linux-kernel - Re: [PATCH v3 03/22] cachefiles: extract generic function for daemon methods

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Date:   Thu, 17 Feb 2022 16:17:03 +0800
From:   Liu Bo <bo.liu@...ux.alibaba.com>
To:     Jeffle Xu <jefflexu@...ux.alibaba.com>
Cc:     dhowells@...hat.com, linux-cachefs@...hat.com, xiang@...nel.org,
        chao@...nel.org, linux-erofs@...ts.ozlabs.org,
        torvalds@...ux-foundation.org, gregkh@...uxfoundation.org,
        willy@...radead.org, linux-fsdevel@...r.kernel.org,
        joseph.qi@...ux.alibaba.com, tao.peng@...ux.alibaba.com,
        gerry@...ux.alibaba.com, eguan@...ux.alibaba.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 03/22] cachefiles: extract generic function for daemon
 methods

On Wed, Feb 09, 2022 at 02:00:49PM +0800, Jeffle Xu wrote:
> ... so that the following new devnode can reuse most of the code when
> implementing its own methods.
>

Looks good.

Reviewed-by: Liu Bo <bo.liu@...ux.alibaba.com>
liubo

> Signed-off-by: Jeffle Xu <jefflexu@...ux.alibaba.com>
> ---
>  fs/cachefiles/daemon.c | 70 +++++++++++++++++++++++++++---------------
>  1 file changed, 45 insertions(+), 25 deletions(-)
> 
> diff --git a/fs/cachefiles/daemon.c b/fs/cachefiles/daemon.c
> index 7ac04ee2c0a0..6b8d7c5bbe5d 100644
> --- a/fs/cachefiles/daemon.c
> +++ b/fs/cachefiles/daemon.c
> @@ -78,6 +78,34 @@ static const struct cachefiles_daemon_cmd cachefiles_daemon_cmds[] = {
>  	{ "",		NULL				}
>  };
>  
> +static struct cachefiles_cache *cachefiles_daemon_open_cache(void)
> +{
> +	struct cachefiles_cache *cache;
> +
> +	/* allocate a cache record */
> +	cache = kzalloc(sizeof(struct cachefiles_cache), GFP_KERNEL);
> +	if (cache) {
> +		mutex_init(&cache->daemon_mutex);
> +		init_waitqueue_head(&cache->daemon_pollwq);
> +		INIT_LIST_HEAD(&cache->volumes);
> +		INIT_LIST_HEAD(&cache->object_list);
> +		spin_lock_init(&cache->object_list_lock);
> +
> +		/* set default caching limits
> +		 * - limit at 1% free space and/or free files
> +		 * - cull below 5% free space and/or free files
> +		 * - cease culling above 7% free space and/or free files
> +		 */
> +		cache->frun_percent = 7;
> +		cache->fcull_percent = 5;
> +		cache->fstop_percent = 1;
> +		cache->brun_percent = 7;
> +		cache->bcull_percent = 5;
> +		cache->bstop_percent = 1;
> +	}
> +
> +	return cache;
> +}
>  
>  /*
>   * Prepare a cache for caching.
> @@ -96,31 +124,13 @@ static int cachefiles_daemon_open(struct inode *inode, struct file *file)
>  	if (xchg(&cachefiles_open, 1) == 1)
>  		return -EBUSY;
>  
> -	/* allocate a cache record */
> -	cache = kzalloc(sizeof(struct cachefiles_cache), GFP_KERNEL);
> +
> +	cache = cachefiles_daemon_open_cache();
>  	if (!cache) {
>  		cachefiles_open = 0;
>  		return -ENOMEM;
>  	}
>  
> -	mutex_init(&cache->daemon_mutex);
> -	init_waitqueue_head(&cache->daemon_pollwq);
> -	INIT_LIST_HEAD(&cache->volumes);
> -	INIT_LIST_HEAD(&cache->object_list);
> -	spin_lock_init(&cache->object_list_lock);
> -
> -	/* set default caching limits
> -	 * - limit at 1% free space and/or free files
> -	 * - cull below 5% free space and/or free files
> -	 * - cease culling above 7% free space and/or free files
> -	 */
> -	cache->frun_percent = 7;
> -	cache->fcull_percent = 5;
> -	cache->fstop_percent = 1;
> -	cache->brun_percent = 7;
> -	cache->bcull_percent = 5;
> -	cache->bstop_percent = 1;
> -
>  	file->private_data = cache;
>  	cache->cachefilesd = file;
>  	return 0;
> @@ -209,10 +219,11 @@ static ssize_t cachefiles_daemon_read(struct file *file, char __user *_buffer,
>  /*
>   * Take a command from cachefilesd, parse it and act on it.
>   */
> -static ssize_t cachefiles_daemon_write(struct file *file,
> -				       const char __user *_data,
> -				       size_t datalen,
> -				       loff_t *pos)
> +static ssize_t cachefiles_daemon_do_write(struct file *file,
> +					  const char __user *_data,
> +					  size_t datalen,
> +					  loff_t *pos,
> +			const struct cachefiles_daemon_cmd *cmds)
>  {
>  	const struct cachefiles_daemon_cmd *cmd;
>  	struct cachefiles_cache *cache = file->private_data;
> @@ -261,7 +272,7 @@ static ssize_t cachefiles_daemon_write(struct file *file,
>  	}
>  
>  	/* run the appropriate command handler */
> -	for (cmd = cachefiles_daemon_cmds; cmd->name[0]; cmd++)
> +	for (cmd = cmds; cmd->name[0]; cmd++)
>  		if (strcmp(cmd->name, data) == 0)
>  			goto found_command;
>  
> @@ -284,6 +295,15 @@ static ssize_t cachefiles_daemon_write(struct file *file,
>  	goto error;
>  }
>  
> +static ssize_t cachefiles_daemon_write(struct file *file,
> +				       const char __user *_data,
> +				       size_t datalen,
> +				       loff_t *pos)
> +{
> +	return cachefiles_daemon_do_write(file, _data, datalen, pos,
> +					  cachefiles_daemon_cmds);
> +}
> +
>  /*
>   * Poll for culling state
>   * - use EPOLLOUT to indicate culling state
> -- 
> 2.27.0