From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: [PATCH v2] blkif.h: enhance comments related to the discard feature Date: Mon, 27 Jan 2014 11:12:24 -0500 Message-ID: <20140127161224.GB23059@phenom.dumpdata.com> References: <1390818970-737-1-git-send-email-olaf@aepfle.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <1390818970-737-1-git-send-email-olaf@aepfle.de> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Olaf Hering Cc: JBeulich@suse.com, xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On Mon, Jan 27, 2014 at 11:36:10AM +0100, Olaf Hering wrote: > Also fix the name of the discard-alignment property, add the missing 'n'. > > Signed-off-by: Olaf Hering Acked-by: Konrad Rzeszutek Wilk Thanks! > --- > v2: > include changes suggested by Jan and Konrad which make it more clear that > both properties have to be present, if required. > > xen/include/public/io/blkif.h | 17 +++++++++++++---- > 1 file changed, 13 insertions(+), 4 deletions(-) > > diff --git a/xen/include/public/io/blkif.h b/xen/include/public/io/blkif.h > index 84eb7fd..542f123 100644 > --- a/xen/include/public/io/blkif.h > +++ b/xen/include/public/io/blkif.h > @@ -175,7 +175,7 @@ > * > *------------------------- Backend Device Properties ------------------------- > * > - * discard-aligment > + * discard-alignment > * Values: > * Default Value: 0 > * Notes: 4, 5 > @@ -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 +324,15 @@ > * 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. If the backing device has such discardable extents the > + * backend should provide both discard-granularity and discard-alignment. > + * Providing just one of the two may be considered an error by the frontend. > + * Backends supporting discard should include discard-granularity and > + * discard-alignment even if it supports discarding individual sectors. > + * Frontends should assume discard-alignment == 0 and discard-granularity > + * == sector size if these keys are missing. > * (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 +351,8 @@ > * 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. > */ > > /*