[PATCH] Btrfs: Refactor btrfs_lock_cluster() to kill compiler warning

Geert Uytterhoeven
2014-06-22T12:30:21Z

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>
---
Please review, compile tested only.
---
fs/btrfs/extent-tree.c | 42 ++++++++++++++++++++----------------------
1 file changed, 20 insertions(+), 22 deletions(-)

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 99c253918208..e151c4a73d7b 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -6397,36 +6397,34 @@ btrfs_lock_cluster(struct btrfs_block_group_cache *block_group,
int delalloc)
{
struct btrfs_block_group_cache *used_bg;
- bool locked = false;
-again:
+
spin_lock(&cluster->refill_lock);
- if (locked) {
- if (used_bg == cluster->block_group)
- return used_bg;
+ while (1) {
+ used_bg = cluster->block_group;
+ if (!used_bg)
+ return NULL;

- up_read(&used_bg->data_rwsem);
- btrfs_put_block_group(used_bg);
- }
+ if (used_bg == block_group)
+ return used_bg;

- used_bg = cluster->block_group;
- if (!used_bg)
- return NULL;
+ btrfs_get_block_group(used_bg);

- if (used_bg == block_group)
- return used_bg;
+ if (!delalloc)
+ return used_bg;

- btrfs_get_block_group(used_bg);
+ if (down_read_trylock(&used_bg->data_rwsem))
+ return used_bg;

- if (!delalloc)
- return used_bg;
+ spin_unlock(&cluster->refill_lock);
+ 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
--
1.9.1