xfs: validate inode numbers in file handles correctly

[Christoph Hellwig]

Guoquan and hank,

are you using 32-bit or 64-bit kernels?  I just noticed we have a
problem with exporting 64-bit inodes on 32-bit kernel because the
VFS i_ino field is just 32-bits long.  The patch below would fix
that issue.

--- xfs.orig/fs/xfs/linux-2.6/xfs_export.c	2011-11-28 12:11:08.923630697 +0100
+++ xfs/fs/xfs/linux-2.6/xfs_export.c	2011-11-28 12:13:21.766244360 +0100
@@ -61,6 +61,8 @@ xfs_fs_encode_fh(
 	struct fid		*fid = (struct fid *)fh;
 	struct xfs_fid64	*fid64 = (struct xfs_fid64 *)fh;
 	struct inode		*inode = dentry->d_inode;
+	struct inode		*parent;
+	struct xfs_inode	*ip = XFS_I(inode);
 	int			fileid_type;
 	int			len;
 
@@ -98,22 +100,24 @@ xfs_fs_encode_fh(
 	switch (fileid_type) {
 	case FILEID_INO32_GEN_PARENT:
 		spin_lock(&dentry->d_lock);
-		fid->i32.parent_ino = dentry->d_parent->d_inode->i_ino;
-		fid->i32.parent_gen = dentry->d_parent->d_inode->i_generation;
+		parent = dentry->d_parent->d_inode;
+		fid->i32.parent_ino = XFS_I(parent)->i_ino;
+		fid->i32.parent_gen = parent->i_generation;
 		spin_unlock(&dentry->d_lock);
 		/*FALLTHRU*/
 	case FILEID_INO32_GEN:
-		fid->i32.ino = inode->i_ino;
+		fid->i32.ino = ip->i_ino;
 		fid->i32.gen = inode->i_generation;
 		break;
 	case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 		spin_lock(&dentry->d_lock);
-		fid64->parent_ino = dentry->d_parent->d_inode->i_ino;
-		fid64->parent_gen = dentry->d_parent->d_inode->i_generation;
+		parent = dentry->d_parent->d_inode;
+		fid64->parent_ino = XFS_I(parent)->i_ino;
+		fid64->parent_gen = parent->i_generation;
 		spin_unlock(&dentry->d_lock);
 		/*FALLTHRU*/
 	case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
-		fid64->ino = inode->i_ino;
+		fid64->ino = ip->i_ino;
 		fid64->gen = inode->i_generation;
 		break;
 	}