linux-kernel - Re: [PATCH 3/4] f2fs: optimize scan_nat

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Date:	Tue, 07 May 2013 19:36:28 +0900
From:	Jaegeuk Kim <jaegeuk.kim@...sung.com>
To:	Haicheng Li <haicheng.li@...ux.intel.com>
Cc:	linux-fsdevel@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org, Haicheng Li <haicheng.lee@...il.com>
Subject: Re: [PATCH 3/4] f2fs: optimize scan_nat_page()

Hi,

2013-05-06 (월), 23:15 +0800, Haicheng Li:
> When nm_i->fcnt > 2 * MAX_FREE_NIDS, stop scanning other NAT entries.
> 
> Signed-off-by: Haicheng Li <haicheng.li@...ux.intel.com>
> ---
>  fs/f2fs/node.c |   13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> index 1b45dd0..1fe3fe2 100644
> --- a/fs/f2fs/node.c
> +++ b/fs/f2fs/node.c
> @@ -1254,7 +1254,7 @@ static int add_free_nid(struct f2fs_nm_info *nm_i, nid_t nid)
>  	struct free_nid *i;
>  
>  	if (nm_i->fcnt > 2 * MAX_FREE_NIDS)
> -		return 0;
> +		return -1;

We should check all the handler of add_free_nid().
So, plz see the below modified patch.

>  
>  	/* 0 nid should not be used */
>  	if (nid == 0)
> @@ -1302,12 +1302,17 @@ static void scan_nat_page(struct f2fs_nm_info *nm_i,
>  	i = start_nid % NAT_ENTRY_PER_BLOCK;
>  
>  	for (; i < NAT_ENTRY_PER_BLOCK; i++, start_nid++) {
> +		int cnt;
> +
>  		if (start_nid >= nm_i->max_nid)
>  			break;
> -		blk_addr  = le32_to_cpu(nat_blk->entries[i].block_addr);
> +		blk_addr = le32_to_cpu(nat_blk->entries[i].block_addr);
>  		BUG_ON(blk_addr == NEW_ADDR);
> -		if (blk_addr == NULL_ADDR)
> -			add_free_nid(nm_i, start_nid);
> +		if (blk_addr == NULL_ADDR) {
> +			cnt = add_free_nid(nm_i, start_nid);
> +			if (cnt < 0)
> +				break;
> +		}

Here we need to eliminate cnt.

>  	}
>  }
>  


-----
From e2da02f0ba045f792d166ac8215d04474c06f319 Mon Sep 17 00:00:00 2001
From: Haicheng Li <haicheng.li@...ux.intel.com>
Date: Mon, 6 May 2013 23:15:43 +0800
Subject: [PATCH] f2fs: optimize scan_nat_page()
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-f2fs-devel@...ts.sourceforge.net

When nm_i->fcnt > 2 * MAX_FREE_NIDS, stop scanning other NAT entries.

Signed-off-by: Haicheng Li <haicheng.li@...ux.intel.com>
[Jaegeuk Kim: fix handling the return value of add_free_nid()]
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@...sung.com>
---
 fs/f2fs/node.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index 122200e..e42934e 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -1254,7 +1254,7 @@ static int add_free_nid(struct f2fs_nm_info *nm_i,
nid_t nid)
 	struct free_nid *i;
 
 	if (nm_i->fcnt > 2 * MAX_FREE_NIDS)
-		return 0;
+		return -1;
 
 	/* 0 nid should not be used */
 	if (nid == 0)
@@ -1302,12 +1302,16 @@ static void scan_nat_page(struct f2fs_nm_info
*nm_i,
 	i = start_nid % NAT_ENTRY_PER_BLOCK;
 
 	for (; i < NAT_ENTRY_PER_BLOCK; i++, start_nid++) {
+
 		if (start_nid >= nm_i->max_nid)
 			break;
-		blk_addr  = le32_to_cpu(nat_blk->entries[i].block_addr);
+
+		blk_addr = le32_to_cpu(nat_blk->entries[i].block_addr);
 		BUG_ON(blk_addr == NEW_ADDR);
-		if (blk_addr == NULL_ADDR)
-			add_free_nid(nm_i, start_nid);
+		if (blk_addr == NULL_ADDR) {
+			if (add_free_nid(nm_i, start_nid) < 0)
+				break;
+		}
 	}
 }
 
@@ -1655,7 +1659,7 @@ flush_now:
 		}
 
 		if (nat_get_blkaddr(ne) == NULL_ADDR &&
-					!add_free_nid(NM_I(sbi), nid)) {
+				add_free_nid(NM_I(sbi), nid) <= 0) {
 			write_lock(&nm_i->nat_tree_lock);
 			__del_from_nat_cache(nm_i, ne);
 			write_unlock(&nm_i->nat_tree_lock);
-- 
1.8.1.3.566.gaa39828





-- 
Jaegeuk Kim
Samsung

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