Re: [Qemu-devel] [PATCH v4 4/7] block: Add checks of blocker in block operations

[Paolo Bonzini <pbonzini@redhat.com>]

Il 22/11/2013 06:24, Fam Zheng ha scritto:
> Before operate on a BlockDriverState, respective types are checked
> against bs->op_blockers and it will error out if there's a blocker.

How did you choose them?  I understand blocking change (and eject?), but
not blocking set-io-throttle.

In particular, this means that old in_use users, which did not block
commands such as nbd-server-add, will now block it.

Paolo

> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---
>  blockdev-nbd.c |  4 ++++
>  blockdev.c     | 25 +++++++++++++++++++++++++
>  2 files changed, 29 insertions(+)
> 
> diff --git a/blockdev-nbd.c b/blockdev-nbd.c
> index 922cf56..c49feae 100644
> --- a/blockdev-nbd.c
> +++ b/blockdev-nbd.c
> @@ -92,6 +92,10 @@ void qmp_nbd_server_add(const char *device, bool has_writable, bool writable,
>          return;
>      }
>  
> +    if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_NBD_SERVER_ADD, errp)) {
> +        return;
> +    }
> +
>      if (!has_writable) {
>          writable = false;
>      }
> diff --git a/blockdev.c b/blockdev.c
> index eb55b74..1921d27 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -1001,6 +1001,11 @@ SnapshotInfo *qmp_blockdev_snapshot_delete_internal_sync(const char *device,
>          return NULL;
>      }
>  
> +    if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_INTERNAL_SNAPSHOT_DELETE,
> +                           errp)) {
> +        return NULL;
> +    }
> +
>      ret = bdrv_snapshot_find_by_id_and_name(bs, id, name, &sn, &local_err);
>      if (error_is_set(&local_err)) {
>          error_propagate(errp, local_err);
> @@ -1098,6 +1103,10 @@ static void internal_snapshot_prepare(BlkTransactionState *common,
>          return;
>      }
>  
> +    if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_INTERNAL_SNAPSHOT, errp)) {
> +        return;
> +    }
> +
>      if (!bdrv_is_inserted(bs)) {
>          error_set(errp, QERR_DEVICE_HAS_NO_MEDIUM, device);
>          return;
> @@ -1485,6 +1494,10 @@ void qmp_block_passwd(const char *device, const char *password, Error **errp)
>          return;
>      }
>  
> +    if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_PASSWD, errp)) {
> +        return;
> +    }
> +
>      err = bdrv_set_key(bs, password);
>      if (err == -EINVAL) {
>          error_set(errp, QERR_DEVICE_NOT_ENCRYPTED, bdrv_get_device_name(bs));
> @@ -1536,6 +1549,10 @@ void qmp_change_blockdev(const char *device, const char *filename,
>          return;
>      }
>  
> +    if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_CHANGE, errp)) {
> +        return;
> +    }
> +
>      if (format) {
>          drv = bdrv_find_whitelisted_format(format, bs->read_only);
>          if (!drv) {
> @@ -1586,6 +1603,10 @@ void qmp_block_set_io_throttle(const char *device, int64_t bps, int64_t bps_rd,
>          return;
>      }
>  
> +    if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_SET_IO_THROTTLE, errp)) {
> +        return;
> +    }
> +
>      memset(&cfg, 0, sizeof(cfg));
>      cfg.buckets[THROTTLE_BPS_TOTAL].avg = bps;
>      cfg.buckets[THROTTLE_BPS_READ].avg  = bps_rd;
> @@ -1684,6 +1705,10 @@ void qmp_block_resize(const char *device, int64_t size, Error **errp)
>          return;
>      }
>  
> +    if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_RESIZE, errp)) {
> +        return;
> +    }
> +
>      if (size < 0) {
>          error_set(errp, QERR_INVALID_PARAMETER_VALUE, "size", "a >0 size");
>          return;
>