Date: Fri, 18 Jan 2008 10:43:35 -0800 (PST)
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Miklos Szeredi <miklos@szeredi.hu>
cc: peterz@infradead.org, salikhmetov@gmail.com, linux-mm@kvack.org,
       jakob@unthought.net, linux-kernel@vger.kernel.org,
       valdis.kletnieks@vt.edu, riel@redhat.com, ksm@42.dk,
       staubach@redhat.com, jesper.juhl@gmail.com, akpm@linux-foundation.org,
       protasnb@gmail.com, r.e.wolff@bitwizard.nl, hidave.darkstar@gmail.com,
       hch@infradead.org
Subject: Re: [PATCH -v6 2/2] Updating ctime and mtime for memory-mapped
 files
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On Fri, 18 Jan 2008, Miklos Szeredi wrote:
> 
> That would need a new page flag (PG_mmap_dirty?).  Do we have one
> available?

Yeah, that would be bad. We probably have flags free, but those page flags 
are always a pain. Scratch that.

How about just setting a per-vma dirty flag, and then instead of updating 
the mtime when taking the dirty-page fault, we just set that flag?

Then, on unmap and msync, we just do

	if (vma->dirty-flag) {
		vma->dirty_flag = 0;
		update_file_times(vma->vm_file);
	}

and be done with it? 
		

			Linus
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