[rfc v2 6/7] fs, exportfs: Add export_encode_inode_fh helper

[Cyrill Gorcunov]

To provide fsnotify object inodes being watched without
binding to alphabetical path we need to encode them with
exportfs help. This patch adds a helper which operates
with plain inodes directly.

This feature is CONFIG_CHECKPOINT_RESTORE only.

Signed-off-by: Cyrill Gorcunov <gorcunov@xxxxxxxxxx>
CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
CC: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
CC: James Bottomley <jbottomley@xxxxxxxxxxxxx>
---
 fs/exportfs/expfs.c      |   21 +++++++++++++++++++++
 include/linux/exportfs.h |    4 ++++
 2 files changed, 25 insertions(+)

Index: linux-2.6.git/fs/exportfs/expfs.c
===================================================================
--- linux-2.6.git.orig/fs/exportfs/expfs.c
+++ linux-2.6.git/fs/exportfs/expfs.c
@@ -302,6 +302,27 @@ out:
 	return error;
 }
 
+#ifdef CONFIG_CHECKPOINT_RESTORE
+int export_encode_inode_fh(struct inode *inode, struct fid *fid, int *max_len)
+{
+	int len = *max_len;
+	int type = FILEID_INO32_GEN;
+
+	if (len < 2) {
+		*max_len = 2;
+		return 255;
+	}
+
+	len = 2;
+	fid->i32.ino = inode->i_ino;
+	fid->i32.gen = inode->i_generation;
+	*max_len = len;
+
+	return type;
+}
+EXPORT_SYMBOL_GPL(export_encode_inode_fh);
+#endif
+
 /**
  * export_encode_fh - default export_operations->encode_fh function
  * @dentry:  the dentry to encode
Index: linux-2.6.git/include/linux/exportfs.h
===================================================================
--- linux-2.6.git.orig/include/linux/exportfs.h
+++ linux-2.6.git/include/linux/exportfs.h
@@ -177,6 +177,10 @@ struct export_operations {
 	int (*commit_metadata)(struct inode *inode);
 };
 
+#ifdef CONFIG_CHECKPOINT_RESTORE
+extern int export_encode_inode_fh(struct inode *inode, struct fid *fid, int *max_len);
+#endif
+
 extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid,
 	int *max_len, int connectable);
 extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,

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