linux-kernel - Re: [PATCH 2/2] zram: delete zram_init

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Date:	Tue, 25 Feb 2014 11:51:07 +0100
From:	Jerome Marchand <jmarchan@...hat.com>
To:	Minchan Kim <minchan@...nel.org>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	Nitin Gupta <ngupta@...are.org>,
	Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] zram: delete zram_init_device() function

On 02/25/2014 02:08 AM, Minchan Kim wrote:
> From: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
> 
> allocate new `zram_meta' in disksize_store() only for uninitialised
> zram device, saving a number of allocations and deallocations in case
> if disksize_store() was called on currently used device. at the same
> time zram_meta stack variable is not necessary, because we can set
> ->meta directly. there is also no need in setting QUEUE_FLAG_NONROT
> queue on every disksize_store(), set it once during device creation.
> 
> [minchan@...nel.org]: handled zram->meta alloc fail case.
> Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
> Signed-off-by: Minchan Kim <minchan@...nel.org>

Acked-by: Jerome Marchand <jmarchan@...hat.com>

> ---
>  drivers/block/zram/zram_drv.c | 25 +++++++++----------------
>  1 file changed, 9 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> index 21aee3edcb25..9baac5b76bfe 100644
> --- a/drivers/block/zram/zram_drv.c
> +++ b/drivers/block/zram/zram_drv.c
> @@ -533,40 +533,32 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity)
>  	up_write(&zram->init_lock);
>  }
>  
> -static void zram_init_device(struct zram *zram, struct zram_meta *meta)
> -{
> -	/* zram devices sort of resembles non-rotational disks */
> -	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
> -	zram->meta = meta;
> -	pr_debug("Initialization done!\n");
> -}
> -
>  static ssize_t disksize_store(struct device *dev,
>  		struct device_attribute *attr, const char *buf, size_t len)
>  {
>  	u64 disksize;
> -	struct zram_meta *meta;
>  	struct zram *zram = dev_to_zram(dev);
>  
>  	disksize = memparse(buf, NULL);
>  	if (!disksize)
>  		return -EINVAL;
>  
> -	disksize = PAGE_ALIGN(disksize);
> -	meta = zram_meta_alloc(disksize);
> -	if (!meta)
> -		return -ENOMEM;
>  	down_write(&zram->init_lock);
>  	if (init_done(zram)) {
>  		up_write(&zram->init_lock);
> -		zram_meta_free(meta);
>  		pr_info("Cannot change disksize for initialized device\n");
>  		return -EBUSY;
>  	}
>  
> +	disksize = PAGE_ALIGN(disksize);
> +	zram->meta = zram_meta_alloc(disksize);
> +	if (!zram->meta) {
> +		up_write(&zram->init_lock);
> +		return -ENOMEM;
> +	}
> +
>  	zram->disksize = disksize;
>  	set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
> -	zram_init_device(zram, meta);
>  	up_write(&zram->init_lock);
>  
>  	return len;
> @@ -776,7 +768,8 @@ static int create_device(struct zram *zram, int device_id)
>  
>  	/* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
>  	set_capacity(zram->disk, 0);
> -
> +	/* zram devices sort of resembles non-rotational disks */
> +	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
>  	/*
>  	 * To ensure that we always get PAGE_SIZE aligned
>  	 * and n*PAGE_SIZED sized I/O requests.
> 

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