+ bool alloc_srcu;
I found the following statement multiple times in this patch:
WARN_ON_ONCE(q->alloc_srcu != !!(q->tag_set->flags & BLK_MQ_F_BLOCKING));
Does this mean that the new q->alloc_srcu member variable can be left out
and that it can be replaced with the following test?
q->tag_set->flags & BLK_MQ_F_BLOCKING
q->tag_set can't be used anymore after blk_cleanup_queue() returns,
and we need the flag for freeing request_queue instance.
Why not just look at the queue->srcu pointer? it is allocated only
for BLK_MQ_F_BLOCKING no?
Yeah, we can add one extra srcu pointer to request queue, but this way
needs one extra fetch to q->srcu in fast path compared with current
code base, so io_uring workload may be affected a bit.
Yea you're right. We should at some point make has_srcu and
mq_sysfs_init_done bits in a flags member, but we have like 6 more
before we need to do it...
