linux-master/block/blk-flush.c

9  * optional steps - PREFLUSH, DATA and POSTFLUSH - according to the request
12  * If a request doesn't have data, only REQ_PREFLUSH makes sense, which
13  * indicates a simple flush request.  If there is data, REQ_PREFLUSH indicates
15  * REQ_FUA means that the data must be on non-volatile media on request
28  * The actual execution of flush is double buffered.  Whenever a request
42  * C2. Flush is deferred if any request is executing DATA of its sequence.
46  * C3. The second condition is ignored if there is a request which has
54  * Note that a sequenced PREFLUSH/FUA request with DATA is completed twice.
61  * The above peculiarity requires that each PREFLUSH/FUA request has only one
103 static unsigned int blk_flush_policy(unsigned long fflags, struct request *rq)
120 static unsigned int blk_flush_cur_seq(struct request *rq)
125 static void blk_flush_restore_request(struct request *rq)
136 	/* make @rq a normal request */
141 static void blk_account_io_flush(struct request *rq)
154  * @rq: PREFLUSH/FUA request being sequenced
165 static void blk_flush_complete_seq(struct request *rq,
203 		 * flush data request completion path.  Restore @rq for
218 static enum rq_end_io_ret flush_end_io(struct request *flush_rq,
223 	struct request *rq, *n;
238 	 * Flush request has to be marked as IDLE when it is really ended
258 	/* account completion of the flush request */
273 bool is_flush_rq(struct request *rq)
279  * blk_kick_flush - consider issuing flush request
282  * @flags: cmd_flags of the original request
284  * Flush related states of @q have changed, consider issuing flush request.
295 	struct request *first_rq =
296 		list_first_entry(pending, struct request, queuelist);
297 	struct request *flush_rq = fq->flush_rq;
318 	 * In case of none scheduler, borrow tag from the first request
353 static enum rq_end_io_ret mq_flush_data_end_io(struct request *rq,
385 static void blk_rq_init_flush(struct request *rq)
394  * Insert a PREFLUSH/FUA request into the flush state machine.
395  * Returns true if the request has been consumed by the flush state machine,
398 bool blk_insert_flush(struct request *rq)
405 	/* FLUSH/FUA request must never be merged */
419 	 * the request accounting.
429 		 * complete the request.
435 		 * If there's data, but no flush is necessary, the request can
453 		 * Mark the request as part of a flush sequence and submit it
484 	int rq_sz = sizeof(struct request);
510 	/* bio based request queue hasn't flush queue */