From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from zeniv.linux.org.uk (zeniv.linux.org.uk [62.89.141.173]) (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 0D34C26136D; Tue, 20 May 2025 15:25:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=62.89.141.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747754742; cv=none; b=OnYPkUKYITODbo8vebDWoqqXTJHvbFP2Y/coCpZuAfNei2Tcgb23AsS54s/cQwZKlmyOf7VlGXBgY6qb0wgozOHgew8TmO9AmTDfYUkprh47uuwpZwWHUl674gWOZtXDoxB4omPhEHheltrRe07wcsDYG8r0EOOeRUkCIZXQPHs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747754742; c=relaxed/simple; bh=UbxbrDjiPpBtkxeRkQ8NtBY8wwQKKNRtoyv/7gh0Dmg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=qHbNRRzZNW9uMips1uoIMl24pRRRKVe9J+4lvw6RtyvmgaU0DjUolvfI6N+hm2mvllqbUZ9HcCpVs44nnk5HAgUJXzrWj/MRCAy+DUS0i9S+xSAisd6AM20RAlOVj/LHdiR7DZKdHnLR5Me4D450HID6twEP6K3erxlDuG8hGRs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zeniv.linux.org.uk; spf=none smtp.mailfrom=ftp.linux.org.uk; dkim=pass (2048-bit key) header.d=linux.org.uk header.i=@linux.org.uk header.b=rtBImGae; arc=none smtp.client-ip=62.89.141.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zeniv.linux.org.uk Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=ftp.linux.org.uk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linux.org.uk header.i=@linux.org.uk header.b="rtBImGae" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=linux.org.uk; s=zeniv-20220401; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=Am/sNS1781WyMPpChSgtEv4NfxAbfezIgyeON7xSp6E=; b=rtBImGaes5whKznFFL/nOXPuLS FMEZ7x8O93+hdriUj7LJZpF78e+/TWhUp2cvIt89rnGj67K6893Z9+v1VUvE+/4WXUykvajcf2skc guArY6YuHimgSP5EL+ND2zin9qPMvkzklubSdzDvLSaCZ34udQfv9mYDUsMSPG92lmKlhngZNZGTY YjP7251EJ5nWiq5cTeNn82+YQXHZealZ8lxxUVBUj5SmUDhw6BxEqCy6LtVpWoXocu+YRkJ4cYm/Q Tr1FiXnIvZpBli1QNQmulZFy/If7vuCcinnKhMOqardkbRl4ISwntkA424V7r26nT9EJTMeP2IjC/ MgyAYoGw==; Received: from viro by zeniv.linux.org.uk with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1uHOqW-00000000wOJ-2FdS; Tue, 20 May 2025 15:25:36 +0000 Date: Tue, 20 May 2025 16:25:36 +0100 From: Al Viro To: Kent Overstreet Cc: linux-fsdevel@vger.kernel.org, linux-bcachefs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-unionfs@vger.kernel.org, Miklos Szeredi , Amir Goldstein , Christian Brauner , Jan Kara Subject: Re: [PATCH 4/6] fs: dcache locking for exlusion between overlayfs, casefolding Message-ID: <20250520152536.GD2023217@ZenIV> References: <20250520051600.1903319-1-kent.overstreet@linux.dev> <20250520051600.1903319-5-kent.overstreet@linux.dev> Precedence: bulk X-Mailing-List: linux-bcachefs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250520051600.1903319-5-kent.overstreet@linux.dev> Sender: Al Viro On Tue, May 20, 2025 at 01:15:56AM -0400, Kent Overstreet wrote: > +int d_casefold_enable(struct dentry *dentry, struct d_casefold_enable *e) > +{ > + struct dentry *root = dentry->d_sb->s_root; > + int ret = 0; > + > + guard(mutex)(&no_casefold_dentries_lock); > + > + for (struct dentry *i = dentry; > + i && i->d_inode->i_flags & S_NO_CASEFOLD; > + i = i != root ? i->d_parent : NULL) { > + ret = darray_push(&e->refs, i); > + if (ret) > + goto err; > + > + ret = no_casefold_dentry_get(i, ref_casefold_enable); Beyond being fucking ugly, this is outright broken. Lose the timeslice (e.g. on allocation in that thing), and there's nothing to prevent your 'i' from pointing to freed memory.