Re: [PATCH] vfs: dont chain pipe/anon/socket on superblock s_inodeslist

[Christoph Hellwig]

On Tue, Jul 26, 2011 at 12:43:33PM +0200, Eric Dumazet wrote:
> BTW, we have one atomic op that could be avoided in new_inode()
> 
> spin_lock(&inode->i_lock);
> inode->i_state = 0;
> spin_unlock(&inode->i_lock);
> 
> can probably be changed to something less expensive...
> 
> inode->i_state = 0;
> smp_wmb();
> 
> Not clear if we really need a memory barrier either....

I think we already had this in some of the earlier vfs/inode scale
series, but it got lost when Al asked to just put the fundamental
changes in.

For plain new_inode() the barrier shouldn't be needed as we take
the sb list lock just a little later.  I'm not sure about your new
variant, so I'll rather lave that to you.

There's a few other things missing from earlier iterations, most notable
the non-atomic i_count, and the bucket locks for the inode hash, if
you're eager enough to look into that area.

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