do_mounts: add device info to mount message

In the past, I used the root=...  command line parameter to specify the
root filesystem to the kernel.  Now it seems that specifying it is not
necessary.  The kernel detects the root filesystem even if the kernel
command line is empty.  My root fs is on a raid1 device by the way, and I
am not using initrd for the boot process.

If the kernel detects the root filesystem somehow, I think it should print
out the result of this detection, otherwise I will not know which device
has the root filesystem.  Or is there an easy way to get this information
on a running system?  I had a quick look at the /proc and /sys
filesystems, but haven't found anything useful there.
Signed-off-by: Marton Balint <cus@fazekas.hu>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

init/do_mounts.c

@@ -220,10 +220,10 @@ static int __init do_mount_root(char *name, char *fs, int flags, void *data)
 
 	sys_chdir("/root");
 	ROOT_DEV = current->fs->pwd.mnt->mnt_sb->s_dev;
-	printk("VFS: Mounted root (%s filesystem)%s.\n",
+	printk("VFS: Mounted root (%s filesystem)%s on device %u:%u.\n",
 	       current->fs->pwd.mnt->mnt_sb->s_type->name,
 	       current->fs->pwd.mnt->mnt_sb->s_flags & MS_RDONLY ?
-	       " readonly" : "");
+	       " readonly" : "", MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
 	return 0;
 }