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block-backend: Defer shared_perm tightening migration completion 

As in the case of nbd_export_new(), bdrv_invalidate_cache() can be
called when migration is still in progress. In this case we are not
ready to tighten the shared permissions fenced by blk->disable_perm.

Defer to a VM state change handler.

Signed-off-by: Fam Zheng <famz@redhat.com>
Message-Id: <20170815130740.31229-4-famz@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
This commit is contained in:
Fam Zheng 2017-08-15 21:07:39 +08:00 committed by Eric Blake
parent 3dff24f2df
commit 5f7772c4d0
1 changed files with 41 additions and 0 deletions
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41
block/block-backend.c
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@ -20,6 +20,7 @@
#include "qapi-event.h"
#include "qemu/id.h"
#include "trace.h"
#include "migration/misc.h"
/* Number of coroutines to reserve per attached device model */
#define COROUTINE_POOL_RESERVATION 64
@ -68,6 +69,7 @@ struct BlockBackend {
NotifierList remove_bs_notifiers, insert_bs_notifiers;
int quiesce_counter;
VMChangeStateEntry *vmsh;
};
typedef struct BlockBackendAIOCB {
@ -129,6 +131,23 @@ static const char *blk_root_get_name(BdrvChild *child)
return blk_name(child->opaque);
}
static void blk_vm_state_changed(void *opaque, int running, RunState state)
{
Error *local_err = NULL;
BlockBackend *blk = opaque;
if (state == RUN_STATE_INMIGRATE) {
return;
}
qemu_del_vm_change_state_handler(blk->vmsh);
blk->vmsh = NULL;
blk_set_perm(blk, blk->perm, blk->shared_perm, &local_err);
if (local_err) {
error_report_err(local_err);
}
}
/*
* Notifies the user of the BlockBackend that migration has completed. qdev
* devices can tighten their permissions in response (specifically revoke
@ -147,6 +166,24 @@ static void blk_root_activate(BdrvChild *child, Error **errp)
blk->disable_perm = false;
blk_set_perm(blk, blk->perm, BLK_PERM_ALL, &local_err);
if (local_err) {
error_propagate(errp, local_err);
blk->disable_perm = true;
return;
}
if (runstate_check(RUN_STATE_INMIGRATE)) {
/* Activation can happen when migration process is still active, for
* example when nbd_server_add is called during non-shared storage
* migration. Defer the shared_perm update to migration completion. */
if (!blk->vmsh) {
blk->vmsh = qemu_add_vm_change_state_handler(blk_vm_state_changed,
blk);
}
return;
}
blk_set_perm(blk, blk->perm, blk->shared_perm, &local_err);
if (local_err) {
error_propagate(errp, local_err);
@ -291,6 +328,10 @@ static void blk_delete(BlockBackend *blk)
if (blk->root) {
blk_remove_bs(blk);
}
if (blk->vmsh) {
qemu_del_vm_change_state_handler(blk->vmsh);
blk->vmsh = NULL;
}
assert(QLIST_EMPTY(&blk->remove_bs_notifiers.notifiers));
assert(QLIST_EMPTY(&blk->insert_bs_notifiers.notifiers));
QTAILQ_REMOVE(&block_backends, blk, link);