1BLK_QUEUE_MAKE_REQUE(9)          Block Devices         BLK_QUEUE_MAKE_REQUE(9)
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NAME

6       blk_queue_make_request - define an alternate make_request function for
7       a device
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SYNOPSIS

10       void blk_queue_make_request(struct request_queue * q,
11                                   make_request_fn * mfn);
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ARGUMENTS

14       q
15           the request queue for the device to be affected
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17       mfn
18           the alternate make_request function
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DESCRIPTION

21       The normal way for struct bios to be passed to a device driver is for
22       them to be collected into requests on a request queue, and then to
23       allow the device driver to select requests off that queue when it is
24       ready. This works well for many block devices. However some block
25       devices (typically virtual devices such as md or lvm) do not benefit
26       from the processing on the request queue, and are served best by having
27       the requests passed directly to them. This can be achieved by providing
28       a function to blk_queue_make_request.
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CAVEAT

31       The driver that does this *must* be able to deal appropriately with
32       buffers in “highmemory”. This can be accomplished by either calling
33       __bio_kmap_atomic to get a temporary kernel mapping, or by calling
34       blk_queue_bounce to create a buffer in normal memory.
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37Kernel Hackers Manual 3.10         June 2019           BLK_QUEUE_MAKE_REQUE(9)
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