Commit 9f5e0fe5 authored by SeongJae Park's avatar SeongJae Park Committed by Juergen Gross
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xen-blkfront: Advertise feature-persistent as user requested 



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
74a85247 ("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: 74a85247 ("xen-blkfront: add a parameter for disabling of persistent grants")
Cc: <stable@vger.kernel.org> # 5.10.x
Suggested-by: default avatarJuergen Gross <jgross@suse.com>
Signed-off-by: default avatarSeongJae Park <sj@kernel.org>
Tested-by: default avatarMarek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Reviewed-by: default avatarJuergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20220831165824.94815-3-sj@kernel.org


Signed-off-by: default avatarJuergen Gross <jgross@suse.com>
parent 06ba5d2e

drivers/block/xen-blkfront.c

+6 −2
Original line number Diff line number Diff line
@@ -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);