> 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 TRUE otherwise
> it returns FALSE.
>
> There is also new Error parameter which will containt error messeage if
> something goes wrong.
>
> Signed-off-by: Pavel Hrdina <phrd...@redhat.com>
> ---
> savevm.c | 93
> ++++++++++++++++++++++++++++++++++++++++++++++------------------
> 1 file changed, 67 insertions(+), 26 deletions(-)
>
> diff --git a/savevm.c b/savevm.c
> index ba97c41..1622c55 100644
> --- a/savevm.c
> +++ b/savevm.c
> @@ -2262,26 +2262,66 @@ out:
> return ret;
> }
>
> -static int bdrv_snapshot_find(BlockDriverState *bs, QEMUSnapshotInfo
> *sn_info,
> - const char *name)
> +static bool bdrv_snapshot_find(BlockDriverState *bs, QEMUSnapshotInfo
> *sn_info,
> + const char *name, const char *id, Error
> **errp,
> + bool old_match)
suggest directly drop old_match parameter here, or squash patch 12
into this one, mark the change in commit message, then the logic will
be clearer.
Personally hope to place parameter *id before *name.
> {
> QEMUSnapshotInfo *sn_tab, *sn;
> - int nb_sns, i, ret;
> + int nb_sns, i;
> + bool found = false;
> +
> + assert(name || id);
>
> - ret = -ENOENT;
> nb_sns = bdrv_snapshot_list(bs, &sn_tab);
> - if (nb_sns < 0)
> - return ret;
> - for(i = 0; i < nb_sns; i++) {
> + if (nb_sns < 0) {
> + error_setg_errno(errp, -nb_sns, "Failed to get a snapshot list");
> + return found;
> + }
> +
> + if (nb_sns == 0) {
> + error_setg(errp, "Device has no snapshots");
> + return found;
> + }
suggest not set errp here, which can be used to tip exception, but
having not found one is a normal case.
> +
> + for (i = 0; i < nb_sns; i++) {
> 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 = true;
> + break;
> + }
> + } else if (name) {
> + /* for compatibility for old bdrv_snapshot_find call
> + * will be removed */
> + if (old_match) {
> + if (!strcmp(sn->id_str, name) || !strcmp(sn->name, name)) {
> + *sn_info = *sn;
> + found = true;
> + break;
> + }
> + } else {
> + if (!strcmp(sn->name, name)) {
> + *sn_info = *sn;
> + found = true;
> + break;
> + }
> + }
> + } else if (id) {
> + if (!strcmp(sn->id_str, id)) {
> + *sn_info = *sn;
> + found = true;
> + break;
> + }
> }
> }
suggest change the sequence:
if (name && id) {
for () {
}
} else if (name){
for () {
}
} else if (id) {
for () {
}
}
slightly faster, and make logic more clear.
> +
> + if (!found) {
> + error_setg(errp, "Failed to find snapshot '%s'", name ? name : id);
suggest not to set error, since it is a normal case.
> + }
> +
> g_free(sn_tab);
> - return ret;
> + return found;
> }
>
> /*
> @@ -2296,7 +2336,7 @@ 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)
> + bdrv_snapshot_find(bs, snapshot, name, NULL, NULL, true))
> {
> bdrv_snapshot_delete(bs, name, &local_err);
> if (error_is_set(&local_err)) {
> @@ -2358,8 +2398,7 @@ 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, NULL, NULL, true)) {
> pstrcpy(sn->name, sizeof(sn->name), old_sn->name);
> pstrcpy(sn->id_str, sizeof(sn->id_str), old_sn->id_str);
> } else {
> @@ -2440,6 +2479,7 @@ int load_vmstate(const char *name)
> BlockDriverState *bs, *bs_vm_state;
> QEMUSnapshotInfo sn;
> QEMUFile *f;
> + Error *local_err = NULL;
> int ret;
>
> bs_vm_state = bdrv_snapshots();
> @@ -2449,9 +2489,10 @@ 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, NULL, &local_err, true))
> {
> + error_report("Snapshot doesn't exist: %s",
> error_get_pretty(local_err));
> + error_free(local_err);
> + return -ENOENT;
> } else if (sn.vm_state_size == 0) {
> error_report("This is a disk-only snapshot. Revert to it offline "
> "using qemu-img.");
> @@ -2473,11 +2514,11 @@ int load_vmstate(const char *name)
> return -ENOTSUP;
> }
>
> - ret = bdrv_snapshot_find(bs, &sn, name);
> - if (ret < 0) {
> - error_report("Device '%s' does not have the requested snapshot
> '%s'",
> - bdrv_get_device_name(bs), name);
> - return ret;
> + if (!bdrv_snapshot_find(bs, &sn, name, NULL, &local_err, true)) {
> + error_report("Snapshot doesn't exist for device '%s': %s",
> + bdrv_get_device_name(bs),
> error_get_pretty(local_err));
> + error_free(local_err);
> + return -ENOENT;
> }
> }
>
> @@ -2546,7 +2587,7 @@ 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];
> @@ -2577,8 +2618,8 @@ 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->id_str, NULL, NULL,
> + true)) {
> available = 0;
> break;
> }
>
--
Best Regards
Wenchao Xia
