Re: [PATCH 14/18] fs: Protect inode->i_state with th einode->i_lock

[Christoph Hellwig]

On Fri, Oct 08, 2010 at 04:21:28PM +1100, Dave Chinner wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
> 
> We currently protect the per-inode state flags with the inode_lock.
> Using a global lock to protect per-object state is overkill when we
> coul duse a per-inode lock to protect the state.  Use the
> inode->i_lock for this, and wrap all the state changes and checks
> with the inode->i_lock.
> 
> Based on work originally written by Nick Piggin.

> @@ -884,9 +897,9 @@ struct inode *new_inode(struct super_block *sb)
>  	inode = alloc_inode(sb);
>  	if (inode) {
>  		spin_lock(&inode_lock);
> -		__inode_add_to_lists(sb, NULL, inode);
>  		inode->i_ino = ++last_ino;
>  		inode->i_state = 0;
> +		__inode_add_to_lists(sb, NULL, inode);
>  		spin_unlock(&inode_lock);
>  	}
>  	return inode;

What's the point in doing this move?

> @@ -953,8 +966,8 @@ static struct inode *get_new_inode(struct super_block *sb,
>  			if (set(inode, data))
>  				goto set_failed;
>  
> -			__inode_add_to_lists(sb, b, inode);
>  			inode->i_state = I_NEW;
> +			__inode_add_to_lists(sb, b, inode);

Same here.



Otherwise it looks good.  But all this moving around of i_lock really
hurts my brain.  I guess I'll need to review the placement on a tree
with the fully applied series again.


Reviewed-by: Christoph Hellwig <hch@xxxxxx>
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