1 files changed, 24 insertions, 1 deletions

diff --git a/mm/memory.c b/mm/memory.c
index d8dde07a3656..e249088908c4 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1770,9 +1770,32 @@ out_big:
 out_busy:
         return -ETXTBSY;
 }
-
 EXPORT_SYMBOL(vmtruncate);
 
+int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end)
+{
+        struct address_space *mapping = inode->i_mapping;
+
+        /*
+         * If the underlying filesystem is not going to provide
+         * a way to truncate a range of blocks (punch a hole) -
+         * we should return failure right now.
+         */
+        if (!inode->i_op || !inode->i_op->truncate_range)
+                return -ENOSYS;
+
+        down(&inode->i_sem);
+        down_write(&inode->i_alloc_sem);
+        unmap_mapping_range(mapping, offset, (end - offset), 1);
+        truncate_inode_pages_range(mapping, offset, end);
+        inode->i_op->truncate_range(inode, offset, end);
+        up_write(&inode->i_alloc_sem);
+        up(&inode->i_sem);
+
+        return 0;
+}
+EXPORT_SYMBOL(vmtruncate_range);
+
 /* 
  * Primitive swap readahead code. We simply read an aligned block of
  * (1 << page_cluster) entries in the swap area. This method is chosen