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Re: [Qemu-devel] [RFC PATCH 1/4] qapi: Convert savevm
From: |
Luiz Capitulino |
Subject: |
Re: [Qemu-devel] [RFC PATCH 1/4] qapi: Convert savevm |
Date: |
Mon, 23 Jul 2012 17:41:08 -0300 |
On Thu, 12 Jul 2012 18:55:15 +0200
Pavel Hrdina <address@hidden> wrote:
> Signed-off-by: Pavel Hrdina <address@hidden>
> ---
> hmp-commands.hx | 2 +-
> hmp.c | 10 ++++++++++
> hmp.h | 1 +
> qapi-schema.json | 22 ++++++++++++++++++++++
> qerror.c | 24 ++++++++++++++++++++++++
> qerror.h | 18 ++++++++++++++++++
> qmp-commands.hx | 26 ++++++++++++++++++++++++++
> savevm.c | 29 ++++++++++++++---------------
> sysemu.h | 1 -
> 9 files changed, 116 insertions(+), 17 deletions(-)
>
> diff --git a/hmp-commands.hx b/hmp-commands.hx
> index f5d9d91..e8c5325 100644
> --- a/hmp-commands.hx
> +++ b/hmp-commands.hx
> @@ -267,7 +267,7 @@ ETEXI
> .args_type = "name:s?",
> .params = "[tag|id]",
> .help = "save a VM snapshot. If no tag or id are provided, a
> new snapshot is created",
> - .mhandler.cmd = do_savevm,
> + .mhandler.cmd = hmp_savevm,
> },
>
> STEXI
> diff --git a/hmp.c b/hmp.c
> index 4c6d4ae..491599d 100644
> --- a/hmp.c
> +++ b/hmp.c
> @@ -1002,3 +1002,13 @@ void hmp_netdev_del(Monitor *mon, const QDict *qdict)
> qmp_netdev_del(id, &err);
> hmp_handle_error(mon, &err);
> }
> +
> +void hmp_savevm(Monitor *mon, const QDict *qdict)
> +{
> + const char *name = qdict_get_try_str(qdict, "name");
> + Error *err = NULL;
> +
> + qmp_savevm(!!name, name, &err);
> +
> + hmp_handle_error(mon, &err);
> +}
> diff --git a/hmp.h b/hmp.h
> index 79d138d..dc6410b 100644
> --- a/hmp.h
> +++ b/hmp.h
> @@ -64,5 +64,6 @@ void hmp_device_del(Monitor *mon, const QDict *qdict);
> void hmp_dump_guest_memory(Monitor *mon, const QDict *qdict);
> void hmp_netdev_add(Monitor *mon, const QDict *qdict);
> void hmp_netdev_del(Monitor *mon, const QDict *qdict);
> +void hmp_savevm(Monitor *mon, const QDict *qdict);
>
> #endif
> diff --git a/qapi-schema.json b/qapi-schema.json
> index 1ab5dbd..4db1447 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -1868,3 +1868,25 @@
> # Since: 0.14.0
> ##
> { 'command': 'netdev_del', 'data': {'id': 'str'} }
> +
> +##
> +# @savevm:
Let's call it save-vm.
> +#
> +# Create a snapshot of the whole virtual machine. If 'tag' is provided,
> +# it is used as human readable identifier. If there is already a snapshot
> +# with the same tag or ID, it is replaced.
Please, document that the vm is automatically stopped and resumed, and that
this can take a long time.
> +#
> +# @name: tag or id of new or existing snapshot
I don't like the idea of making 'name' optional in QMP. We could (and should)
have it as optional in HMP though. This means that we should move the code
that auto-generates it to HMP.
Also, I remember an old discussion about distinguishing between 'tag' and 'id'.
I remember it was difficult to do, so we could choose not to do it, but let's
re-evaluate this again.
> +#
> +# Returns: Nothing on success
> +# If there is a writable device not supporting snapshots,
> +# SnapshotNotSupported
> +# If no block device can accept snapshots, SnapshotNotAccepted
> +# If an error occures while creating a snapshot,
> SnapshotCreateFailed
> +# If open a block device for vm state fail, SnapshotOpenFailed
> +# If an error uccures while writing vm state, SnapshotWriteFailed
> +# If delete snapshot with same 'name' fail, SnapshotDeleteFailed
I don't think we should re-create all these errors, more comments on that
below.
> +#
> +# Since: 1.2
> +##
> +{ 'command': 'savevm', 'data': {'*name': 'str'} }
> \ No newline at end of file
> diff --git a/qerror.c b/qerror.c
> index 92c4eff..4e6efa1 100644
> --- a/qerror.c
> +++ b/qerror.c
> @@ -309,6 +309,30 @@ static const QErrorStringTable qerror_table[] = {
> .desc = "Could not start VNC server on %(target)",
> },
> {
> + .error_fmt = QERR_SNAPSHOT_CREATE_FAILED,
> + .desc = "Error '%(errno)' while creating snapshot on
> '%(device)'",
> + },
> + {
> + .error_fmt = QERR_SNAPSHOT_DELETE_FAILED,
> + .desc = "Error '%(errno)' while deleting snapshot on
> '%(device)'",
> + },
> + {
> + .error_fmt = QERR_SNAPSHOT_NOT_ACCEPTED,
> + .desc = "No block device can accept snapshots",
> + },
> + {
> + .error_fmt = QERR_SNAPSHOT_NOT_SUPPORTED,
> + .desc = "Device '%(device)' is writable but does not support
> snapshots",
> + },
> + {
> + .error_fmt = QERR_SNAPSHOT_OPEN_FAILED,
> + .desc = "Error while opening snapshot on '%(device)'",
> + },
> + {
> + .error_fmt = QERR_SNAPSHOT_WRITE_FAILED,
> + .desc = "Error '%(errno)' while writing snapshot on
> '%(device)'",
> + },
> + {
> .error_fmt = QERR_SOCKET_CONNECT_IN_PROGRESS,
> .desc = "Connection can not be completed immediately",
> },
> diff --git a/qerror.h b/qerror.h
> index b4c8758..bc47f4a 100644
> --- a/qerror.h
> +++ b/qerror.h
> @@ -251,6 +251,24 @@ QError *qobject_to_qerror(const QObject *obj);
> #define QERR_VNC_SERVER_FAILED \
> "{ 'class': 'VNCServerFailed', 'data': { 'target': %s } }"
>
> +#define QERR_SNAPSHOT_CREATE_FAILED \
> + "{ 'class': 'SnapshotCreateFailed', 'data': { 'device': %s, 'errno': %d
> } }"
> +
> +#define QERR_SNAPSHOT_DELETE_FAILED \
> + "{ 'class': 'SnapshotDeleteFailed', 'data': { 'device': %s, 'errno': %d
> } }"
> +
> +#define QERR_SNAPSHOT_NOT_ACCEPTED \
> + "{ 'class': 'SnapshotNotAccepted', 'data': {} }"
> +
> +#define QERR_SNAPSHOT_NOT_SUPPORTED \
> + "{ 'class': 'SnapshotNotSupported', 'data': { 'device': %s } }"
> +
> +#define QERR_SNAPSHOT_OPEN_FAILED \
> + "{ 'class': 'SnapshotOpenFailed', 'data': { 'device': %s } }"
> +
> +#define QERR_SNAPSHOT_WRITE_FAILED \
> + "{ 'class': 'SnapshotWriteFailed', 'data': { 'device': %s, 'errno': %d }
> }"
> +
> #define QERR_SOCKET_CONNECT_IN_PROGRESS \
> "{ 'class': 'SockConnectInprogress', 'data': {} }"
>
> diff --git a/qmp-commands.hx b/qmp-commands.hx
> index 2e1a38e..a1c82f7 100644
> --- a/qmp-commands.hx
> +++ b/qmp-commands.hx
> @@ -1061,6 +1061,32 @@ Example:
>
> EQMP
> {
> + .name = "savevm",
> + .args_type = "name:s?",
> + .params = "name",
> + .help = "save a VM snapshot. If no tag or id are provided, a
> new snapshot is created",
> + .mhandler.cmd_new = qmp_marshal_input_savevm
> + },
> +
> +SQMP
> +savevm
> +------
> +
> +Create a snapshot of the whole virtual machine. If 'tag' is provided,
> +it is used as human readable identifier. If there is already a snapshot
> +with the same tag or ID, it is replaced.
> +
> +Arguments:
> +
> +- "name": tag or id of new or existing snapshot
> +
> +Example:
> +
> +-> { "execute": "savevm", "arguments": { "name": "my_snapshot" } }
> +<- { "return": {} }
> +
> +EQMP
> + {
> .name = "qmp_capabilities",
> .args_type = "",
> .params = "",
> diff --git a/savevm.c b/savevm.c
> index a15c163..9fc1b53 100644
> --- a/savevm.c
> +++ b/savevm.c
> @@ -2033,7 +2033,7 @@ static int bdrv_snapshot_find(BlockDriverState *bs,
> QEMUSnapshotInfo *sn_info,
> /*
> * Deletes snapshots of a given name in all opened images.
> */
> -static int del_existing_snapshots(Monitor *mon, const char *name)
> +static int del_existing_snapshots(Error **errp, const char *name)
> {
> BlockDriverState *bs;
> QEMUSnapshotInfo sn1, *snapshot = &sn1;
> @@ -2046,9 +2046,8 @@ static int del_existing_snapshots(Monitor *mon, const
> char *name)
> {
> ret = bdrv_snapshot_delete(bs, name);
> if (ret < 0) {
> - monitor_printf(mon,
> - "Error while deleting snapshot on '%s'\n",
> - bdrv_get_device_name(bs));
> + error_set(errp, QERR_SNAPSHOT_DELETE_FAILED,
> + bdrv_get_device_name(bs), ret);
The Right Thing to do here is to change bdrv_snapshot_delete() to take an Error
argument and let it set the real error cause. Three considerations:
1. The QMP command shouldn't delete existing snapshots by default. Either,
we add a 'force' argument to it or don't delete snapshots in save-vm
at all (in which case a mngt app would have to delete the snapshots with the
same name manually, I prefer this approach btw)
2. This has to be done in a separate series
3. It's a good idea to wait for my series improving error_set() to be merged
before doing this
> return -1;
> }
> }
> @@ -2057,7 +2056,7 @@ static int del_existing_snapshots(Monitor *mon, const
> char *name)
> return 0;
> }
>
> -void do_savevm(Monitor *mon, const QDict *qdict)
> +void qmp_savevm(bool has_name, const char *name, Error **errp)
> {
> BlockDriverState *bs, *bs1;
> QEMUSnapshotInfo sn1, *sn = &sn1, old_sn1, *old_sn = &old_sn1;
> @@ -2072,7 +2071,6 @@ void do_savevm(Monitor *mon, const QDict *qdict)
> struct timeval tv;
> struct tm tm;
> #endif
> - const char *name = qdict_get_try_str(qdict, "name");
>
> /* Verify if there is a device that doesn't support snapshots and is
> writable */
> bs = NULL;
> @@ -2083,15 +2081,15 @@ void do_savevm(Monitor *mon, const QDict *qdict)
> }
>
> if (!bdrv_can_snapshot(bs)) {
> - monitor_printf(mon, "Device '%s' is writable but does not
> support snapshots.\n",
> - bdrv_get_device_name(bs));
> + error_set(errp, QERR_SNAPSHOT_NOT_SUPPORTED,
> + bdrv_get_device_name(bs));
Please, use QERR_NOT_SUPPORTED instead. I know it doesn't allow any arguments
today, but I'm working on a series which will allow you to pass any arguments
you wish.
> return;
> }
> }
>
> bs = bdrv_snapshots();
> if (!bs) {
> - monitor_printf(mon, "No block device can accept snapshots\n");
> + error_set(errp, QERR_SNAPSHOT_NOT_ACCEPTED);
I think we should use QERR_NOT_SUPPORTED here too.
> return;
> }
>
> @@ -2112,7 +2110,7 @@ void do_savevm(Monitor *mon, const QDict *qdict)
> #endif
> sn->vm_clock_nsec = qemu_get_clock_ns(vm_clock);
>
> - if (name) {
> + if (has_name) {
> ret = bdrv_snapshot_find(bs, old_sn, name);
> if (ret >= 0) {
> pstrcpy(sn->name, sizeof(sn->name), old_sn->name);
> @@ -2133,21 +2131,22 @@ void do_savevm(Monitor *mon, const QDict *qdict)
> }
>
> /* Delete old snapshots of the same name */
> - if (name && del_existing_snapshots(mon, name) < 0) {
> + if (has_name && del_existing_snapshots(errp, name) < 0) {
> goto the_end;
> }
The QMP command should not delete existing snapshots, as said above.
>
> /* save the VM state */
> f = qemu_fopen_bdrv(bs, 1);
> if (!f) {
> - monitor_printf(mon, "Could not open VM state file\n");
> + error_set(errp, QERR_SNAPSHOT_OPEN_FAILED, bdrv_get_device_name(bs));
Please, use QERR_OPEN_FILE_FAILED instead. The filename should be the backing
file name.
> goto the_end;
> }
> ret = qemu_savevm_state(f);
> vm_state_size = qemu_ftell(f);
> qemu_fclose(f);
> if (ret < 0) {
> - monitor_printf(mon, "Error %d while writing VM\n", ret);
> + error_set(errp, QERR_SNAPSHOT_WRITE_FAILED,
> + bdrv_get_device_name(bs), ret);
The Right Thing to do here it to convert qemu_savevm_sstate() to take
an Error argument. The same considerations I wrote above about
del_existing_snapshots() apply here, except that you can report IOError
for most qemu_savevm_state() errors.
> goto the_end;
> }
>
> @@ -2160,8 +2159,8 @@ void do_savevm(Monitor *mon, const QDict *qdict)
> sn->vm_state_size = (bs == bs1 ? vm_state_size : 0);
> ret = bdrv_snapshot_create(bs1, sn);
> if (ret < 0) {
> - monitor_printf(mon, "Error while creating snapshot on
> '%s'\n",
> - bdrv_get_device_name(bs1));
> + error_set(errp, QERR_SNAPSHOT_CREATE_FAILED,
> + bdrv_get_device_name(bs1), ret);
Here too, bdrv_snapshot_create() should be changed to take an Error
argument.
> }
> }
> }
> diff --git a/sysemu.h b/sysemu.h
> index 6540c79..95d1207 100644
> --- a/sysemu.h
> +++ b/sysemu.h
> @@ -69,7 +69,6 @@ void qemu_remove_exit_notifier(Notifier *notify);
>
> void qemu_add_machine_init_done_notifier(Notifier *notify);
>
> -void do_savevm(Monitor *mon, const QDict *qdict);
> int load_vmstate(const char *name);
> void do_delvm(Monitor *mon, const QDict *qdict);
> void do_info_snapshots(Monitor *mon);
[Qemu-devel] [RFC PATCH 4/4] qapi: Convert info snapshots, Pavel Hrdina, 2012/07/12
[Qemu-devel] [RFC PATCH 2/4] qapi: Convert loadvm, Pavel Hrdina, 2012/07/12