On Mon, Feb 27, 2017 at 09:47:53AM -0800, Omar Sandoval wrote:
> From: Omar Sandoval <osan...@fb.com>
>
> blk_mq_alloc_request_hctx() allocates a driver request directly, unlike
> its blk_mq_alloc_request() counterpart. It also crashes because it
> doesn't update the tags->rqs map.
>
> Fix it by making it allocate a scheduler request.
>
> Reported-by: Sagi Grimberg <s...@grimberg.me>
> Signed-off-by: Omar Sandoval <osan...@fb.com>
> ---
> I think this should do it. Verified that normal operation still works
> for me, but I'm not sure how to test the actual _hctx() alloc path.
> Sagi, could you please test this series out?
Hm, Sagi, your mail server seems to have rejected patches 2 and 3
because git-send-email duplicated the in-reply-to header for some
reason. I've attached the patches instead.
>From dcfe49f597dc1eec3b326024c86a6ad3afb82fa8 Mon Sep 17 00:00:00 2001
Message-Id: <dcfe49f597dc1eec3b326024c86a6ad3afb82fa8.1488217516.git.osan...@fb.com>
From: Omar Sandoval <osan...@fb.com>
Date: Mon, 27 Feb 2017 09:34:20 -0800
Subject: [PATCH 1/3] blk-mq: make blk_mq_alloc_request_hctx() allocate a
scheduler request
blk_mq_alloc_request_hctx() allocates a driver request directly, unlike
its blk_mq_alloc_request() counterpart. It also crashes because it
doesn't update the tags->rqs map.
Fix it by making it allocate a scheduler request.
Reported-by: Sagi Grimberg <s...@grimberg.me>
Signed-off-by: Omar Sandoval <osan...@fb.com>
---
I think this should do it. Verified that normal operation still works
for me, but I'm not sure how to test the actual _hctx() alloc path.
Sagi, could you please test this series out?
block/blk-mq-sched.c | 11 +++++------
block/blk-mq.c | 34 +++++++++++++++-------------------
2 files changed, 20 insertions(+), 25 deletions(-)
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 46ca965fff5c..5697b23412a1 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -110,15 +110,14 @@ struct request *blk_mq_sched_get_request(struct request_queue *q,
struct blk_mq_alloc_data *data)
{
struct elevator_queue *e = q->elevator;
- struct blk_mq_hw_ctx *hctx;
- struct blk_mq_ctx *ctx;
struct request *rq;
blk_queue_enter_live(q);
- ctx = blk_mq_get_ctx(q);
- hctx = blk_mq_map_queue(q, ctx->cpu);
-
- blk_mq_set_alloc_data(data, q, data->flags, ctx, hctx);
+ data->q = q;
+ if (likely(!data->ctx))
+ data->ctx = blk_mq_get_ctx(q);
+ if (likely(!data->hctx))
+ data->hctx = blk_mq_map_queue(q, data->ctx->cpu);
if (e) {
data->flags |= BLK_MQ_REQ_INTERNAL;
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 9611cd9920e9..cc9713f574a5 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -273,10 +273,9 @@ EXPORT_SYMBOL(blk_mq_alloc_request);
struct request *blk_mq_alloc_request_hctx(struct request_queue *q, int rw,
unsigned int flags, unsigned int hctx_idx)
{
- struct blk_mq_hw_ctx *hctx;
- struct blk_mq_ctx *ctx;
+ struct blk_mq_alloc_data alloc_data = { .flags = flags };
struct request *rq;
- struct blk_mq_alloc_data alloc_data;
+ unsigned int cpu;
int ret;
/*
@@ -299,26 +298,23 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q, int rw,
* Check if the hardware context is actually mapped to anything.
* If not tell the caller that it should skip this queue.
*/
- hctx = q->queue_hw_ctx[hctx_idx];
- if (!blk_mq_hw_queue_mapped(hctx)) {
- ret = -EXDEV;
- goto out_queue_exit;
+ alloc_data.hctx = q->queue_hw_ctx[hctx_idx];
+ if (!blk_mq_hw_queue_mapped(alloc_data.hctx)) {
+ blk_queue_exit(q);
+ return ERR_PTR(-EXDEV);
}
- ctx = __blk_mq_get_ctx(q, cpumask_first(hctx->cpumask));
+ cpu = cpumask_first(alloc_data.hctx->cpumask);
+ alloc_data.ctx = __blk_mq_get_ctx(q, cpu);
- blk_mq_set_alloc_data(&alloc_data, q, flags, ctx, hctx);
- rq = __blk_mq_alloc_request(&alloc_data, rw);
- if (!rq) {
- ret = -EWOULDBLOCK;
- goto out_queue_exit;
- }
- alloc_data.hctx->tags->rqs[rq->tag] = rq;
-
- return rq;
+ rq = blk_mq_sched_get_request(q, NULL, rw, &alloc_data);
-out_queue_exit:
+ blk_mq_put_ctx(alloc_data.ctx);
blk_queue_exit(q);
- return ERR_PTR(ret);
+
+ if (!rq)
+ return ERR_PTR(-EWOULDBLOCK);
+
+ return rq;
}
EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx);
--
2.12.0
>From 87aa35aa12f2edd4a9c56c382bf85ee580edf156 Mon Sep 17 00:00:00 2001
Message-Id: <87aa35aa12f2edd4a9c56c382bf85ee580edf156.1488217516.git.osan...@fb.com>
In-Reply-To: <dcfe49f597dc1eec3b326024c86a6ad3afb82fa8.1488217516.git.osan...@fb.com>
References: <dcfe49f597dc1eec3b326024c86a6ad3afb82fa8.1488217516.git.osan...@fb.com>
From: Omar Sandoval <osan...@fb.com>
Date: Mon, 27 Feb 2017 09:38:58 -0800
Subject: [PATCH 2/3] blk-mq: kill blk_mq_set_alloc_data()
Nothing is using it anymore.
Signed-off-by: Omar Sandoval <osan...@fb.com>
---
block/blk-mq.h | 10 ----------
1 file changed, 10 deletions(-)
diff --git a/block/blk-mq.h b/block/blk-mq.h
index 24b2256186f3..088ced003c13 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -146,16 +146,6 @@ struct blk_mq_alloc_data {
struct blk_mq_hw_ctx *hctx;
};
-static inline void blk_mq_set_alloc_data(struct blk_mq_alloc_data *data,
- struct request_queue *q, unsigned int flags,
- struct blk_mq_ctx *ctx, struct blk_mq_hw_ctx *hctx)
-{
- data->q = q;
- data->flags = flags;
- data->ctx = ctx;
- data->hctx = hctx;
-}
-
static inline struct blk_mq_tags *blk_mq_tags_from_data(struct blk_mq_alloc_data *data)
{
if (data->flags & BLK_MQ_REQ_INTERNAL)
--
2.12.0
>From 4715cce107df8b579734a074093a34001efd01d0 Mon Sep 17 00:00:00 2001
Message-Id: <4715cce107df8b579734a074093a34001efd01d0.1488217516.git.osan...@fb.com>
In-Reply-To: <dcfe49f597dc1eec3b326024c86a6ad3afb82fa8.1488217516.git.osan...@fb.com>
References: <dcfe49f597dc1eec3b326024c86a6ad3afb82fa8.1488217516.git.osan...@fb.com>
From: Omar Sandoval <osan...@fb.com>
Date: Mon, 27 Feb 2017 09:40:34 -0800
Subject: [PATCH 3/3] blk-mq: move update of tags->rqs to
__blk_mq_alloc_request()
No functional difference, it just makes a little more sense to update
the tag map where we actually allocate the tag.
Signed-off-by: Omar Sandoval <osan...@fb.com>
---
Optional cleanup, since there's only one place that does this.
block/blk-mq-sched.c | 2 --
block/blk-mq.c | 1 +
2 files changed, 1 insertion(+), 2 deletions(-)
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 5697b23412a1..09af8ff18719 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -134,8 +134,6 @@ struct request *blk_mq_sched_get_request(struct request_queue *q,
rq = __blk_mq_alloc_request(data, op);
} else {
rq = __blk_mq_alloc_request(data, op);
- if (rq)
- data->hctx->tags->rqs[rq->tag] = rq;
}
if (rq) {
diff --git a/block/blk-mq.c b/block/blk-mq.c
index cc9713f574a5..452c1caf978f 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -234,6 +234,7 @@ struct request *__blk_mq_alloc_request(struct blk_mq_alloc_data *data,
}
rq->tag = tag;
rq->internal_tag = -1;
+ data->hctx->tags->rqs[rq->tag] = rq;
}
blk_mq_rq_ctx_init(data->q, data->ctx, rq, op);
--
2.12.0
