dm kcopyd: add dm_kcopyd_zero to zero an area

This patch introduces dm_kcopyd_zero() to make it easy to use
kcopyd to write zeros into the requested areas instead
instead of copying.  It is implemented by passing a NULL
copying source to dm_kcopyd_copy().

The forthcoming thin provisioning target uses this.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/include/linux/dm-kcopyd.h b/include/linux/dm-kcopyd.h
index 5e54458e920f..47d9d376e4e7 100644
--- a/include/linux/dm-kcopyd.h
+++ b/include/linux/dm-kcopyd.h
@@ -57,5 +57,9 @@ void *dm_kcopyd_prepare_callback(struct dm_kcopyd_client *kc,
                                  dm_kcopyd_notify_fn fn, void *context);
 void dm_kcopyd_do_callback(void *job, int read_err, unsigned long write_err);
 
+int dm_kcopyd_zero(struct dm_kcopyd_client *kc,
+                   unsigned num_dests, struct dm_io_region *dests,
+                   unsigned flags, dm_kcopyd_notify_fn fn, void *context);
+
 #endif  /* __KERNEL__ */
 #endif  /* _LINUX_DM_KCOPYD_H */