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Date: Thu, 19 Jul 2018 18:21:23 +0800
From: Ming Lei <ming.lei@redhat.com>
To: Martin Wilck <mwilck@suse.com>
Cc: Jens Axboe <axboe@kernel.dk>, Jan Kara <jack@suse.com>,
	Hannes Reinecke <hare@suse.de>,
	Johannes Thumshirn <jthumshirn@suse.de>,
	Kent Overstreet <kent.overstreet@gmail.com>,
	Christoph Hellwig <hch@lst.de>, linux-block@vger.kernel.org
Subject: Re: [PATCH 2/2] blkdev: __blkdev_direct_IO_simple: make sure to fill
 up the bio
Message-ID: <20180719102122.GA20700@ming.t460p>
References: <20180718075440.GA15254@ming.t460p>
 <20180719093918.28876-1-mwilck@suse.com>
 <20180719093918.28876-3-mwilck@suse.com>
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In-Reply-To: <20180719093918.28876-3-mwilck@suse.com>
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On Thu, Jul 19, 2018 at 11:39:18AM +0200, Martin Wilck wrote:
> bio_iov_iter_get_pages() returns only pages for a single non-empty
> segment of the input iov_iter's iovec. This may be much less than the number
> of pages __blkdev_direct_IO_simple() is supposed to process. Call

In bio_iov_iter_get_pages(), iov_iter_get_pages() supposes to retrieve
as many as possible pages since both 'maxsize' and 'maxpages' are provided
to cover all.

So the question is why iov_iter_get_pages() doesn't work as expected?

Thanks,
Ming