OpenWrt – Rev 4

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From: Felix Fietkau <nbd@nbd.name>
Subject: jffs2: use .rename2 and add RENAME_WHITEOUT support

It is required for renames on overlayfs

Signed-off-by: Felix Fietkau <nbd@nbd.name>
---

--- a/fs/jffs2/dir.c
+++ b/fs/jffs2/dir.c
@@ -752,6 +752,24 @@ static int jffs2_mknod (struct inode *di
        return ret;
 }
 
+static int jffs2_whiteout (struct inode *old_dir, struct dentry *old_dentry)
+{
+       struct dentry *wh;
+       int err;
+
+       wh = d_alloc(old_dentry->d_parent, &old_dentry->d_name);
+       if (!wh)
+               return -ENOMEM;
+
+       err = jffs2_mknod(old_dir, wh, S_IFCHR | WHITEOUT_MODE,
+                         WHITEOUT_DEV);
+       if (err)
+               return err;
+
+       d_rehash(wh);
+       return 0;
+}
+
 static int jffs2_rename (struct inode *old_dir_i, struct dentry *old_dentry,
                         struct inode *new_dir_i, struct dentry *new_dentry,
                         unsigned int flags)
@@ -762,7 +780,7 @@ static int jffs2_rename (struct inode *o
        uint8_t type;
        uint32_t now;
 
-       if (flags & ~RENAME_NOREPLACE)
+       if (flags & ~(RENAME_NOREPLACE|RENAME_WHITEOUT))
                return -EINVAL;
 
        /* The VFS will check for us and prevent trying to rename a
@@ -828,9 +846,14 @@ static int jffs2_rename (struct inode *o
        if (d_is_dir(old_dentry) && !victim_f)
                inc_nlink(new_dir_i);
 
-       /* Unlink the original */
-       ret = jffs2_do_unlink(c, JFFS2_INODE_INFO(old_dir_i),
-                             old_dentry->d_name.name, old_dentry->d_name.len, NULL, now);
+       if (flags & RENAME_WHITEOUT)
+               /* Replace with whiteout */
+               ret = jffs2_whiteout(old_dir_i, old_dentry);
+       else
+               /* Unlink the original */
+               ret = jffs2_do_unlink(c, JFFS2_INODE_INFO(old_dir_i),
+                                     old_dentry->d_name.name,
+                                     old_dentry->d_name.len, NULL, now);
 
        /* We don't touch inode->i_nlink */