Date: Wed, 19 Oct 2005 13:00:10 -0700
From: Andrew Morton <akpm@osdl.org>
To: Badari Pulavarty <pbadari@gmail.com>
Cc: uszhaoxin@gmail.com, linux-kernel@vger.kernel.org
Subject: Re: Is ext3 flush data to disk when files are closed?
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Badari Pulavarty <pbadari@gmail.com> wrote:
>
> On Wed, 2005-10-19 at 11:31 -0400, Xin Zhao wrote:
> > As far as I know, if an application modifies a file on an ext3 file
> > ssytem, it actually change the page cache, and the dirty pages will be
> > flushed to disk by kupdate periodically.
> > 
> > My question is: if a file is to be closed, but some of its data pages
> > are marked as dirty, will system block on close() and wait for dirty
> > pages being flushed to disk? If so, it seems to decrease performance
> > significantly if a lot of updates on many small files are involved.
> > 
> > Can someone point me to the right place to check how it works? Thanks!
> 
> On the last close() of the file, it should be flushed through ..
> 
> 	iput_final() -> generic_drop_inode() -> write_inode_now()
> 		-> __writeback_single_inode() -> __sync_single_inode()
> 			-> do_writepages()

The dcache's reference to the inode will prevent this from happening at
close() time.

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