Hi guys,
I find that a call to blk_mq_alloc_request_hctx() sometimes has rq->bio
set when returned, when I didn't think it should. I notice that we
explicitly zero this field (and data len and sector) in
blk_mq_alloc_request().
This trips up scsi_setup_scsi_cmd() for me, which checks these fields.
This is what I thought needs changing:
---8<----
From 396d0b64b73cc6fb5193189d9da2c6107dbeff83 Mon Sep 17 00:00:00 2001
From: John Garry <john.garry@xxxxxxxxxx>
Date: Fri, 21 Oct 2022 11:56:11 +0100
Subject: [PATCH] blk-mq: Properly init rq and fix queue enter/exit in
blk_mq_alloc_request_hctx()
diff --git a/block/blk-mq.c b/block/blk-mq.c
index f33ea455dd72..cce5cda3c442 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -611,6 +611,7 @@ struct request *blk_mq_alloc_request_hctx(struct
request_queue *q,
.nr_tags = 1,
};
u64 alloc_time_ns = 0;
+ struct request *rq;
unsigned int cpu;
unsigned int tag;
int ret;
@@ -660,8 +661,15 @@ struct request *blk_mq_alloc_request_hctx(struct
request_queue *q,
tag = blk_mq_get_tag(&data);
if (tag == BLK_MQ_NO_TAG)
goto out_queue_exit;
- return blk_mq_rq_ctx_init(&data, blk_mq_tags_from_data(&data), tag,
+ rq = blk_mq_rq_ctx_init(&data, blk_mq_tags_from_data(&data), tag,
alloc_time_ns);
+ if (!rq)
+ goto out_queue_exit;
+
+ rq->__data_len = 0;
+ rq->__sector = (sector_t) -1;
+ rq->bio = rq->biotail = NULL;
+ return rq;
--->8---
What that, now my code under dev looks ok. Is that change correct? Seems
strange to be missed..
Cheers,
John
