From mboxrd@z Thu Jan  1 00:00:00 1970
From: newsham@lava.net (Tim Newsham)
Date: Thu, 1 May 2008 16:45:22 -1000 (HST)
Subject: [Unix-jun72] Anyone working on V1 mkfs?
In-Reply-To: <20080502023122.GA82050@minnie.tuhs.org>
References: <20080501234225.GA77327@minnie.tuhs.org> <5372.1209688415@mini>
	<20080502005808.GA79200@minnie.tuhs.org>
	<20080502023122.GA82050@minnie.tuhs.org>
Message-ID: <Pine.BSI.4.64.0805011642080.20114@malasada.lava.net>

>  a) the i-mode bitmap is missing bits 0 to 40, but

    The first bit is for i-number 41, yes.
    if(n >= 41) then to check if i-number n is allocated:
        map[(n-41)/8] & (1 << ((n-41)%8)

    if I read the bit ordering correctly.

>  b) the actual i-nodes 0 to 40 do exist, and

    Almost, there is no i-number 0.  The first one is i-number 1 which
    starts at byte zero of block 2.

       inode-block(n) = (n+31)/16
       inode-offset(n) = 32 * ((n+31)%16)

>  c) the system can still "read i-node 7", even if it can't allocate i-node 7.

    sounds like it.

> Let me know if that sounds right, or if I'm off-base somewhere.

Sounds like you got it, except for the i-numbering starting at 1.

> 	Warren

Tim Newsham
http://www.thenewsh.com/~newsham/