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Date: Fri, 9 Jan 1998 01:40:29 -0500 (EST)
From: "Christopher T. Johnson" <cjohnson@neunacht.netgsi.com>
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Subject: kern/5467: unlink() leaves unrefed files on file sytem
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>Number:         5467
>Category:       kern
>Synopsis:       unlink() leaves unrefed files on file sytem
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    freebsd-bugs
>State:          open
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu Jan  8 22:40:01 PST 1998
>Last-Modified:
>Originator:     Christopher T. Johnson
>Organization:
NetGSI, Inc
>Release:        FreeBSD 3.0-CURRENT i386
>Environment:
FreeBSD-CURRENT as of a CVSUP around Dec 28th.
	

>Description:
When a file has been mmap()ed, and then is unlinked, it seems that even
when the file is munmap()ed, the inode is not cleared.

This problem was noticed when /var, a 300Mb filesystem, suddenly started
running out of space.

We run a perl script that uses a C program to analyse files and then unlink
files that the program rejects (with databasing added).  The processing
sequence is:
	perl script discovers a file to analyis.
	perl script sends file name to C program over an unamed pipe.
	C program uses mmap() to access the file.
	C program analysises the file
	C program sends result to perl script
	perl script unlinks file if file is unwanted
LOOP:
	perl script finds next file
	perl script send file name to C program
	C program uses munmap() to release previous file
	C program uses mmap() to access the new file
	C program send result to perl script
	perl script unlinks file if file is unwanted
	GOTO LOOP

>How-To-Repeat:

	

>Fix:
	
	

>Audit-Trail:
>Unformatted: