Am 16.04.2013 um 18:05 hat Pavel Hrdina geschrieben:
> Finding snapshot by a name which could also be an id isn't best way
> how to do it. There will be rewrite of savevm, loadvm and delvm to
> improve the behavior of these commands. The savevm and loadvm will
> have their own patch series.
>
> Now bdrv_snapshot_find takes more parameters. The name parameter will
> be matched only against the name of the snapshot and the same applies
> to id parameter.
>
> There is one exception. If you set the last parameter, the name parameter
> will be matched against the name or the id of a snapshot. This exception
> is only for backward compatibility for other commands and it will be
> dropped after all commands will be rewritten.
>
> We only need to know if that snapshot exists or not. We don't care
> about any error message. If snapshot exists it returns 1 otherwise
> it returns 0.
Sounds like it should be true/false rather than 1/0.
Also, isn't there a difference between "there is no snapshot foo" and "we
couldn't find out if there is a snapshot foo because there was an
error"?
> Signed-off-by: Pavel Hrdina <phrd...@redhat.com>
> ---
> savevm.c | 73
> ++++++++++++++++++++++++++++++++++++++++++++--------------------
> 1 file changed, 50 insertions(+), 23 deletions(-)
>
> diff --git a/savevm.c b/savevm.c
> index 6af84fd..96a2340 100644
> --- a/savevm.c
> +++ b/savevm.c
> @@ -2197,25 +2197,55 @@ out:
> }
>
> static int bdrv_snapshot_find(BlockDriverState *bs, QEMUSnapshotInfo
> *sn_info,
> - const char *name)
> + const char *name, const char *id, bool
> old_match)
> {
> QEMUSnapshotInfo *sn_tab, *sn;
> - int nb_sns, i, ret;
> + int nb_sns, i, found = 0;
> +
> + if (!name && !id) {
> + return found;
> + }
Why not just an explicit return 0? Or actually, while you touch the
prototype you could make the function return a bool and return false.
>
> - ret = -ENOENT;
> nb_sns = bdrv_snapshot_list(bs, &sn_tab);
> - if (nb_sns < 0)
> - return ret;
> + if (nb_sns < 0) {
> + return found;
> + }
Same here.
> +
> for(i = 0; i < nb_sns; i++) {
You can add a space after 'for' while touching the function.
> sn = &sn_tab[i];
> - if (!strcmp(sn->id_str, name) || !strcmp(sn->name, name)) {
> - *sn_info = *sn;
> - ret = 0;
> - break;
> + if (name && id) {
> + if (!strcmp(sn->id_str, id) && !strcmp(sn->name, name)) {
> + *sn_info = *sn;
> + found = 1;
> + break;
> + }
> + } else if (name) {
> + /* for compatibility for old bdrv_snapshot_find call
> + * will be removed */
> + if (old_match) {
> + if (!strcmp(sn->id_str, id) || !strcmp(sn->name, name)) {
> + *sn_info = *sn;
> + found = 1;
> + break;
> + }
> + } else {
> + if (!strcmp(sn->name, name)) {
> + *sn_info = *sn;
> + found = 1;
> + break;
> + }
> + }
> + } else if (id) {
> + if (!strcmp(sn->id_str, id)) {
> + *sn_info = *sn;
> + found = 1;
> + break;
> + }
> }
> }
> +
> g_free(sn_tab);
> - return ret;
> + return found;
> }
>
> /*
> @@ -2229,8 +2259,8 @@ static int del_existing_snapshots(Monitor *mon, const
> char *name)
>
> bs = NULL;
> while ((bs = bdrv_next(bs))) {
> - if (bdrv_can_snapshot(bs) &&
> - bdrv_snapshot_find(bs, snapshot, name) >= 0)
> + if (bdrv_can_snapshot(bs)
> + && bdrv_snapshot_find(bs, snapshot, name, name, true))
It would only retain the old behaviour if you specified NULL for id.
Now _both_ name and id must match, which will happen almost never.
How did you test this patch? Sounds like something that a qemu-iotests
case using the Python QMP methods could easily test.
> {
> bdrv_snapshot_delete(bs, name, &local_err);
> if (error_is_set(&local_err)) {
> @@ -2289,8 +2319,7 @@ void do_savevm(Monitor *mon, const QDict *qdict)
> sn->vm_clock_nsec = qemu_get_clock_ns(vm_clock);
>
> if (name) {
> - ret = bdrv_snapshot_find(bs, old_sn, name);
> - if (ret >= 0) {
> + if (bdrv_snapshot_find(bs, old_sn, name, name, true)) {
Same problem.
> pstrcpy(sn->name, sizeof(sn->name), old_sn->name);
> pstrcpy(sn->id_str, sizeof(sn->id_str), old_sn->id_str);
> } else {
> @@ -2380,9 +2409,8 @@ int load_vmstate(const char *name)
> }
>
> /* Don't even try to load empty VM states */
> - ret = bdrv_snapshot_find(bs_vm_state, &sn, name);
> - if (ret < 0) {
> - return ret;
> + if (!bdrv_snapshot_find(bs_vm_state, &sn, name, name, true)) {
And again.
> + return -ENOENT;
We're losing the real error message here. The old code said exactly what
happened, the new one always claims that the snapshot doesn't exist even
in case of I/O errors or anything.
> } else if (sn.vm_state_size == 0) {
> error_report("This is a disk-only snapshot. Revert to it offline "
> "using qemu-img.");
> @@ -2404,11 +2432,10 @@ int load_vmstate(const char *name)
> return -ENOTSUP;
> }
>
> - ret = bdrv_snapshot_find(bs, &sn, name);
> - if (ret < 0) {
> + if (!bdrv_snapshot_find(bs, &sn, name, name, true)) {
> error_report("Device '%s' does not have the requested snapshot
> '%s'",
> bdrv_get_device_name(bs), name);
> - return ret;
> + return -ENOENT;
> }
> }
>
> @@ -2474,7 +2501,7 @@ void do_info_snapshots(Monitor *mon, const QDict *qdict)
> {
> BlockDriverState *bs, *bs1;
> QEMUSnapshotInfo *sn_tab, *sn, s, *sn_info = &s;
> - int nb_sns, i, ret, available;
> + int nb_sns, i, available;
> int total;
> int *available_snapshots;
> char buf[256];
> @@ -2505,8 +2532,8 @@ void do_info_snapshots(Monitor *mon, const QDict *qdict)
>
> while ((bs1 = bdrv_next(bs1))) {
> if (bdrv_can_snapshot(bs1) && bs1 != bs) {
> - ret = bdrv_snapshot_find(bs1, sn_info, sn->id_str);
> - if (ret < 0) {
> + if (!bdrv_snapshot_find(bs1, sn_info, sn->name, sn->id_str,
> + true)) {
Is it intention that both id and name must match here? I suspect that no
because you set old_match == true, which is however ignored because both
id and name are set.
> available = 0;
> break;
> }
Kevin
