linux-kernel - Re: [PATCH 01/10] Replace ioctls with sysfs interface

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Date:	Mon, 9 Aug 2010 21:34:48 +0300
From:	Pekka Enberg <penberg@...nel.org>
To:	Nitin Gupta <ngupta@...are.org>
Cc:	Pekka Enberg <penberg@...helsinki.fi>,
	Minchan Kim <minchan.kim@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Greg KH <greg@...ah.com>,
	Linux Driver Project <devel@...uxdriverproject.org>,
	linux-mm <linux-mm@...ck.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 01/10] Replace ioctls with sysfs interface

On Mon, Aug 9, 2010 at 8:26 PM, Nitin Gupta <ngupta@...are.org> wrote:
> Creates per-device sysfs nodes in /sys/block/zram<id>/
> Currently following stats are exported:
>  - disksize
>  - num_reads
>  - num_writes
>  - invalid_io
>  - zero_pages
>  - orig_data_size
>  - compr_data_size
>  - mem_used_total
>
> By default, disksize is set to 0. So, to start using
> a zram device, fist write a disksize value and then
> initialize device by writing any positive value to
> initstate. For example:
>
>        # initialize /dev/zram0 with 50MB disksize
>        echo 50*1024*1024 | bc > /sys/block/zram0/disksize
>        echo 1 > /sys/block/zram0/initstate
>
> When done using a disk, issue reset to free its memory
> by writing any positive value to reset node:
>
>        echo 1 > /sys/block/zram0/reset
>
> This change also obviates the need for 'rzscontrol' utility.
>
> Signed-off-by: Nitin Gupta <ngupta@...are.org>

Looks good to me (but I'm not a sysfs guy).

Acked-by: Pekka Enberg <penberg@...nel.org>

>  /* Module params (documentation at end) */
> -static unsigned int num_devices;
> +unsigned int num_devices;
> +
> +static void zram_stat_inc(u32 *v)
> +{
> +       *v = *v + 1;
> +}
> +
> +static void zram_stat_dec(u32 *v)
> +{
> +       *v = *v - 1;
> +}
> +
> +static void zram_stat64_add(struct zram *zram, u64 *v, u64 inc)
> +{
> +       spin_lock(&zram->stat64_lock);
> +       *v = *v + inc;
> +       spin_unlock(&zram->stat64_lock);
> +}
> +
> +static void zram_stat64_sub(struct zram *zram, u64 *v, u64 dec)
> +{
> +       spin_lock(&zram->stat64_lock);
> +       *v = *v - dec;
> +       spin_unlock(&zram->stat64_lock);
> +}
> +
> +static void zram_stat64_inc(struct zram *zram, u64 *v)
> +{
> +       zram_stat64_add(zram, v, 1);
> +}

These could probably use atomic_inc(), atomic64_inc(), and friends, no?
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