Still Problems with /dev/btrfs-control

Thanks for the quick reply!

But I still have problems with btrfsctl:

File: `/dev/btrfs-control'
Size: 0 Blocks: 0 IO Block: 4096 block special file
Device: ch/12d Inode: 659848 Links: 1 Device type: a,3e
Access: (0644/brw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
Access: 2010-01-09 11:31:15.757979602 +0100
Modify: 2010-01-09 11:31:15.757979602 +0100
Change: 2010-01-09 11:31:15.757979602 +0100

/dev/sda3 on / type btrfs (rw,relatime,noacl) [Alpha4]

failed to open /dev/btrfs-control: No such device or address

Remark: When the btrfs-filesystem is originally mounted (from the startup-code in the initial ramdisk), /dev/btrfs-control is not yet existant, because the dev-directory is contained in the btrfs-filesystem.

Everything else works fine.

Greetings, Michael

Hi Michael

Ok, two things:

1) btrfs-control is a *character* device and _not_ a *block device*
2) on my system it is allocated under 10,55 (major/minor).

	$ stat /dev/btrfs-control
	  File: `/dev/btrfs-control'
	  Size: 0  Blocks: 0 IO Block: 4096   character special file
	Device: fh/15d  Inode: 2404        Links: 1     Device type: a,37
	Access: (0660/crw-rw----)  Uid: (0/ root)   Gid: ( 0/ root)
	Access: 2010-01-09 11:35:30.764909719 +0100
	Modify: 2010-01-09 11:35:30.764909719 +0100
	Change: 2010-01-09 11:35:30.764909719 +0100
	ghigo@venice:~$ ls -l /dev/btrfs-control
	crw-rw---- 1 root root 10, 55 2010-01-09 11:35 /dev/btrfs-control

Looking at the source

btrfs-unstable/fs/btrfs$ grep -A 2 -B 2 "btrfs-control" *.c super.c-static struct miscdevice btrfs_misc = {
super.c- .minor = MISC_DYNAMIC_MINOR,
super.c: .name = "btrfs-control",
super.c- .fops = &btrfs_ctl_fops
super.c-};

It seems that it is dynamically allocated. The "major" should be always 10, the minor may be find with

	$ cat /proc/misc  | grep btrfs-control
	 55 btrfs-control

Or by

	$ cat /sys/class/misc/btrfs-control/dev
	10:55

Regards
Goffredo

code

gpg key@ keyserver.linux.it: Goffredo Baroncelli (ghigo) <kreijackATinwind.it>
Key fingerprint = 4769 7E51 5293 D36C 814E  C054 BF04 F161 3DC5 0512

Am Samstag 09 Januar 2010 12:05:34 schrieb Goffredo Baroncelli:

This must be checked on the target machine, as the minor number is allocated dynamically.

regards,
Johannes