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nvme: fix refcounting imbalance when all paths are down 

When the last path to a ns_head drops the current code
removes the ns_head from the subsystem list, but will only
delete the disk itself if the last reference to the ns_head
drops. This is causing an refcounting imbalance eg when
applications have a reference to the disk, as then they'll
never get notified that the disk is in fact dead.
This patch moves the call 'del_gendisk' into nvme_mpath_check_last_path(),
ensuring that the disk can be properly removed and applications get the
appropriate notifications.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Hannes Reinecke 2021-07-16 13:30:35 +02:00 committed by Christoph Hellwig
parent 7764656b10
commit 5396fdac56
3 changed files with 21 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
drivers/nvme/host/core.c
View File

@ -3807,6 +3807,8 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid,
static void nvme_ns_remove(struct nvme_ns *ns)
{
bool last_path = false;
if (test_and_set_bit(NVME_NS_REMOVING, &ns->flags))
return;
@ -3815,8 +3817,6 @@ static void nvme_ns_remove(struct nvme_ns *ns)
mutex_lock(&ns->ctrl->subsys->lock);
list_del_rcu(&ns->siblings);
if (list_empty(&ns->head->list))
list_del_init(&ns->head->entry);
mutex_unlock(&ns->ctrl->subsys->lock);
synchronize_rcu(); /* guarantee not available in head->list */
@ -3836,7 +3836,15 @@ static void nvme_ns_remove(struct nvme_ns *ns)
list_del_init(&ns->list);
up_write(&ns->ctrl->namespaces_rwsem);
nvme_mpath_check_last_path(ns);
/* Synchronize with nvme_init_ns_head() */
mutex_lock(&ns->head->subsys->lock);
if (list_empty(&ns->head->list)) {
list_del_init(&ns->head->entry);
last_path = true;
}
mutex_unlock(&ns->head->subsys->lock);
if (last_path)
nvme_mpath_shutdown_disk(ns->head);
nvme_put_ns(ns);
}

9
drivers/nvme/host/multipath.c
View File

@ -760,14 +760,21 @@ void nvme_mpath_add_disk(struct nvme_ns *ns, struct nvme_id_ns *id)
#endif
}
void nvme_mpath_remove_disk(struct nvme_ns_head *head)
void nvme_mpath_shutdown_disk(struct nvme_ns_head *head)
{
if (!head->disk)
return;
kblockd_schedule_work(&head->requeue_work);
if (head->disk->flags & GENHD_FL_UP) {
nvme_cdev_del(&head->cdev, &head->cdev_device);
del_gendisk(head->disk);
}
}
void nvme_mpath_remove_disk(struct nvme_ns_head *head)
{
if (!head->disk)
return;
blk_set_queue_dying(head->disk->queue);
/* make sure all pending bios are cleaned up */
kblockd_schedule_work(&head->requeue_work);

11
drivers/nvme/host/nvme.h
View File

@ -716,14 +716,7 @@ void nvme_mpath_uninit(struct nvme_ctrl *ctrl);
void nvme_mpath_stop(struct nvme_ctrl *ctrl);
bool nvme_mpath_clear_current_path(struct nvme_ns *ns);
void nvme_mpath_clear_ctrl_paths(struct nvme_ctrl *ctrl);
static inline void nvme_mpath_check_last_path(struct nvme_ns *ns)
{
struct nvme_ns_head *head = ns->head;
if (head->disk && list_empty(&head->list))
kblockd_schedule_work(&head->requeue_work);
}
void nvme_mpath_shutdown_disk(struct nvme_ns_head *head);
static inline void nvme_trace_bio_complete(struct request *req)
{
@ -772,7 +765,7 @@ static inline bool nvme_mpath_clear_current_path(struct nvme_ns *ns)
static inline void nvme_mpath_clear_ctrl_paths(struct nvme_ctrl *ctrl)
{
}
static inline void nvme_mpath_check_last_path(struct nvme_ns *ns)
static inline void nvme_mpath_shutdown_disk(struct nvme_ns_head *head)
{
}
static inline void nvme_trace_bio_complete(struct request *req)