amd64/167066: ZVOLs not appearing in /dev/zvol

[Aldo]

>Number:         167066
>Category:       amd64
>Synopsis:       ZVOLs not appearing in /dev/zvol
>Confidential:   no
>Severity:       serious
>Priority:       low
>Responsible:    freebsd-amd64
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Wed Apr 18 16:30:03 UTC 2012
>Closed-Date:
>Last-Modified:
>Originator:     Aldo
>Release:        9.0-RELEASE FreeBSD 9.0-RELEASE #0
>Organization:
>Environment:
FreeBSD -snip- 9.0-RELEASE FreeBSD 9.0-RELEASE #0: Tue Jan 3 07:46:30 UTC 2012 root at farrell.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC amd64

>Description:
I do 
zfs send -I mypool/iscsi0 at 20120415 mypool/iscsi0 at 20120416 | ssh root at bckserver zfs receive -v cloned/iscsi0

from my machine where the iscsi0 zvol is backing an iscsi target.
The receiving machine gets it, it appears in "zfs list" but no correspoinding device is created in /dev/zvol. If I reboot the machine the device appears and works ok.
If I create a new zvol on the receiving machine, the device appears.
Only zfs received zvols do not appear.

Also, zfs rollback cloned at iscsi0@mysnap never returns the prompt. Top says zfs is stuck in STOP state. After a reboot the command succedes.

Using v28 pool upgraded froma v15 created on OpenSolaris.
>How-To-Repeat:
Send a zvol from from machine A to machine B.
>Fix:
Reboot the server

>Release-Note:
>Audit-Trail:
>Unformatted: