diff options
| -rw-r--r-- | block/blk-core.c | 81 | ||||
| -rw-r--r-- | include/linux/blkdev.h | 3 |
2 files changed, 84 insertions, 0 deletions
diff --git a/block/blk-core.c b/block/blk-core.c index 527d43e982b..b8ffbfe85ca 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1530,6 +1530,87 @@ void submit_bio(int rw, struct bio *bio) EXPORT_SYMBOL(submit_bio); /** + * blk_rq_check_limits - Helper function to check a request for the queue limit + * @q: the queue + * @rq: the request being checked + * + * Description: + * @rq may have been made based on weaker limitations of upper-level queues + * in request stacking drivers, and it may violate the limitation of @q. + * Since the block layer and the underlying device driver trust @rq + * after it is inserted to @q, it should be checked against @q before + * the insertion using this generic function. + * + * This function should also be useful for request stacking drivers + * in some cases below, so export this fuction. + * Request stacking drivers like request-based dm may change the queue + * limits while requests are in the queue (e.g. dm's table swapping). + * Such request stacking drivers should check those requests agaist + * the new queue limits again when they dispatch those requests, + * although such checkings are also done against the old queue limits + * when submitting requests. + */ +int blk_rq_check_limits(struct request_queue *q, struct request *rq) +{ + if (rq->nr_sectors > q->max_sectors || + rq->data_len > q->max_hw_sectors << 9) { + printk(KERN_ERR "%s: over max size limit.\n", __func__); + return -EIO; + } + + /* + * queue's settings related to segment counting like q->bounce_pfn + * may differ from that of other stacking queues. + * Recalculate it to check the request correctly on this queue's + * limitation. + */ + blk_recalc_rq_segments(rq); + if (rq->nr_phys_segments > q->max_phys_segments || + rq->nr_phys_segments > q->max_hw_segments) { + printk(KERN_ERR "%s: over max segments limit.\n", __func__); + return -EIO; + } + + return 0; +} +EXPORT_SYMBOL_GPL(blk_rq_check_limits); + +/** + * blk_insert_cloned_request - Helper for stacking drivers to submit a request + * @q: the queue to submit the request + * @rq: the request being queued + */ +int blk_insert_cloned_request(struct request_queue *q, struct request *rq) +{ + unsigned long flags; + + if (blk_rq_check_limits(q, rq)) + return -EIO; + +#ifdef CONFIG_FAIL_MAKE_REQUEST + if (rq->rq_disk && rq->rq_disk->part0.make_it_fail && + should_fail(&fail_make_request, blk_rq_bytes(rq))) + return -EIO; +#endif + + spin_lock_irqsave(q->queue_lock, flags); + + /* + * Submitting request must be dequeued before calling this function + * because it will be linked to another request_queue + */ + BUG_ON(blk_queued_rq(rq)); + + drive_stat_acct(rq, 1); + __elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 0); + + spin_unlock_irqrestore(q->queue_lock, flags); + + return 0; +} +EXPORT_SYMBOL_GPL(blk_insert_cloned_request); + +/** * __end_that_request_first - end I/O on a request * @req: the request being processed * @error: %0 for success, < %0 for error diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index e82a84c9f37..964c246bc27 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -693,6 +693,9 @@ extern void __blk_put_request(struct request_queue *, struct request *); 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_insert_cloned_request(struct request_queue *q, + struct request *rq); extern void blk_plug_device(struct request_queue *); extern void blk_plug_device_unlocked(struct request_queue *); extern int blk_remove_plug(struct request_queue *); |