From patchwork Wed Nov 1 06:20:55 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Al Viro X-Patchwork-Id: 13442546 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8BEB84C9D for ; Wed, 1 Nov 2023 06:21:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linux.org.uk header.i=@linux.org.uk header.b="KZ9rrlK/" Received: from zeniv.linux.org.uk (zeniv.linux.org.uk [IPv6:2a03:a000:7:0:5054:ff:fe1c:15ff]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B7E6D109 for ; Tue, 31 Oct 2023 23:21:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=linux.org.uk; s=zeniv-20220401; h=Sender:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description; bh=bVAC0xn/T//BfwlaeunxSYF+WLil1xBRbyJlVwXrimo=; b=KZ9rrlK/37OftthbMYIHj35NVO U2MPqS6MfRmCHf3SS90oA4P2dasHYlacKGSjWiqiakNA78wHLNZxz7OXYOD+sU0nCoL7w7a7vgYzj 9KXPY8QPIRkxVX75no96H/uKabr+ou1/9jpUQyAURAnMI+RhRsEolg2YJR+lNcTQILESKkrWXJLUK fNadKDsrjC155MW+X4zc3QWmYurd/ruv9ileL9qaD/uQBXDyN/vMya+4Slfb9SLTMWd/EDQ8kHB/+ NxivTy9E5B1/waIWrZ5b4DxRfKxFWG8V9l3IqGjatdlb9CPRej+hpj57/UA0qQzaH+fL5NWbPrs8g lr/IEbdA==; Received: from viro by zeniv.linux.org.uk with local (Exim 4.96 #2 (Red Hat Linux)) id 1qy4bB-008pbI-0n; Wed, 01 Nov 2023 06:21:05 +0000 From: Al Viro To: Linus Torvalds Cc: linux-fsdevel@vger.kernel.org Subject: [PATCH 06/15] __dentry_kill(): get consistent rules for ->d_count Date: Wed, 1 Nov 2023 06:20:55 +0000 Message-Id: <20231101062104.2104951-6-viro@zeniv.linux.org.uk> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20231101062104.2104951-1-viro@zeniv.linux.org.uk> References: <20231031061226.GC1957730@ZenIV> <20231101062104.2104951-1-viro@zeniv.linux.org.uk> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Sender: Al Viro Currently we call it with ->d_count equal to 1 when called from dentry_kill(); all other callers have ->d_count equal to 0. Make it always be called with zero ->d_count; on this step we just decrement it before the calls in dentry_kill(). That is safe, since all places that care about the value of ->d_count either do that under ->d_lock or hold a reference to dentry in question. Either is sufficient to prevent observing a dentry immediately prior to __dentry_kill() call from dentry_kill(). Signed-off-by: Al Viro --- fs/dcache.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/dcache.c b/fs/dcache.c index 0114b5195535..c89337ae30ce 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -729,6 +729,7 @@ static struct dentry *dentry_kill(struct dentry *dentry) goto slow_positive; } } + dentry->d_lockref.count--; __dentry_kill(dentry); return parent; @@ -741,6 +742,7 @@ static struct dentry *dentry_kill(struct dentry *dentry) if (unlikely(dentry->d_lockref.count != 1)) { dentry->d_lockref.count--; } else if (likely(!retain_dentry(dentry))) { + dentry->d_lockref.count--; __dentry_kill(dentry); return parent; } else {