ACK/CMNT: [SRU][N/J:linux-azure][PATCH 0/1] azure: SAUCE: add a knob for serializing open/close operations on NFSv4.x

[Alice C. Munduruca]

On Tue Jan 20, 2026 at 2:51 PM EST, Vinicius Peixoto wrote:
> BugLink: https://bugs.launchpad.net/bugs/2138752
>
> [Impact]
>
> Azure customers are running into issues on Azure Files due to an NFS server bug related to parallel open/close operations, and a fix for the server bug cannot be implemented in the near future.
>
> [Fix]
>
> Implement a client-side workaround by adding a knob to force the serialization of problematic parallel operations in the client. Other distros (such as SLES) have already implemented this workaround. This change will target the 5.15 and 6.8 linux-azure kernels.
>
> [Test plan]
>
> Build tested only; the Azure Files team will run reproducers on their side to evaluate the fix.
>
> [Where problems could occur]
>
> This change is very small and self-contained, having a low risk of introducing crashes, but will likely incur performance regressions for clients that enable this workaround due to the serialization of operations. This was considered an acceptable tradeoff since this is a temporary solution for circumventing the underlying issue.
>
> [Other info]
> SF #00421129
>
> NeilBrown (1):
>   UBUNTU: SAUCE: NFSv4.x: by default serialize open/close operations.
>
>  fs/nfs/nfs4proc.c | 7 +++++++
>  1 file changed, 7 insertions(+)

The backport notes should probably have a space on the second line,
however since these are both cherry picks this doesn't fail a
ubuntu-check-commit.

Compile tested.

Acked-by: Alice C. Munduruca <alice.munduruca at canonical.com>