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From: bad@flatlin.ka.sub.org (Christoph Badura)
Subject: Re: a cache_lookup() question
Organization: Guru Systems/Funware Department
Date: Wed, 1 Sep 1993 23:54:18 GMT
Message-ID: <CCp92J.Fvy@flatlin.ka.sub.org>
References: <2616m7$cpm@acsc.com>
Lines: 16
In <2616m7$cpm@acsc.com> jerry@acsc.com (Jerry Chen) writes:
>I am reading the ufs source code to learn the file system. Here is yet
>another question. When the kernel finds an entry in the name cache,
>and nc_vp is NULL and it is not creating an entry, then it will move
>the entry to the end of the LRU chain. Why? I do not understand.
You've just stumbled over the code that handles the case when a file
is known *not* to exist in a directory. That is an important
optimisation as it allows the code not to scan the whole directory to
see whether a file exists or not.
--
Christoph Badura --- bad@flatlin.ka.sub.org --- +49 721 606137
Personally, I don't care whether someone is cool enough to quote Doug
Gwyn--I only care whether Doug Gwyn is cool enough to quote. -- Larry Wall