RE: scsi_set_medium_removal timeout issue

[Zengtao (B)]

Hi:

>-----Original Message-----
>From: Oliver Neukum [mailto:oneukum@xxxxxxxx]
>Sent: Tuesday, October 30, 2018 4:56 PM
>To: Zengtao (B) <prime.zeng@xxxxxxxxxxxxx>; jejb@xxxxxxxxxxxxxxxxxx;
>gregkh@xxxxxxxxxxxxxxxxxxx; martin.petersen@xxxxxxxxxx;
>stern@xxxxxxxxxxxxxxxxxxx
>Cc: usb-storage@xxxxxxxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
>linux-scsi@xxxxxxxxxxxxxxx; linux-usb@xxxxxxxxxxxxxxx
>Subject: Re: scsi_set_medium_removal timeout issue
>
>On Di, 2018-10-30 at 08:28 +0000,  Zengtao (B)  wrote:
>> Hi
>
>> For the issue itself, there is my observation:
>> In the step 4, the Host will issue an
>PREVENT_ALLOW_MEDIUM_REMOVAL scsi command.
>> and and timeout happens due to the device 's very slow
>fsg_lun_fsync_sub.
>> I found there are two methods to workaround the issue:
>> 1. Change the timeout value of host scsi command
>> PREVENT_ALLOW_MEDIUM_REMOVAL to to about 60 seconds from 10
>seconds.
>
>That is near useless, because the gadget can be used with other systems.
>

Is it reasonable to keep the current value? Or can we change it to cover
as much systems as possible. 

>> 2. Remove the fsg_lun_fsync_sub in the device's Mass storage gadget
>driver.
>
>It exists for a reason. The blocks have to be on the medium.
>It seems to me that your gadget just allows too many dirty pages in the
>cache.
>
>	Regards
>		Oliver

Regards
Zengtao