| From 06ba5d2e943e97bb66e75c152e87f1d2c7027a67 Mon Sep 17 00:00:00 2001 |
| From: SeongJae Park <sj@kernel.org> |
| Date: Wed, 31 Aug 2022 16:58:22 +0000 |
| Subject: xen-blkback: Advertise feature-persistent as user requested |
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| |
| From: SeongJae Park <sj@kernel.org> |
| |
| commit 06ba5d2e943e97bb66e75c152e87f1d2c7027a67 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 |
| aac8a70db24b ("xen-blkback: add a parameter for disabling of persistent |
| grants") made a field of blkback, 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 blkback saves the |
| parameter value in a separate place and advertises the support based on |
| only the saved value. |
| |
| Fixes: aac8a70db24b ("xen-blkback: add a parameter for disabling of persistent grants") |
| Cc: <stable@vger.kernel.org> # 5.10.x |
| Suggested-by: Juergen Gross <jgross@suse.com> |
| Signed-off-by: SeongJae Park <sj@kernel.org> |
| Tested-by: Marek Marczykowski-Gรณrecki <marmarek@invisiblethingslab.com> |
| Reviewed-by: Juergen Gross <jgross@suse.com> |
| Link: https://lore.kernel.org/r/20220831165824.94815-2-sj@kernel.org |
| Signed-off-by: Juergen Gross <jgross@suse.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| drivers/block/xen-blkback/common.h | 3 +++ |
| drivers/block/xen-blkback/xenbus.c | 6 ++++-- |
| 2 files changed, 7 insertions(+), 2 deletions(-) |
| |
| --- a/drivers/block/xen-blkback/common.h |
| +++ b/drivers/block/xen-blkback/common.h |
| @@ -226,6 +226,9 @@ struct xen_vbd { |
| sector_t size; |
| unsigned int flush_support:1; |
| unsigned int discard_secure:1; |
| + /* Connect-time cached feature_persistent parameter value */ |
| + unsigned int feature_gnt_persistent_parm:1; |
| + /* Persistent grants feature negotiation result */ |
| unsigned int feature_gnt_persistent:1; |
| unsigned int overflow_max_grants:1; |
| }; |
| --- a/drivers/block/xen-blkback/xenbus.c |
| +++ b/drivers/block/xen-blkback/xenbus.c |
| @@ -907,7 +907,7 @@ again: |
| xen_blkbk_barrier(xbt, be, be->blkif->vbd.flush_support); |
| |
| err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u", |
| - be->blkif->vbd.feature_gnt_persistent); |
| + be->blkif->vbd.feature_gnt_persistent_parm); |
| if (err) { |
| xenbus_dev_fatal(dev, err, "writing %s/feature-persistent", |
| dev->nodename); |
| @@ -1085,7 +1085,9 @@ static int connect_ring(struct backend_i |
| return -ENOSYS; |
| } |
| |
| - blkif->vbd.feature_gnt_persistent = feature_persistent && |
| + blkif->vbd.feature_gnt_persistent_parm = feature_persistent; |
| + blkif->vbd.feature_gnt_persistent = |
| + blkif->vbd.feature_gnt_persistent_parm && |
| xenbus_read_unsigned(dev->otherend, "feature-persistent", 0); |
| |
| blkif->vbd.overflow_max_grants = 0; |
