'\" t
.\"     Title: bdev_direct_access
.\"    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: The Linux VFS
.\"    Source: Kernel Hackers Manual 4.8.15
.\"  Language: English
.\"
.TH "BDEV_DIRECT_ACCESS" "9" "January 2017" "Kernel Hackers Manual 4\&.8\&." "The Linux VFS"
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.SH "NAME"
bdev_direct_access \- Get the address for directly\-accessibly memory
.SH "SYNOPSIS"
.HP \w'long\ bdev_direct_access('u
.BI "long bdev_direct_access(struct\ block_device\ *\ " "bdev" ", struct\ blk_dax_ctl\ *\ " "dax" ");"
.SH "ARGUMENTS"
.PP
\fIbdev\fR
.RS 4
The device containing the memory
.RE
.PP
\fIdax\fR
.RS 4
control and output parameters for \->direct_access
.RE
.SH "DESCRIPTION"
.PP
If a block device is made up of directly addressable memory, this function will tell the caller the PFN and the address of the memory\&. The address may be directly dereferenced within the kernel without the need to call
\fBioremap\fR,
\fBkmap\fR
or similar\&. The PFN is suitable for inserting into page tables\&.
.SH "RETURN"
.PP
negative errno if an error occurs, otherwise the number of bytes accessible at this address\&.
.SH "COPYRIGHT"
.br