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 2.6.         June 2019            BLK_RQ_MAP_USER_IOV(9)
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