From 0305138546dfaf6c3a2dfa52d2f28d941546b7ce Mon Sep 17 00:00:00 2001
From: Josef Bacik <jbacik@fusionio.com>
Date: Fri, 14 Sep 2012 13:43:01 -0400
Subject: [PATCH] --- yaml --- r: 332577 b: refs/heads/master c:
 b5bae2612af92fd8e7bcdcf7ce3e0259e8d341c9 h: refs/heads/master i:   332575:
 4f9474a25905de165449c899f20f2db0fc39eae0 v: v3

---
 [refs]                     |  2 +-
 trunk/fs/btrfs/extent_io.c | 23 +++++++++++++++++++----
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/[refs] b/[refs]
index 09bb020a1115..ec1ebe3c1521 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: ff44c6e36dc9dcc02652a1105b120bdf08cea9f7
+refs/heads/master: b5bae2612af92fd8e7bcdcf7ce3e0259e8d341c9
diff --git a/trunk/fs/btrfs/extent_io.c b/trunk/fs/btrfs/extent_io.c
index 90bd9f768c0a..a2c21570adf5 100644
--- a/trunk/fs/btrfs/extent_io.c
+++ b/trunk/fs/btrfs/extent_io.c
@@ -3256,19 +3256,34 @@ int btree_write_cache_pages(struct address_space *mapping,
 				break;
 			}
 
+			spin_lock(&mapping->private_lock);
+			if (!PagePrivate(page)) {
+				spin_unlock(&mapping->private_lock);
+				continue;
+			}
+
 			eb = (struct extent_buffer *)page->private;
+
+			/*
+			 * Shouldn't happen and normally this would be a BUG_ON
+			 * but no sense in crashing the users box for something
+			 * we can survive anyway.
+			 */
 			if (!eb) {
+				spin_unlock(&mapping->private_lock);
 				WARN_ON(1);
 				continue;
 			}
 
-			if (eb == prev_eb)
+			if (eb == prev_eb) {
+				spin_unlock(&mapping->private_lock);
 				continue;
+			}
 
-			if (!atomic_inc_not_zero(&eb->refs)) {
-				WARN_ON(1);
+			ret = atomic_inc_not_zero(&eb->refs);
+			spin_unlock(&mapping->private_lock);
+			if (!ret)
 				continue;
-			}
 
 			prev_eb = eb;
 			ret = lock_extent_buffer_for_io(eb, fs_info, &epd);