[2.1] linux/spl/kmem_cache: undefine kmem_cache_alloc before defining it
#15143
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RaitoBezarius
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kmem_cache_alloc before defining itkmem_cache_alloc before defining it
This was referenced Aug 2, 2023
When compiling a kernel with bcachefs and zfs, the two macros will collide, making it impossible to have both filesystems. It is sufficient to just undefine the macro before calling it. On why this should be in ZFS rather than bcachefs, currently, bcachefs is not a in-tree filesystem, but, it has a reasonably high chance of getting included soon. This avoids the breakage in ZFS early, this patch may be distributed downstream in NixOS and is already used there.
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behlendorf
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Aug 2, 2023
| * or in-tree filesystem that may define kmem_cache_alloc, | ||
| * like bcachefs does it now. | ||
| */ | ||
| #undef kmem_cache_alloc |
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I'd recommend wrapping this #undef with a #ifdef kmem_cache_alloc guard. This will avoid any pedantic compiler warnings about undef'ing a define which doesn't exist.
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Done in #15144 which is the rebased version.
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We can close this one if you want.
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Great. Let's go ahead and open new PRs for the backports after it's merged.
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Motivation and Context
When compiling a kernel with bcachefs and zfs, the two macros will collide, making it impossible to have both filesystems.
It is sufficient to just undefine the macro before calling it.
On why this should be in ZFS rather than bcachefs, currently, bcachefs is not an in-tree filesystem, but, it has a reasonably high chance of getting included soon.
This avoids the breakage in ZFS early, this patch may be distributed downstream in NixOS and is already used there.
I will send the PR for 2.2 too (on master).
Description
Undefining the macro
kmem_cache_allocbefore its redefinition to ensure we have "the right one".How Has This Been Tested?
I have been running a NixOS system with a bcachefs rootfs and various ZFS external disks with it for more than 2 weeks now.
I did not run specific tests beyond workstation-class usage.
See NixOS/nixpkgs#243075 the downstream PR.
Types of changes
Checklist:
Signed-off-by.