Re: [PATCH v3 03/12] btrfs: Handle pending/pinned chunks before blockgroup relocation during device shrink

[David Sterba <dsterba@suse.cz>]

On Mon, Mar 25, 2019 at 02:31:23PM +0200, Nikolay Borisov wrote:
> During device shrink pinned/pending chunks (i.e those which have been
> deleted/created respectively, in the current transaction and haven't
> touched disk) need to be accounted when doing device shrink. Presently
> this happens after the main relocation loop in btrfs_shrink_device,
> which could lead to making another go in the body of the function.
> 
> Since there is no hard requirement to perform pinned/pending chunks
> handling after the relocation loop, move the code before it. This leads
> to simplifying the code flow around - i.e no need to use 'goto again'.
> 
> Signed-off-by: Nikolay Borisov <nborisov@suse.com>
> ---
>  fs/btrfs/volumes.c | 54 ++++++++++++++++++----------------------------
>  1 file changed, 21 insertions(+), 33 deletions(-)
> 
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 3f81380265e5..b49cc5ad758e 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -4722,15 +4722,15 @@ int btrfs_shrink_device(struct btrfs_device *device, u64 new_size)
>  	int slot;
>  	int failed = 0;
>  	bool retried = false;
> -	bool checked_pending_chunks = false;
>  	struct extent_buffer *l;
>  	struct btrfs_key key;
>  	struct btrfs_super_block *super_copy = fs_info->super_copy;
>  	u64 old_total = btrfs_super_total_bytes(super_copy);
>  	u64 old_size = btrfs_device_get_total_bytes(device);
>  	u64 diff;
> +	u64 start;
>  
> -	new_size = round_down(new_size, fs_info->sectorsize);
> +	start = new_size = round_down(new_size, fs_info->sectorsize);

Please don't do that in new code, ie. no chained initializations.