linux-kernel - Re: [PATCH 20/21] iomap: Support multi-page folios in invalidatepage

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Message-ID: <20211103160323.GM24307@magnolia>
Date:   Wed, 3 Nov 2021 09:03:23 -0700
From:   "Darrick J. Wong" <djwong@...nel.org>
To:     "Matthew Wilcox (Oracle)" <willy@...radead.org>
Cc:     linux-xfs@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
        Jens Axboe <axboe@...nel.dk>,
        Christoph Hellwig <hch@...radead.org>
Subject: Re: [PATCH 20/21] iomap: Support multi-page folios in invalidatepage

On Mon, Nov 01, 2021 at 08:39:28PM +0000, Matthew Wilcox (Oracle) wrote:
> If we're punching a hole in a multi-page folio, we need to remove the
> per-folio iomap data as the folio is about to be split and each page will
> need its own.  If a dirty folio is only partially-uptodate, the iomap
> data contains the information about which blocks cannot be written back,
> so assert that a dirty folio is fully uptodate.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>

Looks good to me,
Reviewed-by: Darrick J. Wong <djwong@...nel.org>

--D

> ---
>  fs/iomap/buffered-io.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index 3b93fdfedb72..9d7c91f9ec1d 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -470,13 +470,18 @@ void iomap_invalidate_folio(struct folio *folio, size_t offset, size_t len)
>  	trace_iomap_invalidatepage(folio->mapping->host, offset, len);
>  
>  	/*
> -	 * If we're invalidating the entire page, clear the dirty state from it
> -	 * and release it to avoid unnecessary buildup of the LRU.
> +	 * If we're invalidating the entire folio, clear the dirty state
> +	 * from it and release it to avoid unnecessary buildup of the LRU.
>  	 */
>  	if (offset == 0 && len == folio_size(folio)) {
>  		WARN_ON_ONCE(folio_test_writeback(folio));
>  		folio_cancel_dirty(folio);
>  		iomap_page_release(folio);
> +	} else if (folio_test_multi(folio)) {
> +		/* Must release the iop so the page can be split */
> +		WARN_ON_ONCE(!folio_test_uptodate(folio) &&
> +			     folio_test_dirty(folio));
> +		iomap_page_release(folio);
>  	}
>  }
>  EXPORT_SYMBOL_GPL(iomap_invalidate_folio);
> -- 
> 2.33.0
>