nvme: Skip checking heads without namespaces

If a task is holding a reference to a namespace on a removed controller,
the head will not be released. If the same controller is added again
later, its namespaces may not be successfully added. Instead, the user
will see kernel message "Duplicate IDs for nsid <X>".

This patch fixes that by skipping heads that don't have namespaces when
considering if a new namespace is safe to add.

Reported-by: Alex Gagniuc <Alex_Gagniuc@Dellteam.com>
Cc: stable@vger.kernel.org
Signed-off-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index f29a07ef122f107de61fda89f6f090d1727895ca..7811b4886e63fcf21ec037badd5aa8d21ba70444 100644 (file)
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2809,6 +2809,7 @@ static int __nvme_check_ids(struct nvme_subsystem *subsys,
 
        list_for_each_entry(h, &subsys->nsheads, entry) {
                if (nvme_ns_ids_valid(&new->ids) &&
+                   !list_empty(&h->list) &&
                    nvme_ns_ids_equal(&new->ids, &h->ids))
                        return -EINVAL;
        }