diff options
Diffstat (limited to 'blockdev.c')
| -rw-r--r-- | blockdev.c | 30 |
1 files changed, 8 insertions, 22 deletions
diff --git a/blockdev.c b/blockdev.c index 257cb37682..fa8630cb41 100644 --- a/blockdev.c +++ b/blockdev.c @@ -1470,8 +1470,7 @@ static void external_snapshot_prepare(BlkActionState *common, DO_UPCAST(ExternalSnapshotState, common, common); TransactionAction *action = common->action; AioContext *aio_context; - AioContext *old_context; - int ret; + uint64_t perm, shared; /* 'blockdev-snapshot' and 'blockdev-snapshot-sync' have similar * purpose but a different set of parameters */ @@ -1586,16 +1585,17 @@ static void external_snapshot_prepare(BlkActionState *common, goto out; } - if (bdrv_has_blk(state->new_bs)) { + /* + * Allow attaching a backing file to an overlay that's already in use only + * if the parents don't assume that they are already seeing a valid image. + * (Specifically, allow it as a mirror target, which is write-only access.) + */ + bdrv_get_cumulative_perm(state->new_bs, &perm, &shared); + if (perm & BLK_PERM_CONSISTENT_READ) { error_setg(errp, "The overlay is already in use"); goto out; } - if (bdrv_op_is_blocked(state->new_bs, BLOCK_OP_TYPE_EXTERNAL_SNAPSHOT, - errp)) { - goto out; - } - if (state->new_bs->backing != NULL) { error_setg(errp, "The overlay already has a backing image"); goto out; @@ -1606,20 +1606,6 @@ static void external_snapshot_prepare(BlkActionState *common, goto out; } - /* Honor bdrv_try_set_aio_context() context acquisition requirements. */ - old_context = bdrv_get_aio_context(state->new_bs); - aio_context_release(aio_context); - aio_context_acquire(old_context); - - ret = bdrv_try_set_aio_context(state->new_bs, aio_context, errp); - - aio_context_release(old_context); - aio_context_acquire(aio_context); - - if (ret < 0) { - goto out; - } - /* This removes our old bs and adds the new bs. This is an operation that * can fail, so we need to do it in .prepare; undoing it for abort is * always possible. */ |