JFS: Fix rampant data corruption

A recent change causes pervasive data corruption by over-writing inode
metadata with a word of garbage.  The field, di_rdev, should only be set
for a device inode.

fs/jfs/jfs_imap.c

@@ -3041,10 +3041,11 @@ static int copy_from_dinode(struct dinode * dip, struct inode *ip)
 	jfs_ip->next_index = le32_to_cpu(dip->di_next_index);
 	jfs_ip->otime = le32_to_cpu(dip->di_otime.tv_sec);
 	jfs_ip->acltype = le32_to_cpu(dip->di_acltype);
-	jfs_ip->dev = le32_to_cpu(dip->di_rdev);
 
-	if (S_ISCHR(ip->i_mode) || S_ISBLK(ip->i_mode))
+	if (S_ISCHR(ip->i_mode) || S_ISBLK(ip->i_mode)) {
+		jfs_ip->dev = le32_to_cpu(dip->di_rdev);
 		ip->i_rdev = old_decode_dev(jfs_ip->dev);
+	}
 
 	if (S_ISDIR(ip->i_mode)) {
 		memcpy(&jfs_ip->i_dirtable, &dip->di_dirtable, 384);
@@ -3101,7 +3102,8 @@ static void copy_to_dinode(struct dinode * dip, struct inode *ip)
 	dip->di_otime.tv_sec = cpu_to_le32(jfs_ip->otime);
 	dip->di_otime.tv_nsec = 0;
 	dip->di_acltype = cpu_to_le32(jfs_ip->acltype);
-	dip->di_rdev = cpu_to_le32(jfs_ip->dev);
+	if (S_ISCHR(ip->i_mode) || S_ISBLK(ip->i_mode))
+		dip->di_rdev = cpu_to_le32(jfs_ip->dev);
 }
 
 #ifdef	_JFS_DEBUG_IMAP