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block: remove non mq parts from the flush code
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Reviewed-by: Hannes Reinecke <[email protected]>
Tested-by: Ming Lei <[email protected]>
Reviewed-by: Omar Sandoval <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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@axboe
axboe committed Nov 7, 2018
1 parent 7ca0192 commit 7e992f8
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Showing 2 changed files with 31 additions and 127 deletions.
154 changes: 30 additions & 124 deletions block/blk-flush.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -134,16 +134,8 @@ static void blk_flush_restore_request(struct request *rq)

static bool blk_flush_queue_rq(struct request *rq, bool add_front)
{
if (rq->q->mq_ops) {
blk_mq_add_to_requeue_list(rq, add_front, true);
return false;
} else {
if (add_front)
list_add(&rq->queuelist, &rq->q->queue_head);
else
list_add_tail(&rq->queuelist, &rq->q->queue_head);
return true;
}
blk_mq_add_to_requeue_list(rq, add_front, true);
return false;
}

/**
Expand Down Expand Up @@ -204,10 +196,7 @@ static bool blk_flush_complete_seq(struct request *rq,
BUG_ON(!list_empty(&rq->queuelist));
list_del_init(&rq->flush.list);
blk_flush_restore_request(rq);
if (q->mq_ops)
blk_mq_end_request(rq, error);
else
__blk_end_request_all(rq, error);
blk_mq_end_request(rq, error);
break;

default:
Expand All @@ -226,20 +215,17 @@ static void flush_end_io(struct request *flush_rq, blk_status_t error)
struct request *rq, *n;
unsigned long flags = 0;
struct blk_flush_queue *fq = blk_get_flush_queue(q, flush_rq->mq_ctx);
struct blk_mq_hw_ctx *hctx;

if (q->mq_ops) {
struct blk_mq_hw_ctx *hctx;

/* release the tag's ownership to the req cloned from */
spin_lock_irqsave(&fq->mq_flush_lock, flags);
hctx = blk_mq_map_queue(q, flush_rq->mq_ctx->cpu);
if (!q->elevator) {
blk_mq_tag_set_rq(hctx, flush_rq->tag, fq->orig_rq);
flush_rq->tag = -1;
} else {
blk_mq_put_driver_tag_hctx(hctx, flush_rq);
flush_rq->internal_tag = -1;
}
/* release the tag's ownership to the req cloned from */
spin_lock_irqsave(&fq->mq_flush_lock, flags);
hctx = blk_mq_map_queue(q, flush_rq->mq_ctx->cpu);
if (!q->elevator) {
blk_mq_tag_set_rq(hctx, flush_rq->tag, fq->orig_rq);
flush_rq->tag = -1;
} else {
blk_mq_put_driver_tag_hctx(hctx, flush_rq);
flush_rq->internal_tag = -1;
}

running = &fq->flush_queue[fq->flush_running_idx];
Expand All @@ -248,9 +234,6 @@ static void flush_end_io(struct request *flush_rq, blk_status_t error)
/* account completion of the flush request */
fq->flush_running_idx ^= 1;

if (!q->mq_ops)
elv_completed_request(q, flush_rq);

/* and push the waiting requests to the next stage */
list_for_each_entry_safe(rq, n, running, flush.list) {
unsigned int seq = blk_flush_cur_seq(rq);
Expand All @@ -259,24 +242,8 @@ static void flush_end_io(struct request *flush_rq, blk_status_t error)
queued |= blk_flush_complete_seq(rq, fq, seq, error);
}

/*
* Kick the queue to avoid stall for two cases:
* 1. Moving a request silently to empty queue_head may stall the
* queue.
* 2. When flush request is running in non-queueable queue, the
* queue is hold. Restart the queue after flush request is finished
* to avoid stall.
* This function is called from request completion path and calling
* directly into request_fn may confuse the driver. Always use
* kblockd.
*/
if (queued || fq->flush_queue_delayed) {
WARN_ON(q->mq_ops);
blk_run_queue_async(q);
}
fq->flush_queue_delayed = 0;
if (q->mq_ops)
spin_unlock_irqrestore(&fq->mq_flush_lock, flags);
spin_unlock_irqrestore(&fq->mq_flush_lock, flags);
}

/**
Expand All @@ -301,6 +268,7 @@ static bool blk_kick_flush(struct request_queue *q, struct blk_flush_queue *fq,
struct request *first_rq =
list_first_entry(pending, struct request, flush.list);
struct request *flush_rq = fq->flush_rq;
struct blk_mq_hw_ctx *hctx;

/* C1 described at the top of this file */
if (fq->flush_pending_idx != fq->flush_running_idx || list_empty(pending))
Expand Down Expand Up @@ -334,19 +302,15 @@ static bool blk_kick_flush(struct request_queue *q, struct blk_flush_queue *fq,
* In case of IO scheduler, flush rq need to borrow scheduler tag
* just for cheating put/get driver tag.
*/
if (q->mq_ops) {
struct blk_mq_hw_ctx *hctx;

flush_rq->mq_ctx = first_rq->mq_ctx;

if (!q->elevator) {
fq->orig_rq = first_rq;
flush_rq->tag = first_rq->tag;
hctx = blk_mq_map_queue(q, first_rq->mq_ctx->cpu);
blk_mq_tag_set_rq(hctx, first_rq->tag, flush_rq);
} else {
flush_rq->internal_tag = first_rq->internal_tag;
}
flush_rq->mq_ctx = first_rq->mq_ctx;

if (!q->elevator) {
fq->orig_rq = first_rq;
flush_rq->tag = first_rq->tag;
hctx = blk_mq_map_queue(q, first_rq->mq_ctx->cpu);
blk_mq_tag_set_rq(hctx, first_rq->tag, flush_rq);
} else {
flush_rq->internal_tag = first_rq->internal_tag;
}

flush_rq->cmd_flags = REQ_OP_FLUSH | REQ_PREFLUSH;
Expand All @@ -358,49 +322,6 @@ static bool blk_kick_flush(struct request_queue *q, struct blk_flush_queue *fq,
return blk_flush_queue_rq(flush_rq, false);
}

static void flush_data_end_io(struct request *rq, blk_status_t error)
{
struct request_queue *q = rq->q;
struct blk_flush_queue *fq = blk_get_flush_queue(q, NULL);

lockdep_assert_held(q->queue_lock);

/*
* Updating q->in_flight[] here for making this tag usable
* early. Because in blk_queue_start_tag(),
* q->in_flight[BLK_RW_ASYNC] is used to limit async I/O and
* reserve tags for sync I/O.
*
* More importantly this way can avoid the following I/O
* deadlock:
*
* - suppose there are 40 fua requests comming to flush queue
* and queue depth is 31
* - 30 rqs are scheduled then blk_queue_start_tag() can't alloc
* tag for async I/O any more
* - all the 30 rqs are completed before FLUSH_PENDING_TIMEOUT
* and flush_data_end_io() is called
* - the other rqs still can't go ahead if not updating
* q->in_flight[BLK_RW_ASYNC] here, meantime these rqs
* are held in flush data queue and make no progress of
* handling post flush rq
* - only after the post flush rq is handled, all these rqs
* can be completed
*/

elv_completed_request(q, rq);

/* for avoiding double accounting */
rq->rq_flags &= ~RQF_STARTED;

/*
* After populating an empty queue, kick it to avoid stall. Read
* the comment in flush_end_io().
*/
if (blk_flush_complete_seq(rq, fq, REQ_FSEQ_DATA, error))
blk_run_queue_async(q);
}

static void mq_flush_data_end_io(struct request *rq, blk_status_t error)
{
struct request_queue *q = rq->q;
Expand Down Expand Up @@ -443,9 +364,6 @@ void blk_insert_flush(struct request *rq)
unsigned int policy = blk_flush_policy(fflags, rq);
struct blk_flush_queue *fq = blk_get_flush_queue(q, rq->mq_ctx);

if (!q->mq_ops)
lockdep_assert_held(q->queue_lock);

/*
* @policy now records what operations need to be done. Adjust
* REQ_PREFLUSH and FUA for the driver.
Expand All @@ -468,10 +386,7 @@ void blk_insert_flush(struct request *rq)
* complete the request.
*/
if (!policy) {
if (q->mq_ops)
blk_mq_end_request(rq, 0);
else
__blk_end_request(rq, 0, 0);
blk_mq_end_request(rq, 0);
return;
}

Expand All @@ -484,10 +399,7 @@ void blk_insert_flush(struct request *rq)
*/
if ((policy & REQ_FSEQ_DATA) &&
!(policy & (REQ_FSEQ_PREFLUSH | REQ_FSEQ_POSTFLUSH))) {
if (q->mq_ops)
blk_mq_request_bypass_insert(rq, false);
else
list_add_tail(&rq->queuelist, &q->queue_head);
blk_mq_request_bypass_insert(rq, false);
return;
}

Expand All @@ -499,17 +411,12 @@ void blk_insert_flush(struct request *rq)
INIT_LIST_HEAD(&rq->flush.list);
rq->rq_flags |= RQF_FLUSH_SEQ;
rq->flush.saved_end_io = rq->end_io; /* Usually NULL */
if (q->mq_ops) {
rq->end_io = mq_flush_data_end_io;

spin_lock_irq(&fq->mq_flush_lock);
blk_flush_complete_seq(rq, fq, REQ_FSEQ_ACTIONS & ~policy, 0);
spin_unlock_irq(&fq->mq_flush_lock);
return;
}
rq->end_io = flush_data_end_io;
rq->end_io = mq_flush_data_end_io;

spin_lock_irq(&fq->mq_flush_lock);
blk_flush_complete_seq(rq, fq, REQ_FSEQ_ACTIONS & ~policy, 0);
spin_unlock_irq(&fq->mq_flush_lock);
}

/**
Expand Down Expand Up @@ -575,8 +482,7 @@ struct blk_flush_queue *blk_alloc_flush_queue(struct request_queue *q,
if (!fq)
goto fail;

if (q->mq_ops)
spin_lock_init(&fq->mq_flush_lock);
spin_lock_init(&fq->mq_flush_lock);

rq_sz = round_up(rq_sz + cmd_size, cache_line_size());
fq->flush_rq = kzalloc_node(rq_sz, flags, node);
Expand Down
4 changes: 1 addition & 3 deletions block/blk.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -114,9 +114,7 @@ static inline void queue_flag_clear(unsigned int flag, struct request_queue *q)
static inline struct blk_flush_queue *blk_get_flush_queue(
struct request_queue *q, struct blk_mq_ctx *ctx)
{
if (q->mq_ops)
return blk_mq_map_queue(q, ctx->cpu)->fq;
return q->fq;
return blk_mq_map_queue(q, ctx->cpu)->fq;
}

static inline void __blk_get_queue(struct request_queue *q)
Expand Down

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