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Date: Fri, 29 Dec 2000 17:03:05 -0800 (PST)
From: Linus Torvalds <torvalds@transmeta.com>
To: Alexander Viro <viro@math.psu.edu>
cc: Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Alexander Viro <aviro@redhat.com>,
        "Stephen C. Tweedie" <sct@redhat.com>, "Marco d'Itri" <md@Linux.IT>,
        Jeff Lightfoot <jeffml@pobox.com>, Dan Aloni <karrde@callisto.yi.org>,
        Anton Blanchard <anton@linuxcare.com.au>
Subject: Re: test13-pre6
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On Fri, 29 Dec 2000, Alexander Viro wrote:
> 
> Two examples: devices and bitmaps-in-pagecache trick. But both belong to
> 2.5, so...

Also, they can easily be done with a private inode, if required. So even
in 2.5.x this may not be a major problem.

> BTW, nice timing ;-) -pre6 appeared 5 minutes after I've started testing
> sane-s_lock patch (SMP-safe lock_super() and friends, refcount on superblocks,
> death of mount_sem, beginning of SMP-safe super.c). Oh, well...
> 
> Oblock_super(): what the hell is wait_on_super() doing in fsync_file()?
> It gives absolutely no warranties - ->write_super() can easily block, so
> it looks very odd.

A lot of the superblock locking has been odd. It should probably be a
lock_super() + unlock_super(). At least that's what sync_supers() does.

> BTW, while we are dropping the junk from vm_operations_struct, could we lose
> ->protect() and ->wppage()?

Sure. I think sync() and unmap() fall under that heading too - it used to
do a msync(), but that was before we handled dirty pages directly, so...

		Linus

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