The Linux Manuals (man pages) document is an important part of Linux documents. Linux Manuals are organized as several sections. Each section has a group of commands for a specific area in Linux usage, administration or development.
blk_update_request – Special helper function for request stacking drivers Synopsis bool blk_update_request(struct request * req, int error, unsigned int nr_bytes); Arguments req the request being processed error 0 for success, < 0 for error nr_bytes number of bytes to complete req Description Ends I/O on a number of bytes attached to req, but doesn’t complete the request structure even…
blk_unprep_request – unprepare a request Synopsis void blk_unprep_request(struct request *req); Arguments req the request Description This function makes a request ready for complete resubmission (or completion). It happens only after all error handling is complete, so represents the appropriate moment to deallocate any resources that were allocated to the request in the prep_rq_fn. The queue…
blk_trace_shutdown – stop and cleanup trace structures Synopsis void blk_trace_shutdown(struct request_queue *q); Arguments q the request queue associated with the device Copyright
blk_trace_ioctl – handle the ioctls associated with tracing Synopsis int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg); Arguments bdev the block device cmd the ioctl cmd arg the argument data, if any Copyright
blk_sync_queue – cancel any pending callbacks on a queue Synopsis void blk_sync_queue(struct request_queue *q); Arguments q the queue Description The block layer may perform asynchronous callback activity on a queue, such as calling the unplug function after a timeout. A block device may call blk_sync_queue to ensure that any such activity is cancelled, thus allowing…
blk_stop_queue – stop a queue Synopsis void blk_stop_queue(struct request_queue *q); Arguments q The struct request_queue in question Description The Linux block layer assumes that a block driver will consume all entries on the request queue when the request_fn strategy is called. Often this will not happen, because of hardware limitations (queue depth settings). If a…
blk_start_request – start request processing on the driver Synopsis void blk_start_request(struct request *req); Arguments req request to dequeue Description Dequeue req and start timeout timer on it. This hands off the request to the driver. Block internal functions which don’t want to start timer should call blk_dequeue_request. Context queue_lock must be held. Copyright
blk_start_queue_async – asynchronously restart a previously stopped queue Synopsis void blk_start_queue_async(struct request_queue *q); Arguments q The struct request_queue in question Description blk_start_queue_async will clear the stop flag on the queue, and ensure that the request_fn for the queue is run from an async context. Copyright
blk_start_queue – restart a previously stopped queue Synopsis void blk_start_queue(struct request_queue *q); Arguments q The struct request_queue in question Description blk_start_queue will clear the stop flag on the queue, and call the request_fn for the queue if it was in a stopped state when entered. Also see blk_stop_queue. Queue lock must be held. Copyright
blk_start_plug – initialize blk_plug and track it inside the task_struct Synopsis void blk_start_plug(struct blk_plug *plug); Arguments plug The struct blk_plug that needs to be initialized Description Tracking blk_plug inside the task_struct will help with auto-flushing the pending I/O should the task end up blocking between blk_start_plug and blk_finish_plug. This is important from a performance perspective,…
blk_stack_limits – adjust queue_limits for stacked devices Synopsis int blk_stack_limits(struct queue_limits *t, struct queue_limits *b, sector_t start); Arguments t the stacking driver limits (top device) b the underlying queue limits (bottom, component device) start first data sector within component device Description This function is used by stacking drivers like MD and DM to ensure that…
blk_set_stacking_limits – set default limits for stacking devices Synopsis void blk_set_stacking_limits(struct queue_limits *lim); Arguments lim the queue_limits structure to reset Description Returns a queue_limit struct to its default state. Should be used by stacking drivers like DM that have no internal limits. Copyright
blk_set_runtime_active – Force runtime status of the queue to be active Synopsis void blk_set_runtime_active(struct request_queue *q); Arguments q the queue of the device Description If the device is left runtime suspended during system suspend the resume hook typically resumes the device and corrects runtime status accordingly. However, that does not affect the queue runtime PM…
blk_set_default_limits – reset limits to default values Synopsis void blk_set_default_limits(struct queue_limits *lim); Arguments lim the queue_limits structure to reset Description Returns a queue_limit struct to its default state. Copyright
blk_run_queue_async – run a single device queue in workqueue context Synopsis void blk_run_queue_async(struct request_queue *q); Arguments q The queue to run Description Tells kblockd to perform the equivalent of blk_run_queue on behalf of us. The caller must hold the queue lock. Copyright
blk_run_queue – run a single device queue Synopsis void blk_run_queue(struct request_queue *q); Arguments 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. Copyright
blk_rq_unprep_clone – Helper function to free all bios in a cloned request Synopsis void blk_rq_unprep_clone(struct request *rq); Arguments rq the clone request to be cleaned up Description Free all bios in rq for a cloned request. Copyright
blk_rq_unmap_user – unmap a request with user data Synopsis int blk_rq_unmap_user(struct bio *bio); Arguments bio start of bio list Description Unmap a rq previously mapped by blk_rq_map_user. The caller must supply the original rq->bio from the blk_rq_map_user return, since the I/O completion may have changed rq->bio. Copyright
blk_rq_set_block_pc – initialize a request to type BLOCK_PC Synopsis void blk_rq_set_block_pc(struct request *rq); Arguments rq request to be initialized Copyright
blk_rq_prep_clone – Helper function to setup clone request Synopsis int blk_rq_prep_clone(struct request *rq, struct request *rq_src, struct bio_set *bs, gfp_t gfp_mask, int (*bio_ctr)(struct bio *, struct bio *, void *), void *data); Arguments rq the request to be setup rq_src original request to be cloned bs bio_set that bios for clone are allocated from gfp_mask…