btrfs: Streamline replace sem unlock in btrfs_dev_replace_start

There are only 2 branches which goto leave label with need_unlock set
to true. Essentially need_unlock is used as a substitute for directly
calling up_write. Since the branches needing this are only 2 and their
context is not that big it's more clear to just call up_write where
required. No functional changes.
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/dev-replace.c

@@ -400,7 +400,6 @@ static int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
 	int ret;
 	struct btrfs_device *tgt_device = NULL;
 	struct btrfs_device *src_device = NULL;
-	bool need_unlock;
 
 	src_device = btrfs_find_device_by_devspec(fs_info, srcdevid,
 						  srcdev_name);
@@ -432,7 +431,6 @@ static int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
 	if (ret)
 		return ret;
 
-	need_unlock = true;
 	down_write(&dev_replace->rwsem);
 	switch (dev_replace->replace_state) {
 	case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
@@ -443,6 +441,7 @@ static int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
 	case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 		ASSERT(0);
 		ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_ALREADY_STARTED;
+		up_write(&dev_replace->rwsem);
 		goto leave;
 	}
 
@@ -471,7 +470,6 @@ static int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
 	atomic64_set(&dev_replace->num_write_errors, 0);
 	atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
 	up_write(&dev_replace->rwsem);
-	need_unlock = false;
 
 	ret = btrfs_sysfs_add_device_link(tgt_device->fs_devices, tgt_device);
 	if (ret)
@@ -483,12 +481,12 @@ static int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
 	trans = btrfs_start_transaction(root, 0);
 	if (IS_ERR(trans)) {
 		ret = PTR_ERR(trans);
-		need_unlock = true;
 		down_write(&dev_replace->rwsem);
 		dev_replace->replace_state =
 			BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED;
 		dev_replace->srcdev = NULL;
 		dev_replace->tgtdev = NULL;
+		up_write(&dev_replace->rwsem);
 		goto leave;
 	}
 
@@ -510,8 +508,6 @@ static int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
 	return ret;
 
 leave:
-	if (need_unlock)
-		up_write(&dev_replace->rwsem);
 	btrfs_destroy_dev_replace_tgtdev(tgt_device);
 	return ret;
 }