btrfs: remove lock protection for BLOCK_GROUP_FLAG_TO_COPY

We use this during device replace for zoned devices, we were simply
taking the lock because it was in a bit field and we needed the lock to
be safe with other modifications in the bitfield.  With the bit helpers
we no longer require that locking.
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

fs/btrfs/dev-replace.c

@@ -545,10 +545,7 @@ static int mark_block_group_to_copy(struct btrfs_fs_info *fs_info,
 		if (!cache)
 			continue;
 
-		spin_lock(&cache->lock);
 		set_bit(BLOCK_GROUP_FLAG_TO_COPY, &cache->runtime_flags);
-		spin_unlock(&cache->lock);
-
 		btrfs_put_block_group(cache);
 	}
 	if (iter_ret < 0)
@@ -610,9 +607,7 @@ bool btrfs_finish_block_group_to_copy(struct btrfs_device *srcdev,
 	}
 
 	/* Last stripe on this device */
-	spin_lock(&cache->lock);
 	clear_bit(BLOCK_GROUP_FLAG_TO_COPY, &cache->runtime_flags);
-	spin_unlock(&cache->lock);
 
 	return true;
 }

fs/btrfs/scrub.c

@@ -3755,13 +3755,11 @@ int scrub_enumerate_chunks(struct scrub_ctx *sctx,
 		}
 
 		if (sctx->is_dev_replace && btrfs_is_zoned(fs_info)) {
-			spin_lock(&cache->lock);
 			if (!test_bit(BLOCK_GROUP_FLAG_TO_COPY, &cache->runtime_flags)) {
 				spin_unlock(&cache->lock);
 				btrfs_put_block_group(cache);
 				goto skip;
 			}
-			spin_unlock(&cache->lock);
 		}
 
 		/*

fs/btrfs/volumes.c

@@ -6153,9 +6153,7 @@ static bool is_block_group_to_copy(struct btrfs_fs_info *fs_info, u64 logical)
 
 	cache = btrfs_lookup_block_group(fs_info, logical);
 
-	spin_lock(&cache->lock);
 	ret = test_bit(BLOCK_GROUP_FLAG_TO_COPY, &cache->runtime_flags);
-	spin_unlock(&cache->lock);
 
 	btrfs_put_block_group(cache);
 	return ret;