[PATCH 1/3] nvme: decouple nvme_ctrl_get_by_path()

[Chaitanya Kulkarni]

Right now nvme_ctrl_get_by_path() accepts ctrl path, based on that it
opens a file and calls nvme_get_ctrl(). In order to take module
refcount it is important to distinguish the error between file_open()
and module file ops check so that we can unwind the code in the caller
nvmet_passthru_ctrl_enable() in the error path.

Rename nvme_ctrl_get_by_path() -> nvme_ctrl_get_by_file() and lift
the file opening and error handling in the caller so that we can unwind
appropriately in the error path.

Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni at wdc.com>
---
 drivers/nvme/host/core.c       | 10 ++--------
 drivers/nvme/host/nvme.h       |  2 +-
 drivers/nvme/target/nvmet.h    |  1 +
 drivers/nvme/target/passthru.c | 17 +++++++++++++----
 4 files changed, 17 insertions(+), 13 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 5702a3843746..fa7c0def9184 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -4641,14 +4641,9 @@ void nvme_sync_queues(struct nvme_ctrl *ctrl)
 }
 EXPORT_SYMBOL_GPL(nvme_sync_queues);
 
-struct nvme_ctrl *nvme_ctrl_get_by_path(const char *path)
+struct nvme_ctrl *nvme_ctrl_get_by_file(struct file *f)
 {
 	struct nvme_ctrl *ctrl;
-	struct file *f;
-
-	f = filp_open(path, O_RDWR, 0);
-	if (IS_ERR(f))
-		return ERR_CAST(f);
 
 	if (f->f_op != &nvme_dev_fops) {
 		ctrl = ERR_PTR(-EINVAL);
@@ -4659,10 +4654,9 @@ struct nvme_ctrl *nvme_ctrl_get_by_path(const char *path)
 	nvme_get_ctrl(ctrl);
 
 out_close:
-	filp_close(f, NULL);
 	return ctrl;
 }
-EXPORT_SYMBOL_NS_GPL(nvme_ctrl_get_by_path, NVME_TARGET_PASSTHRU);
+EXPORT_SYMBOL_NS_GPL(nvme_ctrl_get_by_file, NVME_TARGET_PASSTHRU);
 
 /*
  * Check we didn't inadvertently grow the command structure sizes:
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 2910f6caab7d..590cc880834a 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -836,7 +836,7 @@ static inline void nvme_hwmon_init(struct nvme_ctrl *ctrl) { }
 u32 nvme_command_effects(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
 			 u8 opcode);
 void nvme_execute_passthru_rq(struct request *rq);
-struct nvme_ctrl *nvme_ctrl_get_by_path(const char *path);
+struct nvme_ctrl *nvme_ctrl_get_by_file(struct file *f);
 struct nvme_ns *nvme_find_get_ns(struct nvme_ctrl *ctrl, unsigned nsid);
 void nvme_put_ns(struct nvme_ns *ns);
 
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index 47ee3fb193bd..477439acb8e1 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -248,6 +248,7 @@ struct nvmet_subsys {
 #ifdef CONFIG_NVME_TARGET_PASSTHRU
 	struct nvme_ctrl	*passthru_ctrl;
 	char			*passthru_ctrl_path;
+	struct file             *passthru_ctrl_file;
 	struct config_group	passthru_group;
 #endif /* CONFIG_NVME_TARGET_PASSTHRU */
 };
diff --git a/drivers/nvme/target/passthru.c b/drivers/nvme/target/passthru.c
index 8bd7f656e240..14a842408035 100644
--- a/drivers/nvme/target/passthru.c
+++ b/drivers/nvme/target/passthru.c
@@ -473,6 +473,7 @@ u16 nvmet_parse_passthru_admin_cmd(struct nvmet_req *req)
 
 int nvmet_passthru_ctrl_enable(struct nvmet_subsys *subsys)
 {
+	const char *pt_path = subsys->passthru_ctrl_path;
 	struct nvme_ctrl *ctrl;
 	int ret = -EINVAL;
 	void *old;
@@ -480,7 +481,7 @@ int nvmet_passthru_ctrl_enable(struct nvmet_subsys *subsys)
 	mutex_lock(&subsys->lock);
 	if (!subsys->passthru_ctrl_path)
 		goto out_unlock;
-	if (subsys->passthru_ctrl)
+	if (!pt_path)
 		goto out_unlock;
 
 	if (subsys->nr_namespaces) {
@@ -488,13 +489,18 @@ int nvmet_passthru_ctrl_enable(struct nvmet_subsys *subsys)
 		goto out_unlock;
 	}
 
-	ctrl = nvme_ctrl_get_by_path(subsys->passthru_ctrl_path);
+	subsys->passthru_ctrl_file = filp_open(pt_path, O_RDWR, 0);
+	if (IS_ERR(subsys->passthru_ctrl_file)) {
+		ret = PTR_ERR(subsys->passthru_ctrl_file);
+		goto out_unlock;
+	}
+
+	ctrl = nvme_ctrl_get_by_file(subsys->passthru_ctrl_file);
 	if (IS_ERR(ctrl)) {
 		ret = PTR_ERR(ctrl);
 		pr_err("failed to open nvme controller %s\n",
 		       subsys->passthru_ctrl_path);
-
-		goto out_unlock;
+		goto out_put_file;
 	}
 
 	old = xa_cmpxchg(&passthru_subsystems, ctrl->cntlid, NULL,
@@ -522,6 +528,8 @@ int nvmet_passthru_ctrl_enable(struct nvmet_subsys *subsys)
 
 out_put_ctrl:
 	nvme_put_ctrl(ctrl);
+out_put_file:
+	filp_close(subsys->passthru_ctrl_file, NULL);
 out_unlock:
 	mutex_unlock(&subsys->lock);
 	return ret;
@@ -531,6 +539,7 @@ static void __nvmet_passthru_ctrl_disable(struct nvmet_subsys *subsys)
 {
 	if (subsys->passthru_ctrl) {
 		xa_erase(&passthru_subsystems, subsys->passthru_ctrl->cntlid);
+		filp_close(subsys->passthru_ctrl_file, NULL);
 		nvme_put_ctrl(subsys->passthru_ctrl);
 	}
 	subsys->passthru_ctrl = NULL;
-- 
2.22.1