From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from aserp2120.oracle.com ([141.146.126.78]:48078 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753671AbeFJFHe (ORCPT ); Sun, 10 Jun 2018 01:07:34 -0400 Received: from pps.filterd (aserp2120.oracle.com [127.0.0.1]) by aserp2120.oracle.com (8.16.0.22/8.16.0.22) with SMTP id w5A57XsT141958 for ; Sun, 10 Jun 2018 05:07:33 GMT Received: from userv0022.oracle.com (userv0022.oracle.com [156.151.31.74]) by aserp2120.oracle.com with ESMTP id 2jgecx94ma-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Sun, 10 Jun 2018 05:07:33 +0000 Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by userv0022.oracle.com (8.14.4/8.14.4) with ESMTP id w5A57W0K020152 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Sun, 10 Jun 2018 05:07:32 GMT Received: from abhmp0007.oracle.com (abhmp0007.oracle.com [141.146.116.13]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id w5A57W6f013185 for ; Sun, 10 Jun 2018 05:07:32 GMT From: Allison Henderson Subject: [PATCH v7 13/23] xfs: define parent pointer xattr format Date: Sat, 9 Jun 2018 22:04:58 -0700 Message-Id: <1528607108-11059-14-git-send-email-allison.henderson@oracle.com> In-Reply-To: <1528607108-11059-1-git-send-email-allison.henderson@oracle.com> References: <1528607108-11059-1-git-send-email-allison.henderson@oracle.com> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: linux-xfs@vger.kernel.org From: Dave Chinner We need to define the parent pointer attribute format before we start adding support for it into all the code that needs to use it. The EA format we will use encodes the following information: name={parent inode #, parent inode generation, dirent offset} value={dirent filename} The inode/gen gives all the information we need to reliably identify the parent without requiring child->parent lock ordering, and allows userspace to do pathname component level reconstruction without the kernel ever needing to verify the parent itself as part of ioctl calls. By using the dirent offset in the EA name, we have a method of knowing the exact parent pointer EA we need to modify/remove in rename/unlink without an unbound EA name search. By keeping the dirent name in the value, we have enough information to be able to validate and reconstruct damaged directory trees. While the diroffset of a filename alone is not unique enough to identify the child, the {diroffset,filename,child_inode} tuple is sufficient. That is, if the diroffset gets reused and points to a different filename, we can detect that from the contents of EA. If a link of the same name is created, then we can check whether it points at the same inode as the parent EA we current have. [achender: rebased, changed __unint32_t to xfs_dir2_dataptr_t, changed p_ino to xfs_ino_t and p_namelen to uint8_t, moved to xfs_da_format for xfs_dir2_dataptr_t] Signed-off-by: Dave Chinner Signed-off-by: Allison Henderson Reviewed-by: Darrick J. Wong --- fs/xfs/libxfs/xfs_da_format.h | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/fs/xfs/libxfs/xfs_da_format.h b/fs/xfs/libxfs/xfs_da_format.h index 9bd2e6b..bb5d8ec 100644 --- a/fs/xfs/libxfs/xfs_da_format.h +++ b/fs/xfs/libxfs/xfs_da_format.h @@ -885,4 +885,29 @@ static inline unsigned int xfs_dir2_dirblock_bytes(struct xfs_sb *sbp) return 1 << (sbp->sb_blocklog + sbp->sb_dirblklog); } +/* + * Parent pointer attribute format definition + * + * EA name encodes the parent inode number, generation and the offset of + * the dirent that points to the child inode. The EA value contains the + * same name as the dirent in the parent directory. + */ +struct xfs_parent_name_rec { + __be64 p_ino; + __be32 p_gen; + __be32 p_diroffset; +}; + +/* + * incore version of the above, also contains name pointers so callers + * can pass/obtain all the parent pointer information in a single structure + */ +struct xfs_parent_name_irec { + xfs_ino_t p_ino; + uint32_t p_gen; + xfs_dir2_dataptr_t p_diroffset; + const char *p_name; + uint8_t p_namelen; +}; + #endif /* __XFS_DA_FORMAT_H__ */ -- 2.7.4