From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from userp2120.oracle.com ([156.151.31.85]:57486 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755110AbeEHRAT (ORCPT ); Tue, 8 May 2018 13:00:19 -0400 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.22/8.16.0.22) with SMTP id w48GpQNe041635 for ; Tue, 8 May 2018 17:00:18 GMT Received: from aserv0022.oracle.com (aserv0022.oracle.com [141.146.126.234]) by userp2120.oracle.com with ESMTP id 2hs5939j6b-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Tue, 08 May 2018 17:00:18 +0000 Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by aserv0022.oracle.com (8.14.4/8.14.4) with ESMTP id w48H0G6E030421 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Tue, 8 May 2018 17:00:17 GMT Received: from abhmp0010.oracle.com (abhmp0010.oracle.com [141.146.116.16]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id w48H0Geu032106 for ; Tue, 8 May 2018 17:00:16 GMT From: Allison Henderson Subject: Re: [PATCH 12/21] xfs: define parent pointer xattr format References: <1525627494-12873-1-git-send-email-allison.henderson@oracle.com> <1525627494-12873-13-git-send-email-allison.henderson@oracle.com> <20180507223542.GJ11261@magnolia> Message-ID: Date: Tue, 8 May 2018 10:00:15 -0700 MIME-Version: 1.0 In-Reply-To: <20180507223542.GJ11261@magnolia> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: "Darrick J. Wong" Cc: linux-xfs@vger.kernel.org On 05/07/2018 03:35 PM, Darrick J. Wong wrote: > On Sun, May 06, 2018 at 10:24:45AM -0700, Allison Henderson wrote: >> 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 | 26 +++++++++++++++++++++++++- >> 1 file changed, 25 insertions(+), 1 deletion(-) >> >> diff --git a/fs/xfs/libxfs/xfs_da_format.h b/fs/xfs/libxfs/xfs_da_format.h >> index 9bd2e6b..d1c1221 100644 >> --- a/fs/xfs/libxfs/xfs_da_format.h >> +++ b/fs/xfs/libxfs/xfs_da_format.h >> @@ -878,11 +878,35 @@ struct xfs_attr3_rmt_hdr { >> #define XFS_ATTR3_RMT_BUF_SPACE(mp, bufsize) \ >> ((bufsize) - (xfs_sb_version_hascrc(&(mp)->m_sb) ? \ >> sizeof(struct xfs_attr3_rmt_hdr) : 0)) >> - > > Unrelated/unnecessary whitespace removal? Otherwise this is still > Reviewed-by: Darrick J. Wong > > --D > Sorry, not sure how that got in there. Will clean up. Thx! Allison > >> /* Number of bytes in a directory block. */ >> 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 >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html