From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linux.org.uk header.i=@linux.org.uk header.b="a2QncgnU" 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 7820D9A; Thu, 23 Nov 2023 11:53:35 -0800 (PST) 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=dqAMuOipmlmjkedrTMrMYw6IQ27y72GpypxSjNpVMec=; b=a2QncgnUb6QJ1Lg5GgMVA+2T3/ fbNoKVoUugUVzcl9emA543J3GMHcNhnm+oCBdO+j36w8Ysf6RcjIRGYk8ImVYrVP6NTpC6pPk8Yfy ne4FO/7UHfFZQh3ZdS9FUageGdGYES9sh/7udHCFJmQ3qeUssJW+M1jt/WbkzSDuJZw74EONPufr0 8qecS/s8O3lCDY2qu9K8GlNYUNsehkx8PmzntcsDJvtos+abYityUdLWCHM/tjdfSSBaPldfUHiNj iG0QoeEfxs2RnQinORy9UydAqRtMS5T2sMUKNxto2pYOktOZqlUdoEBPaQgQS3JpvIF5AyZX5Xa/i WfrihlkQ==; Received: from viro by zeniv.linux.org.uk with local (Exim 4.96 #2 (Red Hat Linux)) id 1r6FlP-002EPf-1m; Thu, 23 Nov 2023 19:53:27 +0000 Date: Thu, 23 Nov 2023 19:53:27 +0000 From: Al Viro To: Gabriel Krisman Bertazi Cc: Linus Torvalds , Christian Brauner , tytso@mit.edu, linux-f2fs-devel@lists.sourceforge.net, ebiggers@kernel.org, linux-fsdevel@vger.kernel.org, jaegeuk@kernel.org, linux-ext4@vger.kernel.org Subject: Re: [f2fs-dev] [PATCH v6 0/9] Support negative dentries on case-insensitive ext4 and f2fs Message-ID: <20231123195327.GP38156@ZenIV> References: <20231025-selektiert-leibarzt-5d0070d85d93@brauner> <655a9634.630a0220.d50d7.5063SMTPIN_ADDED_BROKEN@mx.google.com> <20231120-nihilismus-verehren-f2b932b799e0@brauner> <20231121022734.GC38156@ZenIV> <20231122211901.GJ38156@ZenIV> <20231123171255.GN38156@ZenIV> <20231123182426.GO38156@ZenIV> <87bkbki91c.fsf@> Precedence: bulk X-Mailing-List: linux-fsdevel@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: <87bkbki91c.fsf@> Sender: Al Viro On Thu, Nov 23, 2023 at 02:06:39PM -0500, Gabriel Krisman Bertazi wrote: > > A paragraph above you've said that it's not constant over the entire > > filesystem. > > The same ->d_op is used by every dentry in the filesystem if the superblock > has the casefold bit enabled, regardless of whether a specific inode is > casefolded or not. See generic_set_encrypted_ci_d_ops in my tree. It is > called unconditionally by ext4_lookup and only checks the superblock: > > void generic_set_encrypted_ci_d_ops(struct dentry *dentry) > { > if (dentry->d_sb->s_encoding) { > d_set_d_op(dentry, &generic_encrypted_ci_dentry_ops); > return; > } > ... > > What I meant was that this used to be set once at sb->s_d_op, and > propagated during dentry allocation. Therefore, the propagation to the > alias would happen inside __d_alloc. Once we enabled fscrypt and > casefold to work together, sb->s_d_op is NULL Why? That's what I don't understand - if you really want it for all dentries on that filesystem, that's what ->s_d_op is for. If it is not, you have that problem, no matter which way you flip ->d_op value. > and we always set the same > handler for every dentry during lookup. Not every dentry goes through lookup - see upthread for details. > > Look, it's really simple - any setup work of that sort done in ->lookup() > > is either misplaced, or should be somehow transferred over to the alias > > if one gets picked. > > > > As for d_obtain_alias()... AFAICS, it's far more limited in what information > > it could access. It knows the inode, but it has no idea about the parent > > to be. > > Since it has the inode, d_obtain_alias has the superblock. I think that's all > we need for generic_set_encrypted_ci_d_ops. Huh? If it really depends only upon the superblock, just set it in ->s_d_op when you set the superblock up. Again, whatever setup you do for dentry in ->lookup(), you either * have a filesystem that never picks an existing directory alias (e.g. doesn't allow open-by-fhandle or has a very unusual implementation of related methods, like e.g. shmem), or * have that setup misplaced, in part that applies to all dentries out there (->s_d_op for universal ->d_op value, ->d_init() for uniform allocation of objects hanging from ->d_fsdata and other things like that), or * need to figure out how to transfer the result to alias (manually after d_splice_alias(), if races do not matter or using a new method explicitly for that), or * lose that state for aliases.