[PATCH 1/4] f2fs: bugfix for alloc_nid_failed()

[Haicheng Li]

Directly drop the free_nid cache when nm_i->fcnt > 2 * MAX_FREE_NIDS

Since there is NOT nmi->free_nid_list_lock spinlock protection between
a sequential calling of alloc_nid() and alloc_nid_failed(), some other
threads may already add new free_nid to the free_nid_list during this
period.

We need to make sure nmi->fcnt is never > 2 * MAX_FREE_NIDS.

Signed-off-by: Haicheng Li <haicheng.li@xxxxxxxxxxxxxxx>
---
 fs/f2fs/node.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index 7209d63..532ac57 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -1439,8 +1439,12 @@ void alloc_nid_failed(struct f2fs_sb_info *sbi, nid_t nid)
 	spin_lock(&nm_i->free_nid_list_lock);
 	i = __lookup_free_nid_list(nid, &nm_i->free_nid_list);
 	BUG_ON(!i || i->state != NID_ALLOC);
-	i->state = NID_NEW;
-	nm_i->fcnt++;
+	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);
 }
 
-- 
1.7.9.5

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