linux-kernel - [PATCH 1/2] f2fs: optimize scan_nat

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Date:	Fri,  3 May 2013 20:43:22 +0800
From:	Haicheng Li <haicheng.li@...ux.intel.com>
To:	linux-fsdevel@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net,
	Jaegeuk Kim <jaegeuk.kim@...sung.com>
Cc:	linux-kernel@...r.kernel.org, Haicheng Li <haicheng.lee@...il.com>,
	Haicheng Li <haicheng.li@...ux.intel.com>
Subject: [PATCH 1/2] f2fs: optimize scan_nat_page()

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 |   14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index e275218..6276467 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -1216,7 +1216,7 @@ 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;
 retry:
 	i = kmem_cache_alloc(free_nid_slab, GFP_NOFS);
 	if (!i) {
@@ -1265,10 +1265,16 @@ static int 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++) {
-		blk_addr  = le32_to_cpu(nat_blk->entries[i].block_addr);
+		int cnt;
+
+		blk_addr = le32_to_cpu(nat_blk->entries[i].block_addr);
 		BUG_ON(blk_addr == NEW_ADDR);
-		if (blk_addr == NULL_ADDR)
-			fcnt += add_free_nid(nm_i, start_nid);
+		if (blk_addr == NULL_ADDR) {
+			cnt = add_free_nid(nm_i, start_nid);
+			if (cnt < 0)
+				break;
+			fcnt += cnt;
+		}
 	}
 	return fcnt;
 }
-- 
1.7.9.5

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