Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!haven!mimsy!chris
From: chris@mimsy.umd.edu (Chris Torek)
Newsgroups: comp.unix.wizards
Subject: Re: Re^2: 4BSD file system structure
Message-ID: <20895@mimsy.umd.edu>
Date: 23 Nov 89 18:05:52 GMT
References: <1727@neon.siesoft.co.uk> <20893@mimsy.umd.edu>
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 17

In article I wrote:
>The things *in* ip->i_db[i] are in terms of fragments.

Aack!  They are in terms of DEV_BSIZE (512, on the VAX; 1024 on the
Tahoe) byte blocks.

>More specifically, on an 8k/1k file system, if you want to find
>the set of 1024-byte disk `blocks' that contain bytes 8192..16383
>of a given file, you look at ip->i_db[1].  If this contains the
>number 2000, those bytes are in the eight consecutive 1024-byte
>fragments numbered 2000, 2001, 2002, ..., 2007.

You would see 4000, and use blocks 4000, 4002, 4004, ..., 4014.
(Or you could see 2000, and use 2000, 2002, 2004, ..., 2014.)
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris@cs.umd.edu	Path:	uunet!mimsy!chris