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Date: Thu, 9 Nov 2000 23:00:22 +0100 (CET)
From: Jimmy <olgeni@uli.it>
To: FreeBSD-gnats-submit@freebsd.org
Subject: kern/22726: mkfifo can cause ext2fs to break sync at shutdown
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>Number:         22726
>Category:       kern
>Synopsis:       mkfifo can cause ext2fs to break sync at shutdown
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu Nov 09 14:10:00 PST 2000
>Closed-Date:
>Last-Modified:
>Originator:     Jimmy Olgeni
>Release:        FreeBSD 4.2-BETA i386
>Organization:
Colby
>Environment:

FreeBSD 4.2-BETA (recent cvsup)

>Description:

Running mkfifo on a mounted ext2 filesystem (removable media) can
cause the sync at shutdown time to fail. Filesystems are not umounted
and checked by fsck at the next reboot.

>How-To-Repeat:

* Create an ext2fs partition on a removable media (I tried with a SCSI
  MO drive)

* Mount the partition, run "mkfifo SOMEFIFO" on the mounted
  filesystem.

* Run "sync" just to be sure, and umount the partition. sysstat will report
  that there are 0 dirty buffers.

* Eject the media (the drive becomes unlocked at umount time and allows eject). 

* Run "shutdown -h now", the kernel will try to write on the removed media
  (even after umount) and will complain about the missing disk. The "syncing
  disks" sequence will fail and the system will shut down with some buffers
  not committed. At the next reboot the other filesystems will be checked by
  fsck. ext2fs must be repaired on Linux: e2fsck will complain about "bitmap
  differences".

>Fix:

Running shutdown with the media still in the drive helps, but I didn't
try to insert a different disk and see what gets written.


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


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