Btrfs: cleanup the code of used_block_group in find_free_extent()

used_block_group is just used for the space cluster which doesn't
belong to the current block group, the other place needn't use it.
Or the logic of code seems unclear.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 13 insertions, 20 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 1efcc262be47..b55a4fd13ecc 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -6159,7 +6159,6 @@ static noinline int find_free_extent(struct btrfs_root *orig_root,
         struct btrfs_root *root = orig_root->fs_info->extent_root;
         struct btrfs_free_cluster *last_ptr = NULL;
         struct btrfs_block_group_cache *block_group = NULL;
-        struct btrfs_block_group_cache *used_block_group;
         u64 search_start = 0;
         u64 max_extent_size = 0;
         int empty_cluster = 2 * 1024 * 1024;
@@ -6220,7 +6219,6 @@ static noinline int find_free_extent(struct btrfs_root *orig_root,
         if (search_start == hint_byte) {
                 block_group = btrfs_lookup_block_group(root->fs_info,
                                                        search_start);
-                used_block_group = block_group;
                 /*
                  * we don't want to use the block group if it doesn't match our
                  * allocation bits, or if its not cached.
@@ -6257,7 +6255,6 @@ search:
                 u64 offset;
                 int cached;
 
-                used_block_group = block_group;
                 btrfs_get_block_group(block_group);
                 search_start = block_group->key.objectid;
 
@@ -6300,6 +6297,7 @@ have_block_group:
                  * lets look there
                  */
                 if (last_ptr) {
+                        struct btrfs_block_group_cache *used_block_group;
                         unsigned long aligned_cluster;
                         /*
                          * the refill lock keeps out other
@@ -6310,10 +6308,8 @@ have_block_group:
                         if (used_block_group != block_group &&
                             (!used_block_group ||
                              used_block_group->ro ||
-                             !block_group_bits(used_block_group, flags))) {
-                                used_block_group = block_group;
+                             !block_group_bits(used_block_group, flags)))
                                 goto refill_cluster;
-                        }
 
                         if (used_block_group != block_group)
                                 btrfs_get_block_group(used_block_group);
@@ -6328,16 +6324,17 @@ have_block_group:
                                 spin_unlock(&last_ptr->refill_lock);
                                 trace_btrfs_reserve_extent_cluster(root,
                                         block_group, search_start, num_bytes);
+                                if (used_block_group != block_group) {
+                                        btrfs_put_block_group(block_group);
+                                        block_group = used_block_group;
+                                }
                                 goto checks;
                         }
 
                         WARN_ON(last_ptr->block_group != used_block_group);
-                        if (used_block_group != block_group) {
+                        if (used_block_group != block_group)
                                 btrfs_put_block_group(used_block_group);
-                                used_block_group = block_group;
-                        }
 refill_cluster:
-                        BUG_ON(used_block_group != block_group);
                         /* If we are on LOOP_NO_EMPTY_SIZE, we can't
                          * set up a new clusters, so lets just skip it
                          * and let the allocator find whatever block
@@ -6456,25 +6453,25 @@ unclustered_alloc:
                         goto loop;
                 }
 checks:
-                search_start = stripe_align(root, used_block_group,
+                search_start = stripe_align(root, block_group,
                                             offset, num_bytes);
 
                 /* move on to the next group */
                 if (search_start + num_bytes >
-                    used_block_group->key.objectid + used_block_group->key.offset) {
-                        btrfs_add_free_space(used_block_group, offset, num_bytes);
+                    block_group->key.objectid + block_group->key.offset) {
+                        btrfs_add_free_space(block_group, offset, num_bytes);
                         goto loop;
                 }
 
                 if (offset < search_start)
-                        btrfs_add_free_space(used_block_group, offset,
+                        btrfs_add_free_space(block_group, offset,
                                              search_start - offset);
                 BUG_ON(offset > search_start);
 
-                ret = btrfs_update_reserved_bytes(used_block_group, num_bytes,
+                ret = btrfs_update_reserved_bytes(block_group, num_bytes,
                                                   alloc_type);
                 if (ret == -EAGAIN) {
-                        btrfs_add_free_space(used_block_group, offset, num_bytes);
+                        btrfs_add_free_space(block_group, offset, num_bytes);
                         goto loop;
                 }
 
@@ -6484,16 +6481,12 @@ checks:
 
                 trace_btrfs_reserve_extent(orig_root, block_group,
                                            search_start, num_bytes);
-                if (used_block_group != block_group)
-                        btrfs_put_block_group(used_block_group);
                 btrfs_put_block_group(block_group);
                 break;
 loop:
                 failed_cluster_refill = false;
                 failed_alloc = false;
                 BUG_ON(index != get_block_group_index(block_group));
-                if (used_block_group != block_group)
-                        btrfs_put_block_group(used_block_group);
                 btrfs_put_block_group(block_group);
         }
         up_read(&space_info->groups_sem);