Re: [PATCH 1/4] block: add zone open, close and finish support

Matias Bjørling
2019-06-25T10:35:01Z

On 6/25/19 12:27 AM, Chaitanya Kulkarni wrote:
> On 6/24/19 12:43 PM, Bart Van Assche wrote:
>> On 6/21/19 6:07 AM, Matias Bjørling wrote:
>>> diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
>>> index 95202f80676c..067ef9242275 100644
>>> --- a/include/linux/blk_types.h
>>> +++ b/include/linux/blk_types.h
>>> @@ -284,13 +284,20 @@ enum req_opf {
>>> REQ_OP_DISCARD = 3,
>>> /* securely erase sectors */
>>> REQ_OP_SECURE_ERASE = 5,
>>> - /* reset a zone write pointer */
>>> - REQ_OP_ZONE_RESET = 6,
>>> /* write the same sector many times */
>>> REQ_OP_WRITE_SAME = 7,
>>> /* write the zero filled sector many times */
>>> REQ_OP_WRITE_ZEROES = 9,
>>>
>>> + /* reset a zone write pointer */
>>> + REQ_OP_ZONE_RESET = 16,
>>> + /* Open zone(s) */
>>> + REQ_OP_ZONE_OPEN = 17,
>>> + /* Close zone(s) */
>>> + REQ_OP_ZONE_CLOSE = 18,
>>> + /* Finish zone(s) */
>>> + REQ_OP_ZONE_FINISH = 19,
>>> +
>>> /* SCSI passthrough using struct scsi_request */
>>> REQ_OP_SCSI_IN = 32,
>>> REQ_OP_SCSI_OUT = 33,
>>> @@ -375,6 +382,22 @@ static inline void bio_set_op_attrs(struct bio *bio, unsigned op,
>>> bio->bi_opf = op | op_flags;
>>> }
>>
>> Are the new operation types ever passed to op_is_write()? The definition
>> of that function is as follows:
>>
> May be we should change numbering since blktrace also relies on the
> having on_is_write() without looking at the rq_ops().
>
> 197 * Data direction bit lookup
> 198 */
> 199 static const u32 ddir_act[2] = { BLK_TC_ACT(BLK_TC_READ),
> 200 BLK_TC_ACT(BLK_TC_WRITE) }; <----
> 201
> 202 #define BLK_TC_RAHEAD BLK_TC_AHEAD
> 203 #define BLK_TC_PREFLUSH BLK_TC_FLUSH
> 204
> 205 /* The ilog2() calls fall out because they're constant */
> 206 #define MASK_TC_BIT(rw, __name) ((rw & REQ_ ## __name) << \
> 207 (ilog2(BLK_TC_ ## __name) + BLK_TC_SHIFT - __REQ_ ##
> __name))
> 208
> 209 /*
> 210 * The worker for the various blk_add_trace*() types. Fills out a
> 211 * blk_io_trace structure and places it in a per-cpu subbuffer.
> 212 */
> 213 static void __blk_add_trace(struct blk_trace *bt, sector_t sector,
> int bytes,
> 214 int op, int op_flags, u32 what, int error,
> int pdu_len,
> 215 void *pdu_data, union kernfs_node_id *cgid)
> 216 {
> 217 struct task_struct *tsk = current;
> 218 struct ring_buffer_event *event = NULL;
> 219 struct ring_buffer *buffer = NULL;
> 220 struct blk_io_trace *t;
> 221 unsigned long flags = 0;
> 222 unsigned long *sequence;
> 223 pid_t pid;
> 224 int cpu, pc = 0;
> 225 bool blk_tracer = blk_tracer_enabled;
> 226 ssize_t cgid_len = cgid ? sizeof(*cgid) : 0;
> 227
> 228 if (unlikely(bt->trace_state != Blktrace_running &&
> !blk_tracer))
> 229 return;
> 230
> 231 what |= ddir_act[op_is_write(op) ? WRITE : READ]; <---
>
>
>> static inline bool op_is_write(unsigned int op)
>> {
>> return (op & 1);
>> }
>>
>

The zone mgmt commands are neither write nor reads commands. I guess,
one could characterize them as write commands, but they don't write any
data, they update a state of a zone on a drive. One should keep it as
is? and make sure the zone mgmt commands don't get categorized as either
read/write.