Re: Re: block allocation in ext2fs

From: Gabriel Benhanokh (gabriel@SANgate.com)
Date: Tue May 09 2000 - 14:09:28 EST


>
> hi
> very true i missed out a few more details , the buffer block after
> being marked uptodate is also required to wake up any process sleeping on
> its wait queue this is done by execution of b_end_io function in the
> buffer head (ll_rw_blk) but this is all done only when the buffer block
> has been flushed by bdflush or sync command line(this generates request
> for the under laying disk driver by make_request) and successfully written
> on the disk.
> a very simple solution for your problem can be one of these
> 1. you don't allow your buffer block to be ever processed by ll_rw_blk
> function hence always mark it uptodate , wake up all waiting process and
> not dirty
how do i do this?
will maring the buffer clean and than calling bforget won't do this ?

> 2. you trap the request call at disk driver level(this is fairly easy) and
> don't allow the block to be written but call end_request(1)(this does
> everything for you) without executing the real request function of the
> disk driver thus data is never written
i think that this will only help not to do the disk io, but won't avoid the
cache wiping problem. i will still be using too many un-nessceary cache
buffers.
and beside for this i must change the driver which i don't want.
i'm trying to just add another module without changing any other stuff.

THX
/gaby

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