Weirdness with romfs automatic filesystem detection

[Jonathan Bastien-Filiatrault <lintuxicated@yahoo.ca>]

(SRY for the double post, the yahoo web interface is borked)
Hi to you all,
	Recently(yesterday), I had trouble getting the kernel(2.6.3) to mount
my romfs initrd. After hours of tinkering, I found out that I HAD to
specify rootfstype in order to make it work(ext2 worked w/o rootfstype).
	So, I did a little investigating(see patch below), I found out that
when the romfs driver is the first to try to mount the initrd, it does
allright, but when it tries after all the other drivers, it fails with
code -22(EINVAL I think)

Conclusions:
-This is expected behaviour (hope not).
-The filesystem drivers modify the initrd or its state.
-The romfs driver has something nasty in it.
-Im only a n00b and I dont know what im talking about.

It would be great if I could get help solving this mistery, as my
hacking skills are lacking...

Sincerly, Joe

Below is my kernel output:

By leaving the kernel determine the filesystem type (copied by hand):

(next line when using compressed ramdisk)
RAMDISK: Compressed image found at block 0
(next two lines w/o compression)
RAMDISK: romfs filesystem found at block 0
RAMDISK: Loading 1093 blocks [1 disk] into ram disk... done.
Trying to mount root as type reiserfs: got -22
Trying to mount root as type minix: got -22
Trying to mount root as type vfat: got -22
Trying to mount root as type iso9660: got -22
Trying to mount root as type ntfs: got -22
Trying to mount root as type romfs: VFS: Can't find a romfs filesystem
on dev ram0.
got -22
...
Panic, could not mount root fs, etc


By specifiyng rootfstype=romfs:

(next line when using compressed ramdisk)
RAMDISK: Compressed image found at block 0
(next two lines w/o compression)
RAMDISK: romfs filesystem found at block 0
RAMDISK: Loading 1093 blocks [1 disk] into ram disk... done.
Trying to mount root as type romfs: VFS: Mounted root (romfs filesystem)
readonly.
got 0
...
success, initrd mounts system, etc...

This patch show the code returned by the different fs drivers.

diff -uprN linux-2.6.3/fs/romfs/inode.c linux-modded/fs/romfs/inode.c
--- linux-2.6.3/fs/romfs/inode.c	2004-02-17 22:58:40.000000000 -0500
+++ linux-modded/fs/romfs/inode.c	2004-03-10 21:54:41.000000000 -0500
@@ -116,6 +116,7 @@ static int romfs_fill_super(struct super
 	struct buffer_head *bh;
 	struct romfs_super_block *rsb;
 	int sz;
+	silent = 0;
 
 	/* I would parse the options here, but there are none.. :) */
 
diff -uprN linux-2.6.3/init/do_mounts.c linux-modded/init/do_mounts.c
--- linux-2.6.3/init/do_mounts.c	2004-02-17 22:57:28.000000000 -0500
+++ linux-modded/init/do_mounts.c	2004-03-10 21:44:32.000000000 -0500
@@ -274,7 +274,10 @@ void __init mount_block_root(char *name,
 	get_fs_names(fs_names);
 retry:
 	for (p = fs_names; *p; p += strlen(p)+1) {
-		int err = do_mount_root(name, p, flags, root_mount_data);
+		int err;
+		printk("Trying to mount root as type %s: ", p);
+		err = do_mount_root(name, p, flags, root_mount_data);
+		printk("got %d\n", err);
 		switch (err) {
 			case 0:
 				goto out;