Re: [PATCH v21 1/6] iomap: Don't get an reference on ZERO_PAGE for direct I/O block zeroing

From: Jan Kara <jack@suse.cz>
To: David Howells <dhowells@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>, Al Viro <viro@zeniv.linux.org.uk>,
	Christoph Hellwig <hch@infradead.org>,
	Matthew Wilcox <willy@infradead.org>, Jan Kara <jack@suse.cz>,
	Jeff Layton <jlayton@kernel.org>,
	David Hildenbrand <david@redhat.com>,
	Jason Gunthorpe <jgg@nvidia.com>,
	Logan Gunthorpe <logang@deltatee.com>,
	Hillf Danton <hdanton@sina.com>,
	Christian Brauner <brauner@kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	John Hubbard <jhubbard@nvidia.com>,
	Dave Chinner <dchinner@redhat.com>,
	Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v21 1/6] iomap: Don't get an reference on ZERO_PAGE for direct I/O block zeroing
Date: Tue, 23 May 2023 10:07:02 +0200	[thread overview]
Message-ID: <20230523080702.vo5n3vanhc5kxcen@quack3> (raw)
In-Reply-To: <20230522205744.2825689-2-dhowells@redhat.com>

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@redhat.com>
> Reviewed-by: David Hildenbrand <david@redhat.com>
> Reviewed-by: John Hubbard <jhubbard@nvidia.com>
> Reviewed-by: Dave Chinner <dchinner@redhat.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> cc: Al Viro <viro@zeniv.linux.org.uk>
> cc: linux-fsdevel@vger.kernel.org

Looks good to me. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.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@suse.com>
SUSE Labs, CR