From: Al Viro <viro@zeniv.linux.org.uk>
To: Miklos Szeredi <miklos@szeredi.hu>
Cc: Miklos Szeredi <mszeredi@redhat.com>,
linux-fsdevel@vger.kernel.org, NeilBrown <neil@brown.name>
Subject: Re: [PATCH] fuse: prevent exchange/revalidate races
Date: Wed, 17 Sep 2025 18:43:50 +0100 [thread overview]
Message-ID: <20250917174350.GW39973@ZenIV> (raw)
In-Reply-To: <CAJfpegvYJD8UUuukNY7oj7-PSu48y6hXn+iV9iHzrO4fdgWXQw@mail.gmail.com>
On Wed, Sep 17, 2025 at 07:27:25PM +0200, Miklos Szeredi wrote:
> On Wed, 17 Sept 2025 at 18:41, Al Viro <viro@zeniv.linux.org.uk> wrote:
> >
> > On Wed, Sep 17, 2025 at 05:42:18PM +0200, Miklos Szeredi wrote:
> > > > ... and if the call of ->d_revalidate() had been with parent locked, you've
> > > > just got a deadlock in that case.
> > >
> > > Why?
> >
> > Because the locking order on directories is "ancestors first"; you are trying
> > to grab an inode that is also a directory and might be anywhere in the tree
> > by that point - that's precisely what you are trying to check, isn't it?
>
> But if parent is locked, it must not have been renamed, hence
> parent-child relationship holds.
Not if parent is held shared.
next prev parent reply other threads:[~2025-09-17 17:43 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-17 15:30 [PATCH] fuse: prevent exchange/revalidate races Miklos Szeredi
2025-09-17 15:36 ` Al Viro
2025-09-17 15:42 ` Miklos Szeredi
2025-09-17 16:41 ` Al Viro
2025-09-17 17:27 ` Miklos Szeredi
2025-09-17 17:43 ` Al Viro [this message]
2025-09-17 17:45 ` Al Viro
2025-09-18 1:43 ` NeilBrown
2025-09-18 10:02 ` Miklos Szeredi
2025-09-19 8:20 ` Miklos Szeredi
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