kern/111262: unionfs fills up the underlaying layer (df)

[Harald Schmalzbauer]

>Number:         111262
>Category:       kern
>Synopsis:       unionfs fills up the underlaying layer (df)
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu Apr 05 09:20:03 GMT 2007
>Closed-Date:
>Last-Modified:
>Originator:     Harald Schmalzbauer
>Release:        FreeBSD 6.2-STABLE i386
>Organization:
>Environment:
System: FreeBSD titan.flintsbach.schmalzbauer.de 6.2-STABLE FreeBSD 6.2-STABLE #0: Thu Apr 5 09:48:05 CEST 2007 compilator at titan.flintsbach.schmalzbauer.de:/usr/obj/usr/src/sys/TITAN i386


	
>Description:
	The rewritten unionfs implementation doesn't sync the used space with
	the underlaying layer. It occupies space but doesn't free it after
	the file written to the above layer has been deleted.
>How-To-Repeat:
	mkdir /testunion
	mount_unionfs -o copymode=transparent /var /testunion
	dd if=/dev/zero of=/testunion/testfile bs=16k count=10k
	Now you should see the occupied space with df (depending on the
	size of your var)
	After removing /testunion/testfile df still shows the same usage.
	Only umounting /testunion corrects the /var usage!!
>Fix:

	


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