'\" t
.\"     Title: mpage_writepages
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.78.1 <http://docbook.sf.net/>
.\"      Date: May 2018
.\"    Manual: The Linux VFS
.\"    Source: Kernel Hackers Manual 3.16.56
.\"  Language: English
.\"
.TH "MPAGE_WRITEPAGES" "9" "May 2018" "Kernel Hackers Manual 3\&.16\&" "The Linux VFS"
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.SH "NAME"
mpage_writepages \- walk the list of dirty pages of the given address space & \fBwritepage\fR all of them
.SH "SYNOPSIS"
.HP \w'int\ mpage_writepages('u
.BI "int mpage_writepages(struct\ address_space\ *\ " "mapping" ", struct\ writeback_control\ *\ " "wbc" ", get_block_t\ " "get_block" ");"
.SH "ARGUMENTS"
.PP
\fImapping\fR
.RS 4
address space structure to write
.RE
.PP
\fIwbc\fR
.RS 4
subtract the number of written pages from *\fIwbc\fR\->nr_to_write
.RE
.PP
\fIget_block\fR
.RS 4
the filesystem\*(Aqs block mapper function\&. If this is NULL then use a_ops\->writepage\&. Otherwise, go direct\-to\-BIO\&.
.RE
.SH "DESCRIPTION"
.PP
This is a library function, which implements the
\fBwritepages\fR
address_space_operation\&.
.PP
If a page is already under I/O,
\fBgeneric_writepages\fR
skips it, even if it\*(Aqs dirty\&. This is desirable behaviour for memory\-cleaning writeback, but it is INCORRECT for data\-integrity system calls such as
\fBfsync\fR\&.
\fBfsync\fR
and
\fBmsync\fR
need to guarantee that all the data which was dirty at the time the call was made get new I/O started against them\&. If wbc\->sync_mode is WB_SYNC_ALL then we were called for data integrity and we must wait for existing IO to complete\&.
.SH "COPYRIGHT"
.br