[PATCH] dm table: add target flush

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>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/md/dm-table.c

@@ -1001,6 +1001,11 @@ int dm_table_flush_all(struct dm_table *t)
 {
 	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);

include/linux/device-mapper.h

@@ -55,6 +55,7 @@ typedef int (*dm_endio_fn) (struct dm_target *ti,
 			    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;

include/linux/dm-ioctl.h

@@ -285,7 +285,7 @@ typedef char ioctl_struct[308];
 #define DM_DEV_SET_GEOMETRY	_IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl)
 
 #define DM_VERSION_MAJOR	4
-#define DM_VERSION_MINOR	9
+#define DM_VERSION_MINOR	10
 #define DM_VERSION_PATCHLEVEL	0
 #define DM_VERSION_EXTRA	"-ioctl (2006-09-14)"