This is a note to let you know that I've just added the patch titled xen-blkfront: Advertise feature-persistent as user requested to the 5.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: xen-blkfront-advertise-feature-persistent-as-user-requested.patch and it can be found in the queue-5.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 9f5e0fe5d05f7e8de7f39b2b10089834eb0ff787 Mon Sep 17 00:00:00 2001 From: SeongJae Park <sj@xxxxxxxxxx> Date: Wed, 31 Aug 2022 16:58:23 +0000 Subject: xen-blkfront: Advertise feature-persistent as user requested MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: SeongJae Park <sj@xxxxxxxxxx> commit 9f5e0fe5d05f7e8de7f39b2b10089834eb0ff787 upstream. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/block/xen-blkfront.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -211,6 +211,9 @@ 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; @@ -1941,7 +1944,7 @@ again: 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"); @@ -2391,7 +2394,8 @@ static void blkfront_gather_backend_feat 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); Patches currently in stable-queue which might be from sj@xxxxxxxxxx are queue-5.10/xen-blkfront-advertise-feature-persistent-as-user-requested.patch queue-5.10/xen-blkback-advertise-feature-persistent-as-user-requested.patch