nvme: Skip checking heads without namespaces

commit 2079699c10c8c60a9572540c2f77d045abf036eb upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 9355930321236a4ec7410cc6b8dcd3fbf0b830e9..bbe69e147b48ea661ed06913beade0ba6b000f69 100644 (file)
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2720,6 +2720,7 @@ 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;
        }