From: Al Viro <viro@ZenIV.linux.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [rfc][possible solution] RCU vfsmounts
Date: Sun, 29 Sep 2013 07:06:01 +0100 [thread overview]
Message-ID: <20130929060601.GL13318@ZenIV.linux.org.uk> (raw)
In-Reply-To: <CA+55aFzrjiM6bgqNgdckJGAZks2fR8ZD+R_5AqxvrnS64DD3ow@mail.gmail.com>
On Sat, Sep 28, 2013 at 01:43:49PM -0700, Linus Torvalds wrote:
> Sounds reasonable to to me.
Sigh... Looks like there's a lot of fun in shrink_dcache_for_umount() -
at the very least, it needs to bump ->d_seq on everything, because with
that change we *can* walk into a filesystem in the middle of that.
We obviously don't want to slap rcu_barrier() into the final mntput() -
it's far too costly; even one in deactivate_locked_super() (in the
wrong place and gone since a while back) had been causing problems.
Moreover, any filesystem that has e.g. ->d_hash() use an object hanging
off private data of superblock and freed by its ->kill_sb() before
generic_shutdown_super() will have an additional set of PITA; there
shouldn't be many of those, though.
Oh, well - this is going to be a fun series, by the look of it...
next prev parent reply other threads:[~2013-09-29 6:06 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-28 20:27 [rfc][possible solution] RCU vfsmounts Al Viro
2013-09-28 20:43 ` Linus Torvalds
2013-09-29 6:06 ` Al Viro [this message]
2013-09-29 17:19 ` Linus Torvalds
2013-09-29 18:10 ` Al Viro
2013-09-29 18:26 ` Linus Torvalds
2013-09-30 10:48 ` Miklos Szeredi
2013-09-29 18:49 ` Al Viro
2013-09-29 19:04 ` Al Viro
2013-09-30 19:49 ` Al Viro
2013-10-02 1:30 ` Al Viro
2013-10-03 6:14 ` Al Viro
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