This patch adds support for a per-target dm_flush_fn method.
This is needed to allow dm-loop to invalidate page cache 
mappings in response to BLKFLSBUF ioctl commands.

Signed-off-by: Bryn Reeves <breeves@redhat.com>

Index: linux-2.6.17/drivers/md/dm-table.c
===================================================================
--- linux-2.6.17.orig/drivers/md/dm-table.c	2006-08-10 19:28:24.000000000 +0100
+++ linux-2.6.17/drivers/md/dm-table.c	2006-08-10 19:28:27.000000000 +0100
@@ -1001,6 +1001,11 @@ int dm_table_flush_all(struct dm_table *
 {
 	struct list_head *d, *devices = dm_table_get_devices(t);
 	int ret = 0;
+	unsigned i;
+
+	for (i = 0; i < t->num_targets; i++)
+		if (t->targets[i].type->flush)
+			t->targets[i].type->flush(&t->targets[i]);
 
 	for (d = devices->next; d != devices; d = d->next) {
 		struct dm_dev *dd = list_entry(d, struct dm_dev, list);
Index: linux-2.6.17/include/linux/device-mapper.h
===================================================================
--- linux-2.6.17.orig/include/linux/device-mapper.h	2006-08-10 19:28:24.000000000 +0100
+++ linux-2.6.17/include/linux/device-mapper.h	2006-08-10 19:28:27.000000000 +0100
@@ -55,6 +55,7 @@ typedef int (*dm_endio_fn) (struct dm_ta
 			    struct bio *bio, int error,
 			    union map_info *map_context);
 
+typedef void (*dm_flush_fn) (struct dm_target *ti);
 typedef void (*dm_presuspend_fn) (struct dm_target *ti);
 typedef void (*dm_postsuspend_fn) (struct dm_target *ti);
 typedef int (*dm_preresume_fn) (struct dm_target *ti);
@@ -96,6 +97,7 @@ struct target_type {
 	dm_dtr_fn dtr;
 	dm_map_fn map;
 	dm_endio_fn end_io;
+	dm_flush_fn flush;
 	dm_presuspend_fn presuspend;
 	dm_postsuspend_fn postsuspend;
 	dm_preresume_fn preresume;