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Re: [Qemu-devel] [PATCH 2/6] qcow2: simplify qcow2_cache_put() and qcow2
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH 2/6] qcow2: simplify qcow2_cache_put() and qcow2_cache_entry_mark_dirty() |
Date: |
Tue, 05 May 2015 09:21:58 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 |
On 04/30/2015 04:11 AM, Alberto Garcia wrote:
> Since all tables are now stored together, it is possible to obtain
> the position of a particular table directly from its address, so the
> operation becomes O(1).
>
> Signed-off-by: Alberto Garcia <address@hidden>
> ---
> block/qcow2-cache.c | 22 +++++-----------------
> 1 file changed, 5 insertions(+), 17 deletions(-)
>
> diff --git a/block/qcow2-cache.c b/block/qcow2-cache.c
> index 586880b..d3274f4 100644
> --- a/block/qcow2-cache.c
> +++ b/block/qcow2-cache.c
> @@ -335,16 +335,12 @@ int qcow2_cache_get_empty(BlockDriverState *bs,
> Qcow2Cache *c, uint64_t offset,
>
> int qcow2_cache_put(BlockDriverState *bs, Qcow2Cache *c, void **table)
> {
> - int i;
> + int i = (*table - c->table_array) / c->table_size;
Arithmetic on void* is not portable.
> void qcow2_cache_entry_mark_dirty(Qcow2Cache *c, void *table)
> {
> - int i;
> -
> - for (i = 0; i < c->size; i++) {
> - if (table_addr(c, i) == table) {
> - goto found;
> - }
> - }
> - abort();
> -
> -found:
> + int i = (table - c->table_array) / c->table_size;
and again.
> + assert(c->entries[i].offset != 0);
> c->entries[i].dirty = true;
> }
>
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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