On Fri, 2019-04-05 at 05:43 +0800, Ming Lei wrote:
> On Thu, Apr 04, 2019 at 10:08:43AM -0700, Bart Van Assche wrote:
> > blk_mq_try_issue_directly() can return BLK_STS*_RESOURCE for
> > requests that
> > have been queued. If that happens when blk_mq_try_issue_directly()
> > is called
> > by the dm-mpath driver then dm-mpath will try to resubmit a request
> > that is
> > already queued and a kernel crash follows. Since it is nontrivial
> > to fix
> > blk_mq_request_issue_directly(), revert the
> > blk_mq_request_issue_directly()
> > changes that went into kernel v5.0.
> >
> > This patch reverts the following commits:
> > * d6a51a97c0b2 ("blk-mq: replace and kill
> > blk_mq_request_issue_directly") # v5.0.
> > * 5b7a6f128aad ("blk-mq: issue directly with bypass 'false' in
> > blk_mq_sched_insert_requests") # v5.0.
> > * 7f556a44e61d ("blk-mq: refactor the code of issue request
> > directly") # v5.0.
>
> I am fine to revert them now.
>
> However, could you revert them one by one so that they can be
> reviewed
> easily?
>
> Thanks,
> Ming
Hello Ming
I did them 1 by 1 here for you
commit cff8d4710f8cc0817950942252bcf0809a95aa4a
Author: Laurence Oberman <[email protected]>
Date: Thu Apr 4 19:51:33 2019 -0400
Revert "blk-mq: replace and kill blk_mq_request_issue_directly"
This reverts commit d6a51a97c0b2e21fec224746c2683ff739bcf4ae.
diff --git a/block/blk-core.c b/block/blk-core.c
index 4673ebe..a55389b 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1245,8 +1245,6 @@ static int blk_cloned_rq_check_limits(struct
request_queue *q,
*/
blk_status_t blk_insert_cloned_request(struct request_queue *q, struct
request *rq)
{
- blk_qc_t unused;
-
if (blk_cloned_rq_check_limits(q, rq))
return BLK_STS_IOERR;
@@ -1262,7 +1260,7 @@ blk_status_t blk_insert_cloned_request(struct
request_queue *q, struct request *
* bypass a potential scheduler on the bottom device for
* insert.
*/
- return blk_mq_try_issue_directly(rq->mq_hctx, rq, &unused,
true, true);
+ return blk_mq_request_issue_directly(rq, true);
}
EXPORT_SYMBOL_GPL(blk_insert_cloned_request);
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 3ff3d7b..536b176 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1800,7 +1800,7 @@ static blk_status_t
__blk_mq_issue_directly(struct blk_mq_hw_ctx *hctx,
return ret;
}
-blk_status_t blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
+static blk_status_t blk_mq_try_issue_directly(struct blk_mq_hw_ctx
*hctx,
struct request *rq,
blk_qc_t *cookie,
bool bypass, bool last)
@@ -1872,6 +1872,13 @@ blk_status_t blk_mq_try_issue_directly(struct
blk_mq_hw_ctx *hctx,
return ret;
}
+blk_status_t blk_mq_request_issue_directly(struct request *rq, bool
last)
+{
+ blk_qc_t unused;
+
+ return blk_mq_try_issue_directly(rq->mq_hctx, rq, &unused,
true, last);
+}
+
void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx,
struct list_head *list)
{
diff --git a/block/blk-mq.h b/block/blk-mq.h
index d704fc7..423ea88 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -70,10 +70,8 @@ void __blk_mq_insert_request(struct blk_mq_hw_ctx
*hctx, struct request *rq,
void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct
blk_mq_ctx *ctx,
struct list_head *list);
-blk_status_t blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
- struct request *rq,
- blk_qc_t *cookie,
- bool bypass, bool
last);
+/* Used by blk_insert_cloned_request() to issue request directly */
+blk_status_t blk_mq_request_issue_directly(struct request *rq, bool
last);
void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx,
struct list_head *list);
commit 9b7f3de27504aefae8304dfd9640a1477599de8b
Author: Laurence Oberman <[email protected]>
Date: Thu Apr 4 19:53:23 2019 -0400
Revert "blk-mq: issue directly with bypass 'false' in
blk_mq_sched_insert_requests"
This reverts commit 5b7a6f128aad761b471ca0ff620b4841b38e596f.
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 4090553..aa6bc5c 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -423,10 +423,12 @@ void blk_mq_sched_insert_requests(struct
blk_mq_hw_ctx *hctx,
* busy in case of 'none' scheduler, and this way may
save
* us one extra enqueue & dequeue to sw queue.
*/
- if (!hctx->dispatch_busy && !e && !run_queue_async)
+ if (!hctx->dispatch_busy && !e && !run_queue_async) {
blk_mq_try_issue_list_directly(hctx, list);
- else
- blk_mq_insert_requests(hctx, ctx, list);
+ if (list_empty(list))
+ return;
+ }
+ blk_mq_insert_requests(hctx, ctx, list);
}
blk_mq_run_hw_queue(hctx, run_queue_async);
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 536b176..df2150e 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1882,20 +1882,22 @@ blk_status_t
blk_mq_request_issue_directly(struct request *rq, bool last)
void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx,
struct list_head *list)
{
- blk_qc_t unused;
- blk_status_t ret = BLK_STS_OK;
-
while (!list_empty(list)) {
+ blk_status_t ret;
struct request *rq = list_first_entry(list, struct
request,
queuelist);
list_del_init(&rq->queuelist);
- if (ret == BLK_STS_OK)
- ret = blk_mq_try_issue_directly(hctx, rq,
&unused,
- false,
+ ret = blk_mq_request_issue_directly(rq,
list_empty(list));
+ if (ret != BLK_STS_OK) {
+ if (ret == BLK_STS_RESOURCE ||
+ ret == BLK_STS_DEV_RESOURCE) {
+ blk_mq_request_bypass_insert(rq,
list_empty(list
));
- else
- blk_mq_sched_insert_request(rq, false, true,
false);
+ break;
+ }
+ blk_mq_end_request(rq, ret);
+ }
}
/*
@@ -1903,7 +1905,7 @@ void blk_mq_try_issue_list_directly(struct
blk_mq_hw_ctx *hctx,
* the driver there was more coming, but that turned out to
* be a lie.
*/
- if (ret != BLK_STS_OK && hctx->queue->mq_ops->commit_rqs)
+ if (!list_empty(list) && hctx->queue->mq_ops->commit_rqs)
hctx->queue->mq_ops->commit_rqs(hctx);
}
commit 6db32dc1b5cb3d236f26f77947094f1d895ba557
Author: Laurence Oberman <[email protected]>
Date: Thu Apr 4 19:54:28 2019 -0400
Revert "blk-mq: refactor the code of issue request directly"
This reverts commit 7f556a44e61d0b62d78db9a2662a5f0daef010f2.
diff --git a/block/blk-mq.c b/block/blk-mq.c
index df2150e..afac6c2 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1800,83 +1800,78 @@ static blk_status_t
__blk_mq_issue_directly(struct blk_mq_hw_ctx *hctx,
return ret;
}
-static blk_status_t blk_mq_try_issue_directly(struct blk_mq_hw_ctx
*hctx,
+static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx
*hctx,
struct request *rq,
blk_qc_t *cookie,
- bool bypass, bool last)
+ bool bypass_insert,
bool last)
{
struct request_queue *q = rq->q;
bool run_queue = true;
- blk_status_t ret = BLK_STS_RESOURCE;
- int srcu_idx;
- bool force = false;
- hctx_lock(hctx, &srcu_idx);
/*
- * hctx_lock is needed before checking quiesced flag.
+ * RCU or SRCU read lock is needed before checking quiesced
flag.
*
- * When queue is stopped or quiesced, ignore 'bypass', insert
- * and return BLK_STS_OK to caller, and avoid driver to try to
- * dispatch again.
+ * When queue is stopped or quiesced, ignore 'bypass_insert'
from
+ * blk_mq_request_issue_directly(), and return BLK_STS_OK to
caller,
+ * and avoid driver to try to dispatch again.
*/
- if (unlikely(blk_mq_hctx_stopped(hctx) ||
blk_queue_quiesced(q))) {
+ if (blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q)) {
run_queue = false;
- bypass = false;
- goto out_unlock;
+ bypass_insert = false;
+ goto insert;
}
- if (unlikely(q->elevator && !bypass))
- goto out_unlock;
+ if (q->elevator && !bypass_insert)
+ goto insert;
if (!blk_mq_get_dispatch_budget(hctx))
- goto out_unlock;
+ goto insert;
if (!blk_mq_get_driver_tag(rq)) {
blk_mq_put_dispatch_budget(hctx);
- goto out_unlock;
+ goto insert;
}
- /*
- * Always add a request that has been through
- *.queue_rq() to the hardware dispatch list.
- */
- force = true;
- ret = __blk_mq_issue_directly(hctx, rq, cookie, last);
-out_unlock:
- hctx_unlock(hctx, srcu_idx);
- switch (ret) {
- case BLK_STS_OK:
- break;
- case BLK_STS_DEV_RESOURCE:
- case BLK_STS_RESOURCE:
- if (force) {
- blk_mq_request_bypass_insert(rq, run_queue);
- /*
- * We have to return BLK_STS_OK for the DM
- * to avoid livelock. Otherwise, we return
- * the real result to indicate whether the
- * request is direct-issued successfully.
- */
- ret = bypass ? BLK_STS_OK : ret;
- } else if (!bypass) {
- blk_mq_sched_insert_request(rq, false,
- run_queue, false);
- }
- break;
- default:
- if (!bypass)
- blk_mq_end_request(rq, ret);
- break;
- }
+ return __blk_mq_issue_directly(hctx, rq, cookie, last);
+insert:
+ if (bypass_insert)
+ return BLK_STS_RESOURCE;
- return ret;
+ blk_mq_request_bypass_insert(rq, run_queue);
+ return BLK_STS_OK;
+}
+
+static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
+ struct request *rq, blk_qc_t *cookie)
+{
+ blk_status_t ret;
+ int srcu_idx;
+
+ might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
+
+ hctx_lock(hctx, &srcu_idx);
+
+ ret = __blk_mq_try_issue_directly(hctx, rq, cookie, false,
true);
+ if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE)
+ blk_mq_request_bypass_insert(rq, true);
+ else if (ret != BLK_STS_OK)
+ blk_mq_end_request(rq, ret);
+
+ hctx_unlock(hctx, srcu_idx);
}
blk_status_t blk_mq_request_issue_directly(struct request *rq, bool
last)
{
- blk_qc_t unused;
+ blk_status_t ret;
+ int srcu_idx;
+ blk_qc_t unused_cookie;
+ struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
- return blk_mq_try_issue_directly(rq->mq_hctx, rq, &unused,
true, last);
+ hctx_lock(hctx, &srcu_idx);
+ ret = __blk_mq_try_issue_directly(hctx, rq, &unused_cookie,
true, last);
+ hctx_unlock(hctx, srcu_idx);
+
+ return ret;
}
void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx,
@@ -2018,13 +2013,13 @@ static blk_qc_t blk_mq_make_request(struct
request_queue *q, struct bio *bio)
if (same_queue_rq) {
data.hctx = same_queue_rq->mq_hctx;
blk_mq_try_issue_directly(data.hctx,
same_queue_rq,
- &cookie, false, true);
+ &cookie);
}
} else if ((q->nr_hw_queues > 1 && is_sync) || (!q->elevator &&
!data.hctx->dispatch_busy)) {
blk_mq_put_ctx(data.ctx);
blk_mq_bio_to_request(rq, bio);
- blk_mq_try_issue_directly(data.hctx, rq, &cookie,
false, true);
+ blk_mq_try_issue_directly(data.hctx, rq, &cookie);
} else {
blk_mq_put_ctx(data.ctx);
blk_mq_bio_to_request(rq, bio);
