Re: [Qemu-devel] [PATCH v3 2/2] qcow2: add update refcount table realization for update_refcount

[Jun Li]

Please ignore this patch, I have submit v4. thx.

On Mon, 10/13 13:04, Jun Li wrote:
> When every item of refcount block is NULL, free refcount block and reset the
> corresponding item of refcount table with NULL. At the same time, put this
> cluster to s->free_cluster_index.
> 
> Signed-off-by: Jun Li <address@hidden>
> ---
> This version adding handle self-describing refcount blocks.
> ---
>  block/qcow2-refcount.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 44 insertions(+)
> 
> diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
> index 2bcaaf9..8594ffd 100644
> --- a/block/qcow2-refcount.c
> +++ b/block/qcow2-refcount.c
> @@ -28,6 +28,7 @@
>  #include "qemu/range.h"
>  
>  static int64_t alloc_clusters_noref(BlockDriverState *bs, uint64_t size);
> +static int write_reftable_entry(BlockDriverState *bs, int rt_index);
>  static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs,
>                              int64_t offset, int64_t length,
>                              int addend, enum qcow2_discard_type type);
> @@ -599,6 +600,49 @@ static int QEMU_WARN_UNUSED_RESULT 
> update_refcount(BlockDriverState *bs,
>          if (refcount == 0 && s->discard_passthrough[type]) {
>              update_refcount_discard(bs, cluster_offset, s->cluster_size);
>          }
> +
> +        unsigned int refcount_table_index;
> +        refcount_table_index = cluster_index >> (s->cluster_bits -
> +                               REFCOUNT_SHIFT);
> +
> +        uint64_t refcount_block_offset =
> +            s->refcount_table[refcount_table_index] & REFT_OFFSET_MASK;
> +
> +        int64_t self_block_index = refcount_block_offset >> s->cluster_bits;
> +        int self_block_index2 = (refcount_block_offset >> s->cluster_bits) &
> +            ((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1);
> +
> +        /* When refcount block is NULL, update refcount table */
> +        if (!be16_to_cpu(refcount_block[0]) || self_block_index2 == 0) {
> +            int k;
> +            int refcount_block_entries = s->cluster_size /
> +                                         sizeof(refcount_block[0]);
> +            for (k = 0; k < refcount_block_entries; k++) {
> +                if (k == self_block_index2) {
> +                    k++;
> +                }
> +
> +                if (be16_to_cpu(refcount_block[k])) {
> +                    break;
> +                }
> +            }
> +
> +            if (k == refcount_block_entries) {
> +                if (self_block_index < s->free_cluster_index) {
> +                    s->free_cluster_index = self_block_index;
> +                }
> +
> +                /* update refcount table */
> +                s->refcount_table[refcount_table_index] = 0;
> +                ret = write_reftable_entry(bs, refcount_table_index);
> +                if (ret < 0) {
> +                    fprintf(stderr, "Could not update refcount table: %s\n",
> +                            strerror(-ret));
> +                    goto fail;
> +                }
> +
> +            }
> +        }
>      }
>  
>      ret = 0;
> -- 
> 1.9.3
>