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, 4 insertions, 1 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 21398a5d688d..9608839552b3 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -124,6 +124,7 @@ extern int dir_notify_enable;
 #define MS_SHARED       (1<<20) /* change to shared */
 #define MS_RELATIME     (1<<21) /* Update atime relative to mtime/ctime. */
 #define MS_KERNMOUNT    (1<<22) /* this is a kern_mount call */
+#define MS_I_VERSION    (1<<23) /* Update inode I_version field */
 #define MS_ACTIVE       (1<<30)
 #define MS_NOUSER       (1<<31)
 
@@ -173,6 +174,7 @@ extern int dir_notify_enable;
                                         ((inode)->i_flags & (S_SYNC|S_DIRSYNC)))
 #define IS_MANDLOCK(inode)      __IS_FLG(inode, MS_MANDLOCK)
 #define IS_NOATIME(inode)   __IS_FLG(inode, MS_RDONLY|MS_NOATIME)
+#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)
@@ -599,7 +601,7 @@ struct inode {
         uid_t                   i_uid;
         gid_t                   i_gid;
         dev_t                   i_rdev;
-        unsigned long           i_version;
+        u64                     i_version;
         loff_t                  i_size;
 #ifdef __NEED_I_SIZE_ORDERED
         seqcount_t              i_size_seqcount;
@@ -1394,6 +1396,7 @@ static inline void inode_dec_link_count(struct inode *inode)
         mark_inode_dirty(inode);
 }
 
+extern void inode_inc_iversion(struct inode *inode);
 extern void touch_atime(struct vfsmount *mnt, struct dentry *dentry);
 static inline void file_accessed(struct file *file)
 {