Re: [PATCH] knfsd: Replace lock_kernel with a mutex in nfsd pool stats.

["J. Bruce Fields" <bfields@fieldses.org>]

On Sun, Aug 16, 2009 at 12:54:41AM +0900, YOSHIFUJI Hideaki wrote:
> From: Ryusei Yamaguchi <mandel59@gmail.com>
> Subject: [PATCH] knfsd: Replace lock_kernel with a mutex in nfsd pool stats.
> 
> lock_kernel() in knfsd was replaced with a mutex. The later
> commit 03cf6c9f49a8fea953d38648d016e3f46e814991 ("knfsd:
> add file to export stats about nfsd pools") did not follow
> that change. This patch fixes the issue.

OK, and you're moving the code to get/put nfsd_serv to open/close
(instead of start/stop) methods in order to allow returning an error in
case the server's down?  Got it, makes sense--applied.

--b.

> 
> Signed-off-by: Ryusei Yamaguchi <mandel59@gmail.com>
> Signed-off-by: Isaku Yamahata <yamahata-jCdQPDEk3idL9jVzuh4AOg@public.gmane.org>
> Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
> 
> ---
>  fs/nfsd/nfsctl.c      |    3 ++-
>  fs/nfsd/nfssvc.c      |   23 +++++++++++++++++++++--
>  net/sunrpc/svc_xprt.c |   11 -----------
>  3 files changed, 23 insertions(+), 14 deletions(-)
> 
> diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
> index 6d08475..6b1b917 100644
> --- a/fs/nfsd/nfsctl.c
> +++ b/fs/nfsd/nfsctl.c
> @@ -173,12 +173,13 @@ static const struct file_operations exports_operations = {
>  };
>  
>  extern int nfsd_pool_stats_open(struct inode *inode, struct file *file);
> +extern int nfsd_pool_stats_release(struct inode *inode, struct file *file);
>  
>  static struct file_operations pool_stats_operations = {
>  	.open		= nfsd_pool_stats_open,
>  	.read		= seq_read,
>  	.llseek		= seq_lseek,
> -	.release	= seq_release,
> +	.release	= nfsd_pool_stats_release,
>  	.owner		= THIS_MODULE,
>  };
>  
> diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
> index 492c79b..32e64fc 100644
> --- a/fs/nfsd/nfssvc.c
> +++ b/fs/nfsd/nfssvc.c
> @@ -34,6 +34,7 @@
>  #include <linux/nfsd/syscall.h>
>  #include <linux/lockd/bind.h>
>  #include <linux/nfsacl.h>
> +#include <linux/seq_file.h>
>  
>  #define NFSDDBG_FACILITY	NFSDDBG_SVC
>  
> @@ -605,7 +606,25 @@ nfsd_dispatch(struct svc_rqst *rqstp, __be32 *statp)
>  
>  int nfsd_pool_stats_open(struct inode *inode, struct file *file)
>  {
> -	if (nfsd_serv == NULL)
> +	int ret;
> +	mutex_lock(&nfsd_mutex);
> +	if (nfsd_serv == NULL) {
> +		mutex_unlock(&nfsd_mutex);
>  		return -ENODEV;
> -	return svc_pool_stats_open(nfsd_serv, file);
> +	}
> +	/* bump up the psudo refcount while traversing */
> +	svc_get(nfsd_serv);
> +	ret = svc_pool_stats_open(nfsd_serv, file);
> +	mutex_unlock(&nfsd_mutex);
> +	return ret;
> +}
> +
> +int nfsd_pool_stats_release(struct inode *inode, struct file *file)
> +{
> +	int ret = seq_release(inode, file);
> +	mutex_lock(&nfsd_mutex);
> +	/* this function really, really should have been called svc_put() */
> +	svc_destroy(nfsd_serv);
> +	mutex_unlock(&nfsd_mutex);
> +	return ret;
>  }
> diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
> index 27d4433..dcd2d1e 100644
> --- a/net/sunrpc/svc_xprt.c
> +++ b/net/sunrpc/svc_xprt.c
> @@ -1166,11 +1166,6 @@ static void *svc_pool_stats_start(struct seq_file *m, loff_t *pos)
>  
>  	dprintk("svc_pool_stats_start, *pidx=%u\n", pidx);
>  
> -	lock_kernel();
> -	/* bump up the pseudo refcount while traversing */
> -	svc_get(serv);
> -	unlock_kernel();
> -
>  	if (!pidx)
>  		return SEQ_START_TOKEN;
>  	return (pidx > serv->sv_nrpools ? NULL : &serv->sv_pools[pidx-1]);
> @@ -1198,12 +1193,6 @@ static void *svc_pool_stats_next(struct seq_file *m, void *p, loff_t *pos)
>  
>  static void svc_pool_stats_stop(struct seq_file *m, void *p)
>  {
> -	struct svc_serv *serv = m->private;
> -
> -	lock_kernel();
> -	/* this function really, really should have been called svc_put() */
> -	svc_destroy(serv);
> -	unlock_kernel();
>  }
>  
>  static int svc_pool_stats_show(struct seq_file *m, void *p)
> -- 
> 1.4.4.4
> 
> 
> --yoshfuji
> --
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