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Linux/block/blk-exec.c

  1 /*
  2  * Functions related to setting various queue properties from drivers
  3  */
  4 #include <linux/kernel.h>
  5 #include <linux/module.h>
  6 #include <linux/bio.h>
  7 #include <linux/blkdev.h>
  8 #include <linux/blk-mq.h>
  9 #include <linux/sched/sysctl.h>
 10 
 11 #include "blk.h"
 12 
 13 /*
 14  * for max sense size
 15  */
 16 #include <scsi/scsi_cmnd.h>
 17 
 18 /**
 19  * blk_end_sync_rq - executes a completion event on a request
 20  * @rq: request to complete
 21  * @error: end I/O status of the request
 22  */
 23 static void blk_end_sync_rq(struct request *rq, int error)
 24 {
 25         struct completion *waiting = rq->end_io_data;
 26 
 27         rq->end_io_data = NULL;
 28 
 29         /*
 30          * complete last, if this is a stack request the process (and thus
 31          * the rq pointer) could be invalid right after this complete()
 32          */
 33         complete(waiting);
 34 }
 35 
 36 /**
 37  * blk_execute_rq_nowait - insert a request into queue for execution
 38  * @q:          queue to insert the request in
 39  * @bd_disk:    matching gendisk
 40  * @rq:         request to insert
 41  * @at_head:    insert request at head or tail of queue
 42  * @done:       I/O completion handler
 43  *
 44  * Description:
 45  *    Insert a fully prepared request at the back of the I/O scheduler queue
 46  *    for execution.  Don't wait for completion.
 47  *
 48  * Note:
 49  *    This function will invoke @done directly if the queue is dead.
 50  */
 51 void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk,
 52                            struct request *rq, int at_head,
 53                            rq_end_io_fn *done)
 54 {
 55         int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK;
 56 
 57         WARN_ON(irqs_disabled());
 58         WARN_ON(rq->cmd_type == REQ_TYPE_FS);
 59 
 60         rq->rq_disk = bd_disk;
 61         rq->end_io = done;
 62 
 63         /*
 64          * don't check dying flag for MQ because the request won't
 65          * be reused after dying flag is set
 66          */
 67         if (q->mq_ops) {
 68                 blk_mq_insert_request(rq, at_head, true, false);
 69                 return;
 70         }
 71 
 72         spin_lock_irq(q->queue_lock);
 73 
 74         if (unlikely(blk_queue_dying(q))) {
 75                 rq->rq_flags |= RQF_QUIET;
 76                 rq->errors = -ENXIO;
 77                 __blk_end_request_all(rq, rq->errors);
 78                 spin_unlock_irq(q->queue_lock);
 79                 return;
 80         }
 81 
 82         __elv_add_request(q, rq, where);
 83         __blk_run_queue(q);
 84         spin_unlock_irq(q->queue_lock);
 85 }
 86 EXPORT_SYMBOL_GPL(blk_execute_rq_nowait);
 87 
 88 /**
 89  * blk_execute_rq - insert a request into queue for execution
 90  * @q:          queue to insert the request in
 91  * @bd_disk:    matching gendisk
 92  * @rq:         request to insert
 93  * @at_head:    insert request at head or tail of queue
 94  *
 95  * Description:
 96  *    Insert a fully prepared request at the back of the I/O scheduler queue
 97  *    for execution and wait for completion.
 98  */
 99 int blk_execute_rq(struct request_queue *q, struct gendisk *bd_disk,
100                    struct request *rq, int at_head)
101 {
102         DECLARE_COMPLETION_ONSTACK(wait);
103         char sense[SCSI_SENSE_BUFFERSIZE];
104         int err = 0;
105         unsigned long hang_check;
106 
107         if (!rq->sense) {
108                 memset(sense, 0, sizeof(sense));
109                 rq->sense = sense;
110                 rq->sense_len = 0;
111         }
112 
113         rq->end_io_data = &wait;
114         blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq);
115 
116         /* Prevent hang_check timer from firing at us during very long I/O */
117         hang_check = sysctl_hung_task_timeout_secs;
118         if (hang_check)
119                 while (!wait_for_completion_io_timeout(&wait, hang_check * (HZ/2)));
120         else
121                 wait_for_completion_io(&wait);
122 
123         if (rq->errors)
124                 err = -EIO;
125 
126         if (rq->sense == sense) {
127                 rq->sense = NULL;
128                 rq->sense_len = 0;
129         }
130 
131         return err;
132 }
133 EXPORT_SYMBOL(blk_execute_rq);
134 

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