1BLK_RQ_MAP_USER_IOV(9)           Block Devices          BLK_RQ_MAP_USER_IOV(9)
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NAME

6       blk_rq_map_user_iov - map user data to a request, for REQ_TYPE_BLOCK_PC
7       usage
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SYNOPSIS

10       int blk_rq_map_user_iov(struct request_queue * q, struct request * rq,
11                               struct rq_map_data * map_data,
12                               struct sg_iovec * iov, int iov_count,
13                               unsigned int len, gfp_t gfp_mask);
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ARGUMENTS

16       q
17           request queue where request should be inserted
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19       rq
20           request to map data to
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22       map_data
23           pointer to the rq_map_data holding pages (if necessary)
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25       iov
26           pointer to the iovec
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28       iov_count
29           number of elements in the iovec
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31       len
32           I/O byte count
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34       gfp_mask
35           memory allocation flags
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DESCRIPTION

38       Data will be mapped directly for zero copy I/O, if possible. Otherwise
39       a kernel bounce buffer is used.
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41       A matching blk_rq_unmap_user must be issued at the end of I/O, while
42       still in process context.
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NOTE

45       The mapped bio may need to be bounced through blk_queue_bounce before
46       being submitted to the device, as pages mapped may be out of reach.
47       It's the callers responsibility to make sure this happens. The original
48       bio must be passed back in to blk_rq_unmap_user for proper unmapping.
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51Kernel Hackers Manual 3.10         June 2019            BLK_RQ_MAP_USER_IOV(9)
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