ovl: create ovl_need_index() helper

The helper determines which lower file needs to be indexed
on copy up and before nlink changes.

For index=on, the helper evaluates to true for lower hardlinks.

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

1 files changed, 20 insertions, 4 deletions

diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index ae81d878248e..55ab99131a72 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -463,6 +463,23 @@ void ovl_inuse_unlock(struct dentry *dentry)
         }
 }
 
+/*
+ * Does this overlay dentry need to be indexed on copy up?
+ */
+bool ovl_need_index(struct dentry *dentry)
+{
+        struct dentry *lower = ovl_dentry_lower(dentry);
+
+        if (!lower || !ovl_indexdir(dentry->d_sb))
+                return false;
+
+        /* Index only lower hardlinks on copy up */
+        if (!d_is_dir(lower) && d_inode(lower)->i_nlink > 1)
+                return true;
+
+        return false;
+}
+
 /* Caller must hold OVL_I(inode)->lock */
 static void ovl_cleanup_index(struct dentry *dentry)
 {
@@ -533,11 +550,11 @@ int ovl_nlink_start(struct dentry *dentry, bool *locked)
 
         /*
          * With inodes index is enabled, we store the union overlay nlink
-         * in an xattr on the index inode. When whiting out lower hardlinks
+         * in an xattr on the index inode. When whiting out an indexed lower,
          * we need to decrement the overlay persistent nlink, but before the
          * first copy up, we have no upper index inode to store the xattr.
          *
-         * As a workaround, before whiteout/rename over of a lower hardlink,
+         * As a workaround, before whiteout/rename over an indexed lower,
          * copy up to create the upper index. Creating the upper index will
          * initialize the overlay nlink, so it could be dropped if unlink
          * or rename succeeds.
@@ -545,8 +562,7 @@ int ovl_nlink_start(struct dentry *dentry, bool *locked)
          * TODO: implement metadata only index copy up when called with
          *       ovl_copy_up_flags(dentry, O_PATH).
          */
-        if (ovl_indexdir(dentry->d_sb) && !ovl_dentry_has_upper_alias(dentry) &&
-            d_inode(ovl_dentry_lower(dentry))->i_nlink > 1) {
+        if (ovl_need_index(dentry) && !ovl_dentry_has_upper_alias(dentry)) {
                 err = ovl_copy_up(dentry);
                 if (err)
                         return err;