ext4: Add inode version support in ext4

This patch adds 64-bit inode version support to ext4. The lower 32 bits
are stored in the osd1.linux1.l_i_version field while the high 32 bits
are stored in the i_version_hi field newly created in the ext4_inode.
This field is incremented in case the ext4_inode is large enough. A
i_version mount option has been added to enable the feature.

Signed-off-by: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: Andreas Dilger <adilger@clusterfs.com>
Signed-off-by: Kalpak Shah <kalpak@clusterfs.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Jean Noel Cordenner <jean-noel.cordenner@bull.net>

2 files changed, 20 insertions, 2 deletions

diff --git a/include/linux/ext4_fs.h b/include/linux/ext4_fs.h
index cd406dba0e64..b6092940c8b8 100644
--- a/include/linux/ext4_fs.h
+++ b/include/linux/ext4_fs.h
@@ -292,7 +292,7 @@ struct ext4_inode {
         __le32  i_flags;        /* File flags */
         union {
                 struct {
-                        __u32  l_i_reserved1;
+                        __le32  l_i_version;
                 } linux1;
                 struct {
                         __u32  h_i_translator;
@@ -334,6 +334,7 @@ struct ext4_inode {
         __le32  i_atime_extra;  /* extra Access time      (nsec << 2 | epoch) */
         __le32  i_crtime;       /* File Creation time */
         __le32  i_crtime_extra; /* extra FileCreationtime (nsec << 2 | epoch) */
+        __le32  i_version_hi;   /* high 32 bits for 64-bit version */
 };
 
 
@@ -407,6 +408,8 @@ do {									       \
                                        raw_inode->xtime ## _extra);            \
 } while (0)
 
+#define i_disk_version osd1.linux1.l_i_version
+
 #if defined(__KERNEL__) || defined(__linux__)
 #define i_reserved1     osd1.linux1.l_i_reserved1
 #define i_file_acl_high osd2.linux2.l_i_file_acl_high
@@ -469,6 +472,7 @@ do {									       \
 #define EXT4_MOUNT_EXTENTS              0x400000 /* Extents support */
 #define EXT4_MOUNT_JOURNAL_CHECKSUM     0x800000 /* Journal checksums */
 #define EXT4_MOUNT_JOURNAL_ASYNC_COMMIT 0x1000000 /* Journal Async Commit */
+#define EXT4_MOUNT_I_VERSION            0x2000000 /* i_version support */
 /* Compatibility, for having both ext2_fs.h and ext4_fs.h included at once */
 #ifndef _LINUX_EXT2_FS_H
 #define clear_opt(o, opt)               o &= ~EXT4_MOUNT_##opt
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 9608839552b3..a516b6716870 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1396,7 +1396,21 @@ static inline void inode_dec_link_count(struct inode *inode)
         mark_inode_dirty(inode);
 }
 
-extern void inode_inc_iversion(struct inode *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)
 {