From f79cc15e5b579e26ff8992dd7d9e1790d18f95fd Mon Sep 17 00:00:00 2001
From: "Yan, Zheng" <zheng.yan@oracle.com>
Date: Thu, 4 Feb 2010 08:46:56 +0000
Subject: [PATCH] Btrfs: fix race between allocate and release extent buffer.

Increase extent buffer's reference count while holding the lock.
Otherwise it can race with try_release_extent_buffer.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
---
 fs/btrfs/extent_io.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 96577e8bf9fdb..b177ed3196126 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -3165,10 +3165,9 @@ struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree,
 		spin_unlock(&tree->buffer_lock);
 		goto free_eb;
 	}
-	spin_unlock(&tree->buffer_lock);
-
 	/* add one reference for the tree */
 	atomic_inc(&eb->refs);
+	spin_unlock(&tree->buffer_lock);
 	return eb;
 
 free_eb:
-- 
2.39.5