What is the Linux kernel change so that we can check for this change being
back ported into other kernels that have a lesser version number? Thanks.
On March 9, 2026 9:47:58 PM Cheyenne Wills <[email protected]> wrote:
I believe that I found the problem that can result in stale dentries.
The fix should be fairly simple. An old configure test was masking a
change in the Linux kernel.
--
Cheyenne Wills
[email protected]
On Mon, 9 Mar 2026 14:29:29 +0100
Gaja Sophie Peters <[email protected]> wrote:
TLDR: OpenAFS on Ubuntu with kernel 6.17 is in certain circumstances
not updating the Cache on file-deletion or file-creation happening on
a different machine, the only fix is: echo 3 >/proc/sys/vm/drop_caches
Long version: We discovered a problem with the recent advent of the
kernel 6.17 as the newest "hardware enablement kernel" in Ubuntu
24.04. Basically the existence or non-existence of a file is not
correctly reflected by the AFS-Cache, when a file is deleted or
created on another machine after the file was seen (or not) on the
current machine.
### first test: file deletion not propagated
#this command on a different machine# echo X >test-afs
$ cat test-afs
X
#this command on the other machine# rm test-afs
$ cat test-afs
X
$ fs flushall
$ cat test-afs
cat: test-afs: Input/output error
#as root# echo 3 >/proc/sys/vm/drop_caches
$ cat test-afs
cat: test-afs: No such file or directory
### second test: file creation not propagated
#this command on a different machine# echo Y >test-afs
$ cat test-afs
cat: test-afs: No such file or directory
$ fs flushall
$ cat test-afs
cat: test-afs: No such file or directory
#as root# echo 3 >/proc/sys/vm/drop_caches
$ cat test-afs
Y
We haven't yet tried to pinpoint at which exact kernel-version that
problem got introduced, but the Ubuntu-kernels 6.8 and 6.14 are
unaffected, the Ubuntu-kernel 6.17 is affected (kAFS on 6.17 is
unaffected). It doesn't make a difference, if the OpenAFS-version is
1.8.14 with the Ubuntu-patches for Kernel 6.17 or if it is OpenAFS
1.8.15
The file server hosting the volume was originally 1.8.13.2-1 from
Debian Trixie, but updating to 1.8.15 does not change anything,
either.
Is this known? Any idea how to deal with it?
Greetings,
Gaja Peters
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