Re: [PATCH 18/20] dax: Make cache flushing protected by entry lock

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On Tue, Sep 27, 2016 at 06:08:22PM +0200, Jan Kara wrote:
> Currently, flushing of caches for DAX mappings was ignoring entry lock.
> So far this was ok (modulo a bug that a difference in entry lock could
> cause cache flushing to be mistakenly skipped) but in the following
> patches we will write-protect PTEs on cache flushing and clear dirty
> tags. For that we will need more exclusion. So do cache flushing under
> an entry lock. This allows us to remove one lock-unlock pair of
> mapping->tree_lock as a bonus.
> 
> Signed-off-by: Jan Kara <jack@xxxxxxx>

> @@ -716,15 +736,13 @@ static int dax_writeback_one(struct block_device *bdev,
>  	}
>  
>  	wb_cache_pmem(dax.addr, dax.size);
> -
> -	spin_lock_irq(&mapping->tree_lock);
> -	radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_TOWRITE);
> -	spin_unlock_irq(&mapping->tree_lock);
> - unmap:
> +unmap:
>  	dax_unmap_atomic(bdev, &dax);
> +	put_locked_mapping_entry(mapping, index, entry);
>  	return ret;
>  
> - unlock:
> +put_unlock:

I know there's an ongoing debate about this, but can you please stick a space
in front of the labels to make the patches pretty & to be consistent with the
rest of the DAX code?

Reviewed-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>

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