[comp.unix.wizards] creeping fsck bug with System V FIFO

cracraft@venera.isi.edu (Stuart Cracraft) (10/25/88)

I have a System V machine; When I do an fsck, it reports
Possible file size error, and then "I=nnnn" where the
inode is named.

When inspected with ncheck, this inode turns out to be
that for /usr/spool/lp/FIFO. If I delete this file and
then run fsck again, I figured it would clean things up.

A half hour later I discovered FIFO was back again and
fsck was getting the same error again.

Any idea what's happening oh great wizards?

	Stuart

asa@unisoft.UUCP (Asa Romberger) (10/26/88)

In article <6607@venera.isi.edu> cracraft@venera.isi.edu (Stuart Cracraft) writes:
>I have a System V machine; When I do an fsck, it reports
>Possible file size error, and then "I=nnnn" where the
>inode is named.
>
>When inspected with ncheck, this inode turns out to be
>that for /usr/spool/lp/FIFO. If I delete this file and
>then run fsck again, I figured it would clean things up.
>
>A half hour later I discovered FIFO was back again and
>fsck was getting the same error again.

1/ /usr/spool/lp/FIFO is created by lp when it runs, if it does not already
   exist. It is a named pipe.
2/ Some versions of fsck for System V do not handle named pipes correctly and
   frequently list them as "Possible file size error".

davidsen@steinmetz.ge.com (William E. Davidsen Jr) (10/28/88)

In article <6607@venera.isi.edu> cracraft@venera.isi.edu (Stuart Cracraft) writes:
| I have a System V machine; When I do an fsck, it reports
| Possible file size error, and then "I=nnnn" where the
| inode is named.

Some versions of fsck report this for a FIFO, and also for a sparse
file, such as some forms of database and core dumps. I'm not sure I've
ever seen a case in which there really was an error with that error
message, but I suppose that there must be SOME case.
-- 
	bill davidsen		(wedu@ge-crd.arpa)
  {uunet | philabs}!steinmetz!crdos1!davidsen
"Stupidity, like virtue, is its own reward" -me

allbery@ncoast.UUCP (Brandon S. Allbery) (11/03/88)

As quoted from <6607@venera.isi.edu> by cracraft@venera.isi.edu (Stuart Cracraft):
+---------------
| When inspected with ncheck, this inode turns out to be
| that for /usr/spool/lp/FIFO. If I delete this file and
| then run fsck again, I figured it would clean things up.
| A half hour later I discovered FIFO was back again and
| fsck was getting the same error again.
+---------------

The only bug here is that fsck doesn't quite know what to do with a FIFO.
/usr/spool/lp/FIFO is part of the spooler system, and is quite normal aside
from fsck's slight brain damage.

However, removing it while the spooler is running is a good way to f*ck up
the spooler.

Recommended treatment:  none.  Ignore the error (my experience is that if
the POSSIBLE FILE SIZE ERROR isn't matched by a later error for the same
inode, it's just a piece of fsck braindamage that can be ignored).  Maybe
complain to whoever ported the UNIX; I've seen System V fsck's which
understand FIFOs and files with holes in them.

++Brandon
-- 
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