From 16b920a81a475f3433921722fe6b7b0ac2055c9a Mon Sep 17 00:00:00 2001 From: SeongJae Park Date: Fri, 15 Jul 2022 22:51:08 +0000 Subject: [PATCH] xen-blkfront: Apply 'feature_persistent' parameter when connect commit 805810b39745c4333888530a8c4ff5830ad3053f upstream. In some use cases[1], the backend is created while the frontend doesn't support the persistent grants feature, but later the frontend can be changed to support the feature and reconnect. In the past, 'blkback' enabled the persistent grants feature since it unconditionally checked if frontend supports the persistent grants feature for every connect ('connect_ring()') and decided whether it should use persistent grans or not. However, commit 3d14b04b1cc9 ("xen-blkback: add a parameter for disabling of persistent grants") has mistakenly changed the behavior. It made the frontend feature support check to not be repeated once it shown the 'feature_persistent' as 'false', or the frontend doesn't support persistent grants. Similar behavioral change has made on 'blkfront' by commit bd2bac1f49a3 ("xen-blkfront: add a parameter for disabling of persistent grants"). This commit changes the behavior of the parameter to make effect for every connect, so that the previous behavior of 'blkfront' can be restored. [1] https://lore.kernel.org/xen-devel/CAJwUmVB6H3iTs-C+U=v-pwJB7-_ZRHPxHzKRJZ22xEPW7z8a=g@mail.gmail.com/ Fixes: bd2bac1f49a3 ("xen-blkfront: add a parameter for disabling of persistent grants") Cc: # 5.10.x Signed-off-by: SeongJae Park Reviewed-by: Maximilian Heyne Reviewed-by: Juergen Gross Link: https://lore.kernel.org/r/20220715225108.193398-4-sj@kernel.org Signed-off-by: Juergen Gross Signed-off-by: Greg Kroah-Hartman --- Documentation/ABI/testing/sysfs-driver-xen-blkfront | 2 +- drivers/block/xen-blkfront.c | 4 +--- 2 files changed, 2 insertions(+), 4 deletions(-) diff --git a/Documentation/ABI/testing/sysfs-driver-xen-blkfront b/Documentation/ABI/testing/sysfs-driver-xen-blkfront index 28008905615f0..1f7659aa085c2 100644 --- a/Documentation/ABI/testing/sysfs-driver-xen-blkfront +++ b/Documentation/ABI/testing/sysfs-driver-xen-blkfront @@ -15,5 +15,5 @@ KernelVersion: 5.10 Contact: SeongJae Park Description: Whether to enable the persistent grants feature or not. Note - that this option only takes effect on newly created frontends. + that this option only takes effect on newly connected frontends. The default is Y (enable). diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index f6f679702b832..23fc4c8f26039 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -2014,8 +2014,6 @@ static int blkfront_probe(struct xenbus_device *dev, info->vdevice = vdevice; info->connected = BLKIF_STATE_DISCONNECTED; - info->feature_persistent = feature_persistent; - /* Front end dir is a number, which is used as the id. */ info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0); dev_set_drvdata(&dev->dev, info); @@ -2309,7 +2307,7 @@ static void blkfront_gather_backend_features(struct blkfront_info *info) if (xenbus_read_unsigned(info->xbdev->otherend, "feature-discard", 0)) blkfront_setup_discard(info); - if (info->feature_persistent) + if (feature_persistent) info->feature_persistent = !!xenbus_read_unsigned(info->xbdev->otherend, "feature-persistent", 0); -- 2.39.5