Re: [PATCH 01/13] ovl: don't warn when the lazy lowerdata lookup fails in ovl_d_real()

[sashiko-bot@kernel.org]

> ovl_d_real() looks up the data of a metacopy file in a data-only layer
> itself if nothing has done that yet. If that lookup fails it WARN()s and
> returns the overlayfs dentry.
> 
> Commit 42dd69ae1af4 ("ovl: implement lazy lookup of lowerdata in
> data-only layers") assumed that the file would be read before
> trace_uprobe places a uprobe on it so the data would be there already.
> 
> But nothing actually guarantees that. trace_uprobe takes the path from
> kern_path() and calls d_real_inode() on it when the event is created and
> again when it is enabled. So a uprobe on a metacopy file whose redirect
> points at nothing warns twice:
> 
>   ovl_d_real(/f, 0): real dentry not found
>   WARNING: fs/overlayfs/super.c:79 at ovl_d_real+0xc9/0x210, CPU#2: sh/279
> [ ... ]
> Reported-by: Sashiko <sashiko-bot@kernel.org>
> Closes: https://lore.kernel.org/all/sashiko-outbox-214581@kernel.org
> Reported-by: Chris Down <chris@chrisdown.name>
> Closes: https://lore.kernel.org/all/20261114120557.4bc1eb6e57218cdc@chrisdown.name
> Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261115-work-ovl-d_real-v1-0-ca155efbcb2e@kernel.org?part=1