Commit 2a32c6e8 authored by John Snow's avatar John Snow Committed by Kevin Wolf
Browse files

blockdev: move BDRV_O_NO_BACKING option forward 



For both external_snapshot_prepare and qmp_drive_mirror, we eventually
append the option BDRV_O_NO_BACKING. However, we generally do so after
we create the image.

To accommodate image creation wanting to verify that a backing file
exists or not, add this option prior to create to override checking
the existence of the backing file. This prevents QEMU from trying to
re-open a backing file that's already in use (thanks to qcow2 locking).

Signed-off-by: default avatarJohn Snow <jsnow@redhat.com>
Reviewed-by: default avatarEric Blake <eblake@redhat.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent 7c8730d4

blockdev.c

+6 −5
Original line number Diff line number Diff line
@@ -1710,7 +1710,8 @@ static void external_snapshot_prepare(BlkActionState *common, 
        }



        flags = state->old_bs->open_flags;

        flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_COPY_ON_READ);

        flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_COPY_ON_READ);

        flags |= BDRV_O_NO_BACKING;



        /* create new image w/backing file */

        mode = s->has_mode ? s->mode : NEW_IMAGE_MODE_ABSOLUTE_PATHS;
@@ -1735,8 +1736,6 @@ static void external_snapshot_prepare(BlkActionState *common, 
            qdict_put_str(options, "node-name", snapshot_node_name);

        }

        qdict_put_str(options, "driver", format);



        flags |= BDRV_O_NO_BACKING;

    }



    state->new_bs = bdrv_open(new_image_file, snapshot_ref, options, flags,
@@ -3548,6 +3547,9 @@ void qmp_drive_mirror(DriveMirror *arg, Error **errp) 
        backing_mode = MIRROR_OPEN_BACKING_CHAIN;

    }



    /* Don't open backing image in create() */

    flags |= BDRV_O_NO_BACKING;



    if ((arg->sync == MIRROR_SYNC_MODE_FULL || !source)

        && arg->mode != NEW_IMAGE_MODE_EXISTING)

    {
@@ -3587,8 +3589,7 @@ void qmp_drive_mirror(DriveMirror *arg, Error **errp) 
    /* Mirroring takes care of copy-on-write using the source's backing

     * file.

     */

    target_bs = bdrv_open(arg->target, NULL, options,

                          flags | BDRV_O_NO_BACKING, errp);

    target_bs = bdrv_open(arg->target, NULL, options, flags, errp);

    if (!target_bs) {

        goto out;

    }