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>

1 files changed, 22 insertions, 0 deletions

diff --git a/fs/inode.c b/fs/inode.c
index ed35383d0b6c..b48324a94c2b 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1243,6 +1243,23 @@ void touch_atime(struct vfsmount *mnt, struct dentry *dentry)
 EXPORT_SYMBOL(touch_atime);
 
 /**
+ *     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
+ *
+ */
+
+void inode_inc_iversion(struct inode *inode)
+{
+        spin_lock(&inode->i_lock);
+        inode->i_version++;
+        spin_unlock(&inode->i_lock);
+}
+
+/**
  *      file_update_time        -       update mtime and ctime time
  *      @file: file accessed
  *
@@ -1276,6 +1293,11 @@ void file_update_time(struct file *file)
                 sync_it = 1;
         }
 
+        if (IS_I_VERSION(inode)) {
+                inode_inc_iversion(inode);
+                sync_it = 1;
+        }
+
         if (sync_it)
                 mark_inode_dirty_sync(inode);
 }