[tip:perfcounters/core] fs: Provide empty .set_page_dirty() aop for anon inodes

[tip-bot for Peter Zijlstra]

Commit-ID:  d3a9262e59f7fb83c6d44df3b2b1460ed57d3ea1
Gitweb:     http://git.kernel.org/tip/d3a9262e59f7fb83c6d44df3b2b1460ed57d3ea1
Author:     Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
AuthorDate: Thu, 18 Jun 2009 12:54:00 +0200
Committer:  Ingo Molnar <mingo@xxxxxxx>
CommitDate: Thu, 18 Jun 2009 14:46:10 +0200

fs: Provide empty .set_page_dirty() aop for anon inodes

.set_page_dirty() is one of those a_ops that defaults to the
buffer implementation when not set. Therefore provide a dummy
function to make it do nothing.

(Uncovered by perfcounters fd's which can now be writable-mmap-ed.)

Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Davide Libenzi <davidel@xxxxxxxxxxxxxxx>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>


---
 fs/anon_inodes.c |   15 +++++++++++++++
 1 files changed, 15 insertions(+), 0 deletions(-)

diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c
index 1dd96d4..47d4a01 100644
--- a/fs/anon_inodes.c
+++ b/fs/anon_inodes.c
@@ -52,6 +52,19 @@ static const struct dentry_operations anon_inodefs_dentry_operations = {
 	.d_delete	= anon_inodefs_delete_dentry,
 };
 
+/*
+ * nop .set_page_dirty method so that people can use .page_mkwrite on
+ * anon inodes.
+ */
+static int anon_set_page_dirty(struct page *page)
+{
+	return 0;
+};
+
+static const struct address_space_operations anon_aops = {
+	.set_page_dirty = anon_set_page_dirty,
+};
+
 /**
  * anon_inode_getfd - creates a new file instance by hooking it up to an
  *                    anonymous inode, and a dentry that describe the "class"
@@ -151,6 +164,8 @@ static struct inode *anon_inode_mkinode(void)
 
 	inode->i_fop = &anon_inode_fops;
 
+	inode->i_mapping->a_ops = &anon_aops;
+
 	/*
 	 * Mark the inode dirty from the very beginning,
 	 * that way it will never be moved to the dirty
--
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