Re: [PATCH v4] scsi: sd: retry command SYNC CACHE if format in progress

[Yihang Li]

On 2024/8/19 7:55, Damien Le Moal wrote:
> On 8/17/24 10:50, Yihang Li wrote:
>> If formatting a suspended disk (such as formatting with different DIF
>> type), the disk will be resuming first, and then the format command will
>> submit to the disk through SG_IO ioctl.
>>
>> When the disk is processing the format command, the system does not submit
>> other commands to the disk. Therefore, the system attempts to suspend the
>> disk again and sends the SYNC CACHE command. However, the SYNC CACHE
> 
> Why would the system try to suspend the disk with a request in flight ? Sounds
> like there is a bug with PM reference counting, no ?

According to my understand and test, the format command request is finished,
so it is not in flight for the kernel. And the command need a few time to processing
in the disk while no other commands are being sent.

> 
>> command will fail because the disk is in the formatting process, which
>> will cause the runtime_status of the disk to error and it is difficult
>> for user to recover it. Error info like:
>>
>> [  669.925325] sd 6:0:6:0: [sdg] Synchronizing SCSI cache
>> [  670.202371] sd 6:0:6:0: [sdg] Synchronize Cache(10) failed: Result: hostbyte=0x00 driverbyte=DRIVER_OK
>> [  670.216300] sd 6:0:6:0: [sdg] Sense Key : 0x2 [current]
>> [  670.221860] sd 6:0:6:0: [sdg] ASC=0x4 ASCQ=0x4
>>
>> To solve the issue, retry the command until format command is finished.
>>
>> Cc: stable@xxxxxxxxxxxxxxx
>> Signed-off-by: Yihang Li <liyihang9@xxxxxxxxxx>
>> Reviewed-by: Bart Van Assche <bvanassche@xxxxxxx>
>> ---
>> Changes since v3:
>> - Add Cc tag for kernel stable.
>>
>> Changes since v2:
>> - Add Reviewed-by for Bart.
>>
>> Changes since v1:
>> - Updated and added error information to the patch description.
>>
>> ---
>>  drivers/scsi/sd.c | 5 +++++
>>  1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
>> index adeaa8ab9951..5cd88a8eea73 100644
>> --- a/drivers/scsi/sd.c
>> +++ b/drivers/scsi/sd.c
>> @@ -1823,6 +1823,11 @@ static int sd_sync_cache(struct scsi_disk *sdkp)
>>  			    (sshdr.asc == 0x74 && sshdr.ascq == 0x71))	/* drive is password locked */
>>  				/* this is no error here */
>>  				return 0;
>> +
>> +			/* retry if format in progress */
>> +			if (sshdr.asc == 0x4 && sshdr.ascq == 0x4)
>> +				return -EBUSY;
>> +
>>  			/*
>>  			 * This drive doesn't support sync and there's not much
>>  			 * we can do because this is called during shutdown
>