From patchwork Fri Oct 21 13:05:57 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeffrey Layton X-Patchwork-Id: 13014769 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 36B6FC43219 for ; Fri, 21 Oct 2022 13:06:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230170AbiJUNG3 (ORCPT ); Fri, 21 Oct 2022 09:06:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44948 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230093AbiJUNGQ (ORCPT ); Fri, 21 Oct 2022 09:06:16 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 37FCD26B4B6; Fri, 21 Oct 2022 06:06:15 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id DD05BB80C98; Fri, 21 Oct 2022 13:06:13 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8CA75C433D6; Fri, 21 Oct 2022 13:06:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1666357572; bh=HgePQpANeCyNlHouoSiNjOumB4QLppVOqg1bfK18//Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=h9mbxrDiIYcO5M594qgki/ibDkOhScW1YhL3UPYCtHT9f8bCwJB8HCFDKdVUKC6wZ 6R0yel5DiglAUUcuypMfskj4I2Dnsz1Qy8q6Q0at8S8blOCfyYKgNLgvI+7HXh3MFN H8+z2wt25heOIhj7XLCQ4eIWO0hi/F1Ou++t2wk3HuueTb4crdcgIuEqy1YiWr6wte yhRSRrpLky8tlchsXPF0Emje/Gq97Dd8G2TojEbb9qM+k0IIXqbo+ksGyHATZo0ySV woTfZv5gdVrUSVlcW5Y1dwhknZhgwxeu1QYwc5eOiJNfeg+KaYQrOZ9o7pQT02mBPn RWddg7Kx8PrLw== From: Jeff Layton To: tytso@mit.edu, adilger.kernel@dilger.ca, djwong@kernel.org, david@fromorbit.com, trondmy@hammerspace.com, neilb@suse.de, viro@zeniv.linux.org.uk, zohar@linux.ibm.com, xiubli@redhat.com, chuck.lever@oracle.com, lczerner@redhat.com, jack@suse.cz, bfields@fieldses.org, brauner@kernel.org, fweimer@redhat.com Cc: linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, ceph-devel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-nfs@vger.kernel.org, linux-xfs@vger.kernel.org, Jeff Layton Subject: [PATCH v8 3/8] vfs: plumb i_version handling into struct kstat Date: Fri, 21 Oct 2022 09:05:57 -0400 Message-Id: <20221021130602.99099-4-jlayton@kernel.org> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20221021130602.99099-1-jlayton@kernel.org> References: <20221021130602.99099-1-jlayton@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: ceph-devel@vger.kernel.org From: Jeff Layton The NFS server has a lot of special handling for different types of change attribute access, depending on the underlying filesystem. In most cases, it's doing a getattr anyway and then fetching that value after the fact. Rather that do that, add a new STATX_CHANGE_COOKIE flag that is a kernel-only symbol (for now). If requested and getattr can implement it, it can fill out this field. For IS_I_VERSION inodes, add a generic implementation in vfs_getattr_nosec. Take care to mask STATX_CHANGE_COOKIE off in requests from userland and in the result mask. Since not all filesystems can give the same guarantees of monotonicity, claim a STATX_ATTR_CHANGE_MONOTONIC flag that filesystems can set to indicate that they offer an i_version value that can never go backward. Eventually if we decide to make the i_version available to userland, we can just designate a field for it in struct statx, and move the STATX_CHANGE_COOKIE definition to the uapi header. Reviewed-by: NeilBrown Signed-off-by: Jeff Layton --- fs/stat.c | 17 +++++++++++++++-- include/linux/stat.h | 9 +++++++++ 2 files changed, 24 insertions(+), 2 deletions(-) diff --git a/fs/stat.c b/fs/stat.c index ef50573c72a2..06fd3fc1ab84 100644 --- a/fs/stat.c +++ b/fs/stat.c @@ -18,6 +18,7 @@ #include #include #include +#include #include #include @@ -119,6 +120,11 @@ int vfs_getattr_nosec(const struct path *path, struct kstat *stat, stat->attributes_mask |= (STATX_ATTR_AUTOMOUNT | STATX_ATTR_DAX); + if ((request_mask & STATX_CHANGE_COOKIE) && IS_I_VERSION(inode)) { + stat->result_mask |= STATX_CHANGE_COOKIE; + stat->change_cookie = inode_query_iversion(inode); + } + mnt_userns = mnt_user_ns(path->mnt); if (inode->i_op->getattr) return inode->i_op->getattr(mnt_userns, path, stat, @@ -599,9 +605,11 @@ cp_statx(const struct kstat *stat, struct statx __user *buffer) memset(&tmp, 0, sizeof(tmp)); - tmp.stx_mask = stat->result_mask; + /* STATX_CHANGE_COOKIE is kernel-only for now */ + tmp.stx_mask = stat->result_mask & ~STATX_CHANGE_COOKIE; tmp.stx_blksize = stat->blksize; - tmp.stx_attributes = stat->attributes; + /* STATX_ATTR_CHANGE_MONOTONIC is kernel-only for now */ + tmp.stx_attributes = stat->attributes & ~STATX_ATTR_CHANGE_MONOTONIC; tmp.stx_nlink = stat->nlink; tmp.stx_uid = from_kuid_munged(current_user_ns(), stat->uid); tmp.stx_gid = from_kgid_munged(current_user_ns(), stat->gid); @@ -640,6 +648,11 @@ int do_statx(int dfd, struct filename *filename, unsigned int flags, if ((flags & AT_STATX_SYNC_TYPE) == AT_STATX_SYNC_TYPE) return -EINVAL; + /* STATX_CHANGE_COOKIE is kernel-only for now. Ignore requests + * from userland. + */ + mask &= ~STATX_CHANGE_COOKIE; + error = vfs_statx(dfd, filename, flags, &stat, mask); if (error) return error; diff --git a/include/linux/stat.h b/include/linux/stat.h index ff277ced50e9..52150570d37a 100644 --- a/include/linux/stat.h +++ b/include/linux/stat.h @@ -52,6 +52,15 @@ struct kstat { u64 mnt_id; u32 dio_mem_align; u32 dio_offset_align; + u64 change_cookie; }; +/* These definitions are internal to the kernel for now. Mainly used by nfsd. */ + +/* mask values */ +#define STATX_CHANGE_COOKIE 0x40000000U /* Want/got stx_change_attr */ + +/* file attribute values */ +#define STATX_ATTR_CHANGE_MONOTONIC 0x8000000000000000ULL /* version monotonically increases */ + #endif