Commit 5f7772c4 authored by Fam Zheng's avatar Fam Zheng Committed by Eric Blake
Browse files

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: default avatarFam Zheng <famz@redhat.com>
Message-Id: <20170815130740.31229-4-famz@redhat.com>
Signed-off-by: default avatarEric Blake <eblake@redhat.com>
parent 3dff24f2

block/block-backend.c

+41 −0
Original line number Diff line number Diff line
@@ -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);