linux-kernel - Re: [PATCH] fs: inline step_into() and walk

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Message-ID: <CAGudoHHfkwDz33Vzw=t8Fxjym21Wtg2jTj_wB2bYRgOPPD8XYA@mail.gmail.com>
Date: Wed, 19 Nov 2025 21:41:32 +0100
From: Mateusz Guzik <mjguzik@...il.com>
To: Al Viro <viro@...iv.linux.org.uk>
Cc: brauner@...nel.org, jack@...e.cz, linux-kernel@...r.kernel.org, 
	linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH] fs: inline step_into() and walk_component()

> On Wed, Nov 19, 2025 at 9:24 PM Al Viro <viro@...iv.linux.org.uk> wrote:
> >
> > On Wed, Nov 19, 2025 at 08:49:36PM +0100, Mateusz Guzik wrote:
> > > btw, is there a way to combine DCACHE_MANAGED_DENTRY + symlink check
> > > into one branch? The compiler refuses at the moment due to type being
> > > a bitfield. Given how few free flags are remaining this is quite a
> > > bummer.
> >
> > Is that really worth bothering with?  Condition is "bits 15..17 are 000
> > and bits 19..21 are _not_ 110" and I don't see any clean way to change
> > the encoding so that it could be done in one test.  In theory we could
> > do something like swapping the "type" and "managed" bits and use the
> > fact that 6 (symlink) is the maximal type we might run into, turning
> > that into flags & ((7<<15)|(7<<19))) < (6<<15), but...  *ewww*
> >

Forgot to respond to this bit.

I was looking for something *trivial* and hoped I merely missed it.

I completely agree anything complicated/fancy is not warranted.