Linux 6.2 compat: set_acl arg2 is "struct dentry *" and no longer "struct inode *"

[ckane]

Motivation and Context

As of (at least) Linux 6.2rc4, the ZFS kernel module is no longer compiling the set_acl implementation as all of the HAVE_SET_ACL and related tests are failing in configure.

Results in the following:

[ckane@system foo]$ sudo setfacl -m u:root:w a
[sudo] password for ckane: 
setfacl: a: Operation not supported

Description

Linux 6.2 changes the second argument of the set_acl operation to be a "struct dentry *" rather than a "struct inode ". The inode parameter is still available as dentry->d_inode, so adjust the call to the _impl function call to dereference and pass that pointer to it.

Related to: #14403

How Has This Been Tested?

Testing on my machine, and it doesn't break. However, I still experience the failure when attempting to run setfacl on my system. However, I have not really made use of ACLs so I am putting together the PR to discuss the issue and diagnose further, tracking source code commits.

Need to also run the ZFS test suite and ensure that tests/zfs-tests/tests/functional/acl/posix yield a PASS, which I suspect to not be the case presently.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Breaking change (fix or feature that would cause existing functionality to change)
• Library ABI change (libzfs, libzfs_core, libnvpair, libuutil and libzfsbootenv)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the OpenZFS code style requirements.
• I have updated the documentation accordingly.
• I have read the contributing document.
• I have added tests to cover my changes.
• I have run the ZFS Test Suite with this change applied.
• All commit messages are properly formatted and contain Signed-off-by.

[ckane]

I tested setfacl out on my Linux 6.1.7 kernel, and I was able to successfully set the ACL there, and when I boot back into 6.2rc4 with these changes applied, I can use ls to see that the ACL is applied:

[ckane@system foo]$ ls -l
total 1
-rw-rw-r--+ 1 ckane ckane 0 Jan 21 18:38 a

However, I still cannot set the ACL under 6.2 after these changes, so there must be some more implementation(s) that's missing.

[satmandu]

@ckane If you already see the issue, I'll wait for more input before replicating what you've done on my end...

[satmandu]

The latest commit appears to fix the minimal touch a ; sudo setfacl -m u:root:w a test case for me on Linux kernel 6.2-rc5.

I'll continue to use it and see it any other issues crop up...

[ckane]

The latest commit appears to fix the minimal touch a ; sudo setfacl -m u:root:w a test case for me on Linux kernel 6.2-rc5.

I'll continue to use it and see it any other issues crop up...

Thanks for the report! I wonder if there was also a bug upstream in rc4 that got fixed in rc5, related to those API changes

[ckane]

@behlendorf I think this one is ready for your review

[ckane]

@satmandu - can you re-try with the latest version of this patch? Earlier I had accidentally included some stylistic modifications to zfs_acl.c that I did not mean to include in the patch, that were from a code cleanup commit I was looking at earlier when trying to diagnose what might have changed. My latest push has removed those changes.

[satmandu]

@satmandu - can you re-try with the latest version of this patch? Earlier I had accidentally included some stylistic modifications to zfs_acl.c that I did not mean to include in the patch, that were from a code cleanup commit I was looking at earlier when trying to diagnose what might have changed. My latest push has removed those changes.

The latest version appears to work just fine:

satadru@cheekon ~$ uname -a
Linux cheekon 6.2.0-rc5 #1 SMP PREEMPT_DYNAMIC Sun Jan 22 12:26:53 EST 2023 x86_64 x86_64 x86_64 GNU/Linux
satadru@cheekon ~$ rm a
rm: cannot remove 'a': No such file or directory
satadru@cheekon ~$ touch a ; sudo setfacl -m u:root:w a
satadru@cheekon ~$ getfacl a
# file: a
# owner: satadru
# group: satadru
user::rw-
user:root:-w-
group::rw-
mask::rw-
other::r--

[satmandu]

FYI the packages I built to test this PR on my Ubuntu 22.10 system are here:

https://launchpad.net/~satadru-umich/+archive/ubuntu/zfs-experimental/

[behlendorf]

Thanks again for sorting this out. Hopefully these interfaces won't change again, but at least since the code is now using ZFS_LINUX_REQUIRE_API in the check we'll detect it immediately if they do.

[ckane]

Adding a note here that I also confirmed that on 6.2rc4 setfacl won't work, regardless of the patch, and there has been some fix to the ACL code added in 6.2rc5 that, along with this patch, fixes the bug on ZFS.