linux-kernel - Re: [PATCH 3/4] f2fs: fix removing cache entry within proper lock

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Message-id: <1357093127.18226.11.camel@kjgkr>
Date:	Wed, 02 Jan 2013 11:18:47 +0900
From:	Jaegeuk Kim <jaegeuk.kim@...sung.com>
To:	Namjae Jeon <linkinjeon@...il.com>
Cc:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net,
	Namjae Jeon <namjae.jeon@...sung.com>,
	Amit Sahrawat <a.sahrawat@...sung.com>
Subject: Re: [PATCH 3/4] f2fs: fix removing cache entry within proper lock

NAK, we don't need to do this.
There is no relationship between kmem_cache_* and free_nid_list_lock.
Moreover, IMO, it would be better unlock free_nid_list_lock as quickly
as possible in order to reduce lock contention.

2012-12-30 (일), 14:52 +0900, Namjae Jeon:
> From: Namjae Jeon <namjae.jeon@...sung.com>
> 
> Cache entry for free NID, is not getting removed under proper
> lock in case of error in add_free_nid. So, free the cache entry
> first before releasing the spinlock.
> 
> Signed-off-by: Namjae Jeon <namjae.jeon@...sung.com>
> Signed-off-by: Amit Sahrawat <a.sahrawat@...sung.com>
> ---
>  fs/f2fs/node.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> index 5066bfd..09139fb 100644
> --- a/fs/f2fs/node.c
> +++ b/fs/f2fs/node.c
> @@ -1227,8 +1227,8 @@ retry:
>  
>  	spin_lock(&nm_i->free_nid_list_lock);
>  	if (__lookup_free_nid_list(nid, &nm_i->free_nid_list)) {
> -		spin_unlock(&nm_i->free_nid_list_lock);
>  		kmem_cache_free(free_nid_slab, i);
> +		spin_unlock(&nm_i->free_nid_list_lock);
>  		return 0;
>  	}
>  	list_add_tail(&i->list, &nm_i->free_nid_list);

-- 
Jaegeuk Kim
Samsung

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