Btrfs: Refactor btrfs_lock_cluster() to kill compiler warning

fs/btrfs/extent-tree.c: In function ‘btrfs_lock_cluster’:
fs/btrfs/extent-tree.c:6399: warning: ‘used_bg’ may be used uninitialized in this function

  - Replace "again: ... goto again;" by standard C "while (1) { ... }",
  - Move block not processed during the first iteration of the loop to the
    end of the loop, which allows to kill the "locked" variable,

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-and-Tested-by: Miao Xie <miaox@cn.fujitsu.com>
[ the compilation warning has been fixed by other patch, now we want to
  clean up the function ]
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index c0520a94a333cea60a986b54a41ecf279866c13e..b66f460f779ab27986d4e7057f334bfa5cc112cb 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -7025,36 +7025,35 @@ btrfs_lock_cluster(struct btrfs_block_group_cache *block_group,
                   int delalloc)
 {
        struct btrfs_block_group_cache *used_bg = NULL;
-       bool locked = false;
-again:
+
        spin_lock(&cluster->refill_lock);
-       if (locked) {
-               if (used_bg == cluster->block_group)
+       while (1) {
+               used_bg = cluster->block_group;
+               if (!used_bg)
+                       return NULL;
+
+               if (used_bg == block_group)
                        return used_bg;
 
-               up_read(&used_bg->data_rwsem);
-               btrfs_put_block_group(used_bg);
-       }
+               btrfs_get_block_group(used_bg);
 
-       used_bg = cluster->block_group;
-       if (!used_bg)
-               return NULL;
+               if (!delalloc)
+                       return used_bg;
 
-       if (used_bg == block_group)
-               return used_bg;
+               if (down_read_trylock(&used_bg->data_rwsem))
+                       return used_bg;
 
-       btrfs_get_block_group(used_bg);
+               spin_unlock(&cluster->refill_lock);
 
-       if (!delalloc)
-               return used_bg;
+               down_read(&used_bg->data_rwsem);
 
-       if (down_read_trylock(&used_bg->data_rwsem))
-               return used_bg;
+               spin_lock(&cluster->refill_lock);
+               if (used_bg == cluster->block_group)
+                       return used_bg;
 
-       spin_unlock(&cluster->refill_lock);
-       down_read(&used_bg->data_rwsem);
-       locked = true;
-       goto again;
+               up_read(&used_bg->data_rwsem);
+               btrfs_put_block_group(used_bg);
+       }
 }
 
 static inline void