On 18/08/2021 08:38, Ming Lei wrote:
On Mon, Aug 09, 2021 at 10:29:35PM +0800, John Garry wrote:
Add a variant of the init_request function which does not pass a hctx_idx
arg.
This is important for shared sbitmap support, as it needs to be ensured for
introducing shared static rqs that the LLDD cannot think that requests
are associated with a specific HW queue.
Signed-off-by: John Garry<john.garry@xxxxxxxxxx>
---
block/blk-mq.c | 15 ++++++++++-----
include/linux/blk-mq.h | 7 +++++++
2 files changed, 17 insertions(+), 5 deletions(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index f14cc2705f9b..4d6723cfa582 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2427,13 +2427,15 @@ struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set,
static int blk_mq_init_request(struct blk_mq_tag_set *set, struct request *rq,
unsigned int hctx_idx, int node)
{
- int ret;
+ int ret = 0;
- if (set->ops->init_request) {
+ if (set->ops->init_request)
ret = set->ops->init_request(set, rq, hctx_idx, node);
- if (ret)
- return ret;
- }
+ else if (set->ops->init_request_no_hctx)
+ ret = set->ops->init_request_no_hctx(set, rq, node);
Hi Ming,
The only shared sbitmap user of SCSI does not use passed hctx_idx, not
sure we need such new callback.
Sure, actually most versions of init_request callback don't use
hctx_idx. Or numa_node arg.
If you really want to do this, just wondering why not pass '-1' as
hctx_idx in case of shared sbitmap?
Yeah, I did consider that. hctx_idx is an unsigned, and I generally
don't like -1U - but that's no big deal. But I also didn't like how it
relies on the driver init_request callback to check the value, which
changes the semantics.
Obviously we don't add new versions of init_request for new block
drivers which use shared sbitmap everyday, and any new ones would get it
right.
I suppose I can go the way you suggest - I just thought that this method
was neat as well.
Thanks,
John
