From: Anton Eidelman anton@lightbitslabs.com
[ Upstream commit 2181e455612a8db2761eabbf126640552a451e96 ]
When a shared namespace is removed, we call blk_cleanup_queue() when the device can still be accessed as the current path and this can result in submission to a dying queue. Hence, direct_make_request() called by our mpath device may fail (propagating the failure to userspace). Instead, we want to failover this I/O to a different path if one exists. Thus, before we cleanup the request queue, we make sure that the device is cleared from the current path nor it can be selected again as such.
Fix this by: - clear the ns from the head->list and synchronize rcu to make sure there is no concurrent path search that restores it as the current path - clear the mpath current path in order to trigger a subsequent path search and sync srcu to wait for any ongoing request submissions - safely continue to namespace removal and blk_cleanup_queue
Signed-off-by: Anton Eidelman anton@lightbitslabs.com Signed-off-by: Sagi Grimberg sagi@grimberg.me Signed-off-by: Christoph Hellwig hch@lst.de Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/nvme/host/core.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index 3a390b2c7540..cbbdd3dae5a1 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -3341,6 +3341,14 @@ static void nvme_ns_remove(struct nvme_ns *ns) return;
nvme_fault_inject_fini(ns); + + mutex_lock(&ns->ctrl->subsys->lock); + list_del_rcu(&ns->siblings); + mutex_unlock(&ns->ctrl->subsys->lock); + synchronize_rcu(); /* guarantee not available in head->list */ + nvme_mpath_clear_current_path(ns); + synchronize_srcu(&ns->head->srcu); /* wait for concurrent submissions */ + if (ns->disk && ns->disk->flags & GENHD_FL_UP) { del_gendisk(ns->disk); blk_cleanup_queue(ns->queue); @@ -3348,16 +3356,10 @@ static void nvme_ns_remove(struct nvme_ns *ns) blk_integrity_unregister(ns->disk); }
- mutex_lock(&ns->ctrl->subsys->lock); - list_del_rcu(&ns->siblings); - nvme_mpath_clear_current_path(ns); - mutex_unlock(&ns->ctrl->subsys->lock); - down_write(&ns->ctrl->namespaces_rwsem); list_del_init(&ns->list); up_write(&ns->ctrl->namespaces_rwsem);
- synchronize_srcu(&ns->head->srcu); nvme_mpath_check_last_path(ns); nvme_put_ns(ns); }