Re: [Qemu-devel] [PATCH v13 01/12] qcow2: Nicer variable names in qcow2_update_snapshot_refcount()

[Max Reitz <mreitz@redhat.com>]

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On 07.05.2017 02:05, Eric Blake wrote:
> In order to keep checkpatch happy when the next patch changes
> indentation, we first have to shorten some long lines.  The easiest
> approach is to use a new variable in place of
> 'offset & L2E_OFFSET_MASK', except that 'offset' is the best name
> for that variable.  Change '[old_]offset' to '[old_]entry' to
> make room.
> 
> While touching things, also fix checkpatch warnings about unusual
> 'for' statements.
> 
> Suggested by Max Reitz <mreitz@redhat.com>
> Signed-off-by: Eric Blake <eblake@redhat.com>
> 
> ---
> v13: new patch
> ---
>  block/qcow2-refcount.c | 42 ++++++++++++++++++++++--------------------
>  1 file changed, 22 insertions(+), 20 deletions(-)
> 
> diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
> index 4efca7e..db0af2c 100644
> --- a/block/qcow2-refcount.c
> +++ b/block/qcow2-refcount.c

[...]

> @@ -1117,20 +1118,22 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs,
>                  goto fail;
>              }
> 
> -            for(j = 0; j < s->l2_size; j++) {
> +            for (j = 0; j < s->l2_size; j++) {
>                  uint64_t cluster_index;
> +                uint64_t offset;

Actually, introducing entry and old_entry in this scope would have
sufficed, too, because they aren't used anywhere else. But nobody
actually cares (O:-)), so:

Reviewed-by: Max Reitz <mreitz@redhat.com>

> 
> -                offset = be64_to_cpu(l2_table[j]);
> -                old_offset = offset;
> -                offset &= ~QCOW_OFLAG_COPIED;
> +                entry = be64_to_cpu(l2_table[j]);
> +                old_entry = entry;
> +                entry &= ~QCOW_OFLAG_COPIED;
> +                offset = entry & L2E_OFFSET_MASK;
> 
> -                switch (qcow2_get_cluster_type(offset)) {
> +                switch (qcow2_get_cluster_type(entry)) {
>                      case QCOW2_CLUSTER_COMPRESSED:
> -                        nb_csectors = ((offset >> s->csize_shift) &
> +                        nb_csectors = ((entry >> s->csize_shift) &
>                                         s->csize_mask) + 1;
>                          if (addend != 0) {
>                              ret = update_refcount(bs,
> -                                (offset & s->cluster_offset_mask) & ~511,
> +                                (entry & s->cluster_offset_mask) & ~511,
>                                  nb_csectors * 512, abs(addend), addend < 0,
>                                  QCOW2_DISCARD_SNAPSHOT);
>                              if (ret < 0) {


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