On Mon, 1 Sep 2014 18:52:48 +0800
Jun Li <junm...@gmail.com> wrote:
> When every item of refcount block is NULL, free refcount block and reset the
> corresponding item of refcount table with NULL.
>
> Signed-off-by: Jun Li <address@hidden>
> ---
>
> The v2 do following change to modify some potential issue.
>
> +------- Here should start from "0".
> |
> for (k = 0; k < refcount_block_entries; k++) {
> if (refcount_block[k] != cpu_to_be16(0)) {
> ... | |
> } | |
> } | +---- Using "0" is more safe.
> |
> +-------- This should be "k" not "++k".
> ---
> block/qcow2-refcount.c | 31 +++++++++++++++++++++++++++++++
> 1 file changed, 31 insertions(+)
>
> diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
> index 43665b8..63f36e6 100644
> --- a/block/qcow2-refcount.c
> +++ b/block/qcow2-refcount.c
> @@ -586,6 +586,37 @@ 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);
> }
> +
> + /* When refcount block is NULL, update refcount table */
> + if (block_index == 0) {
> + int k = block_index;
Hi,
k = 0 is also done in the for block below...
> + int refcount_block_entries = s->cluster_size / sizeof(uint16_t);
It's better for maintainance to count elements in an array this way:
int refcount_block_entries = s->cluster_size / sizeof(refcount_block[0]);
> + for (k = 0; k < refcount_block_entries; k++) {
> + if (refcount_block[k] != cpu_to_be16(0)) {
> + break;
> + }
> + }
> +
> + if (k == refcount_block_entries) {
> + qemu_vfree(refcount_block);
> + /* update refcount table */
> + unsigned int refcount_table_index;
> + uint64_t data64 = cpu_to_be64(0);
> + refcount_table_index = cluster_index >> (s->cluster_bits -
> + REFCOUNT_SHIFT);
> + ret = bdrv_pwrite_sync(bs->file,
> + s->refcount_table_offset +
> + refcount_table_index *
> + sizeof(uint64_t),
> + &data64, sizeof(data64));
> + if (ret < 0) {
> + goto fail;
> + }
> +
> + s->refcount_table[refcount_table_index] = data64;
> +
> + }
> + }
> }
>
> ret = 0;
Cheers.
--
Gregory Kurz kurzg...@fr.ibm.com
gk...@linux.vnet.ibm.com
Software Engineer @ IBM/Meiosys http://www.ibm.com
Tel +33 (0)562 165 496
"Anarchy is about taking complete responsibility for yourself."
Alan Moore.
