Re: [PATCH 5 of 8] sd: Detect non-rotational devices

[Jeff Garzik <jeff@garzik.org>]

Jens Axboe wrote:
>> +static void sd_read_block_characteristics(struct scsi_disk *sdkp)
>> +{
>> +	char *buffer;
>> +	u16 rot;
>> +
>> +	/* Block Device Characteristics VPD */
>> +	buffer = scsi_get_vpd_page(sdkp->device, 0xb1);
>> +
>> +	if (buffer == NULL)
>> +		return;
>> +
>> +	rot = get_unaligned_be16(&buffer[4]);
>> +
>> +	if (rot == 1)
>> +		queue_flag_set_unlocked(QUEUE_FLAG_NONROT, sdkp->disk->queue);
>> +
>> +	kfree(buffer);
>> +}
>> +
>> +/**
>>   *	sd_revalidate_disk - called the first time a new disk is seen,
>>   *	performs disk spin up, read_capacity, etc.
>>   *	@disk: struct gendisk we care about
>> @@ -1836,6 +1860,7 @@ static int sd_revalidate_disk(struct gen
>>  	 */
>>  	if (sdkp->media_present) {
>>  		sd_read_capacity(sdkp, buffer);
>> +		sd_read_block_characteristics(sdkp);
>>  		sd_read_write_protect_flag(sdkp, buffer);
>>  		sd_read_cache_type(sdkp, buffer);
>>  		sd_read_app_tag_own(sdkp, buffer);
>> @@ -1976,6 +2001,8 @@ static void sd_probe_async(void *data, a
>>  	add_disk(gd);
>>  	sd_dif_config_host(sdkp);
>>  
>> +	sd_revalidate_disk(gd);
>> +
>>  	sd_printk(KERN_NOTICE, sdkp, "Attached SCSI %sdisk\n",
>>  		  sdp->removable ? "removable " : "");
> 
> Make sure this works for libata as well, and then kill the rotational
> check in there instead.

Yep.  libata-scsi.c would need to simulate that VPD page.

Also (to mkp or whoever does the work) -- note Linus's comment, and my 
provisional patch[1], about libata potentially wanting to detect NONROT 
by looking for "*SSD" from IDENTIFY DEVICE'S model string.

	Jeff


[1] partial subject line, from the big "Ext3 latency fixes" thread):
"libata: add SSD detection hueristic; move SSD setup to ata_dev_configure"