nvmet: move the call to nvmet_ns_changed out of nvmet_ns_revalidate

nvmet_ns_changed states via lockdep that the ns->subsys->lock must be
held. The only caller of nvmet_ns_changed which does not acquire that
lock is nvmet_ns_revalidate. nvmet_ns_revalidate has 3 callers,
of which 2 do not acquire that lock: nvmet_execute_identify_cns_cs_ns
and nvmet_execute_identify_ns. The other caller
nvmet_ns_revalidate_size_store does acquire the lock.

Move the call to nvmet_ns_changed from nvmet_ns_revalidate to the callers
so that they can perform the correct locking as needed.

This issue was found using a static type-based analyser and manually
verified.
Reported-by: Niels Dossche <dossche.niels@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>

drivers/nvme/target/admin-cmd.c

@@ -511,7 +511,11 @@ static void nvmet_execute_identify_ns(struct nvmet_req *req)
 		goto done;
 	}
 
-	nvmet_ns_revalidate(req->ns);
+	if (nvmet_ns_revalidate(req->ns)) {
+		mutex_lock(&req->ns->subsys->lock);
+		nvmet_ns_changed(req->ns->subsys, req->ns->nsid);
+		mutex_unlock(&req->ns->subsys->lock);
+	}
 
 	/*
 	 * nuse = ncap = nsze isn't always true, but we have no way to find

drivers/nvme/target/configfs.c

@@ -586,7 +586,8 @@ static ssize_t nvmet_ns_revalidate_size_store(struct config_item *item,
 		mutex_unlock(&ns->subsys->lock);
 		return -EINVAL;
 	}
-	nvmet_ns_revalidate(ns);
+	if (nvmet_ns_revalidate(ns))
+		nvmet_ns_changed(ns->subsys, ns->nsid);
 	mutex_unlock(&ns->subsys->lock);
 	return count;
 }

drivers/nvme/target/core.c

@@ -531,7 +531,7 @@ static void nvmet_p2pmem_ns_add_p2p(struct nvmet_ctrl *ctrl,
 		ns->nsid);
 }
 
-void nvmet_ns_revalidate(struct nvmet_ns *ns)
+bool nvmet_ns_revalidate(struct nvmet_ns *ns)
 {
 	loff_t oldsize = ns->size;
 
@@ -540,8 +540,7 @@ void nvmet_ns_revalidate(struct nvmet_ns *ns)
 	else
 		nvmet_file_ns_revalidate(ns);
 
-	if (oldsize != ns->size)
-		nvmet_ns_changed(ns->subsys, ns->nsid);
+	return oldsize != ns->size;
 }
 
 int nvmet_ns_enable(struct nvmet_ns *ns)

drivers/nvme/target/nvmet.h

@@ -542,7 +542,7 @@ u16 nvmet_file_flush(struct nvmet_req *req);
 void nvmet_ns_changed(struct nvmet_subsys *subsys, u32 nsid);
 void nvmet_bdev_ns_revalidate(struct nvmet_ns *ns);
 void nvmet_file_ns_revalidate(struct nvmet_ns *ns);
-void nvmet_ns_revalidate(struct nvmet_ns *ns);
+bool nvmet_ns_revalidate(struct nvmet_ns *ns);
 u16 blk_to_nvme_status(struct nvmet_req *req, blk_status_t blk_sts);
 
 bool nvmet_bdev_zns_enable(struct nvmet_ns *ns);

drivers/nvme/target/zns.c

@@ -123,7 +123,11 @@ void nvmet_execute_identify_cns_cs_ns(struct nvmet_req *req)
 		goto done;
 	}
 
-	nvmet_ns_revalidate(req->ns);
+	if (nvmet_ns_revalidate(req->ns)) {
+		mutex_lock(&req->ns->subsys->lock);
+		nvmet_ns_changed(req->ns->subsys, req->ns->nsid);
+		mutex_unlock(&req->ns->subsys->lock);
+	}
 	zsze = (bdev_zone_sectors(req->ns->bdev) << 9) >>
 					req->ns->blksize_shift;
 	id_zns->lbafe[0].zsze = cpu_to_le64(zsze);