir->d_inode, newdentry, flags);