From: Al Viro <viro@zeniv.linux.org.uk>
To: Viacheslav Dubeyko <Slava.Dubeyko@ibm.com>
Cc: "idryomov@gmail.com" <idryomov@gmail.com>,
Alex Markuze <amarkuze@redhat.com>,
"slava@dubeyko.com" <slava@dubeyko.com>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"ceph-devel@vger.kernel.org" <ceph-devel@vger.kernel.org>,
Patrick Donnelly <pdonnell@redhat.com>
Subject: Re: [PATCH] ceph: is_root_ceph_dentry() cleanup
Date: Tue, 11 Feb 2025 00:15:21 +0000 [thread overview]
Message-ID: <20250211001521.GF1977892@ZenIV> (raw)
In-Reply-To: <37677603fd082e3435a1fa76224c09ab6141dc22.camel@ibm.com>
On Tue, Feb 11, 2025 at 12:08:21AM +0000, Viacheslav Dubeyko wrote:
> In general, the MDS can issue NULL dentries to clients so that they "know" the
> direntry does not exist without having some capability (or lease) associated
> with it. As far as I can see, if application repeatedly does stat of file, then
> the kernel driver isn't repeatedly going out to the MDS to lookup that file. So,
> I assume that this is the goal of this check and logic.
Er... On repeated stat(2) you will get ->lookup() called the first time around;
afterwards you'll be getting dentry from dcache lookup. With ->d_revalidate()
each time you find it in dcache, and eviction if ->d_revalidate() says it's stale.
In which case a new dentry will be allocated and fed to ->lookup(), passed to
it in negative-unhashed state...
next prev parent reply other threads:[~2025-02-11 0:15 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-28 1:10 [PATCH] ceph: is_root_ceph_dentry() cleanup Viacheslav Dubeyko
2025-01-28 3:07 ` Al Viro
2025-01-28 23:27 ` Viacheslav Dubeyko
2025-01-29 1:12 ` Al Viro
2025-02-11 0:08 ` Viacheslav Dubeyko
2025-02-11 0:15 ` Al Viro [this message]
2025-02-11 18:01 ` Viacheslav Dubeyko
2025-02-11 19:01 ` Al Viro
2025-02-11 19:32 ` Viacheslav Dubeyko
2025-02-11 21:40 ` Al Viro
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