From mboxrd@z Thu Jan  1 00:00:00 1970
From: Sonny Rao <sonny@burdell.org>
Subject: Re: mpage writepage question
Date: Thu, 3 Feb 2005 12:10:05 -0500
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Cc: linux-fsdevel@vger.kernel.org, Andrew Morton <akpm@osdl.org>
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To: Badari Pulavarty <pbadari@us.ibm.com>
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On Thu, Feb 03, 2005 at 08:37:19AM -0800, Badari Pulavarty wrote:
> Hi Andrew,
> 
> I was wondering why mpage_writepage() is only "static" ?
> 
> Is the expectation that, filesystems use
> 
> 	.writepage == block_full_write_page
> 	.writepages == mpage_writepages 
> 
> ? I am little confused on why we have 2 different ways to
> do things ? block_full_write_page() seems to be creating
> buffer heads, where as mpage_writepages() can do directly
> bios. Shouldn't they be using mpage_writepage() instead of
> block_full_write_page() ?
> 

I was wondering the same thing too.  

My only guess is that if you keep the buffer_head attached to the
page, then you don't need to call get_block again if you write the
same page back, and I suppose the fs get_block function could be
expensive and/or require I/O. 

Sonny