'\" t
.\"     Title: blk_rq_map_user_iov
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/>
.\"      Date: January 2017
.\"    Manual: Block Devices
.\"    Source: Kernel Hackers Manual 4.8.15
.\"  Language: English
.\"
.TH "BLK_RQ_MAP_USER_IOV" "9" "January 2017" "Kernel Hackers Manual 4\&.8\&." "Block Devices"
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.SH "NAME"
blk_rq_map_user_iov \- map user data to a request, for REQ_TYPE_BLOCK_PC usage
.SH "SYNOPSIS"
.HP \w'int\ blk_rq_map_user_iov('u
.BI "int blk_rq_map_user_iov(struct\ request_queue\ *\ " "q" ", struct\ request\ *\ " "rq" ", struct\ rq_map_data\ *\ " "map_data" ", const\ struct\ iov_iter\ *\ " "iter" ", gfp_t\ " "gfp_mask" ");"
.SH "ARGUMENTS"
.PP
\fIq\fR
.RS 4
request queue where request should be inserted
.RE
.PP
\fIrq\fR
.RS 4
request to map data to
.RE
.PP
\fImap_data\fR
.RS 4
pointer to the rq_map_data holding pages (if necessary)
.RE
.PP
\fIiter\fR
.RS 4
iovec iterator
.RE
.PP
\fIgfp_mask\fR
.RS 4
memory allocation flags
.RE
.SH "DESCRIPTION"
.PP
Data will be mapped directly for zero copy I/O, if possible\&. Otherwise a kernel bounce buffer is used\&.
.PP
A matching
\fBblk_rq_unmap_user\fR
must be issued at the end of I/O, while still in process context\&.
.SH "NOTE"
.PP
The mapped bio may need to be bounced through
\fBblk_queue_bounce\fR
before being submitted to the device, as pages mapped may be out of reach\&. It\*(Aqs the callers responsibility to make sure this happens\&. The original bio must be passed back in to
\fBblk_rq_unmap_user\fR
for proper unmapping\&.
.SH "COPYRIGHT"
.br