return -EBUSY;
ret = wait_event_interruptible(q->mq_freeze_wq,
- !q->mq_freeze_depth || blk_queue_dying(q));
+ !atomic_read(&q->mq_freeze_depth) ||
+ blk_queue_dying(q));
if (blk_queue_dying(q))
return -ENODEV;
if (ret)
void blk_mq_freeze_queue_start(struct request_queue *q)
{
- bool freeze;
+ int freeze_depth;
- spin_lock_irq(q->queue_lock);
- freeze = !q->mq_freeze_depth++;
- spin_unlock_irq(q->queue_lock);
-
- if (freeze) {
+ freeze_depth = atomic_inc_return(&q->mq_freeze_depth);
+ if (freeze_depth == 1) {
percpu_ref_kill(&q->mq_usage_counter);
blk_mq_run_hw_queues(q, false);
}
void blk_mq_unfreeze_queue(struct request_queue *q)
{
- bool wake;
+ int freeze_depth;
- spin_lock_irq(q->queue_lock);
- wake = !--q->mq_freeze_depth;
- WARN_ON_ONCE(q->mq_freeze_depth < 0);
- spin_unlock_irq(q->queue_lock);
- if (wake) {
+ freeze_depth = atomic_dec_return(&q->mq_freeze_depth);
+ WARN_ON_ONCE(freeze_depth < 0);
+ if (!freeze_depth) {
percpu_ref_reinit(&q->mq_usage_counter);
wake_up_all(&q->mq_freeze_wq);
}
return rq;
}
+static int blk_mq_direct_issue_request(struct request *rq)
+{
+ int ret;
+ struct request_queue *q = rq->q;
+ struct blk_mq_hw_ctx *hctx = q->mq_ops->map_queue(q,
+ rq->mq_ctx->cpu);
+ struct blk_mq_queue_data bd = {
+ .rq = rq,
+ .list = NULL,
+ .last = 1
+ };
+
+ /*
+ * For OK queue, we are done. For error, kill it. Any other
+ * error (busy), just add it to our list as we previously
+ * would have done
+ */
+ ret = q->mq_ops->queue_rq(hctx, &bd);
+ if (ret == BLK_MQ_RQ_QUEUE_OK)
+ return 0;
+ else {
+ __blk_mq_requeue_request(rq);
+
+ if (ret == BLK_MQ_RQ_QUEUE_ERROR) {
+ rq->errors = -EIO;
+ blk_mq_end_request(rq, rq->errors);
+ return 0;
+ }
+ return -1;
+ }
+}
+
/*
* Multiple hardware queue variant. This will not use per-process plugs,
* but will attempt to bypass the hctx queueing if we can go straight to
const int is_flush_fua = bio->bi_rw & (REQ_FLUSH | REQ_FUA);
struct blk_map_ctx data;
struct request *rq;
+ unsigned int request_count = 0;
+ struct blk_plug *plug;
+ struct request *same_queue_rq = NULL;
blk_queue_bounce(q, &bio);
return;
}
+ if (!is_flush_fua && !blk_queue_nomerges(q) &&
+ blk_attempt_plug_merge(q, bio, &request_count, &same_queue_rq))
+ return;
+
rq = blk_mq_map_request(q, bio, &data);
if (unlikely(!rq))
return;
goto run_queue;
}
+ plug = current->plug;
/*
* If the driver supports defer issued based on 'last', then
* queue it up like normal since we can potentially save some
* CPU this way.
*/
- if (is_sync && !(data.hctx->flags & BLK_MQ_F_DEFER_ISSUE)) {
- struct blk_mq_queue_data bd = {
- .rq = rq,
- .list = NULL,
- .last = 1
- };
- int ret;
+ if (((plug && !blk_queue_nomerges(q)) || is_sync) &&
+ !(data.hctx->flags & BLK_MQ_F_DEFER_ISSUE)) {
+ struct request *old_rq = NULL;
blk_mq_bio_to_request(rq, bio);
/*
- * For OK queue, we are done. For error, kill it. Any other
- * error (busy), just add it to our list as we previously
- * would have done
+ * we do limited pluging. If bio can be merged, do merge.
+ * Otherwise the existing request in the plug list will be
+ * issued. So the plug list will have one request at most
*/
- ret = q->mq_ops->queue_rq(data.hctx, &bd);
- if (ret == BLK_MQ_RQ_QUEUE_OK)
- goto done;
- else {
- __blk_mq_requeue_request(rq);
-
- if (ret == BLK_MQ_RQ_QUEUE_ERROR) {
- rq->errors = -EIO;
- blk_mq_end_request(rq, rq->errors);
- goto done;
+ if (plug) {
+ /*
+ * The plug list might get flushed before this. If that
+ * happens, same_queue_rq is invalid and plug list is empty
+ **/
+ if (same_queue_rq && !list_empty(&plug->mq_list)) {
+ old_rq = same_queue_rq;
+ list_del_init(&old_rq->queuelist);
}
- }
+ list_add_tail(&rq->queuelist, &plug->mq_list);
+ } else /* is_sync */
+ old_rq = rq;
+ blk_mq_put_ctx(data.ctx);
+ if (!old_rq)
+ return;
+ if (!blk_mq_direct_issue_request(old_rq))
+ return;
+ blk_mq_insert_request(old_rq, false, true, true);
+ return;
}
if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
run_queue:
blk_mq_run_hw_queue(data.hctx, !is_sync || is_flush_fua);
}
-done:
blk_mq_put_ctx(data.ctx);
}
{
const int is_sync = rw_is_sync(bio->bi_rw);
const int is_flush_fua = bio->bi_rw & (REQ_FLUSH | REQ_FUA);
- unsigned int use_plug, request_count = 0;
+ struct blk_plug *plug;
+ unsigned int request_count = 0;
struct blk_map_ctx data;
struct request *rq;
- /*
- * If we have multiple hardware queues, just go directly to
- * one of those for sync IO.
- */
- use_plug = !is_flush_fua && !is_sync;
-
blk_queue_bounce(q, &bio);
if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
return;
}
- if (use_plug && !blk_queue_nomerges(q) &&
- blk_attempt_plug_merge(q, bio, &request_count))
+ if (!is_flush_fua && !blk_queue_nomerges(q) &&
+ blk_attempt_plug_merge(q, bio, &request_count, NULL))
return;
rq = blk_mq_map_request(q, bio, &data);
* utilize that to temporarily store requests until the task is
* either done or scheduled away.
*/
- if (use_plug) {
- struct blk_plug *plug = current->plug;
-
- if (plug) {
- blk_mq_bio_to_request(rq, bio);
- if (list_empty(&plug->mq_list))
- trace_block_plug(q);
- else if (request_count >= BLK_MAX_REQUEST_COUNT) {
- blk_flush_plug_list(plug, false);
- trace_block_plug(q);
- }
- list_add_tail(&rq->queuelist, &plug->mq_list);
- blk_mq_put_ctx(data.ctx);
- return;
+ plug = current->plug;
+ if (plug) {
+ blk_mq_bio_to_request(rq, bio);
+ if (list_empty(&plug->mq_list))
+ trace_block_plug(q);
+ else if (request_count >= BLK_MAX_REQUEST_COUNT) {
+ blk_flush_plug_list(plug, false);
+ trace_block_plug(q);
}
+ list_add_tail(&rq->queuelist, &plug->mq_list);
+ blk_mq_put_ctx(data.ctx);
+ return;
}
if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
/* Basically redo blk_mq_init_queue with queue frozen */
static void blk_mq_queue_reinit(struct request_queue *q)
{
- WARN_ON_ONCE(!q->mq_freeze_depth);
+ WARN_ON_ONCE(!atomic_read(&q->mq_freeze_depth));
blk_mq_sysfs_unregister(q);
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