From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keir Fraser Subject: Re: [PATCH] blkif.h: enhance comments related to the discard feature Date: Fri, 17 Jan 2014 18:02:48 +0000 Message-ID: References: <1389736679-15637-1-git-send-email-olaf@aepfle.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1389736679-15637-1-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 , xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On 14/01/2014 21:57, "Olaf Hering" wrote: > Also fix the name of the discard-alignment property, add the missing 'n'. > > Signed-off-by: Olaf Hering Acked-by: Keir Fraser Although I am not an authority on this interface... > --- > xen/include/public/io/blkif.h | 16 ++++++++++++---- > 1 file changed, 12 insertions(+), 4 deletions(-) > > diff --git a/xen/include/public/io/blkif.h b/xen/include/public/io/blkif.h > index 84eb7fd..515ea90 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 +324,14 @@ > * 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 must provide both discard-granularity and discard-alignment. > + * 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 +350,8 @@ > * 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. > */ > > /*