fs, exportfs: add exportfs_encode_inode_fh() helper

We will need this helper in the next patch to provide a file handle for
inotify marks in /proc/pid/fdinfo output.

The patch is rather providing the way to use inodes directly when dentry
is not available (like in case of inotify system).

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrey Vagin <avagin@openvz.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: James Bottomley <jbottomley@parallels.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Matthew Helsley <matt.helsley@gmail.com>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@onelan.co.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 16 insertions, 5 deletions

diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c
index 10f137381ac7..606bb074c501 100644
--- a/fs/exportfs/expfs.c
+++ b/fs/exportfs/expfs.c
@@ -341,10 +341,21 @@ static int export_encode_fh(struct inode *inode, struct fid *fid,
         return type;
 }
 
+int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid,
+                             int *max_len, struct inode *parent)
+{
+        const struct export_operations *nop = inode->i_sb->s_export_op;
+
+        if (nop && nop->encode_fh)
+                return nop->encode_fh(inode, fid->raw, max_len, parent);
+
+        return export_encode_fh(inode, fid, max_len, parent);
+}
+EXPORT_SYMBOL_GPL(exportfs_encode_inode_fh);
+
 int exportfs_encode_fh(struct dentry *dentry, struct fid *fid, int *max_len,
                 int connectable)
 {
-        const struct export_operations *nop = dentry->d_sb->s_export_op;
         int error;
         struct dentry *p = NULL;
         struct inode *inode = dentry->d_inode, *parent = NULL;
@@ -357,10 +368,8 @@ int exportfs_encode_fh(struct dentry *dentry, struct fid *fid, int *max_len,
                  */
                 parent = p->d_inode;
         }
-        if (nop && nop->encode_fh)
-                error = nop->encode_fh(inode, fid->raw, max_len, parent);
-        else
-                error = export_encode_fh(inode, fid, max_len, parent);
+
+        error = exportfs_encode_inode_fh(inode, fid, max_len, parent);
         dput(p);
 
         return error;
diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h
index 12291a7ee275..c7e6b6392ab8 100644
--- a/include/linux/exportfs.h
+++ b/include/linux/exportfs.h
@@ -177,6 +177,8 @@ struct export_operations {
         int (*commit_metadata)(struct inode *inode);
 };
 
+extern int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid,
+                                    int *max_len, struct inode *parent);
 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,