[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [PATCH 2/3] qcow2: refactor handle_dependencies() loop body
From: |
Eric Blake |
Subject: |
Re: [PATCH 2/3] qcow2: refactor handle_dependencies() loop body |
Date: |
Thu, 19 Aug 2021 12:58:18 -0500 |
User-agent: |
NeoMutt/20210205-732-28786f |
On Sat, Jul 24, 2021 at 04:38:45PM +0300, Vladimir Sementsov-Ogievskiy wrote:
> No logic change, just prepare for the following commit.
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---
> block/qcow2-cluster.c | 49 ++++++++++++++++++++++++-------------------
> 1 file changed, 28 insertions(+), 21 deletions(-)
>
> diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
> index bd0597842f..967121c7e6 100644
> --- a/block/qcow2-cluster.c
> +++ b/block/qcow2-cluster.c
> @@ -1400,29 +1400,36 @@ static int handle_dependencies(BlockDriverState *bs,
> uint64_t guest_offset,
>
> if (end <= old_start || start >= old_end) {
> /* No intersection */
> - } else {
> - if (start < old_start) {
> - /* Stop at the start of a running allocation */
> - bytes = old_start - start;
> - } else {
> - bytes = 0;
> - }
> + continue;
> + }
>
> - /* Stop if already an l2meta exists. After yielding, it wouldn't
Pre-existing, but...
> - * be valid any more, so we'd have to clean up the old L2Metas
> - * and deal with requests depending on them before starting to
> - * gather new ones. Not worth the trouble. */
> - if (bytes == 0 && *m) {
> - *cur_bytes = 0;
> - return 0;
> - }
> + /* Conflict */
>
> - if (bytes == 0) {
> - /* Wait for the dependency to complete. We need to recheck
> - * the free/allocated clusters when we continue. */
> - qemu_co_queue_wait(&old_alloc->dependent_requests, &s->lock);
> - return -EAGAIN;
> - }
> + if (start < old_start) {
> + /* Stop at the start of a running allocation */
> + bytes = old_start - start;
> + } else {
> + bytes = 0;
> + }
> +
> + /*
> + * Stop if already an l2meta exists. After yielding, it wouldn't
...might as well fix the grammar: Stop if an l2meta already exists.
> + * be valid any more, so we'd have to clean up the old L2Metas
> + * and deal with requests depending on them before starting to
> + * gather new ones. Not worth the trouble.
> + */
> + if (bytes == 0 && *m) {
> + *cur_bytes = 0;
> + return 0;
> + }
> +
> + if (bytes == 0) {
> + /*
> + * Wait for the dependency to complete. We need to recheck
> + * the free/allocated clusters when we continue.
> + */
> + qemu_co_queue_wait(&old_alloc->dependent_requests, &s->lock);
> + return -EAGAIN;
So the change adds a short-circuiting 'continue', then reduces the
indentation of the rest of the loop body.
Reviewed-by: Eric Blake <eblake@redhat.com>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
- Re: [PATCH 2/3] qcow2: refactor handle_dependencies() loop body,
Eric Blake <=