static void blk_invoke_request_fn(struct request_queue *q)
{
+ if (unlikely(blk_queue_stopped(q)))
+ return;
+
/*
* one level of recursion is ok and is much faster than kicking
* the unplug handling
EXPORT_SYMBOL(blk_sync_queue);
/**
- * blk_run_queue - run a single device queue
+ * __blk_run_queue - run a single device queue
* @q: The queue to run
+ *
+ * Description:
+ * See @blk_run_queue. This variant must be called with the queue lock
+ * held and interrupts disabled.
+ *
*/
void __blk_run_queue(struct request_queue *q)
{
/**
* blk_run_queue - run a single device queue
* @q: The queue to run
+ *
+ * Description:
+ * Invoke request handling on this queue, if it has pending work to do.
+ * May be used to restart queueing when a request has completed. Also
+ * See @blk_start_queueing.
+ *
*/
void blk_run_queue(struct request_queue *q)
{
init_timer(&q->unplug_timer);
setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
INIT_LIST_HEAD(&q->timeout_list);
+ INIT_WORK(&q->unplug_work, blk_unplug_work);
kobject_init(&q->kobj, &blk_queue_ktype);
q->request_fn = rfn;
q->prep_rq_fn = NULL;
q->unplug_fn = generic_unplug_device;
- q->queue_flags = (1 << QUEUE_FLAG_CLUSTER);
+ q->queue_flags = (1 << QUEUE_FLAG_CLUSTER |
+ 1 << QUEUE_FLAG_STACKABLE);
q->queue_lock = lock;
blk_queue_segment_boundary(q, 0xffffffff);
*
* This is basically a helper to remove the need to know whether a queue
* is plugged or not if someone just wants to initiate dispatch of requests
- * for this queue.
+ * for this queue. Should be used to start queueing on a device outside
+ * of ->request_fn() context. Also see @blk_run_queue.
*
* The queue lock must be held with interrupts disabled.
*/
void blk_start_queueing(struct request_queue *q)
{
- if (!blk_queue_plugged(q))
+ if (!blk_queue_plugged(q)) {
+ if (unlikely(blk_queue_stopped(q)))
+ return;
q->request_fn(q);
- else
+ } else
__generic_unplug_device(q);
}
EXPORT_SYMBOL(blk_start_queueing);
}
/**
- * part_round_stats() - Round off the performance stats on a struct
- * disk_stats.
+ * part_round_stats() - Round off the performance stats on a struct disk_stats.
+ * @cpu: cpu number for stats access
+ * @part: target partition
*
* The average IO queue length and utilisation statistics are maintained
* by observing the current state of the queue length and the amount of
}
}
-static inline void __end_request(struct request *rq, int uptodate,
- unsigned int nr_bytes)
-{
- int error = 0;
-
- if (uptodate <= 0)
- error = uptodate ? uptodate : -EIO;
-
- __blk_end_request(rq, error, nr_bytes);
-}
-
/**
* blk_rq_bytes - Returns bytes left to complete in the entire request
* @rq: the request being processed
EXPORT_SYMBOL_GPL(blk_rq_cur_bytes);
/**
- * end_queued_request - end all I/O on a queued request
- * @rq: the request being processed
- * @uptodate: error value or %0/%1 uptodate flag
- *
- * Description:
- * Ends all I/O on a request, and removes it from the block layer queues.
- * Not suitable for normal I/O completion, unless the driver still has
- * the request attached to the block layer.
- *
- **/
-void end_queued_request(struct request *rq, int uptodate)
-{
- __end_request(rq, uptodate, blk_rq_bytes(rq));
-}
-EXPORT_SYMBOL(end_queued_request);
-
-/**
- * end_dequeued_request - end all I/O on a dequeued request
- * @rq: the request being processed
- * @uptodate: error value or %0/%1 uptodate flag
- *
- * Description:
- * Ends all I/O on a request. The request must already have been
- * dequeued using blkdev_dequeue_request(), as is normally the case
- * for most drivers.
- *
- **/
-void end_dequeued_request(struct request *rq, int uptodate)
-{
- __end_request(rq, uptodate, blk_rq_bytes(rq));
-}
-EXPORT_SYMBOL(end_dequeued_request);
-
-
-/**
* end_request - end I/O on the current segment of the request
* @req: the request being processed
* @uptodate: error value or %0/%1 uptodate flag
* they have a residual value to account for. For that case this function
* isn't really useful, unless the residual just happens to be the
* full current segment. In other words, don't use this function in new
- * code. Use blk_end_request() or __blk_end_request() to end partial parts
- * of a request, or end_dequeued_request() and end_queued_request() to
- * completely end IO on a dequeued/queued request.
- *
+ * code. Use blk_end_request() or __blk_end_request() to end a request.
**/
void end_request(struct request *req, int uptodate)
{
- __end_request(req, uptodate, req->hard_cur_sectors << 9);
+ int error = 0;
+
+ if (uptodate <= 0)
+ error = uptodate ? uptodate : -EIO;
+
+ __blk_end_request(req, error, req->hard_cur_sectors << 9);
}
EXPORT_SYMBOL(end_request);
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);
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff