scsi: scsi_debug: Create scsi_debug directory in the debugfs filesystem

Create directory scsi_debug in the root of the debugfs filesystem.  Prepare
to add interface for manage error injection.
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Wenchao Hao <haowenchao2@huawei.com>
Link: https://lore.kernel.org/r/20231010092051.608007-2-haowenchao2@huawei.comSigned-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/scsi_debug.c

@@ -41,6 +41,7 @@
 #include <linux/random.h>
 #include <linux/xarray.h>
 #include <linux/prefetch.h>
+#include <linux/debugfs.h>
 
 #include <net/checksum.h>
 
@@ -862,6 +863,8 @@ static const int device_qfull_result =
 
 static const int condition_met_result = SAM_STAT_CONDITION_MET;
 
+static struct dentry *sdebug_debugfs_root;
+
 
 /* Only do the extra work involved in logical block provisioning if one or
  * more of the lbpu, lbpws or lbpws10 parameters are given and we are doing
@@ -7011,6 +7014,10 @@ static int __init scsi_debug_init(void)
 		goto driver_unreg;
 	}
 
+	sdebug_debugfs_root = debugfs_create_dir("scsi_debug", NULL);
+	if (IS_ERR_OR_NULL(sdebug_debugfs_root))
+		pr_info("%s: failed to create initial debugfs directory\n", __func__);
+
 	for (k = 0; k < hosts_to_add; k++) {
 		if (want_store && k == 0) {
 			ret = sdebug_add_host_helper(idx);
@@ -7057,6 +7064,7 @@ static void __exit scsi_debug_exit(void)
 
 	sdebug_erase_all_stores(false);
 	xa_destroy(per_store_ap);
+	debugfs_remove(sdebug_debugfs_root);
 }
 
 device_initcall(scsi_debug_init);