1BLK_INSERT_REQUEST(9)            Block Devices           BLK_INSERT_REQUEST(9)
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NAME

6       blk_insert_request - insert a special request into a request queue
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SYNOPSIS

9       void blk_insert_request(struct request_queue * q, struct request * rq,
10                               int at_head, void * data);
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ARGUMENTS

13       q
14           request queue where request should be inserted
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16       rq
17           request to be inserted
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19       at_head
20           insert request at head or tail of queue
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22       data
23           private data
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DESCRIPTION

26       Many block devices need to execute commands asynchronously, so they
27       don't block the whole kernel from preemption during request execution.
28       This is accomplished normally by inserting aritficial requests tagged
29       as REQ_TYPE_SPECIAL in to the corresponding request queue, and letting
30       them be scheduled for actual execution by the request queue.
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32       We have the option of inserting the head or the tail of the queue.
33       Typically we use the tail for new ioctls and so forth. We use the head
34       of the queue for things like a QUEUE_FULL message from a device, or a
35       host that is unable to accept a particular command.
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38Kernel Hackers Manual 2.6.       November 2011           BLK_INSERT_REQUEST(9)
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