lk: add mkfifo support

[Alex Chiang]

Add mkfifo support. Leave special iops undefined for now.

Tested with the Linux POSIX file system test suite:

/root/crfs/pjd-fstest-20080402/tests/mkfifo/00......ok                       
/root/crfs/pjd-fstest-20080402/tests/mkfifo/01......ok                       
/root/crfs/pjd-fstest-20080402/tests/mkfifo/02......ok                       
/root/crfs/pjd-fstest-20080402/tests/mkfifo/03......ok                       
/root/crfs/pjd-fstest-20080402/tests/mkfifo/04......ok                       
/root/crfs/pjd-fstest-20080402/tests/mkfifo/05......ok                       
/root/crfs/pjd-fstest-20080402/tests/mkfifo/06......ok                       
/root/crfs/pjd-fstest-20080402/tests/mkfifo/07......ok                       
/root/crfs/pjd-fstest-20080402/tests/mkfifo/08......ok                       
/root/crfs/pjd-fstest-20080402/tests/mkfifo/09......ok                       
/root/crfs/pjd-fstest-20080402/tests/mkfifo/10......ok                       
/root/crfs/pjd-fstest-20080402/tests/mkfifo/11......ok                       
/root/crfs/pjd-fstest-20080402/tests/mkfifo/12......ok                       

Signed-off-by: Alex Chiang <achiang at hp.com>
---
diff -r da91356bfe57 lk/inode.c
--- a/lk/inode.c	Mon Apr 07 17:52:34 2008 -0700
+++ b/lk/inode.c	Thu Apr 10 11:57:47 2008 -0600
@@ -90,6 +90,10 @@ int crfs_populate_inode(struct inode *in
 	    case S_IFLNK:
 		    inode->i_op = &crfs_symlink_iops;
 		    break;
+	    case S_IFIFO:
+		    inode->i_op = &crfs_special_iops;
+		    init_special_inode(inode, inode->i_mode, inode->i_rdev);
+		    break;
 	    default:
 		    BUG();
 		    break;
diff -r da91356bfe57 lk/namei.c
--- a/lk/namei.c	Mon Apr 07 17:52:34 2008 -0700
+++ b/lk/namei.c	Thu Apr 10 12:14:13 2008 -0600
@@ -982,3 +982,10 @@ struct inode_operations crfs_dir_iops = 
 //	.link		= crfs_link,
 	.symlink	= crfs_symlink,
 };
+
+/*
+ * Empty for now
+ */
+struct inode_operations crfs_special_iops = {
+
+};
diff -r da91356bfe57 lk/namei.h
--- a/lk/namei.h	Mon Apr 07 17:52:34 2008 -0700
+++ b/lk/namei.h	Thu Apr 10 11:58:38 2008 -0600
@@ -20,6 +20,7 @@
 
 extern struct inode_operations crfs_dir_iops;
 extern struct inode_operations crfs_symlink_iops;
+extern struct inode_operations crfs_special_iops;
 
 /* XXX should these be in their own file? */
 struct crfs_change_func_args;