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Re: [Qemu-devel] [PATCH] iscsi: Refuse to open as writable if the LUN is
From: |
Peter Lieven |
Subject: |
Re: [Qemu-devel] [PATCH] iscsi: Refuse to open as writable if the LUN is write protected |
Date: |
Wed, 29 Oct 2014 22:12:23 +0100 |
Am 29.10.2014 um 19:28 schrieb Paolo Bonzini <address@hidden>:
> On 10/29/2014 05:18 PM, Peter Lieven wrote:
>> Am 29.10.2014 um 14:31 schrieb Paolo Bonzini:
>>>
>>> On 10/29/2014 02:13 PM, Fam Zheng wrote:
>>>> Before, when a write protected iSCSI target is attached as scsi-disk
>>>> with BDRV_O_RDWR, we report it as writable, while in fact all writes
>>>> will fail.
>>>>
>>>> One way to improve this is to report write protect flag as true to
>>>> guest, but a even better way is to refuse using a write protected LUN to
>>>> guest.
>>>>
>>>> Target write protect flag is checked with a mode sense query.
>>>>
>>>> Signed-off-by: Fam Zheng <address@hidden>
>>>> ---
>>>> block/iscsi.c | 30 ++++++++++++++++++++++++++++++
>>>> 1 file changed, 30 insertions(+)
>>>>
>>>> diff --git a/block/iscsi.c b/block/iscsi.c
>>>> index 233f462..c154928 100644
>>>> --- a/block/iscsi.c
>>>> +++ b/block/iscsi.c
>>>> @@ -1339,6 +1339,36 @@ static int iscsi_open(BlockDriverState *bs, QDict
>>>> *options, int flags,
>>>> scsi_free_scsi_task(task);
>>>> task = NULL;
>>>>
>>>> + /* Check the write protect flag of the LUN if we want to write */
>>>> + if (flags & BDRV_O_RDWR) {
>>>> + struct scsi_mode_sense *ms;
>>>> +
>>>> + task = iscsi_modesense6_sync(iscsilun->iscsi, iscsilun->lun,
>>>> + 1, SCSI_MODESENSE_PC_CURRENT,
>>>> + 0x3F,
>>>> + 0, 255);
>>>> +
>>>> + if (task == NULL) {
>>>> + error_setg(errp, "Failed to send MODE_SENSE10 command: %s\n",
>>> This is MODE SENSE(6). Fixed and applied.
>>>
>>> Paolo
>>>
>>>> + iscsi_get_error(iscsilun->iscsi));
>>>> + ret = -EINVAL;
>>>> + goto out;
>>>> + }
>>>> +
>>>> + if (task->status != SCSI_STATUS_GOOD) {
>>>> + error_setg(errp, "MODE_SENSE10 failed: %s\n",
>>>> + iscsi_get_error(iscsi));
>>>> + ret = -EINVAL;
>>>> + goto out;
>>>> + }
>>>> + ms = scsi_datain_unmarshall(task);
>>
>> scsi_datain_unmarshall may fail. You need to check for NULL here.
>
> Thanks for the remark, I fixed this too.
Is it in your repo? I can do some testing tomorrow ;-)
Peter