Commit 6fca6a61 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
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blk-mq: add helper to insert requests from irq context

Both the cache flush state machine and the SCSI midlayer want to submit
requests from irq context, and the current per-request requeue_work
unfortunately causes corruption due to sharing with the csd field for
flushes.  Replace them with a per-request_queue list of requests to
be requeued.

Based on an earlier test by Ming Lei.
Signed-off-by: default avatarChristoph Hellwig <>
Reported-by: default avatarMing Lei <>
Tested-by: default avatarMing Lei <>
Signed-off-by: default avatarJens Axboe <>
parent 7738dac4
......@@ -130,21 +130,13 @@ static void blk_flush_restore_request(struct request *rq)
static void mq_flush_run(struct work_struct *work)
struct request *rq;
rq = container_of(work, struct request, requeue_work);
memset(&rq->csd, 0, sizeof(rq->csd));
blk_mq_insert_request(rq, false, true, false);
static bool blk_flush_queue_rq(struct request *rq, bool add_front)
if (rq->q->mq_ops) {
INIT_WORK(&rq->requeue_work, mq_flush_run);
struct request_queue *q = rq->q;
blk_mq_add_to_requeue_list(rq, add_front);
return false;
} else {
if (add_front)
......@@ -516,10 +516,68 @@ void blk_mq_requeue_request(struct request *rq)
blk_mq_insert_request(rq, true, true, false);
blk_mq_add_to_requeue_list(rq, true);
static void blk_mq_requeue_work(struct work_struct *work)
struct request_queue *q =
container_of(work, struct request_queue, requeue_work);
struct request *rq, *next;
unsigned long flags;
spin_lock_irqsave(&q->requeue_lock, flags);
list_splice_init(&q->requeue_list, &rq_list);
spin_unlock_irqrestore(&q->requeue_lock, flags);
list_for_each_entry_safe(rq, next, &rq_list, queuelist) {
if (!(rq->cmd_flags & REQ_SOFTBARRIER))
rq->cmd_flags &= ~REQ_SOFTBARRIER;
blk_mq_insert_request(rq, true, false, false);
while (!list_empty(&rq_list)) {
rq = list_entry(, struct request, queuelist);
blk_mq_insert_request(rq, false, false, false);
blk_mq_run_queues(q, false);
void blk_mq_add_to_requeue_list(struct request *rq, bool at_head)
struct request_queue *q = rq->q;
unsigned long flags;
* We abuse this flag that is otherwise used by the I/O scheduler to
* request head insertation from the workqueue.
BUG_ON(rq->cmd_flags & REQ_SOFTBARRIER);
spin_lock_irqsave(&q->requeue_lock, flags);
if (at_head) {
rq->cmd_flags |= REQ_SOFTBARRIER;
list_add(&rq->queuelist, &q->requeue_list);
} else {
list_add_tail(&rq->queuelist, &q->requeue_list);
spin_unlock_irqrestore(&q->requeue_lock, flags);
void blk_mq_kick_requeue_list(struct request_queue *q)
struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
return tags->rqs[tag];
......@@ -1812,6 +1870,10 @@ struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
q->sg_reserved_size = INT_MAX;
INIT_WORK(&q->requeue_work, blk_mq_requeue_work);
if (q->nr_hw_queues > 1)
blk_queue_make_request(q, blk_mq_make_request);
......@@ -172,6 +172,8 @@ void blk_mq_end_io(struct request *rq, int error);
void __blk_mq_end_io(struct request *rq, int error);
void blk_mq_requeue_request(struct request *rq);
void blk_mq_add_to_requeue_list(struct request *rq, bool at_head);
void blk_mq_kick_requeue_list(struct request_queue *q);
void blk_mq_complete_request(struct request *rq);
void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx);
......@@ -99,7 +99,6 @@ struct request {
struct list_head queuelist;
union {
struct call_single_data csd;
struct work_struct requeue_work;
unsigned long fifo_time;
......@@ -463,6 +462,10 @@ struct request_queue {
struct request *flush_rq;
spinlock_t mq_flush_lock;
struct list_head requeue_list;
spinlock_t requeue_lock;
struct work_struct requeue_work;
struct mutex sysfs_lock;
int bypass_depth;
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