linux-kernel - Re: [PATCH v21 1/6] iomap: Don't get an reference on ZERO

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Message-ID: <20230523080702.vo5n3vanhc5kxcen@quack3>
Date:   Tue, 23 May 2023 10:07:02 +0200
From:   Jan Kara <jack@...e.cz>
To:     David Howells <dhowells@...hat.com>
Cc:     Jens Axboe <axboe@...nel.dk>, Al Viro <viro@...iv.linux.org.uk>,
        Christoph Hellwig <hch@...radead.org>,
        Matthew Wilcox <willy@...radead.org>, Jan Kara <jack@...e.cz>,
        Jeff Layton <jlayton@...nel.org>,
        David Hildenbrand <david@...hat.com>,
        Jason Gunthorpe <jgg@...dia.com>,
        Logan Gunthorpe <logang@...tatee.com>,
        Hillf Danton <hdanton@...a.com>,
        Christian Brauner <brauner@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-fsdevel@...r.kernel.org, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        John Hubbard <jhubbard@...dia.com>,
        Dave Chinner <dchinner@...hat.com>,
        Christoph Hellwig <hch@....de>
Subject: Re: [PATCH v21 1/6] iomap: Don't get an reference on ZERO_PAGE for
 direct I/O block zeroing

On Mon 22-05-23 21:57:39, David Howells wrote:
> ZERO_PAGE can't go away, no need to hold an extra reference.
> 
> Signed-off-by: David Howells <dhowells@...hat.com>
> Reviewed-by: David Hildenbrand <david@...hat.com>
> Reviewed-by: John Hubbard <jhubbard@...dia.com>
> Reviewed-by: Dave Chinner <dchinner@...hat.com>
> Reviewed-by: Christoph Hellwig <hch@....de>
> cc: Al Viro <viro@...iv.linux.org.uk>
> cc: linux-fsdevel@...r.kernel.org

Looks good to me. Feel free to add:

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

								Honza

> ---
>  fs/iomap/direct-io.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
> index 019cc87d0fb3..66a9f10e3207 100644
> --- a/fs/iomap/direct-io.c
> +++ b/fs/iomap/direct-io.c
> @@ -203,7 +203,7 @@ static void iomap_dio_zero(const struct iomap_iter *iter, struct iomap_dio *dio,
>  	bio->bi_private = dio;
>  	bio->bi_end_io = iomap_dio_bio_end_io;
>  
> -	get_page(page);
> +	bio_set_flag(bio, BIO_NO_PAGE_REF);
>  	__bio_add_page(bio, page, len, 0);
>  	iomap_dio_submit_bio(iter, dio, bio, pos);
>  }
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR