diff options
| -rw-r--r-- | block/blk-core.c | 28 | ||||
| -rw-r--r-- | block/blk-settings.c | 6 | ||||
| -rw-r--r-- | include/linux/blkdev.h | 4 |
3 files changed, 38 insertions, 0 deletions
diff --git a/block/blk-core.c b/block/blk-core.c index c66333d8e48d..b2d0ac8b760e 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -2100,6 +2100,34 @@ void blk_rq_bio_prep(struct request_queue *q, struct request *rq, rq->rq_disk = bio->bi_bdev->bd_disk; } +/** + * blk_lld_busy - Check if underlying low-level drivers of a device are busy + * @q : the queue of the device being checked + * + * Description: + * Check if underlying low-level drivers of a device are busy. + * If the drivers want to export their busy state, they must set own + * exporting function using blk_queue_lld_busy() first. + * + * Basically, this function is used only by request stacking drivers + * to stop dispatching requests to underlying devices when underlying + * devices are busy. This behavior helps more I/O merging on the queue + * of the request stacking driver and prevents I/O throughput regression + * on burst I/O load. + * + * Return: + * 0 - Not busy (The request stacking driver should dispatch request) + * 1 - Busy (The request stacking driver should stop dispatching request) + */ +int blk_lld_busy(struct request_queue *q) +{ + if (q->lld_busy_fn) + return q->lld_busy_fn(q); + + return 0; +} +EXPORT_SYMBOL_GPL(blk_lld_busy); + int kblockd_schedule_work(struct request_queue *q, struct work_struct *work) { return queue_work(kblockd_workqueue, work); diff --git a/block/blk-settings.c b/block/blk-settings.c index 1d0330d0b40a..b21dcdb64151 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -89,6 +89,12 @@ void blk_queue_rq_timed_out(struct request_queue *q, rq_timed_out_fn *fn) } EXPORT_SYMBOL_GPL(blk_queue_rq_timed_out); +void blk_queue_lld_busy(struct request_queue *q, lld_busy_fn *fn) +{ + q->lld_busy_fn = fn; +} +EXPORT_SYMBOL_GPL(blk_queue_lld_busy); + /** * blk_queue_make_request - define an alternate make_request function for a device * @q: the request queue for the device to be affected diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 0cf3e619fb21..9e0ee1a8254e 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -269,6 +269,7 @@ typedef int (merge_bvec_fn) (struct request_queue *, struct bvec_merge_data *, typedef void (prepare_flush_fn) (struct request_queue *, struct request *); typedef void (softirq_done_fn)(struct request *); typedef int (dma_drain_needed_fn)(struct request *); +typedef int (lld_busy_fn) (struct request_queue *q); enum blk_eh_timer_return { BLK_EH_NOT_HANDLED, @@ -325,6 +326,7 @@ struct request_queue softirq_done_fn *softirq_done_fn; rq_timed_out_fn *rq_timed_out_fn; dma_drain_needed_fn *dma_drain_needed; + lld_busy_fn *lld_busy_fn; /* * Dispatch queue sorting @@ -699,6 +701,7 @@ extern struct request *blk_get_request(struct request_queue *, int, gfp_t); extern void blk_insert_request(struct request_queue *, struct request *, int, void *); extern void blk_requeue_request(struct request_queue *, struct request *); extern int blk_rq_check_limits(struct request_queue *q, struct request *rq); +extern int blk_lld_busy(struct request_queue *q); extern int blk_insert_cloned_request(struct request_queue *q, struct request *rq); extern void blk_plug_device(struct request_queue *); @@ -835,6 +838,7 @@ extern void blk_queue_update_dma_pad(struct request_queue *, unsigned int); extern int blk_queue_dma_drain(struct request_queue *q, dma_drain_needed_fn *dma_drain_needed, void *buf, unsigned int size); +extern void blk_queue_lld_busy(struct request_queue *q, lld_busy_fn *fn); extern void blk_queue_segment_boundary(struct request_queue *, unsigned long); extern void blk_queue_prep_rq(struct request_queue *, prep_rq_fn *pfn); extern void blk_queue_merge_bvec(struct request_queue *, merge_bvec_fn *); |