linux-kernel - Re: [PATCH v2 3/4] mm/truncate: bail out early from invalidate_inode_pages2

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Date:   Tue, 25 Apr 2017 10:37:15 +0200
From:   Jan Kara <jack@...e.cz>
To:     Andrey Ryabinin <aryabinin@...tuozzo.com>
Cc:     Alexander Viro <viro@...iv.linux.org.uk>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        Ross Zwisler <ross.zwisler@...ux.intel.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jan Kara <jack@...e.cz>, Jens Axboe <axboe@...nel.dk>,
        Johannes Weiner <hannes@...xchg.org>,
        Alexey Kuznetsov <kuznet@...tuozzo.com>,
        Christoph Hellwig <hch@....de>,
        Nikolay Borisov <n.borisov.lkml@...il.com>,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-mm@...ck.org
Subject: Re: [PATCH v2 3/4] mm/truncate: bail out early from
 invalidate_inode_pages2_range() if mapping is empty

On Mon 24-04-17 19:41:34, Andrey Ryabinin wrote:
> If mapping is empty (both ->nrpages and ->nrexceptional is zero) we can
> avoid pointless lookups in empty radix tree and bail out immediately after
> cleancache invalidation.
> 
> Signed-off-by: Andrey Ryabinin <aryabinin@...tuozzo.com>
> Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>

Looks good. You can add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

> ---
>  mm/truncate.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/mm/truncate.c b/mm/truncate.c
> index 6263aff..8f12b0e 100644
> --- a/mm/truncate.c
> +++ b/mm/truncate.c
> @@ -624,6 +624,9 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
>  	int did_range_unmap = 0;
>  
>  	cleancache_invalidate_inode(mapping);
> +	if (mapping->nrpages == 0 && mapping->nrexceptional == 0)
> +		return 0;
> +
>  	pagevec_init(&pvec, 0);
>  	index = start;
>  	while (index <= end && pagevec_lookup_entries(&pvec, mapping, index,
> -- 
> 2.10.2
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR