ubifs: Fix synced_i_size calculation for xattr inodes

In ubifs_jnl_update() we sync parent and child inodes to the flash,
in case of xattrs, the parent inode (AKA host inode) has a non-zero
data_len. Therefore we need to adjust synced_i_size too.

This issue was reported by ubifs self tests unter a xattr related work
load.
UBIFS error (ubi0:0 pid 1896): dbg_check_synced_i_size: ui_size is 4, synced_i_size is 0, but inode is clean
UBIFS error (ubi0:0 pid 1896): dbg_check_synced_i_size: i_ino 65, i_mode 0x81a4, i_size 4

Cc: <stable@vger.kernel.org>
Fixes: 1e51764a3c2a ("UBIFS: add new flash file system")
Signed-off-by: Richard Weinberger <richard@nod.at>

fs/ubifs/journal.c

@@ -664,6 +664,11 @@ int ubifs_jnl_update(struct ubifs_info *c, const struct inode *dir,
 	spin_lock(&ui->ui_lock);
 	ui->synced_i_size = ui->ui_size;
 	spin_unlock(&ui->ui_lock);
+	if (xent) {
+		spin_lock(&host_ui->ui_lock);
+		host_ui->synced_i_size = host_ui->ui_size;
+		spin_unlock(&host_ui->ui_lock);
+	}
 	mark_inode_clean(c, ui);
 	mark_inode_clean(c, host_ui);
 	return 0;