3 files changed, 25 insertions, 15 deletions

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 19bc6162fb8e..150822ee0a0b 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -80,13 +80,6 @@ noinline void btrfs_clear_path_blocking(struct btrfs_path *p,
 {
         int i;
 
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-        /* lockdep really cares that we take all of these spinlocks
-         * in the right order.  If any of the locks in the path are not
-         * currently blocking, it is going to complain.  So, make really
-         * really sure by forcing the path to blocking before we clear
-         * the path blocking.
-         */
         if (held) {
                 btrfs_set_lock_blocking_rw(held, held_rw);
                 if (held_rw == BTRFS_WRITE_LOCK)
@@ -95,7 +88,6 @@ noinline void btrfs_clear_path_blocking(struct btrfs_path *p,
                         held_rw = BTRFS_READ_LOCK_BLOCKING;
         }
         btrfs_set_path_blocking(p);
-#endif
 
         for (i = BTRFS_MAX_LEVEL - 1; i >= 0; i--) {
                 if (p->nodes[i] && p->locks[i]) {
@@ -107,10 +99,8 @@ noinline void btrfs_clear_path_blocking(struct btrfs_path *p,
                 }
         }
 
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
         if (held)
                 btrfs_clear_lock_blocking_rw(held, held_rw);
-#endif
 }
 
 /* this also releases the path */
@@ -2893,7 +2883,7 @@ cow_done:
                                         }
                                         p->locks[level] = BTRFS_WRITE_LOCK;
                                 } else {
-                                        err = btrfs_try_tree_read_lock(b);
+                                        err = btrfs_tree_read_lock_atomic(b);
                                         if (!err) {
                                                 btrfs_set_path_blocking(p);
                                                 btrfs_tree_read_lock(b);
@@ -3025,7 +3015,7 @@ again:
                         }
 
                         level = btrfs_header_level(b);
-                        err = btrfs_try_tree_read_lock(b);
+                        err = btrfs_tree_read_lock_atomic(b);
                         if (!err) {
                                 btrfs_set_path_blocking(p);
                                 btrfs_tree_read_lock(b);
diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c
index 5665d2149249..f8229ef1b46d 100644
--- a/fs/btrfs/locking.c
+++ b/fs/btrfs/locking.c
@@ -128,6 +128,26 @@ again:
 }
 
 /*
+ * take a spinning read lock.
+ * returns 1 if we get the read lock and 0 if we don't
+ * this won't wait for blocking writers
+ */
+int btrfs_tree_read_lock_atomic(struct extent_buffer *eb)
+{
+        if (atomic_read(&eb->blocking_writers))
+                return 0;
+
+        read_lock(&eb->lock);
+        if (atomic_read(&eb->blocking_writers)) {
+                read_unlock(&eb->lock);
+                return 0;
+        }
+        atomic_inc(&eb->read_locks);
+        atomic_inc(&eb->spinning_readers);
+        return 1;
+}
+
+/*
  * returns 1 if we get the read lock and 0 if we don't
  * this won't wait for blocking writers
  */
@@ -158,9 +178,7 @@ int btrfs_try_tree_write_lock(struct extent_buffer *eb)
             atomic_read(&eb->blocking_readers))
                 return 0;
 
-        if (!write_trylock(&eb->lock))
-                return 0;
-
+        write_lock(&eb->lock);
         if (atomic_read(&eb->blocking_writers) ||
             atomic_read(&eb->blocking_readers)) {
                 write_unlock(&eb->lock);
diff --git a/fs/btrfs/locking.h b/fs/btrfs/locking.h
index b81e0e9a4894..c44a9d5f5362 100644
--- a/fs/btrfs/locking.h
+++ b/fs/btrfs/locking.h
@@ -35,6 +35,8 @@ void btrfs_clear_lock_blocking_rw(struct extent_buffer *eb, int rw);
 void btrfs_assert_tree_locked(struct extent_buffer *eb);
 int btrfs_try_tree_read_lock(struct extent_buffer *eb);
 int btrfs_try_tree_write_lock(struct extent_buffer *eb);
+int btrfs_tree_read_lock_atomic(struct extent_buffer *eb);
+
 
 static inline void btrfs_tree_unlock_rw(struct extent_buffer *eb, int rw)
 {