On 2/25/26 9:09 PM, John Garry wrote:
For switching to use libmultipath, the per-namespace sibling list entry in
nvme_ns.sibling will be replaced with multipath_device.sibling list
pointer.
For when CONFIG_LIBMULTIPATH is disabled, that list of namespaces would no
longer be maintained.
However the core code checks in many places whether there is any
namespace in the head list, like in nvme_ns_remove().
Introduce a separate count of the number of namespaces for the namespace
head and use that count for the places where the per-namespace head list
of namespaces is checked to be empty.
Signed-off-by: John Garry<[email protected]>
---
drivers/nvme/host/core.c | 10 +++++++---
drivers/nvme/host/multipath.c | 4 ++--
drivers/nvme/host/nvme.h | 1 +
3 files changed, 10 insertions(+), 5 deletions(-)
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 37e30caff4149..76249871dd7c2 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -4024,7 +4024,7 @@ static int nvme_init_ns_head(struct nvme_ns *ns, struct
nvme_ns_info *info)
} else {
ret = -EINVAL;
if ((!info->is_shared || !head->shared) &&
- !list_empty(&head->list)) {
+ head->ns_count) {
dev_err(ctrl->device,
"Duplicate unshared namespace %d\n",
info->nsid);
@@ -4047,6 +4047,7 @@ static int nvme_init_ns_head(struct nvme_ns *ns, struct
nvme_ns_info *info)
}
list_add_tail_rcu(&ns->siblings, &head->list);
+ head->ns_count++;
ns->head = head;
mutex_unlock(&ctrl->subsys->lock);
I think we could still access head->mpath_disk->mpath_head->dev_list.
So in that case do we really need to have ->ns_count? Moreover, if
we could maintain a pointer to struct mpath_head from struct
nvme_ns_head then we may avoid one dereference. What do you think?
Thanks,
--Nilay
