linux-kernel - Re: [PATCH] f2fs: introduce f2fs_kmem_cache_alloc to hide the unfailed kmem cache allocation

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Date:	Tue, 22 Oct 2013 14:15:40 +0800
From:	Haicheng Li <haicheng.li@...ux.intel.com>
To:	Gu Zheng <guz.fnst@...fujitsu.com>
Cc:	Gao feng <gaofeng@...fujitsu.com>, Kim <jaegeuk.kim@...sung.com>,
	f2fs <linux-f2fs-devel@...ts.sourceforge.net>,
	fsdevel <linux-fsdevel@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] f2fs: introduce f2fs_kmem_cache_alloc to hide the
 unfailed kmem cache allocation

On Tue, Oct 22, 2013 at 01:34:26PM +0800, Gu Zheng wrote:
> On 10/22/2013 01:16 PM, Haicheng Li wrote:
> 
> > On Tue, Oct 22, 2013 at 11:49:58AM +0800, Gao feng wrote:
> >> On 10/21/2013 03:24 PM, Gu Zheng wrote:
> >>> +static inline void *f2fs_kmem_cache_alloc(struct kmem_cache *cachep,
> >>> +						gfp_t flags)
> >>> +{
> >>> +	void *entry = kmem_cache_alloc(cachep, flags);
> >>> +retry:
> >>
> >> retry after kmem_cache_alloc?
> > 
> > Good catch.
> > 
> > Sorry for the carelessness in my previous review. 
> > Besides this, I also found another issue as below:
> >  
> >> On Mon, Oct 21, 2013 at 03:24:55PM +0800, Gu Zheng wrote: 
> >>> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c 
> >>> index ef80f79..fe3cf8e 100644 
> >>> --- a/fs/f2fs/node.c 
> >>> +++ b/fs/f2fs/node.c 
> >>> @@ -1308,11 +1308,7 @@ static int add_free_nid(struct f2fs_nm_info *nm_i, nid_t nid, bool build) 
> >>>     if (allocated) 
> >>>             return 0; 
> >>>  retry: 
> > -retry?
> 
> Can be removed here, this tag still used by front goto jumping. But it
> seems that we need to use another suitable name rather than "retry".

how about like this?
---
diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index fe3cf8e..4fa3fd5 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -1296,18 +1296,17 @@ static int add_free_nid(struct f2fs_nm_info *nm_i, nid_t nid, bool build)
 	if (nid == 0)
 		return 0;
 
-	if (!build)
-		goto retry;
+	if (build) {
+		/* do not add allocated nids */
+		read_lock(&nm_i->nat_tree_lock);
+		ne = __lookup_nat_cache(nm_i, nid);
+		if (ne && nat_get_blkaddr(ne) != NULL_ADDR)
+			allocated = true;
+		read_unlock(&nm_i->nat_tree_lock);
+		if (allocated)
+			return 0;
+	}
 
-	/* do not add allocated nids */
-	read_lock(&nm_i->nat_tree_lock);
-	ne = __lookup_nat_cache(nm_i, nid);
-	if (ne && nat_get_blkaddr(ne) != NULL_ADDR)
-		allocated = true;
-	read_unlock(&nm_i->nat_tree_lock);
-	if (allocated)
-		return 0;
-retry:
 	i = f2fs_kmem_cache_alloc(free_nid_slab, GFP_NOFS);
 	i->nid = nid;
 	i->state = NID_NEW;
--
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