On 18.03.2016 19:21, Kevin Wolf wrote: > We must forbid changing the WCE flag in bdrv_reopen() in the same patch, > as otherwise the behaviour would change so that the flag takes > precedence over the explicitly specified option. > > The correct value of the WCE flag depends on the BlockBackend user (e.g. > guest device) and isn't a decision that the QMP client makes, so this > change is what we want. > > Signed-off-by: Kevin Wolf <kw...@redhat.com> > --- > block.c | 18 ++++++------------ > qemu-io-cmds.c | 14 +++++++++++++- > tests/qemu-iotests/142 | 2 +- > tests/qemu-iotests/142.out | 2 +- > 4 files changed, 21 insertions(+), 15 deletions(-) >
[...]
> diff --git a/qemu-io-cmds.c b/qemu-io-cmds.c
> index e929d24..7de3754 100644
> --- a/qemu-io-cmds.c
> +++ b/qemu-io-cmds.c
[...]
> @@ -2136,14 +2137,25 @@ static int reopen_f(BlockBackend *blk, int argc, char
> **argv)
> return qemuio_command_usage(&reopen_cmd);
> }
>
> + if (writethrough != blk_enable_write_cache(blk) &&
> + blk_get_attached_dev(blk))
> + {
> + error_report("Cannot change cache.writeback: Device attached");
> + qemu_opts_reset(&reopen_opts);
> + return 0;
> + }
> +
> qopts = qemu_opts_find(&reopen_opts, NULL);
> opts = qopts ? qemu_opts_to_qdict(qopts, NULL) : NULL;
> qemu_opts_reset(&reopen_opts);
>
> + flags |= blk_enable_write_cache(blk) ? BDRV_O_CACHE_WB : 0;
Shouldn't this be bdrv_enable_write_cache(bs)?
With blk_enable_write_cache(blk), reopening a non-WB BB should always
fail because bdrv_reopen_multiple() accuses us of trying to change the
WB mode (whereas we really don't want to change the BDS's mode).
Max
> brq = bdrv_reopen_queue(NULL, bs, opts, flags);
> bdrv_reopen_multiple(brq, &local_err);
> if (local_err) {
> error_report_err(local_err);
> + } else {
> + blk_set_enable_write_cache(blk, !writethrough);
> }
>
> return 0;
signature.asc
Description: OpenPGP digital signature
