linux-kernel - Re: [PATCH v2 1/3] block: provide helpers for reading block count

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Message-ID: <20160627163012.GA11116@linux-80c1.suse>
Date:	Mon, 27 Jun 2016 09:30:12 -0700
From:	Davidlohr Bueso <dave@...olabs.net>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	Jens Axboe <axboe@...com>,
	"Nicholas A . Bellinger" <nab@...ux-iscsi.org>,
	Mike Christie <mchristi@...hat.com>,
	Andy Grover <agrover@...hat.com>,
	Hannes Reinecke <hare@...e.com>, linux-scsi@...r.kernel.org,
	target-devel@...r.kernel.org, linux-kernel@...r.kernel.org,
	Christoph Hellwig <hch@...radead.org>,
	linux-efi@...r.kernel.org, linux-block@...r.kernel.org
Subject: Re: [PATCH v2 1/3] block: provide helpers for reading block count

On Thu, 23 Jun 2016, Arnd Bergmann wrote:

>Several drivers use an expensive do_div() to compute the number
>of logical or physical blocks in a blockdev, which can be done
>more efficiently using a shift, since the blocksize is always
>a power of two number.
>
>Let's introduce bdev_logical_block_count() and bdev_physical_block_count()
>helper functions mirroring the bdev_logical_block_size() and
>bdev_physical_block_size() interfaces for the block size.

>@@ -1226,6 +1226,13 @@ static inline unsigned short bdev_logical_block_size(struct block_device *bdev)
> 	return queue_logical_block_size(bdev_get_queue(bdev));
> }
>
>+static inline sector_t bdev_logical_block_count(struct block_device *bdev)

Curious, why not just return u64 instead for all these instead of sector_t (ie
dealing with lba, it reads weird)?

Thanks,
Davidlohr