Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!utgpu!water!watmath!clyde!burl!codas!killer!jfh
From: jfh@killer.UUCP
Newsgroups: comp.sys.att,comp.unix.wizards
Subject: Re: Wierd 3b inode problem with news.
Message-ID: <2043@killer.UUCP>
Date: Mon, 9-Nov-87 12:48:00 EST
Article-I.D.: killer.2043
Posted: Mon Nov  9 12:48:00 1987
Date-Received: Thu, 12-Nov-87 03:43:09 EST
References: <283@paisano.UUCP> <4259@sdcsvax.UCSD.EDU> <355@minya.UUCP> <33319@sun.uucp>
Organization: Big "D" Home for Wayward Hackers
Lines: 26
Keywords: 3b2 inode file system
Xref: utgpu comp.sys.att:1477 comp.unix.wizards:5014
Summary: Correction ...

In article <33319@sun.uucp>, guy@gorodish.Sun.COM (Guy Harris) writes:
> > But in Sys/V, free inodes are also in a linked list, so the
> > kernel is dependent on inodes being freed properly.
> 
> In the V7 file system, which is used by S5, free inodes are not in any sort of
> linked list.  There is a cache in the superblock that saves the i-numbers of a
> small number of free inodes.  If this cache is emptied, the system has to make
> a linear search through the i-list looking for an inode with a mode word of
> zero.

> 	Guy Harris

Guy - the difference between Version 7 and later versions ( > System III )
is the free inode count is maintained in the superblock.  In Version 7 the
free inode count, which I seem to remember had an entry in the superblock,
was not updated.  So, when an I-node was allocated, the kernel had to search
the entire I-list for a free inode (assuming the superblock cache was empty)
without knowing if an I-node would be found.  Now, the kernel `knows' how
many free inodes are out there without even looking.

- John.
-- 
John F. Haugh II		HECI Exploration Co. Inc.
UUCP:	...!ihnp4!killer!jfh	11910 Greenville Ave, Suite 600
"Don't Have an Oil Well?"	Dallas, TX. 75243
" ... Then Buy One!"		(214) 231-0993