NVMe: Allow user initiated rescan

This exposes ioctl and sysfs methods a user can invoke to request the
driver rescan a controller and its namespaces. This is less harsh than
doing a controller reset, which temporarilly halts all IO, just to
surface a newly attached namespace.

This is mainly useful for controllers that implement the namespace
management command, but do not support the namespace notify change
asynchronous event notification.

Signed-off-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 2de248bd462b96c1469905d906efa9c6679c5d0b..acc05adaa0d4566ac82dd1c18a5e47aa223957ea 100644 (file)
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1212,6 +1212,9 @@ static long nvme_dev_ioctl(struct file *file, unsigned int cmd,
                return ctrl->ops->reset_ctrl(ctrl);
        case NVME_IOCTL_SUBSYS_RESET:
                return nvme_reset_subsystem(ctrl);
+       case NVME_IOCTL_RESCAN:
+               nvme_queue_scan(ctrl);
+               return 0;
        default:
                return -ENOTTY;
        }
@@ -1239,6 +1242,17 @@ static ssize_t nvme_sysfs_reset(struct device *dev,
 }
 static DEVICE_ATTR(reset_controller, S_IWUSR, NULL, nvme_sysfs_reset);
 
+static ssize_t nvme_sysfs_rescan(struct device *dev,
+                               struct device_attribute *attr, const char *buf,
+                               size_t count)
+{
+       struct nvme_ctrl *ctrl = dev_get_drvdata(dev);
+
+       nvme_queue_scan(ctrl);
+       return count;
+}
+static DEVICE_ATTR(rescan_controller, S_IWUSR, NULL, nvme_sysfs_rescan);
+
 static ssize_t wwid_show(struct device *dev, struct device_attribute *attr,
                                                                char *buf)
 {
@@ -1342,6 +1356,7 @@ nvme_show_int_function(cntlid);
 
 static struct attribute *nvme_dev_attrs[] = {
        &dev_attr_reset_controller.attr,
+       &dev_attr_rescan_controller.attr,
        &dev_attr_model.attr,
        &dev_attr_serial.attr,
        &dev_attr_firmware_rev.attr,

diff --git a/include/uapi/linux/nvme_ioctl.h b/include/uapi/linux/nvme_ioctl.h
index c4b2a3f90829328434b80bd369f635eac5d62674..50ff21f748b6fed290490573e924f0539e79e85e 100644 (file)
--- a/include/uapi/linux/nvme_ioctl.h
+++ b/include/uapi/linux/nvme_ioctl.h
@@ -61,5 +61,6 @@ struct nvme_passthru_cmd {
 #define NVME_IOCTL_IO_CMD      _IOWR('N', 0x43, struct nvme_passthru_cmd)
 #define NVME_IOCTL_RESET       _IO('N', 0x44)
 #define NVME_IOCTL_SUBSYS_RESET        _IO('N', 0x45)
+#define NVME_IOCTL_RESCAN      _IO('N', 0x46)
 
 #endif /* _UAPI_LINUX_NVME_IOCTL_H */