kern/38991: "rm -rf" fails with EBUSY

[apb%cequrux.com@localhost]

>Number:         38991
>Category:       kern
>Synopsis:       "rm -rf" fails with EBUSY
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Jun 19 17:35:00 +0000 2008
>Originator:     Alan Barrett
>Release:        NetBSD 4.99.63
>Organization:
Not much
>Environment:
System: NetBSD 4.99.63
Architecture: i386
Machine: i386
>Description:
        Attempting to delete a large directory tree often fails.

        I have seen this problem with both an ffs file system and an
        msdos file system.  The file systems were mounted from external
        USB disks in both cases.  I have not tried to replicate the
        problem on an internal "wd' disk.

        The problem appears even when the file system is otherwise idle
        (the "rm -rf" process is the only thing touching the disk in
        question).

>How-To-Repeat:

        $ mount -t ffs /dev/sd0e /mnt
        $ cd /mnt/backups
        $ sudo rm -rf 20070824
        [ see many messages similar to the following: ]
        rm: 20070824/home/apb/netbsd/current/xsrc/Makefile: Device busy
        rm: 20070824/home/apb/netbsd/current/xsrc/CVS: Device busy
        rm: 20070824/home/apb/netbsd/current/xsrc/dist: Device busy
        rm: 20070824/home/apb/netbsd/current/xsrc/local: Device busy
        rm: 20070824/home/apb/netbsd/current/xsrc/xfree: Device busy
        rm: 20070824/home/apb/netbsd/current/xsrc/xorg: Device busy
        rm: 20070824/home/apb/netbsd/current/xsrc: Directory not empty

>Fix:
        Unknown