path: root/drivers
diff options
authorMaximilian Heyne <mheyne@amazon.de>2022-07-15 22:51:07 +0000
committerJuergen Gross <jgross@suse.com>2022-08-12 12:13:51 +0200
commite94c6101e151b019b8babc518ac2a6ada644a5a1 (patch)
tree05b1ff3635bb1118c0611c6fc245740920af43a6 /drivers
parentfc9be616bb8f3ed9cf560308f86904f5c06be205 (diff)
xen-blkback: Apply 'feature_persistent' parameter when connect
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 aac8a70db24b ("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. This commit changes the behavior of the parameter to make effect for every connect, so that the previous workflow can work again as expected. [1] https://lore.kernel.org/xen-devel/CAJwUmVB6H3iTs-C+U=v-pwJB7-_ZRHPxHzKRJZ22xEPW7z8a=g@mail.gmail.com/ Reported-by: Andrii Chepurnyi <andrii.chepurnyi82@gmail.com> Fixes: aac8a70db24b ("xen-blkback: add a parameter for disabling of persistent grants") Cc: <stable@vger.kernel.org> # 5.10.x Signed-off-by: Maximilian Heyne <mheyne@amazon.de> Signed-off-by: SeongJae Park <sj@kernel.org> Reviewed-by: Maximilian Heyne <mheyne@amazon.de> Reviewed-by: Juergen Gross <jgross@suse.com> Link: https://lore.kernel.org/r/20220715225108.193398-3-sj@kernel.org Signed-off-by: Juergen Gross <jgross@suse.com>
Diffstat (limited to 'drivers')
1 files changed, 3 insertions, 6 deletions
diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index 16c6785d260c..ee7ad2fb432d 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -186,8 +186,6 @@ static struct xen_blkif *xen_blkif_alloc(domid_t domid)
INIT_WORK(&blkif->free_work, xen_blkif_deferred_free);
- blkif->vbd.feature_gnt_persistent = feature_persistent;
return blkif;
@@ -1086,10 +1084,9 @@ static int connect_ring(struct backend_info *be)
xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol);
return -ENOSYS;
- if (blkif->vbd.feature_gnt_persistent)
- blkif->vbd.feature_gnt_persistent =
- xenbus_read_unsigned(dev->otherend,
- "feature-persistent", 0);
+ blkif->vbd.feature_gnt_persistent = feature_persistent &&
+ xenbus_read_unsigned(dev->otherend, "feature-persistent", 0);
blkif->vbd.overflow_max_grants = 0;

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