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[PULL,05/11] xen-block: fix reporting of discard feature

Message ID 20210215150100.436555-6-kwolf@redhat.com (mailing list archive)
State New, archived
Headers show
Series [PULL,01/11] qemu-storage-daemon: Enable object-add | expand

Commit Message

Kevin Wolf Feb. 15, 2021, 3 p.m. UTC
From: Roger Pau Monne <roger.pau@citrix.com>

Linux blkfront expects both "discard-granularity" and
"discard-alignment" present on xenbus in order to properly enable the
feature, not exposing "discard-alignment" left some Linux blkfront
versions with a broken discard setup. This has also been addressed in
Linux with:


Fix QEMU to report a "discard-alignment" of 0, in order for it to work
with older Linux frontends.

Reported-by: Arthur Borsboom <arthurborsboom@gmail.com>
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Message-Id: <20210118153330.82324-1-roger.pau@citrix.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
 hw/block/xen-block.c | 1 +
 1 file changed, 1 insertion(+)
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diff --git a/hw/block/xen-block.c b/hw/block/xen-block.c
index 0e7d66c2a7..a3b69e2709 100644
--- a/hw/block/xen-block.c
+++ b/hw/block/xen-block.c
@@ -253,6 +253,7 @@  static void xen_block_realize(XenDevice *xendev, Error **errp)
         xen_device_backend_printf(xendev, "feature-discard", "%u", 1);
         xen_device_backend_printf(xendev, "discard-granularity", "%u",
+        xen_device_backend_printf(xendev, "discard-alignment", "%u", 0);
     xen_device_backend_printf(xendev, "feature-flush-cache", "%u", 1);