[PATCH] f2fs: optimize alloc_nid_failed()

[Haicheng Li <haicheng.li@linux.intel.com>]

Current alloc_nid_failed() has two issues:
1. unecessarily kmem_cache_free() the free_nid and then realloc a new
   slab cache for it immediately;
2. needs to __lookup_free_nid_list() twice in order to find out the free_nid
   from free_nid_list.

This patch fixes these issues.

Signed-off-by: Haicheng Li <haicheng.li@linux.intel.com>
---
 fs/f2fs/node.c |   17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index e275218..7ce8e9f 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -1403,8 +1403,21 @@ void alloc_nid_done(struct f2fs_sb_info *sbi, nid_t nid)
  */
 void alloc_nid_failed(struct f2fs_sb_info *sbi, nid_t nid)
 {
-	alloc_nid_done(sbi, nid);
-	add_free_nid(NM_I(sbi), nid);
+	struct f2fs_nm_info *nm_i = NM_I(sbi);
+	struct free_nid *i;
+
+	spin_lock(&nm_i->free_nid_list_lock);
+	i = __lookup_free_nid_list(nid, &nm_i->free_nid_list);
+	if (i) {
+		BUG_ON(i->state != NID_ALLOC);
+		if (nm_i->fcnt > 2 * MAX_FREE_NIDS)
+			__del_from_free_nid_list(i);
+		else {
+			i->state = NID_NEW;
+			nm_i->fcnt++;
+		}
+	}
+	spin_unlock(&nm_i->free_nid_list_lock);
 }
 
 void recover_node_page(struct f2fs_sb_info *sbi, struct page *page,
-- 
1.7.9.5