[PATCH] Add a parameter to set sd driver's probe mode.

[PATCH] Add a parameter to set sd driver's probe mode.

[longguang.yue]

Asynchronous probe leads to the change of disk name, so it is hard
to trace disk by its name for monitoring system.

Signed-off-by: longguang.yue <bigclouds@163.com>
---
 drivers/scsi/sd.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 4bb87043e6db..ea0ac8823599 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -99,6 +99,11 @@ MODULE_ALIAS_SCSI_DEVICE(TYPE_ZBC);
 
 #define SD_MINORS	16
 
+static unsigned int async = PROBE_PREFER_ASYNCHRONOUS;
+module_param(async, uint, 0644);
+MODULE_PARM_DESC(async,
+		 "probe scsi disk asynchronously or not. Default is 1 asynchronous.");
+
 static void sd_config_discard(struct scsi_disk *, unsigned int);
 static void sd_config_write_same(struct scsi_disk *);
 static int  sd_revalidate_disk(struct gendisk *);
@@ -3839,6 +3844,9 @@ static int __init init_sd(void)
 
 	SCSI_LOG_HLQUEUE(3, printk("init_sd: sd driver entry point\n"));
 
+	if (async != PROBE_PREFER_ASYNCHRONOUS)
+		sd_template.gendrv.probe_type = PROBE_FORCE_SYNCHRONOUS;
+
 	for (i = 0; i < SD_MAJORS; i++) {
 		if (__register_blkdev(sd_major(i), "sd", sd_default_probe))
 			continue;
-- 
2.34.1

Re: [PATCH] Add a parameter to set sd driver's probe mode.

[James Bottomley]

On Tue, 2023-04-25 at 15:59 +0800, longguang.yue wrote:
> Asynchronous probe leads to the change of disk name, so it is hard
> to trace disk by its name for monitoring system.

This won't work: just not doing async sd attach doesn't fix all the
other causes of asynchronicity that cause sd names to change. You need
to look at addressing disks by one of the permanent /dev/disk/by-*
device files.

James