linux-kernel - [PATCH] mm: filemap: provide dummy filemap_page

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Date:   Mon,  9 Apr 2018 12:55:42 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Jan Kara <jack@...e.cz>, Andrew Morton <akpm@...ux-foundation.org>,
        Jeff Layton <jlayton@...hat.com>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Martin Brandenburg <martin@...ibond.com>,
        Mike Marshall <hubcap@...ibond.com>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Al Viro <viro@...iv.linux.org.uk>,
        Goldwyn Rodrigues <rgoldwyn@...e.com>,
        Matthew Wilcox <mawilcox@...rosoft.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] mm: filemap: provide dummy filemap_page_mkwrite() for NOMMU

Building orangefs on MMU-less machines now results in a link error because
of the newly introduced use of the filemap_page_mkwrite() function:

ERROR: "filemap_page_mkwrite" [fs/orangefs/orangefs.ko] undefined!

This adds a dummy version for it, similar to the existing
generic_file_mmap and generic_file_readonly_mmap stubs in the same file,
to avoid the link error without adding #ifdefs in each file system that
uses these.

Cc: Martin Brandenburg <martin@...ibond.com>
Cc: Mike Marshall <hubcap@...ibond.com>
Fixes: a5135eeab2e5 ("orangefs: implement vm_ops->fault")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 mm/filemap.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index ab77e19ab09c..9276bdb2343c 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2719,7 +2719,6 @@ int filemap_page_mkwrite(struct vm_fault *vmf)
 	sb_end_pagefault(inode->i_sb);
 	return ret;
 }
-EXPORT_SYMBOL(filemap_page_mkwrite);
 
 const struct vm_operations_struct generic_file_vm_ops = {
 	.fault		= filemap_fault,
@@ -2750,6 +2749,10 @@ int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
 	return generic_file_mmap(file, vma);
 }
 #else
+int filemap_page_mkwrite(struct vm_fault *vmf)
+{
+	return -ENOSYS;
+}
 int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
 {
 	return -ENOSYS;
@@ -2760,6 +2763,7 @@ int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
 }
 #endif /* CONFIG_MMU */
 
+EXPORT_SYMBOL(filemap_page_mkwrite);
 EXPORT_SYMBOL(generic_file_mmap);
 EXPORT_SYMBOL(generic_file_readonly_mmap);
 
-- 
2.9.0