Roger Pau Monne
2013-Aug-12 10:48 UTC
[PATCH] blkif: update persistent grants documentation
Update blkif protocol extensions documentation to reflect the new behaviour in Linux persistent grants implementation. Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> Cc: David Vrabel <david.vrabel@citrix.com> --- xen/include/public/io/blkif.h | 6 ++++++ 1 files changed, 6 insertions(+), 0 deletions(-) diff --git a/xen/include/public/io/blkif.h b/xen/include/public/io/blkif.h index b9b9d98..27ae8b6 100644 --- a/xen/include/public/io/blkif.h +++ b/xen/include/public/io/blkif.h @@ -290,6 +290,12 @@ * the previous protocol, a frontend driver can choose to work in * persistent mode even when the backend doesn't support it. * + * When the backend driver needs to unmap a persistent grant it should + * do so prior to completing a request that used that grant reference. + * If a persistent grant is unmapped at any other time, the frontend + * driver may not notice and may be unable to reclaim the grant + * reference. + * * It is recommended that the frontend driver stores the persistently * mapped grants in a LIFO queue, so a subset of all persistently mapped * grants gets used commonly. This is done in case the backend driver -- 1.7.7.5 (Apple Git-26) _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
David Vrabel
2013-Aug-12 15:47 UTC
Re: [PATCH] blkif: update persistent grants documentation
On 12/08/13 11:48, Roger Pau Monne wrote:> Update blkif protocol extensions documentation to reflect the new > behaviour in Linux persistent grants implementation. > > Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> > Cc: David Vrabel <david.vrabel@citrix.com>Thanks. Reviewed-by: David Vrabel <david.vrabel@citrix.com> David> --- > xen/include/public/io/blkif.h | 6 ++++++ > 1 files changed, 6 insertions(+), 0 deletions(-) > > diff --git a/xen/include/public/io/blkif.h b/xen/include/public/io/blkif.h > index b9b9d98..27ae8b6 100644 > --- a/xen/include/public/io/blkif.h > +++ b/xen/include/public/io/blkif.h > @@ -290,6 +290,12 @@ > * the previous protocol, a frontend driver can choose to work in > * persistent mode even when the backend doesn't support it. > * > + * When the backend driver needs to unmap a persistent grant it should > + * do so prior to completing a request that used that grant reference. > + * If a persistent grant is unmapped at any other time, the frontend > + * driver may not notice and may be unable to reclaim the grant > + * reference. > + * > * It is recommended that the frontend driver stores the persistently > * mapped grants in a LIFO queue, so a subset of all persistently mapped > * grants gets used commonly. This is done in case the backend driver_______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel