Re: [Qemu-devel] [PATCH 1/6] qemu-io: Reset qemuio_blk permissions before each command

[Fam Zheng <famz@redhat.com>]

On Fri, 09/15 12:10, Kevin Wolf wrote:
> qemu-io provides a 'reopen' command that allows switching from writable
> to read-only access. We need to make sure that we don't try to keep
> write permissions to a BlockBackend that becomes read-only, otherwise
> things are going to fail.
> 
> command() already makes sure to request any additional permissions that
> a qemu-io command requires, so just resetting the permissions to values
> that are safe for read-only images is enough to fix this.
> 
> As a side effect, this makes the output of qemu-iotests case 187 more
> consistent.
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  qemu-io.c                  | 13 +++++++++++++
>  tests/qemu-iotests/187.out |  2 +-
>  2 files changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/qemu-io.c b/qemu-io.c
> index 265445ad89..9e031f0f8e 100644
> --- a/qemu-io.c
> +++ b/qemu-io.c
> @@ -366,6 +366,12 @@ static void command_loop(void)
>      char *input;
>  
>      for (i = 0; !done && i < ncmdline; i++) {
> +        /* Make sure that we start each command with clean permissions and only
> +         * add whatever the specific cmdinfo_t describes */
> +        if (qemuio_blk) {
> +            blk_set_perm(qemuio_blk, BLK_PERM_CONSISTENT_READ, BLK_PERM_ALL,
> +                         &error_abort);
> +        }
>          done = qemuio_command(qemuio_blk, cmdline[i]);
>      }
>      if (cmdline) {
> @@ -391,6 +397,13 @@ static void command_loop(void)
>          if (input == NULL) {
>              break;
>          }
> +
> +        /* Make sure that we start each command with clean permissions and only
> +         * add whatever the specific cmdinfo_t describes */
> +        if (qemuio_blk) {
> +            blk_set_perm(qemuio_blk, BLK_PERM_CONSISTENT_READ, BLK_PERM_ALL,
> +                         &error_abort);
> +        }
>          done = qemuio_command(qemuio_blk, input);
>          g_free(input);
>  
> diff --git a/tests/qemu-iotests/187.out b/tests/qemu-iotests/187.out
> index 68fb944cd5..30b987f71f 100644
> --- a/tests/qemu-iotests/187.out
> +++ b/tests/qemu-iotests/187.out
> @@ -12,7 +12,7 @@ Start from read-write
>  
>  wrote 65536/65536 bytes at offset 0
>  64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
> -write failed: Operation not permitted
> +Block node is read-only
>  wrote 65536/65536 bytes at offset 0
>  64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
>  *** done
> -- 
> 2.13.5
> 

Reviewed-by: Fam Zheng <famz@redhat.com>