nvmet: make ver stable once connection established

Once some host has connected to the nvmf target, make sure that the
version number is stable and cannot be changed.

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

diff --git a/drivers/nvme/target/configfs.c b/drivers/nvme/target/configfs.c
index 9ef8708..2735551 100644 (file)
--- a/drivers/nvme/target/configfs.c
+++ b/drivers/nvme/target/configfs.c
@@ -1007,13 +1007,26 @@ static ssize_t nvmet_subsys_attr_version_show(struct config_item *item,
                        NVME_MINOR(subsys->ver));
 }
 
-static ssize_t nvmet_subsys_attr_version_store(struct config_item *item,
-                                              const char *page, size_t count)
+static ssize_t
+nvmet_subsys_attr_version_store_locked(struct nvmet_subsys *subsys,
+               const char *page, size_t count)
 {
-       struct nvmet_subsys *subsys = to_subsys(item);
        int major, minor, tertiary = 0;
        int ret;
 
+       if (subsys->subsys_discovered) {
+               if (NVME_TERTIARY(subsys->ver))
+                       pr_err("Can't set version number. %llu.%llu.%llu is already assigned\n",
+                              NVME_MAJOR(subsys->ver),
+                              NVME_MINOR(subsys->ver),
+                              NVME_TERTIARY(subsys->ver));
+               else
+                       pr_err("Can't set version number. %llu.%llu is already assigned\n",
+                              NVME_MAJOR(subsys->ver),
+                              NVME_MINOR(subsys->ver));
+               return -EINVAL;
+       }
+
        /* passthru subsystems use the underlying controller's version */
        if (nvmet_passthru_ctrl(subsys))
                return -EINVAL;
@@ -1022,12 +1035,25 @@ static ssize_t nvmet_subsys_attr_version_store(struct config_item *item,
        if (ret != 2 && ret != 3)
                return -EINVAL;
 
-       down_write(&nvmet_config_sem);
        subsys->ver = NVME_VS(major, minor, tertiary);
-       up_write(&nvmet_config_sem);
 
        return count;
 }
+
+static ssize_t nvmet_subsys_attr_version_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);
+       ret = nvmet_subsys_attr_version_store_locked(subsys, page, count);
+       mutex_unlock(&subsys->lock);
+       up_write(&nvmet_config_sem);
+
+       return ret;
+}
 CONFIGFS_ATTR(nvmet_subsys_, attr_version);
 
 /* See Section 1.5 of NVMe 1.4 */