From patchwork Fri Nov 24 06:04:09 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Al Viro X-Patchwork-Id: 13466997 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linux.org.uk header.i=@linux.org.uk header.b="t84e8Fxe" 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 EC55B10C8; Thu, 23 Nov 2023 22:04:24 -0800 (PST) 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=OhCzST4Viql9jwYwDDeDZI5/cnICIyfnJcJBswRqBMo=; b=t84e8FxetnlLzWy6Ty94DCvdp+ V+lOFj3AjZZCzxAAB+FbLC5E7PoA1tyT2Himsg0ubdZrmaued/gFs8XQ7m90MyynxiIifH8ism8yU eeqc0tw2fyWrC3fa+/3a8wVXuqm929QwW99VDKHNj2DgawwS503lweZLdhrQrgADV0QZRvdanKhvm 6YpA7633x3LGyEB/j4VWDX87FJR7uTJtGN3yM0rUR8yiKg0AwLTBTBLdGe3fBlIf5QUvXQHDFoMrI IvkDn3KWOrqm0Ix3rsp4AwY8FASYrTTYfWeWC+ayNe9q2V8ij3ELqc/Y1u1wR+jR+rt2fHW2q8ct+ hWI6DAtA==; Received: from viro by zeniv.linux.org.uk with local (Exim 4.96 #2 (Red Hat Linux)) id 1r6PId-002PuB-1w; Fri, 24 Nov 2023 06:04:23 +0000 From: Al Viro To: linux-fsdevel@vger.kernel.org Cc: Linus Torvalds , Christian Brauner , linux-kernel@vger.kernel.org Subject: [PATCH v3 08/21] fast_dput(): new rules for refcount Date: Fri, 24 Nov 2023 06:04:09 +0000 Message-Id: <20231124060422.576198-8-viro@zeniv.linux.org.uk> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20231124060422.576198-1-viro@zeniv.linux.org.uk> References: <20231124060200.GR38156@ZenIV> <20231124060422.576198-1-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 By now there is only one place in entire fast_dput() where we return false; that happens after refcount had been decremented and found (under ->d_lock) to be zero. In that case, just prior to returning false to caller, fast_dput() forcibly changes the refcount from 0 to 1. Lift that resetting refcount to 1 into the callers; later in the series it will be massaged out of existence. Reviewed-by: Christian Brauner Signed-off-by: Al Viro --- fs/dcache.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) diff --git a/fs/dcache.c b/fs/dcache.c index 9edabc7e2e64..a00e9ba22480 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -847,13 +847,6 @@ static inline bool fast_dput(struct dentry *dentry) spin_unlock(&dentry->d_lock); return true; } - - /* - * Re-get the reference we optimistically dropped. We hold the - * lock, and we just tested that it was zero, so we can just - * set it to 1. - */ - dentry->d_lockref.count = 1; return false; } @@ -896,6 +889,7 @@ void dput(struct dentry *dentry) } /* Slow case: now with the dentry lock held */ + dentry->d_lockref.count = 1; rcu_read_unlock(); if (likely(retain_dentry(dentry))) { @@ -930,6 +924,7 @@ void dput_to_list(struct dentry *dentry, struct list_head *list) return; } rcu_read_unlock(); + dentry->d_lockref.count = 1; if (!retain_dentry(dentry)) __dput_to_list(dentry, list); spin_unlock(&dentry->d_lock);