block: Replace in_use with operation blocker

This drops BlockDriverState.in_use with op_blockers:

  - Call bdrv_op_block_all in place of bdrv_set_in_use(bs, 1).

  - Call bdrv_op_unblock_all in place of bdrv_set_in_use(bs, 0).

  - Check bdrv_op_is_blocked() in place of bdrv_in_use(bs).

    The specific types are used, e.g. in place of starting block backup,
    bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_BACKUP, ...).

    There is one exception in block_job_create, where
    bdrv_op_blocker_is_empty() is used, because we don't know the operation
    type here. This doesn't matter because in a few commits away we will drop
    the check and move it to callers that _do_ know the type.

  - Check bdrv_op_blocker_is_empty() in place of assert(!bs->in_use).

Note: there is only bdrv_op_block_all and bdrv_op_unblock_all callers at
this moment. So although the checks are specific to op types, this
changes can still be seen as identical logic with previously with
in_use. The difference is error message are improved because of blocker
error info.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Fam Zheng
2014-05-23 21:29:43 +08:00
committed by Stefan Hajnoczi
parent fbe40ff780
commit 3718d8ab65
8 changed files with 45 additions and 43 deletions

View File

@ -59,6 +59,7 @@ typedef struct BlkMigDevState {
unsigned long *aio_bitmap;
int64_t completed_sectors;
BdrvDirtyBitmap *dirty_bitmap;
Error *blocker;
} BlkMigDevState;
typedef struct BlkMigBlock {
@ -361,7 +362,8 @@ static void init_blk_migration_it(void *opaque, BlockDriverState *bs)
bmds->completed_sectors = 0;
bmds->shared_base = block_mig_state.shared_base;
alloc_aio_bitmap(bmds);
bdrv_set_in_use(bs, 1);
error_setg(&bmds->blocker, "block device is in use by migration");
bdrv_op_block_all(bs, bmds->blocker);
bdrv_ref(bs);
block_mig_state.total_sector_sum += sectors;
@ -599,7 +601,8 @@ static void blk_mig_cleanup(void)
blk_mig_lock();
while ((bmds = QSIMPLEQ_FIRST(&block_mig_state.bmds_list)) != NULL) {
QSIMPLEQ_REMOVE_HEAD(&block_mig_state.bmds_list, entry);
bdrv_set_in_use(bmds->bs, 0);
bdrv_op_unblock_all(bmds->bs, bmds->blocker);
error_free(bmds->blocker);
bdrv_unref(bmds->bs);
g_free(bmds->aio_bitmap);
g_free(bmds);