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blk-mq: fix passthrough plugging 

First we can't add request into plug list in blk_mq_request_bypass_insert
which may be called when flushing plug list, so nested plug is caused.

Second if polled passthrough request is inserted via blk_execute_rq(),
it can't be added to plug list too since io polling needs the request
to be issued to driver.

Fixes the two by moving plugging into blk_execute_rq_no_wait().

Cc: Christoph Hellwig <hch@lst.de>
Fixes: 1c2d2fff6d ("block: wire-up support for passthrough plugging")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20220512140010.1458645-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Ming Lei 2022-05-12 22:00:10 +08:00 committed by Jens Axboe
parent f569add471
commit a327c341dc
1 changed files with 63 additions and 51 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

114
block/blk-mq.c
View File

@ -1169,6 +1169,62 @@ static void blk_end_sync_rq(struct request *rq, blk_status_t error)
complete(waiting);
}
/*
* Allow 2x BLK_MAX_REQUEST_COUNT requests on plug queue for multiple
* queues. This is important for md arrays to benefit from merging
* requests.
*/
static inline unsigned short blk_plug_max_rq_count(struct blk_plug *plug)
{
if (plug->multiple_queues)
return BLK_MAX_REQUEST_COUNT * 2;
return BLK_MAX_REQUEST_COUNT;
}
static void blk_add_rq_to_plug(struct blk_plug *plug, struct request *rq)
{
struct request *last = rq_list_peek(&plug->mq_list);
if (!plug->rq_count) {
trace_block_plug(rq->q);
} else if (plug->rq_count >= blk_plug_max_rq_count(plug) ||
(!blk_queue_nomerges(rq->q) &&
blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
blk_mq_flush_plug_list(plug, false);
trace_block_plug(rq->q);
}
if (!plug->multiple_queues && last && last->q != rq->q)
plug->multiple_queues = true;
if (!plug->has_elevator && (rq->rq_flags & RQF_ELV))
plug->has_elevator = true;
rq->rq_next = NULL;
rq_list_add(&plug->mq_list, rq);
plug->rq_count++;
}
static void __blk_execute_rq_nowait(struct request *rq, bool at_head,
rq_end_io_fn *done, bool use_plug)
{
WARN_ON(irqs_disabled());
WARN_ON(!blk_rq_is_passthrough(rq));
rq->end_io = done;
blk_account_io_start(rq);
if (use_plug && current->plug) {
blk_add_rq_to_plug(current->plug, rq);
return;
}
/*
* don't check dying flag for MQ because the request won't
* be reused after dying flag is set
*/
blk_mq_sched_insert_request(rq, at_head, true, false);
}
/**
* blk_execute_rq_nowait - insert a request to I/O scheduler for execution
* @rq: request to insert
@ -1184,18 +1240,8 @@ static void blk_end_sync_rq(struct request *rq, blk_status_t error)
*/
void blk_execute_rq_nowait(struct request *rq, bool at_head, rq_end_io_fn *done)
{
WARN_ON(irqs_disabled());
WARN_ON(!blk_rq_is_passthrough(rq));
__blk_execute_rq_nowait(rq, at_head, done, true);
rq->end_io = done;
blk_account_io_start(rq);
/*
* don't check dying flag for MQ because the request won't
* be reused after dying flag is set
*/
blk_mq_sched_insert_request(rq, at_head, true, false);
}
EXPORT_SYMBOL_GPL(blk_execute_rq_nowait);
@ -1233,8 +1279,13 @@ blk_status_t blk_execute_rq(struct request *rq, bool at_head)
DECLARE_COMPLETION_ONSTACK(wait);
unsigned long hang_check;
/*
* iopoll requires request to be submitted to driver, so can't
* use plug
*/
rq->end_io_data = &wait;
blk_execute_rq_nowait(rq, at_head, blk_end_sync_rq);
__blk_execute_rq_nowait(rq, at_head, blk_end_sync_rq,
!blk_rq_is_poll(rq));
/* Prevent hang_check timer from firing at us during very long I/O */
hang_check = sysctl_hung_task_timeout_secs;
@ -2340,40 +2391,6 @@ void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
blk_mq_hctx_mark_pending(hctx, ctx);
}
/*
* Allow 2x BLK_MAX_REQUEST_COUNT requests on plug queue for multiple
* queues. This is important for md arrays to benefit from merging
* requests.
*/
static inline unsigned short blk_plug_max_rq_count(struct blk_plug *plug)
{
if (plug->multiple_queues)
return BLK_MAX_REQUEST_COUNT * 2;
return BLK_MAX_REQUEST_COUNT;
}
static void blk_add_rq_to_plug(struct blk_plug *plug, struct request *rq)
{
struct request *last = rq_list_peek(&plug->mq_list);
if (!plug->rq_count) {
trace_block_plug(rq->q);
} else if (plug->rq_count >= blk_plug_max_rq_count(plug) ||
(!blk_queue_nomerges(rq->q) &&
blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
blk_mq_flush_plug_list(plug, false);
trace_block_plug(rq->q);
}
if (!plug->multiple_queues && last && last->q != rq->q)
plug->multiple_queues = true;
if (!plug->has_elevator && (rq->rq_flags & RQF_ELV))
plug->has_elevator = true;
rq->rq_next = NULL;
rq_list_add(&plug->mq_list, rq);
plug->rq_count++;
}
/**
* blk_mq_request_bypass_insert - Insert a request at dispatch list.
* @rq: Pointer to request to be inserted.
@ -2387,12 +2404,7 @@ void blk_mq_request_bypass_insert(struct request *rq, bool at_head,
bool run_queue)
{
struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
struct blk_plug *plug = current->plug;
if (plug) {
blk_add_rq_to_plug(plug, rq);
return;
}
spin_lock(&hctx->lock);
if (at_head)
list_add(&rq->queuelist, &hctx->dispatch);