Raspbian compile single kernel module gfs2

Question

I'm trying my best to get GFS2 mounted on top of a dual-primary DRDB /dev/drdb0 volume on Raspbian, but I'm hitting an issue. The DRBD volume has a working stonith/fencing cluster setup using pacemaker and works fine on that side. The cluster is successfully synced across both RPi nodes, in a Primary/Primary configuration.

Note: I have gotten this setup to work using ocfs2, but I would really like to get gfs2 working.

Whenever I format /dev/drbd0 using mkfs.gfs2` and then try to mount the GFS2 volume, I get an error:

mount -t gfs2 -o noatime,nodiratime,noquota /dev/drbd0 /data
mount: mount(2) failed: /data: No such file or directory

I've read up about this and there seems scant information about this. I have determined that the linux kernel config file /usr/src/linux-headers-4.14.79+/.config shows this as an unconfigured part of the kernel module:

CONFIG_GFS2_FS=m
# CONFIG_GFS2_FS_LOCKING_DLM is not set

I think this means it needs to be enabled to CONFIG_GFS2_FS_LOCKING_DLM=y and recompiled.

I am running into a lot of issues with 1) determining the correct module and 2) getting it correctly compiled and installed. I think it is part of fs/gfs2 or fs/dlm.

After setting the .config file, I have been trying to compile them using the commands:

make modules SUBDIRS=fs/dlm
make modules_install SUBDIRS=fs/dlm
make modules SUBDIRS=fs/gfs2
make modules_install SUBDIRS=fs/gfs2

Then:

modprobe dlm
modprobe gfs2

Still I get the same errors when trying to mount the filesystem.

I'm stuck, can anyone help?

Update: Adding output for use of answer by @Ingo (Thanks for responding).

root@raspberrypi4:~# sudo modprobe dlm

root@raspberrypi4:~# sudo modprobe gfs2

root@raspberrypi4:~# lsmod | egrep 'dlm|gfs2'
gfs2                  334544  0
dlm                   153064  8

root@raspberrypi4:~# sudo ls -al /data/
total 8
drwxrwxr-x  2 root root 4096 Jan 22 13:36 .
drwxr-xr-x 23 root root 4096 Jan 22 13:36 ..

root@raspberrypi4:~# mkfs.gfs2 -p lock_dlm -j 2 -t nfs:nfs /dev/drbd0
-su: mkfs.gfs2: command not found

root@raspberrypi4:~# apt-get install gfs2-utils -y
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following NEW packages will be installed:
  gfs2-utils
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 237 kB of archives.
After this operation, 946 kB of additional disk space will be used.
Get:1 http://mirror.serverius.net/raspbian/raspbian stretch/main armhf gfs2-utils armhf 3.1.9-2 [237 kB]
Fetched 237 kB in 9s (24.5 kB/s)
Selecting previously unselected package gfs2-utils.
(Reading database ... 75111 files and directories currently installed.)
Preparing to unpack .../gfs2-utils_3.1.9-2_armhf.deb ...
Unpacking gfs2-utils (3.1.9-2) ...
Processing triggers for man-db (2.7.6.1-2) ...
Setting up gfs2-utils (3.1.9-2) ...

root@raspberrypi4:~# mkfs.gfs2 -p lock_dlm -j 2 -t nfs:nfs /dev/drbd0
/dev/drbd0: Read-only file system

root@raspberrypi4:~# cat /proc/drbd
version: 8.4.10 (api:1/proto:86-101)
srcversion: 7EBAF95052116ECFD37C687
 0: cs:Connected ro:Secondary/Secondary ds:UpToDate/UpToDate C r-----
    ns:265164 nr:0 dw:265164 dr:3104 al:33 bm:0 lo:0 pe:0 ua:0 ap:0 ep:1 wo:d oos:0

root@raspberrypi4:~# drbdadm primary nfs

root@raspberrypi4:~# cat /proc/drbd
version: 8.4.10 (api:1/proto:86-101)
srcversion: 7EBAF95052116ECFD37C687
 0: cs:Connected ro:Primary/Secondary ds:UpToDate/UpToDate C r-----
    ns:265164 nr:0 dw:265164 dr:3104 al:33 bm:0 lo:0 pe:0 ua:0 ap:0 ep:1 wo:d oos:0

root@raspberrypi4:~# mkfs.gfs2 -p lock_dlm -j 2 -t nfs:nfs /dev/drbd0
It appears to contain an existing filesystem (ocfs2)
This will destroy any data on /dev/drbd0
Are you sure you want to proceed? [y/n]y
Discarding device contents (may take a while on large devices): Done
Adding journals: Done
Building resource groups: Done
Creating quota file: Done
Writing superblock and syncing: Done
Device:                    /dev/drbd0
Block size:                4096
Device size:               3.73 GB (978377 blocks)
Filesystem size:           3.73 GB (978374 blocks)
Journals:                  2
Resource groups:           16
Locking protocol:          "lock_dlm"
Lock table:                "nfs:nfs"
UUID:                      bcd37508-ad9b-28cd-ee37-bbe020b7ae4e

root@raspberrypi4:~# sudo mount -t gfs2 -o noatime,nodiratime,noquota /dev/drbd0 /data
mount: mount(2) failed: /data: No such file or directory

root@raspberrypi4:~# dmesg | tail -60
[    3.563656] scsi host0: usb-storage 1-1.3:1.0
[    3.610066] random: systemd-cryptse: uninitialized urandom read (16 bytes read)
[    3.740742] uart-pl011 20201000.serial: no DMA platform data
[    4.453683] systemd[1]: Set up automount Arbitrary Executable File Formats File System Automount Point.
[    4.474723] systemd[1]: Started Forward Password Requests to Wall Directory Watch.
[    4.493617] systemd[1]: Listening on udev Control Socket.
[    4.507598] systemd[1]: Listening on Journal Socket.
[    4.520857] systemd[1]: Listening on Syslog Socket.
[    4.534018] systemd[1]: Listening on udev Kernel Socket.
[    4.547161] systemd[1]: Reached target Swap.
[    4.647540] scsi 0:0:0:0: Direct-Access     Kingston DataTraveler 2.0 PMAP PQ: 0 ANSI: 0 CCS
[    4.717381] sd 0:0:0:0: [sda] 7827456 512-byte logical blocks: (4.01 GB/3.73 GiB)
[    4.717912] sd 0:0:0:0: [sda] Write Protect is off
[    4.717931] sd 0:0:0:0: [sda] Mode Sense: 23 00 00 00
[    4.718439] sd 0:0:0:0: [sda] No Caching mode page found
[    4.718458] sd 0:0:0:0: [sda] Assuming drive cache: write through
[    4.727793]  sda: sda1
[    4.733347] sd 0:0:0:0: [sda] Attached SCSI removable disk
[    7.287521] EXT4-fs (mmcblk0p2): re-mounted. Opts: (null)
[    7.874193] systemd-journald[88]: Received request to flush runtime journal from PID 1
[    7.977196] sd 0:0:0:0: Attached scsi generic sg0 type 0
[   10.981582] snd_bcm2835: module is from the staging directory, the quality is unknown, you have been warned.
[   11.040548] bcm2835_alsa bcm2835_alsa: card created with 8 channels
[   15.313181] smsc95xx 1-1.1:1.0 eth0: hardware isn't capable of remote wakeup
[   16.837859] smsc95xx 1-1.1:1.0 eth0: link up, 100Mbps, full-duplex, lpa 0xC5E1
[   19.067119] random: crng init done
[   19.067142] random: 7 urandom warning(s) missed due to ratelimiting
[   24.793040] drbd: initialized. Version: 8.4.10 (api:1/proto:86-101)
[   24.793062] drbd: srcversion: 7EBAF95052116ECFD37C687
[   24.793069] drbd: registered as block device major 147
[   26.243493] drbd nfs: Starting worker thread (from drbdsetup-84 [452])
[   26.261886] block drbd0: disk( Diskless -> Attaching )
[   26.262112] drbd nfs: Method to ensure write ordering: drain
[   26.262313] block drbd0: max BIO size = 122880
[   26.270502] block drbd0: drbd_bm_resize called with capacity == 7827016
[   26.270677] block drbd0: resync bitmap: bits=978377 words=30576 pages=30
[   26.270696] block drbd0: size = 3822 MB (3913508 KB)
[   26.284493] block drbd0: recounting of set bits took additional 1 jiffies
[   26.284524] block drbd0: 0 KB (0 bits) marked out-of-sync by on disk bit-map.
[   26.284578] block drbd0: disk( Attaching -> Consistent )
[   26.284623] block drbd0: attached to UUIDs DF273E4A603D84AE:0000000000000000:05A4CC7381C320C6:05A3CC7381C320C7
[   27.233543] drbd nfs: conn( StandAlone -> Unconnected )
[   27.236822] drbd nfs: Starting receiver thread (from drbd_w_nfs [456])
[   27.237451] DLM installed
[   27.283266] drbd nfs: receiver (re)started
[   27.283370] drbd nfs: conn( Unconnected -> WFConnection )
[   27.836645] drbd nfs: Handshake successful: Agreed network protocol version 101
[   27.836667] drbd nfs: Feature flags enabled on protocol level: 0x7 TRIM THIN_RESYNC WRITE_SAME.
[   27.839020] drbd nfs: Peer authenticated using 20 bytes HMAC
[   27.840057] drbd nfs: conn( WFConnection -> WFReportParams )
[   27.840088] drbd nfs: Starting ack_recv thread (from drbd_r_nfs [480])
[   27.893199] block drbd0: drbd_sync_handshake:
[   27.893232] block drbd0: self DF273E4A603D84AE:0000000000000000:05A4CC7381C320C6:05A3CC7381C320C7 bits:0 flags:0
[   27.893251] block drbd0: peer DF273E4A603D84AE:0000000000000000:05A4CC7381C320C7:05A3CC7381C320C7 bits:0 flags:0
[   27.893266] block drbd0: uuid_compare()=0 by rule 40
[   27.893320] block drbd0: peer( Unknown -> Secondary ) conn( WFReportParams -> Connected ) disk( Consistent -> UpToDate ) pdsk( DUnknown -> UpToDate )
[   34.963572] Adding 102396k swap on /var/swap.  Priority:-2 extents:1 across:102396k SSFS
[40620.787317] gfs2: GFS2 installed
[40907.496910] block drbd0: role( Secondary -> Primary )
[41161.493128] gfs2: can't find protocol lock_dlm

Answer 1

I use default unmodified Raspbian Stretch Lite and just load the modules:

rpi ~$ sudo modprobe dlm
rpi ~$ sudo modprobe gfs2

Both modules are loaded without any problems:

rpi ~$ lsmod | egrep 'dlm|gfs2'
dlm                   180224  0
gfs2                  380928  0

Then you should check if the mountpoint is available:

rpi ~$ sudo ls -al /data/
drwxr-xr-x  2 root root 4096 Jan 18 21:00 .
drwxr-xr-x 22 root root 4096 Jan 18 21:00 ..

Now you should be able to mount:

rpi ~$ sudo mount -t gfs2 -o noatime,nodiratime,noquota /dev/drbd0 /data

I cannot test it because I do not have a gfs2 file system but there is no need to compile modules. It should work out of the box with default Raspbian.