On 05/21/2012 06:45 AM, Hannes Reinecke wrote:
> On 05/18/2012 06:56 AM, michaelc@xxxxxxxxxxx wrote:
>> From: Mike Christie <michaelc@xxxxxxxxxxx>
>>
>> If a device goes offline while the device is opened then closed
>> while it is still offline, udev will remove the /dev/disk/by-id
>> link. If the device comes back and is set to running, userspace
>> is not notified, and the by-id link will not get remade.
>>
>> This patch has scsi-ml send a KOBJ_CHANGE event so tools like udev
>> will know that it can being to use the device again. With this patch
>> udev see the KOBJ_CHANGE event and will reprobe the device and recreate
>> a /dev/disk/by-id link.
>>
>> v2
>> - Added SDEV_EVT_STATE_RUNNING evt type.
>>
>> Signed-off-by: Mike Christie <michaelc@xxxxxxxxxxx>
>> ---
>> drivers/scsi/scsi_lib.c | 9 +++++++++
>> include/scsi/scsi_device.h | 2 ++
>> 2 files changed, 11 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
>> index d15b243..b54030d 100644
>> --- a/drivers/scsi/scsi_lib.c
>> +++ b/drivers/scsi/scsi_lib.c
>> @@ -2061,6 +2061,7 @@ int
>> scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
>> {
>> enum scsi_device_state oldstate = sdev->sdev_state;
>> + int change_evt = 0;
>>
>> if (state == oldstate)
>> return 0;
>> @@ -2079,6 +2080,11 @@ scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
>> switch (oldstate) {
>> case SDEV_OFFLINE:
>> case SDEV_TRANSPORT_OFFLINE:
>> + /*
>> + * Notify userspace we can accept IO by sending
>> + * change event.
>> + */
>> + change_evt = 1;
>> case SDEV_QUIESCE:
>> case SDEV_BLOCK:
>> case SDEV_CREATED:
>> @@ -2160,6 +2166,8 @@ scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
>>
>> }
>> sdev->sdev_state = state;
>> + if (change_evt)
>> + sdev_evt_send_simple(sdev, SDEV_EVT_STATE_RUNNING, GFP_ATOMIC);
>> return 0;
>>
>> illegal:
>> @@ -2283,6 +2291,7 @@ struct scsi_event *sdev_evt_alloc(enum scsi_device_event evt_type,
>> /* evt_type-specific initialization, if any */
>> switch (evt_type) {
>> case SDEV_EVT_MEDIA_CHANGE:
>> + case SDEV_EVT_STATE_RUNNING:
>> default:
>> /* do nothing */
>> break;
> Hmm. So we're only getting notified if the device switched to OFFLINE?
No from one of the offlines to running.
> Weird. We'll get notified about this eventually anyway (aborting
> I/Os etc).
> I'd be more interested to get notified if the device becomes
> _available_ again, ie when entering RUNNING state. That's really
> hard to figure out without polling.
That is what is happening.
>
> Care to add the 'change_evt' thing to the SDEV_RUNNING case
> statement, too?
>
> Or am I missing something?
>
You are :) I hope :)
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