On 2020/06/26 15:58, Javier González wrote:
> On 26.06.2020 06:42, Damien Le Moal wrote:
>> On 2020/06/26 15:09, Javier González wrote:
>>> On 26.06.2020 01:34, Damien Le Moal wrote:
>>>> On 2020/06/25 21:22, Javier González wrote:
>>>>> From: Javier González <javier.gonz@xxxxxxxxxxx>
>>>>>
>>>>> Add support for offline transition on the zoned block device using the
>>>>> new zone management IOCTL
>>>>>
>>>>> Signed-off-by: Javier González <javier.gonz@xxxxxxxxxxx>
>>>>> Signed-off-by: SelvaKumar S <selvakuma.s1@xxxxxxxxxxx>
>>>>> Signed-off-by: Kanchan Joshi <joshi.k@xxxxxxxxxxx>
>>>>> Signed-off-by: Nitesh Shetty <nj.shetty@xxxxxxxxxxx>
>>>>> ---
>>>>> block/blk-core.c | 2 ++
>>>>> block/blk-zoned.c | 3 +++
>>>>> drivers/nvme/host/core.c | 3 +++
>>>>> include/linux/blk_types.h | 3 +++
>>>>> include/linux/blkdev.h | 1 -
>>>>> include/uapi/linux/blkzoned.h | 1 +
>>>>> 6 files changed, 12 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/block/blk-core.c b/block/blk-core.c
>>>>> index 03252af8c82c..589cbdacc5ec 100644
>>>>> --- a/block/blk-core.c
>>>>> +++ b/block/blk-core.c
>>>>> @@ -140,6 +140,7 @@ static const char *const blk_op_name[] = {
>>>>> REQ_OP_NAME(ZONE_CLOSE),
>>>>> REQ_OP_NAME(ZONE_FINISH),
>>>>> REQ_OP_NAME(ZONE_APPEND),
>>>>> + REQ_OP_NAME(ZONE_OFFLINE),
>>>>> REQ_OP_NAME(WRITE_SAME),
>>>>> REQ_OP_NAME(WRITE_ZEROES),
>>>>> REQ_OP_NAME(SCSI_IN),
>>>>> @@ -1030,6 +1031,7 @@ generic_make_request_checks(struct bio *bio)
>>>>> case REQ_OP_ZONE_OPEN:
>>>>> case REQ_OP_ZONE_CLOSE:
>>>>> case REQ_OP_ZONE_FINISH:
>>>>> + case REQ_OP_ZONE_OFFLINE:
>>>>> if (!blk_queue_is_zoned(q))
>>>>> goto not_supported;
>>>>> break;
>>>>> diff --git a/block/blk-zoned.c b/block/blk-zoned.c
>>>>> index 29194388a1bb..704fc15813d1 100644
>>>>> --- a/block/blk-zoned.c
>>>>> +++ b/block/blk-zoned.c
>>>>> @@ -416,6 +416,9 @@ int blkdev_zone_mgmt_ioctl(struct block_device *bdev, fmode_t mode,
>>>>> case BLK_ZONE_MGMT_RESET:
>>>>> op = REQ_OP_ZONE_RESET;
>>>>> break;
>>>>> + case BLK_ZONE_MGMT_OFFLINE:
>>>>> + op = REQ_OP_ZONE_OFFLINE;
>>>>> + break;
>>>>> default:
>>>>> return -ENOTTY;
>>>>> }
>>>>> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
>>>>> index f1215523792b..5b95c81d2a2d 100644
>>>>> --- a/drivers/nvme/host/core.c
>>>>> +++ b/drivers/nvme/host/core.c
>>>>> @@ -776,6 +776,9 @@ blk_status_t nvme_setup_cmd(struct nvme_ns *ns, struct request *req,
>>>>> case REQ_OP_ZONE_FINISH:
>>>>> ret = nvme_setup_zone_mgmt_send(ns, req, cmd, NVME_ZONE_FINISH);
>>>>> break;
>>>>> + case REQ_OP_ZONE_OFFLINE:
>>>>> + ret = nvme_setup_zone_mgmt_send(ns, req, cmd, NVME_ZONE_OFFLINE);
>>>>> + break;
>>>>> case REQ_OP_WRITE_ZEROES:
>>>>> ret = nvme_setup_write_zeroes(ns, req, cmd);
>>>>> break;
>>>>> diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
>>>>> index 16b57fb2b99c..b3921263c3dd 100644
>>>>> --- a/include/linux/blk_types.h
>>>>> +++ b/include/linux/blk_types.h
>>>>> @@ -316,6 +316,8 @@ enum req_opf {
>>>>> REQ_OP_ZONE_FINISH = 12,
>>>>> /* write data at the current zone write pointer */
>>>>> REQ_OP_ZONE_APPEND = 13,
>>>>> + /* Transition a zone to offline */
>>>>> + REQ_OP_ZONE_OFFLINE = 14,
>>>>>
>>>>> /* SCSI passthrough using struct scsi_request */
>>>>> REQ_OP_SCSI_IN = 32,
>>>>> @@ -456,6 +458,7 @@ static inline bool op_is_zone_mgmt(enum req_opf op)
>>>>> case REQ_OP_ZONE_OPEN:
>>>>> case REQ_OP_ZONE_CLOSE:
>>>>> case REQ_OP_ZONE_FINISH:
>>>>> + case REQ_OP_ZONE_OFFLINE:
>>>>> return true;
>>>>> default:
>>>>> return false;
>>>>> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
>>>>> index bd8521f94dc4..8308d8a3720b 100644
>>>>> --- a/include/linux/blkdev.h
>>>>> +++ b/include/linux/blkdev.h
>>>>> @@ -372,7 +372,6 @@ extern int blkdev_zone_ops_ioctl(struct block_device *bdev, fmode_t mode,
>>>>> unsigned int cmd, unsigned long arg);
>>>>> extern int blkdev_zone_mgmt_ioctl(struct block_device *bdev, fmode_t mode,
>>>>> unsigned int cmd, unsigned long arg);
>>>>> -
>>>>> #else /* CONFIG_BLK_DEV_ZONED */
>>>>>
>>>>> static inline unsigned int blkdev_nr_zones(struct gendisk *disk)
>>>>> diff --git a/include/uapi/linux/blkzoned.h b/include/uapi/linux/blkzoned.h
>>>>> index a8c89fe58f97..d0978ee10fc7 100644
>>>>> --- a/include/uapi/linux/blkzoned.h
>>>>> +++ b/include/uapi/linux/blkzoned.h
>>>>> @@ -155,6 +155,7 @@ enum blk_zone_action {
>>>>> BLK_ZONE_MGMT_FINISH = 0x2,
>>>>> BLK_ZONE_MGMT_OPEN = 0x3,
>>>>> BLK_ZONE_MGMT_RESET = 0x4,
>>>>> + BLK_ZONE_MGMT_OFFLINE = 0x5,
>>>>> };
>>>>>
>>>>> /**
>>>>>
>>>>
>>>> As mentioned in previous email, the usefulness of this is dubious. Please
>>>> elaborate in the commit message. Sure NVMe ZNS defines this and we can support
>>>> it. But without a good use case, what is the point ?
>>>
>>> Use case is to transition zones in read-only state to offline when we
>>> are done moving valid data. It is easier to explicitly managing zones
>>> that are not usable by having all under the offline state.
>>
>> Then adding a simple BLKZONEOFFLINE ioctl, similar to open, close, finish and
>> reset, would be enough. No need for all the new zone management ioctl with flags
>> plumbing.
>
> Ok. We can add that then.
>
> Note that zone management is not motivated by this use case at all, but
> it made sense to implement it here instead of as a new BLKZONEOFFLINE
> IOCTL as ZAC/ZBC users will not be able to use it either way.
Sure, that is fine. We could actually add that to sd_zbc.c since we have zone
tracking there. A read-only zone can be reported as offline to sync-up with zns.
The value of it is dubious though as most applications will treat read-only and
offline zones the same way: as unusable. That is what zonefs does.
>
>>
>>>
>>>>
>>>> scsi SD driver will return BLK_STS_NOTSUPP if this offlining is sent to a
>>>> ZBC/ZAC drive. Not nice. Having a sysfs attribute "max_offline_zone_sectors" or
>>>> the like to indicate support by the device or not would be nicer.
>>>
>>> We can do that.
>>>
>>>>
>>>> Does offling ALL zones make any sense ? Because this patch does not prevent the
>>>> use of the REQ_ZONE_ALL flags introduced in patch 2. Probably not a good idea to
>>>> allow offlining all zones, no ?
>>>
>>> AFAIK the transition to offline is only valid when coming from a
>>> read-only state. I did think of adding a check, but I can see that other
>>> transitions go directly to the driver and then the device, so I decided
>>> to follow the same model. If you think it is better, we can add the
>>> check.
>>
>> My point was that the REQ_ZONE_ALL flag would make no sense for offlining zones
>> but this patch does not have anything checking that. There is no point in
>> sending a command that is known to be incorrect to the drive...
>
> I will add some extra checks then to fail early. I assume these should
> be in the NVMe driver as it is NVMe-specific, right?
If it is a simple BLKZONEOFFLINE ioctl, it can be processed exactly like open,
close and finish, using blkdev_zone_mgmt(). Calling that one for a range of
sectors of more than one zone will likely not make any sense most of the time,
but that is allowed for all other ops, so I guess you can keep it as is for
offline too. blkdev_zone_mgmt() will actually not need any change. You will only
need to wire the ioctl path and update op_is_zone_mgmt(). That's it. Simple that
way.
>
> Javier
>
--
Damien Le Moal
Western Digital Research
