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Message-ID: <20140114145328.GA12888@aepfle.de>
Date: Tue, 14 Jan 2014 15:53:28 +0100
From: Olaf Hering <olaf@...fle.de>
To: David Vrabel <david.vrabel@...rix.com>
Cc: Jan Beulich <JBeulich@...e.com>,
Ian Campbell <Ian.Campbell@...rix.com>,
xen-devel@...ts.xen.org, boris.ostrovsky@...cle.com,
linux-kernel@...r.kernel.org
Subject: Re: [Xen-devel] [PATCH v2] xen-blkfront: remove type check from
blkfront_setup_discard
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
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