[PATCH 1/1] VFS: introduce s_dirty accessors

[Artem Bityutskiy <dedekind1@gmail.com>]

From: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

This patch introduces 3 VFS accessors: 'sb_mark_dirty()',
'sb_mark_clean()', and 'sb_is_dirty()'. They simply
set 'sb->s_dirt' or test 'sb->s_dirt'. The plan is to make
every FS use these accessors later instead of manipulating
the 'sb->s_dirt' flag directly.

Ultimately, this change is a preparation for the periodic
superblock synchronization optimization which is about
preventing the "sync_supers" kernel thread from waking up
even if there is nothing to synchronize.

This patch does not do any functional change, just adds
accessor functions.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
---
 include/linux/fs.h |   13 +++++++++++++
 1 files changed, 13 insertions(+), 0 deletions(-)

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 471e1ff..68ca1b0 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1783,6 +1783,19 @@ extern int get_sb_pseudo(struct file_system_type *, char *,
 	struct vfsmount *mnt);
 extern void simple_set_mnt(struct vfsmount *mnt, struct super_block *sb);
 
+static inline void sb_mark_dirty(struct super_block *sb)
+{
+	sb->s_dirt = 1;
+}
+static inline void sb_mark_clean(struct super_block *sb)
+{
+	sb->s_dirt = 0;
+}
+static inline int sb_is_dirty(struct super_block *sb)
+{
+	return sb->s_dirt;
+}
+
 /* Alas, no aliases. Too much hassle with bringing module.h everywhere */
 #define fops_get(fops) \
 	(((fops) && try_module_get((fops)->owner) ? (fops) : NULL))
-- 
1.7.0.1