On 2024-01-30 21:48, Dave Chinner wrote:
On Tue, Jan 30, 2024 at 11:52:54AM -0500, Mathieu Desnoyers wrote:
Introduce a generic way to query whether the dcache is virtually aliased
on all architectures. Its purpose is to ensure that subsystems which
are incompatible with virtually aliased data caches (e.g. FS_DAX) can
reliably query this.
For dcache aliasing, there are three scenarios dependending on the
architecture. Here is a breakdown based on my understanding:
A) The dcache is always aliasing:
* arc
* csky
* m68k (note: shared memory mappings are incoherent ? SHMLBA is missing there.)
* sh
* parisc
/me wonders why the dentry cache aliasing has problems on these
systems.
Oh, dcache != fs/dcache.c (the VFS dentry cache).
Can you please rename this function appropriately so us dumb
filesystem people don't confuse cpu data cache configurations with
the VFS dentry cache aliasing when we read this code? Something like
cpu_dcache_is_aliased(), perhaps?
Good point, will do. I'm planning go rename as follows for v3 to
eliminate confusion with dentry cache (and with "page cache" in
general):
ARCH_HAS_CACHE_ALIASING -> ARCH_HAS_CPU_CACHE_ALIASING
dcache_is_aliasing() -> cpu_dcache_is_aliasing()
I noticed that you suggested "aliased" rather than "aliasing",
but I followed what arm64 did for icache_is_aliasing(). Do you
have a strong preference one way or another ?
Thanks,
Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com
