From: Miklos Szeredi <miklos@szeredi.hu>
To: Amir Goldstein <amir73il@gmail.com>
Cc: Christian Brauner <brauner@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-unionfs@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 3/6] ovl: reflow ovl_create_or_link()
Date: Fri, 14 Nov 2025 18:41:59 +0100 [thread overview]
Message-ID: <CAJfpegtZhfU7hmYcom9LgnkhXbZ8peLtRm1CDhVy2JXfqJUGkA@mail.gmail.com> (raw)
In-Reply-To: <CAOQ4uxie_CSG7kPBCZaKEfiQmLH7EAcMqrHXvy78ciLqX4QuKA@mail.gmail.com>
On Fri, 14 Nov 2025 at 13:07, Amir Goldstein <amir73il@gmail.com> wrote:
>
> On Fri, Nov 14, 2025 at 1:00 PM Christian Brauner <brauner@kernel.org> wrote:
> >
> > On Fri, Nov 14, 2025 at 12:52:58PM +0100, Amir Goldstein wrote:
> > > On Fri, Nov 14, 2025 at 11:15 AM Christian Brauner <brauner@kernel.org> wrote:
> > > > +
> > > > + if (attr->hardlink)
> > > > + return do_ovl_create_or_link(dentry, inode, attr);
> > > > +
> > >
> > > ^^^ This looks like an optimization (don't setup cred for hardlink).
> > > Is it really an important optimization that is worth complicating the code flow?
> >
> > It elides a bunch of allocations and an rcu cycle from put_cred().
> > So yes, I think it's worth it.
>
> I have no doubt that ovl_setup_cred_for_create() has a price.
> The question is whether hardlinking over ovl is an interesting use case
> to optimize for.
>
> Miklos? WDYT?
Hard link is special cased in several places because it's only
creating the directory entry, but no the inode. As I see it it's not
about optimization, more about hardlink simply being special.
Thanks,
Miklos
next prev parent reply other threads:[~2025-11-14 17:42 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-14 10:15 [PATCH 0/6] ovl: convert creation credential override to cred guard Christian Brauner
2025-11-14 10:15 ` [PATCH 1/6] ovl: add prepare_creds_ovl cleanup guard Christian Brauner
2025-11-14 12:04 ` Amir Goldstein
2025-11-14 13:34 ` Christian Brauner
2025-11-14 10:15 ` [PATCH 2/6] ovl: port ovl_create_tmpfile() to new " Christian Brauner
2025-11-14 10:15 ` [PATCH 3/6] ovl: reflow ovl_create_or_link() Christian Brauner
2025-11-14 11:52 ` Amir Goldstein
2025-11-14 12:00 ` Christian Brauner
2025-11-14 12:07 ` Amir Goldstein
2025-11-14 17:41 ` Miklos Szeredi [this message]
2025-11-14 10:15 ` [PATCH 4/6] ovl: mark ovl_setup_cred_for_create() as unused temporarily Christian Brauner
2025-11-14 10:15 ` [PATCH 5/6] ovl: port ovl_create_or_link() to new prepare_creds_ovl cleanup guard Christian Brauner
2025-11-14 10:15 ` [PATCH 6/6] ovl: drop ovl_setup_cred_for_create() Christian Brauner
2025-11-14 12:15 ` [PATCH 0/6] ovl: convert creation credential override to cred guard Amir Goldstein
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