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block: Revert v5.0 blk_mq_request_issue_directly() changes 

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:
* d6a51a97c0 ("blk-mq: replace and kill blk_mq_request_issue_directly") # v5.0.
* 5b7a6f128a ("blk-mq: issue directly with bypass 'false' in blk_mq_sched_insert_requests") # v5.0.
* 7f556a44e6 ("blk-mq: refactor the code of issue request directly") # v5.0.

Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Jianchao Wang <jianchao.w.wang@oracle.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: James Smart <james.smart@broadcom.com>
Cc: Dongli Zhang <dongli.zhang@oracle.com>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: <stable@vger.kernel.org>
Reported-by: Laurence Oberman <loberman@redhat.com>
Tested-by: Laurence Oberman <loberman@redhat.com>
Fixes: 7f556a44e6 ("blk-mq: refactor the code of issue request directly") # v5.0.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
hifive-unleashed-5.1
Bart Van Assche 2019-04-04 10:08:43 -07:00 committed by Jens Axboe
parent f0d1762554
commit fd9c40f64c
4 changed files with 71 additions and 69 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
block/blk-core.c
View File

@ -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);

8
block/blk-mq-sched.c
View File

@ -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);

122
block/blk-mq.c
View File

@ -1801,74 +1801,76 @@ 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)
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:
return __blk_mq_issue_directly(hctx, rq, cookie, last);
insert:
if (bypass_insert)
return BLK_STS_RESOURCE;
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_status_t ret;
int srcu_idx;
blk_qc_t unused_cookie;
struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
hctx_lock(hctx, &srcu_idx);
ret = __blk_mq_try_issue_directly(hctx, rq, &unused_cookie, true, last);
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 ret;
}
@ -1876,20 +1878,22 @@ out_unlock:
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);
}
}
/*
@ -1897,7 +1901,7 @@ 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);
}
@ -2012,13 +2016,13 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
data.hctx = same_queue_rq->mq_hctx;
trace_block_unplug(q, 1, true);
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);

6
block/blk-mq.h
View File

@ -70,10 +70,8 @@ void blk_mq_request_bypass_insert(struct request *rq, bool run_queue);
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);