Public bug reported:

Redhat just fixed a bug:
https://bugzilla.redhat.com/show_bug.cgi?id=2140017
This bug complains that disk orders maybe unpredictable since 5.3. 
It also affects SUSE:
https://www.suse.com/support/kb/doc/?id=000018449

I checked the latest code of ubuntu. It is identical to the buggy code.
Please check whether it affects ubuntu.

Redhat proposes the following patch:

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
--- a/drivers/scsi/sd.c (revision 71a96fee20fe50b7c204e4ed57653dafa6dfa3fd)
+++ b/drivers/scsi/sd.c (revision 32ab33b828ef7b77647c69cf192ca42d9f6566e9)
@@ -122,6 +122,14 @@
        "write back, no read (daft)"
 };
 
+static const char *sd_probe_types[] = { "async", "sync" };
+
+static char sd_probe_type[6] = "async";
+module_param_string(probe, sd_probe_type, sizeof(sd_probe_type),
+                   S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(probe, "async or sync. Setting to 'sync' disables 
asynchronous "
+                "device number assignments (sda, sdb, ...).");
+
 static void sd_set_flush_flag(struct scsi_disk *sdkp,
                struct queue_limits *lim)
 {
@@ -4349,6 +4357,8 @@
                goto err_out_class;
        }
 
+       if (!strcmp(sd_probe_type, "sync"))
+               sd_template.gendrv.probe_type = PROBE_FORCE_SYNCHRONOUS;
        err = scsi_register_driver(&sd_template.gendrv);
        if (err)
                goto err_out_driver;

However, the upstream linux developers have different opinions and have
not accepted this patch. Maybe ubuntu can propose a better solution?

** Affects: linux (Ubuntu)
     Importance: Undecided
         Status: New

-- 
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https://bugs.launchpad.net/bugs/2091137

Title:
  need kernel parameter to keep disk order consistent

Status in linux package in Ubuntu:
  New

Bug description:
  Redhat just fixed a bug:
  https://bugzilla.redhat.com/show_bug.cgi?id=2140017
  This bug complains that disk orders maybe unpredictable since 5.3. 
  It also affects SUSE:
  https://www.suse.com/support/kb/doc/?id=000018449

  I checked the latest code of ubuntu. It is identical to the buggy
  code. Please check whether it affects ubuntu.

  Redhat proposes the following patch:

  diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
  --- a/drivers/scsi/sd.c       (revision 
71a96fee20fe50b7c204e4ed57653dafa6dfa3fd)
  +++ b/drivers/scsi/sd.c       (revision 
32ab33b828ef7b77647c69cf192ca42d9f6566e9)
  @@ -122,6 +122,14 @@
        "write back, no read (daft)"
   };
   
  +static const char *sd_probe_types[] = { "async", "sync" };
  +
  +static char sd_probe_type[6] = "async";
  +module_param_string(probe, sd_probe_type, sizeof(sd_probe_type),
  +                 S_IRUGO|S_IWUSR);
  +MODULE_PARM_DESC(probe, "async or sync. Setting to 'sync' disables 
asynchronous "
  +              "device number assignments (sda, sdb, ...).");
  +
   static void sd_set_flush_flag(struct scsi_disk *sdkp,
                struct queue_limits *lim)
   {
  @@ -4349,6 +4357,8 @@
                goto err_out_class;
        }
   
  +     if (!strcmp(sd_probe_type, "sync"))
  +             sd_template.gendrv.probe_type = PROBE_FORCE_SYNCHRONOUS;
        err = scsi_register_driver(&sd_template.gendrv);
        if (err)
                goto err_out_driver;

  However, the upstream linux developers have different opinions and
  have not accepted this patch. Maybe ubuntu can propose a better
  solution?

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2091137/+subscriptions


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