Re: [PATCH] 9p: Add missing read barrier in virtio zero-copy path

[Dominique Martinet]

Gui-Dong Han wrote on Fri, May 29, 2026 at 03:54:41PM +0800:
> Commit 2b6e72ed747f ("9P: Add memory barriers to protect request
> fields over cb/rpc threads handoff") added a read barrier after
> p9_client_rpc() waits for req->status, pairing with the write barrier in
> p9_client_cb(). The virtio zero-copy wait path was missed.
> 
> Add the same read barrier after the zero-copy wait before reading the
> completed request.
> 
> Fixes: abfa034e4b8e ("fs/9p: Update zero-copy implementation in 9p")

This doesn't make sense, the wmb was added a few years later, so I guess
this should be
Fixes: 2b6e72ed747f ("9P: Add memory barriers to protect request fields over cb/rpc threads handoff")

With that said, a rmb here makes sense, so picking up (with fix tag
fixed up)

-- 
Dominique