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Date: Sun, 29 Jul 2012 13:26:54 +0530
From: Supriya Kannery <supriyak@linux.vnet.ibm.com>
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Subject: Re: [Qemu-devel] [v1 Patch 3/10]Qemu: Cmd "block_set_hostcache" for
 dynamic cache change
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To: qemu-devel@nongnu.org

On 07/11/2012 07:46 PM, Luiz Capitulino wrote:
> On Sat, 16 Jun 2012 02:17:30 +0530
> Supriya Kannery<supriyak@linux.vnet.ibm.com>  wrote:
>
>> New command "block_set_hostcache" added for dynamically changing
>> host pagecache setting of a block device.
>>
>> Usage:
>>   block_set_hostcache<device>  <option>
>>     <device>  = block device
>>     <option>  = on/off
>>
>> Example:
>>   (qemu) block_set_hostcache ide0-hd0 off
>>
>> Signed-off-by: Supriya Kannery<supriyak@linux.vnet.ibm.com>
>>
>> ---
>>   block.c         |   54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>   block.h         |    2 ++
>>   blockdev.c      |   26 ++++++++++++++++++++++++++
>>   blockdev.h      |    2 ++
>>   hmp-commands.hx |   14 ++++++++++++++
>>   qmp-commands.hx |   27 +++++++++++++++++++++++++++
>>   6 files changed, 125 insertions(+)
>>
>> Index: qemu/block.c
>> ===================================================================
>> --- qemu.orig/block.c
>> +++ qemu/block.c
>> @@ -858,6 +858,35 @@ unlink_and_fail:
>>       return ret;
>>   }
>>
>> +int bdrv_reopen(BlockDriverState *bs, int bdrv_flags)
>> +{
>> +    BlockDriver *drv = bs->drv;
>> +    int ret = 0, open_flags;
>> +
>> +    /* Quiesce IO for the given block device */
>> +    qemu_aio_flush();
>> +    ret = bdrv_flush(bs);
>> +    if (ret != 0) {
>> +        qerror_report(QERR_DATA_SYNC_FAILED, bs->device_name);
>
> Please, use error_set() instead of qerror_report() and as Kevin said IOError
> seems enough here.
>

Sure, will replace qemu_aio_flush() with bdrv_drain_all()
and qerror_report() with error_set().

Combination of bdrv_drain_all() and bdrv_flush(), should
help in flushing out the specific disk.

-thanks, Supriya