Re: [Xen-devel] [PATCH v2] xen-blkfront: remove type check from blkfront_setup_discard

[Olaf Hering <olaf@aepfle.de>]

On Mon, Jan 13, David Vrabel wrote:

> Can we have a patch to blkif.h that clarifies this?

What about this change?

diff --git a/xen/include/public/io/blkif.h b/xen/include/public/io/blkif.h
index 84eb7fd..56e2faa 100644
--- a/xen/include/public/io/blkif.h
+++ b/xen/include/public/io/blkif.h
@@ -194,6 +194,7 @@
  * discard-secure
  *      Values:         0/1 (boolean)
  *      Default Value:  0
+ *      Notes:          10
  *
  *      A value of "1" indicates that the backend can process BLKIF_OP_DISCARD
  *      requests with the BLKIF_DISCARD_SECURE flag set.
@@ -323,9 +324,10 @@
  *     For full interoperability, block front and backends should publish
  *     identical ring parameters, adjusted for unit differences, to the
  *     XenStore nodes used in both schemes.
- * (4) Devices that support discard functionality may internally allocate
- *     space (discardable extents) in units that are larger than the
- *     exported logical block size.
+ * (4) Devices that support discard functionality may internally allocate space
+ *     (discardable extents) in units that are larger than the exported logical
+ *     block size. The properties discard-granularity and discard-alignment may
+ *     be present if the backing device has such requirments.
  * (5) The discard-alignment parameter allows a physical device to be
  *     partitioned into virtual devices that do not necessarily begin or
  *     end on a discardable extent boundary.
@@ -344,6 +346,8 @@
  *     grants that can be persistently mapped in the frontend driver, but
  *     due to the frontent driver implementation it should never be bigger
  *     than RING_SIZE * BLKIF_MAX_SEGMENTS_PER_REQUEST.
+ *(10) The discard-secure property may be present and will be set to 1 if the
+ *     backing device supports secure discard.
  */
 
 /*


Olaf