Re: [PATCH v4 1/2] fuse: Introduce a new notification type for resend pending requests

[Jingbo Xu <jefflexu@linux.alibaba.com>]

Hi, Miklos,

On 1/9/24 5:24 PM, Zhao Chen wrote:
> When a FUSE daemon panics and failover, we aim to minimize the impact on
> applications by reusing the existing FUSE connection. During this process,
> another daemon is employed to preserve the FUSE connection's file
> descriptor. The new started FUSE Daemon will takeover the fd and continue
> to provide service.
> 
> However, it is possible for some inflight requests to be lost and never
> returned. As a result, applications awaiting replies would become stuck
> forever. To address this, we can resend these pending requests to the
> new started FUSE daemon.
> 
> This patch introduces a new notification type "FUSE_NOTIFY_RESEND", which
> can trigger resending of the pending requests, ensuring they are properly
> processed again.
> 
> Signed-off-by: Zhao Chen <winters.zc@antgroup.com>

The notification style is more helpful in the cloud native scenarios
comparing to the original fusectl mechanism.  Recent days we found the
original fusectl based "resend" interface is un-accessible inside a
non-privileged container in our internal use case, as fusectl is
designed as a singleton and has no ability for user namespace mounting.
The new notification styled interface seems extremely helpful in our case.

Thus may I ask if there is any potential modification as for the user
ABI of the resend feature?  I'd like to test and improve it if there's any.

Many thanks!


-- 
Thanks,
Jingbo