From: SeongJae Park <sj@kernel.org> stable inclusion from stable-v5.10.142 commit aa45c507037a617409fef8566d0e71ee6aa91935 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I6CSFH Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- 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-Górecki <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> Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com> Reviewed-by: Zheng Zengkai <zhengzengkai@huawei.com> --- drivers/block/xen-blkback/common.h | 3 +++ drivers/block/xen-blkback/xenbus.c | 6 ++++-- 2 files changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h index 040829e2d016..5eff34767b77 100644 --- 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; }; diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c index 44782b15b9fd..ddea36295931 100644 --- a/drivers/block/xen-blkback/xenbus.c +++ b/drivers/block/xen-blkback/xenbus.c @@ -911,7 +911,7 @@ static void connect(struct backend_info *be) 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); @@ -1089,7 +1089,9 @@ static int connect_ring(struct backend_info *be) 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; -- 2.25.1