From: Eric Sandeen <sandeen@redhat.com>
Date: Tue, 8 Jul 2008 15:24:07 -0500
Subject: [fs] i_version updates
Message-id: 4873CCE7.6020001@redhat.com
O-Subject: [PATCH RHEL5 6/9] i_version updatets
Bugzilla: 443896
RH-Acked-by: Jeff Moyer <jmoyer@redhat.com>
RH-Acked-by: Jeff Layton <jlayton@redhat.com>

This is for:

Bugzilla Bug 443896: RFE: [Ext4 enabler] backport vfs
helpers to facilitate ext4 backport and testing

this one is slightly screwy because it doesn't actually make
i_version universally 64 bits due to KABI.

If/when this matters to us (NFSV4?) I think it can be revisited...

In the meantime it lets ext4 build w/o needing changes to
the inode versioning code ...

From: Jean Noel Cordenner <jean-noel.cordenner@bull.net>
Date: Tue, 29 Jan 2008 04:58:27 +0000 (-0500)
Subject: vfs: Add 64 bit i_version support
X-Git-Tag: v2.6.25-rc1~11662~16
X-Git-Url: http://git.engineering.redhat.com/?p=linux-2.6.git;a=commitdiff_plain;h=7a224228ed79d587ece2304869000aad1b8e97dd

vfs: Add 64 bit i_version support

The i_version field of the inode is changed to be a 64-bit counter that
is set on every inode creation and that is incremented every time the
inode data is modified (similarly to the "ctime" time-stamp).
The aim is to fulfill a NFSv4 requirement for rfc3530.
This first part concerns the vfs, it converts the 32-bit i_version in
the generic inode to a 64-bit, a flag is added in the super block in
order to check if the feature is enabled and the i_version is
incremented in the vfs.

Signed-off-by: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: Jean Noel Cordenner <jean-noel.cordenner@bull.net>
Signed-off-by: Kalpak Shah <kalpak@clusterfs.com>

diff --git a/fs/inode.c b/fs/inode.c
index b3b28db..8875b3c 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1242,6 +1242,11 @@ void file_update_time(struct file *file)
 		sync_it = 1;
 	inode->i_ctime = now;
 
+	if (IS_I_VERSION(inode)) {
+		inode_inc_iversion(inode);
+		sync_it = 1;
+	}
+
 	if (sync_it)
 		mark_inode_dirty_sync(inode);
 }
diff --git a/include/linux/fs.h b/include/linux/fs.h
index fd80f94..18a1fa5 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -121,6 +121,7 @@ extern int dir_notify_enable;
 #define MS_SLAVE	(1<<19)	/* change to slave */
 #define MS_SHARED	(1<<20)	/* change to shared */
 #define MS_NO_LEASES	(1<<21)	/* fs does not support leases */
+#define MS_I_VERSION	(1<<23)	/* Update inode I_version field */
 #define MS_ACTIVE	(1<<30)
 #define MS_NOUSER	(1<<31)
 
@@ -172,6 +173,7 @@ extern int dir_notify_enable;
 #define IS_DIRSYNC(inode)	(__IS_FLG(inode, MS_SYNCHRONOUS|MS_DIRSYNC) || \
 					((inode)->i_flags & (S_SYNC|S_DIRSYNC)))
 #define IS_MANDLOCK(inode)	__IS_FLG(inode, MS_MANDLOCK)
+#define IS_I_VERSION(inode)	__IS_FLG(inode, MS_I_VERSION)
 
 #define IS_NOQUOTA(inode)	((inode)->i_flags & S_NOQUOTA)
 #define IS_APPEND(inode)	((inode)->i_flags & S_APPEND)
@@ -1232,6 +1234,21 @@ static inline void inode_dec_link_count(struct inode *inode)
 	mark_inode_dirty(inode);
 }
 
+/**
+ * inode_inc_iversion - increments i_version
+ * @inode: inode that need to be updated
+ *
+ * Every time the inode is modified, the i_version field will be incremented.
+ * The filesystem has to be mounted with i_version flag
+ */
+
+static inline void inode_inc_iversion(struct inode *inode)
+{
+	spin_lock(&inode->i_lock);
+	inode->i_version++;
+	spin_unlock(&inode->i_lock);
+}
+
 extern void touch_atime(struct vfsmount *mnt, struct dentry *dentry);
 static inline void file_accessed(struct file *file)
 {