kernel_5.8

[CodeImp]

Fixes allow to compile module on the kernel 5.8.
But there is a problem. Since kernel 5.8 make_request_fn can be null.

[crawfxrd]

The KERNEL_VERSION comparison is not usable, because features can be backported. You need to add tests to src/configure-tests/feature-tests to check for any changes.

[CodeImp]

Ok. I did it quickly so that it would compile.
I am concerned about a problem with the null make_request_fn.

[root@localhost tests]# ./test_snapshot.py
FFF
======================================================================
FAIL: test_modify_origin (__main__.TestSnapshot)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/user/dattobd/tests/./test_snapshot.py", line 39, in test_modify_origin
    self.assertEqual(dattobd.setup(self.minor, self.device, self.cow_full_path), 0)
AssertionError: 22 != 0

======================================================================
FAIL: test_next_available_minor (__main__.TestSnapshot)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/user/dattobd/tests/./test_snapshot.py", line 78, in test_next_available_minor
    self.assertEqual(dattobd.setup(0, self.device, self.cow_full_path), 0)
AssertionError: 22 != 0

======================================================================
FAIL: test_track_writes (__main__.TestSnapshot)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/user/dattobd/tests/./test_snapshot.py", line 56, in test_track_writes
    self.assertEqual(dattobd.setup(self.minor, self.device, self.cow_full_path), 0)
AssertionError: 22 != 0

----------------------------------------------------------------------
Ran 3 tests in 0.327s

FAILED (failures=3)
[root@localhost tests]# dmesg | tail -40
[71924.486158] datto: checking block device is not already being traced
[71924.486158] datto: fetching the absolute pathname for the base device
[71924.486161] datto: calculating block device size and offset
[71924.486162] datto: bdev size = 524288, offset = 0
[71924.486163] datto: creating cow manager
[71924.486163] datto: allocating cow manager, seqid = 1
[71924.486164] datto: creating cow file
[71924.486212] datto: allocating cow manager array (16 sections)
[71924.486214] datto: allocating cow file (26843545 bytes)
[71924.486429] datto: finding cow file inode
[71924.486430] datto: getting relative pathname of cow file
[71924.486501] datto: allocating queue
[71924.486516] datto: setting up make request function
[71924.486517] datto: setting queue limits
[71924.486518] datto: allocating gendisk
[71924.486521] datto: initializing gendisk
[71924.486521] datto: naming gendisk
[71924.486522] datto: block device size: 524288
[71924.486523] datto: adding disk
[71924.487090] datto: starting mrf kernel thread
[71924.488296] datto: creating kernel cow thread
[71924.488405] datto: getting the base block device's make_request_fn
[71924.488406] datto: make_request_fn is null: -22
[71924.489153] datto: error setting up tracing: -22
[71924.489930] datto: error setting up tracer as active snapshot: -22
[71924.490643] datto: stopping cow thread
[71924.491842] datto: stopping mrf thread
[71924.491950] datto: freeing gendisk
[71924.492322] datto: freeing request queue
[71924.496350] datto: freeing cow path
[71924.496351] datto: destroying cow manager
[71924.496370] datto: freeing base block device path
[71924.496370] datto: freeing base block device
[71924.496373] datto: error during setup ioctl handler: -22
[71924.497217] datto: minor range = 23 - 0
[71924.531768] datto: module exit
[71924.531768] datto: unregistering control device
[71924.532255] datto: unregistering /proc file
[71924.532257] datto: destroying snap devices
[71924.532258] datto: unregistering device driver from the kernel

[victorstewart]

so dattobd will not work on >=5.8 kernels at the moment?

[CodeImp]

Of course not. And it won't work because struct queue since v5.9 doesn't have a make_request_fn callback. I'm trying to suggest an alternative hook. The latest version was suggested by Hannes https://lwn.net/Articles/837944/, but so far without success.

[lacikaaa]

As Ubuntu 20.04 switched to kernel 5.8 I think this PR should get more attention

[CodeImp]

"more attention" - Yeah. Exactly.

[lacikaaa]

anyway, I have applied your patch on Ubuntu 20.04 with 5.8 and built/installed the module. urbackup is able to successfully use it for backups, so thanks for it.

[yves84]

Manjaro(ArchLinux) use 5.10 (5.11 for testing).

[silverspr]

@lacikaaa you mentioned you applied a patch Jan 15 provided by CodeImp. Can you provide the patch and details how to apply. Do I compile from source? I'm also trying to use this w/urbackup beta for linux.
thanks

[lacikaaa]

@lacikaaa you mentioned you applied a patch Jan 15 provided by CodeImp. Can you provide the patch and details how to apply. Do I compile from source? I'm also trying to use this w/urbackup beta for linux.
thanks

@silverspr the source after installing the package is under /usr/src/dattobd-0.10.15
I have applied the patch from this pr and compiled it using the following commands, not necessarily in this order:

make clean
depmod -a
make default
make install
modprobe dattobd

unfortunately you have to do this every time you have a new kernel