linux-kernel - Re: [rfc][patch 3/3] fs: convert ext2,tmpfs to new truncate

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Date:	Tue, 7 Jul 2009 15:30:14 +0200
From:	Nick Piggin <npiggin@...e.de>
To:	Boaz Harrosh <bharrosh@...asas.com>
Cc:	linux-fsdevel@...r.kernel.org,
	Christoph Hellwig <hch@...radead.org>, Jan Kara <jack@...e.cz>,
	LKML <linux-kernel@...r.kernel.org>, linux-mm@...ck.org
Subject: Re: [rfc][patch 3/3] fs: convert ext2,tmpfs to new truncate

On Tue, Jul 07, 2009 at 02:45:29PM +0300, Boaz Harrosh wrote:
> On 07/06/2009 07:56 PM, Nick Piggin wrote:
> > Convert filemap_xip.c, buffer.c, and some filesystems to the new truncate
> > convention. Converting generic helpers is using some ugly code (testing
> > for i_op->ftruncate) to distinguish new and old callers... better
> > alternative might be just define a new function for these guys.
> > @@ -770,13 +793,22 @@ ext2_nobh_write_begin(struct file *file,
> >  		loff_t pos, unsigned len, unsigned flags,
> >  		struct page **pagep, void **fsdata)
> >  {
> > +	int ret;
> > +
> >  	/*
> >  	 * Dir-in-pagecache still uses ext2_write_begin. Would have to rework
> >  	 * directory handling code to pass around offsets rather than struct
> >  	 * pages in order to make this work easily.
> >  	 */
> > -	return nobh_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
> > +	ret = nobh_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
> >  							ext2_get_block);
> > +	if (ret < 0) {
> > +		loff_t isize;
> > +		isize = i_size_read(inode);
> 
> Unlike the other places you use i_size_read() here, please explain what is the
> locking rules for this?
> 
> Did your patchset change things in this regard?

i_mutex should protect i_size. I was doing a bit of cutting and pasting
so it probably isn't perfect. I'll double check.


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