From: SeongJae Park <sj@xxxxxxxxxx>
The advertisement of the persistent grants feature (writing
'feature-persistent' to xenbus) should mean not the decision for using
the feature but only the availability of the feature. However, commit
74a852479c68 ("xen-blkfront: add a parameter for disabling of persistent
grants") made a field of blkfront, which was a place for saving only the
negotiation result, to be used for yet another purpose: caching of the
'feature_persistent' parameter value. As a result, the advertisement,
which should follow only the parameter value, becomes inconsistent.
This commit fixes the misuse of the semantic by making blkfront saves
the parameter value in a separate place and advertises the support based
on only the saved value.
Fixes: 74a852479c68 ("xen-blkfront: add a parameter for disabling of persistent grants")
Cc: <stable@xxxxxxxxxxxxxxx> # 5.10.x
Suggested-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
Tested-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
Link: https://lore.kernel.org/r/20220831165824.94815-3-sj@xxxxxxxxxx
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
drivers/block/xen-blkfront.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 4e763701b372..276b2ee2a155 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -213,6 +213,9 @@ struct blkfront_info
unsigned int feature_fua:1;
unsigned int feature_discard:1;
unsigned int feature_secdiscard:1;
+ /* Connect-time cached feature_persistent parameter */
+ unsigned int feature_persistent_parm:1;
+ /* Persistent grants feature negotiation result */
unsigned int feature_persistent:1;
unsigned int bounce:1;
unsigned int discard_granularity;
@@ -1848,7 +1851,7 @@ static int talk_to_blkback(struct xenbus_device *dev,
goto abort_transaction;
}
err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u",
- info->feature_persistent);
+ info->feature_persistent_parm);
if (err)
dev_warn(&dev->dev,
"writing persistent grants feature to xenbus");
@@ -2281,7 +2284,8 @@ 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 (feature_persistent)
+ info->feature_persistent_parm = feature_persistent;
+ if (info->feature_persistent_parm)
info->feature_persistent =
!!xenbus_read_unsigned(info->xbdev->otherend,
"feature-persistent", 0);
--
2.34.1
