nvmet: model_number must be immutable once set

In case we have already established connection to nvmf target, it
shouldn't be allowed to change the model_number. E.g. if someone will
identify ctrl and get model_number of "my_model" later on will change
the model_numbel via configfs to "my_new_model" this will break the NVMe
specification for "Get Log Page – Persistent Event Log" that refers to
Model Number as: "This field contains the same value as reported in the
Model Number field of the Identify Controller data structure, bytes
63:24."

Although it doesn't mentioned explicitly that this field can't be
changed, we can assume it.

So allow setting this field only once: using configfs or in the first
identify ctrl operation.

Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

diff --git a/drivers/nvme/target/admin-cmd.c b/drivers/nvme/target/admin-cmd.c
index bc6a774..fe6b8aa 100644 (file)
--- a/drivers/nvme/target/admin-cmd.c
+++ b/drivers/nvme/target/admin-cmd.c
@@ -313,27 +313,40 @@ static void nvmet_execute_get_log_page(struct nvmet_req *req)
        nvmet_req_complete(req, NVME_SC_INVALID_FIELD | NVME_SC_DNR);
 }
 
-static void nvmet_id_set_model_number(struct nvme_id_ctrl *id,
-                                     struct nvmet_subsys *subsys)
+static u16 nvmet_set_model_number(struct nvmet_subsys *subsys)
 {
-       const char *model = NVMET_DEFAULT_CTRL_MODEL;
-       struct nvmet_subsys_model *subsys_model;
+       u16 status = 0;
+
+       mutex_lock(&subsys->lock);
+       if (!subsys->model_number) {
+               subsys->model_number =
+                       kstrdup(NVMET_DEFAULT_CTRL_MODEL, GFP_KERNEL);
+               if (!subsys->model_number)
+                       status = NVME_SC_INTERNAL;
+       }
+       mutex_unlock(&subsys->lock);
 
-       rcu_read_lock();
-       subsys_model = rcu_dereference(subsys->model);
-       if (subsys_model)
-               model = subsys_model->number;
-       memcpy_and_pad(id->mn, sizeof(id->mn), model, strlen(model), ' ');
-       rcu_read_unlock();
+       return status;
 }
 
 static void nvmet_execute_identify_ctrl(struct nvmet_req *req)
 {
        struct nvmet_ctrl *ctrl = req->sq->ctrl;
+       struct nvmet_subsys *subsys = ctrl->subsys;
        struct nvme_id_ctrl *id;
        u32 cmd_capsule_size;
        u16 status = 0;
 
+       /*
+        * If there is no model number yet, set it now.  It will then remain
+        * stable for the life time of the subsystem.
+        */
+       if (!subsys->model_number) {
+               status = nvmet_set_model_number(subsys);
+               if (status)
+                       goto out;
+       }
+
        id = kzalloc(sizeof(*id), GFP_KERNEL);
        if (!id) {
                status = NVME_SC_INTERNAL;
@@ -347,7 +360,8 @@ static void nvmet_execute_identify_ctrl(struct nvmet_req *req)
        memset(id->sn, ' ', sizeof(id->sn));
        bin2hex(id->sn, &ctrl->subsys->serial,
                min(sizeof(ctrl->subsys->serial), sizeof(id->sn) / 2));
-       nvmet_id_set_model_number(id, ctrl->subsys);
+       memcpy_and_pad(id->mn, sizeof(id->mn), subsys->model_number,
+                      strlen(subsys->model_number), ' ');
        memcpy_and_pad(id->fr, sizeof(id->fr),
                       UTS_RELEASE, strlen(UTS_RELEASE), ' ');
 

diff --git a/drivers/nvme/target/configfs.c b/drivers/nvme/target/configfs.c
index 635a7cb..e5dbd19 100644 (file)
--- a/drivers/nvme/target/configfs.c
+++ b/drivers/nvme/target/configfs.c
@@ -1118,16 +1118,12 @@ static ssize_t nvmet_subsys_attr_model_show(struct config_item *item,
                                            char *page)
 {
        struct nvmet_subsys *subsys = to_subsys(item);
-       struct nvmet_subsys_model *subsys_model;
-       char *model = NVMET_DEFAULT_CTRL_MODEL;
        int ret;
 
-       rcu_read_lock();
-       subsys_model = rcu_dereference(subsys->model);
-       if (subsys_model)
-               model = subsys_model->number;
-       ret = snprintf(page, PAGE_SIZE, "%s\n", model);
-       rcu_read_unlock();
+       mutex_lock(&subsys->lock);
+       ret = snprintf(page, PAGE_SIZE, "%s\n", subsys->model_number ?
+                       subsys->model_number : NVMET_DEFAULT_CTRL_MODEL);
+       mutex_unlock(&subsys->lock);
 
        return ret;
 }
@@ -1138,14 +1134,17 @@ static bool nvmet_is_ascii(const char c)
        return c >= 0x20 && c <= 0x7e;
 }
 
-static ssize_t nvmet_subsys_attr_model_store(struct config_item *item,
-                                            const char *page, size_t count)
+static ssize_t nvmet_subsys_attr_model_store_locked(struct nvmet_subsys *subsys,
+               const char *page, size_t count)
 {
-       struct nvmet_subsys *subsys = to_subsys(item);
-       struct nvmet_subsys_model *new_model;
-       char *new_model_number;
        int pos = 0, len;
 
+       if (subsys->model_number) {
+               pr_err("Can't set model number. %s is already assigned\n",
+                      subsys->model_number);
+               return -EINVAL;
+       }
+
        len = strcspn(page, "\n");
        if (!len)
                return -EINVAL;
@@ -1155,28 +1154,25 @@ static ssize_t nvmet_subsys_attr_model_store(struct config_item *item,
                        return -EINVAL;
        }
 
-       new_model_number = kmemdup_nul(page, len, GFP_KERNEL);
-       if (!new_model_number)
+       subsys->model_number = kmemdup_nul(page, len, GFP_KERNEL);
+       if (!subsys->model_number)
                return -ENOMEM;
+       return count;
+}
 
-       new_model = kzalloc(sizeof(*new_model) + len + 1, GFP_KERNEL);
-       if (!new_model) {
-               kfree(new_model_number);
-               return -ENOMEM;
-       }
-       memcpy(new_model->number, new_model_number, len);
+static ssize_t nvmet_subsys_attr_model_store(struct config_item *item,
+                                            const char *page, size_t count)
+{
+       struct nvmet_subsys *subsys = to_subsys(item);
+       ssize_t ret;
 
        down_write(&nvmet_config_sem);
        mutex_lock(&subsys->lock);
-       new_model = rcu_replace_pointer(subsys->model, new_model,
-                                       mutex_is_locked(&subsys->lock));
+       ret = nvmet_subsys_attr_model_store_locked(subsys, page, count);
        mutex_unlock(&subsys->lock);
        up_write(&nvmet_config_sem);
 
-       kfree_rcu(new_model, rcuhead);
-       kfree(new_model_number);
-
-       return count;
+       return ret;
 }
 CONFIGFS_ATTR(nvmet_subsys_, attr_model);
 

diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index 67bbf0e..be6fcda 100644 (file)
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -1532,7 +1532,7 @@ static void nvmet_subsys_free(struct kref *ref)
        nvmet_passthru_subsys_free(subsys);
 
        kfree(subsys->subsysnqn);
-       kfree_rcu(subsys->model, rcuhead);
+       kfree(subsys->model_number);
        kfree(subsys);
 }
 

diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index cdfa537..4b84edb 100644 (file)
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -208,11 +208,6 @@ struct nvmet_ctrl {
        bool                    pi_support;
 };
 
-struct nvmet_subsys_model {
-       struct rcu_head         rcuhead;
-       char                    number[];
-};
-
 struct nvmet_subsys {
        enum nvme_subsys_type   type;
 
@@ -242,7 +237,7 @@ struct nvmet_subsys {
        struct config_group     namespaces_group;
        struct config_group     allowed_hosts_group;
 
-       struct nvmet_subsys_model       __rcu *model;
+       char                    *model_number;
 
 #ifdef CONFIG_NVME_TARGET_PASSTHRU
        struct nvme_ctrl        *passthru_ctrl;