sync-file-range.patch

diff --git a/sys/ufs/ffs/ffs_vnops.c b/sys/ufs/ffs/ffs_vnops.c
index f5a45f1..50296f7 100644
--- a/sys/ufs/ffs/ffs_vnops.c
+++ b/sys/ufs/ffs/ffs_vnops.c
@@ -218,6 +218,29 @@ retry:
 }
 
 int
+ffs_sync_file_range(struct vnode *vp, off_t begin, size_t size)
+{
+       struct buf *bp, *nbp;
+       struct bufobj *bo = &vp->v_bufobj;
+       off_t past_end = begin + size;
+
+       /*
+        * Walk the dirty buffer list looking for buffers that overlap the given
+        * range, and request asynchronous write-back.
+        */
+       BO_LOCK(bo);
+       TAILQ_FOREACH_SAFE(bp, &bo->dirty.bv_hd, b_objufs, nbp) {
+               if (bp->b_offset + bp->bufsize > begin && bp->b_offset < past_end) {
+                       bremfree(bp);
+                       (void) bawrite(bp);
+               }
+       }
+       BO_UNLOCK(bo);
+
+       return (0);
+}
+
+int
 ffs_syncvnode(struct vnode *vp, int waitfor, int flags)
 {
        struct inode *ip;