linux-kernel - Re: [PATCH 3/4] virtual block device driver (ramzswap)

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Date:	Fri, 18 Sep 2009 22:48:39 +0200
From:	Marcin Slusarz <marcin.slusarz@...il.com>
To:	Nitin Gupta <ngupta@...are.org>
CC:	Greg KH <greg@...ah.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Pekka Enberg <penberg@...helsinki.fi>,
	Ed Tomlinson <edt@....ca>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>,
	linux-mm-cc <linux-mm-cc@...top.org>
Subject: Re: [PATCH 3/4] virtual block device driver (ramzswap)

Nitin Gupta wrote:
> (...)
> +
> +static int page_zero_filled(void *ptr)
> +{
> +	u32 pos;
> +	u64 *page;
> +
> +	page = (u64 *)ptr;
> +
> +	for (pos = 0; pos != PAGE_SIZE / sizeof(*page); pos++) {
> +		if (page[pos])
> +			return 0;
> +	}
> +
> +	return 1;
> +}

Wouldn't unsigned long *page be better for both 32-bit and 64-bit machines?

(This function could return bool)

> (...)
> +static void create_device(struct ramzswap *rzs, int device_id)
> +{
> +	mutex_init(&rzs->lock);
> +	INIT_LIST_HEAD(&rzs->backing_swap_extent_list);
> +
> +	rzs->queue = blk_alloc_queue(GFP_KERNEL);
> +	if (!rzs->queue) {
> +		pr_err("Error allocating disk queue for device %d\n",
> +			device_id);
> +		return;
> +	}
> +
> +	blk_queue_make_request(rzs->queue, ramzswap_make_request);
> +	rzs->queue->queuedata = rzs;
> +
> +	 /* gendisk structure */
> +	rzs->disk = alloc_disk(1);
> +	if (!rzs->disk) {
> +		blk_cleanup_queue(rzs->queue);
> +		pr_warning("Error allocating disk structure for device %d\n",
> +			device_id);
> +		return;
> +	}
> +
> +	rzs->disk->major = ramzswap_major;
> +	rzs->disk->first_minor = device_id;
> +	rzs->disk->fops = &ramzswap_devops;
> +	rzs->disk->queue = rzs->queue;
> +	rzs->disk->private_data = rzs;
> +	snprintf(rzs->disk->disk_name, 16, "ramzswap%d", device_id);
> +
> +	/*
> +	 * Actual capacity set using RZSIO_SET_DISKSIZE_KB ioctl
> +	 * or set equal to backing swap device (if provided)
> +	 */
> +	set_capacity(rzs->disk, 0);
> +	add_disk(rzs->disk);
> +
> +	rzs->init_done = 0;
> +
> +	return;
> +}

needless return

Marcin

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