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snapshot: create helper to test that block drivers supports snapshots

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The patch enforces proper locking for this operation.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
Tested-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
This commit is contained in:
Denis V. Lunev 2015-11-19 09:42:01 +03:00 committed by Juan Quintela
parent 5df5416e63
commit e9ff957ac2
3 changed files with 36 additions and 13 deletions
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24
block/snapshot.c
View File

@ -356,3 +356,27 @@ int bdrv_snapshot_load_tmp_by_id_or_name(BlockDriverState *bs,
return ret; return ret;
} }
/* Group operations. All block drivers are involved.
* These functions will properly handle dataplane (take aio_context_acquire
* when appropriate for appropriate block drivers) */
bool bdrv_all_can_snapshot(BlockDriverState **first_bad_bs)
{
bool ok = true;
BlockDriverState *bs = NULL;
while (ok && (bs = bdrv_next(bs))) {
AioContext *ctx = bdrv_get_aio_context(bs);
aio_context_acquire(ctx);
if (bdrv_is_inserted(bs) && !bdrv_is_read_only(bs)) {
ok = bdrv_can_snapshot(bs);
}
aio_context_release(ctx);
}
*first_bad_bs = bs;
return ok;
}

8
include/block/snapshot.h
View File

@ -75,4 +75,12 @@ int bdrv_snapshot_load_tmp(BlockDriverState *bs,
int bdrv_snapshot_load_tmp_by_id_or_name(BlockDriverState *bs, int bdrv_snapshot_load_tmp_by_id_or_name(BlockDriverState *bs,
const char *id_or_name, const char *id_or_name,
Error **errp); Error **errp);
/* Group operations. All block drivers are involved.
* These functions will properly handle dataplane (take aio_context_acquire
* when appropriate for appropriate block drivers */
bool bdrv_all_can_snapshot(BlockDriverState **first_bad_bs);
#endif #endif

17
migration/savevm.c
View File

@ -1958,19 +1958,10 @@ void hmp_savevm(Monitor *mon, const QDict *qdict)
const char *name = qdict_get_try_str(qdict, "name"); const char *name = qdict_get_try_str(qdict, "name");
Error *local_err = NULL; Error *local_err = NULL;
/* Verify if there is a device that doesn't support snapshots and is writable */ if (!bdrv_all_can_snapshot(&bs)) {
bs = NULL; monitor_printf(mon, "Device '%s' is writable but does not "
while ((bs = bdrv_next(bs))) { "support snapshots.\n", bdrv_get_device_name(bs));
return;
if (!bdrv_is_inserted(bs) || bdrv_is_read_only(bs)) {
continue;
}
if (!bdrv_can_snapshot(bs)) {
monitor_printf(mon, "Device '%s' is writable but does not support snapshots.\n",
bdrv_get_device_name(bs));
return;
}
} }
bs = find_vmstate_bs(); bs = find_vmstate_bs();