From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from userp1040.oracle.com ([156.151.31.81]:43415 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751096AbdHOEFI (ORCPT ); Tue, 15 Aug 2017 00:05:08 -0400 Received: from aserv0021.oracle.com (aserv0021.oracle.com [141.146.126.233]) by userp1040.oracle.com (Sentrion-MTA-4.3.2/Sentrion-MTA-4.3.2) with ESMTP id v7F456kT032705 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Tue, 15 Aug 2017 04:05:06 GMT Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by aserv0021.oracle.com (8.14.4/8.14.4) with ESMTP id v7F456SA027747 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Tue, 15 Aug 2017 04:05:06 GMT Received: from abhmp0008.oracle.com (abhmp0008.oracle.com [141.146.116.14]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id v7F456ji025071 for ; Tue, 15 Aug 2017 04:05:06 GMT Subject: Re: [RFC PATCH 05/13] xfs: define parent pointer xattr format References: <1502329293-4091-1-git-send-email-allison.henderson@oracle.com> <1502329293-4091-6-git-send-email-allison.henderson@oracle.com> <20170814235942.GR4796@magnolia> From: Allison Henderson Message-ID: Date: Mon, 14 Aug 2017 21:05:05 -0700 MIME-Version: 1.0 In-Reply-To: <20170814235942.GR4796@magnolia> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: "Darrick J. Wong" Cc: linux-xfs@vger.kernel.org On 08/14/2017 04:59 PM, Darrick J. Wong wrote: > On Wed, Aug 09, 2017 at 06:41:25PM -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] >> >> Signed-off-by: Dave Chinner >> Signed-off-by: Allison Henderson >> --- >> :100644 100644 d4d9bef... 91e2d5a... M fs/xfs/libxfs/xfs_format.h >> fs/xfs/libxfs/xfs_format.h | 27 +++++++++++++++++++++++++++ >> 1 file changed, 27 insertions(+) >> >> diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h >> index d4d9bef..91e2d5a 100644 >> --- a/fs/xfs/libxfs/xfs_format.h >> +++ b/fs/xfs/libxfs/xfs_format.h >> @@ -18,6 +18,8 @@ >> #ifndef __XFS_FORMAT_H__ >> #define __XFS_FORMAT_H__ >> >> +#include "xfs_da_format.h" >> + >> /* >> * XFS On Disk Format Definitions >> * >> @@ -1721,4 +1723,29 @@ struct xfs_acl { >> #define SGI_ACL_FILE_SIZE (sizeof(SGI_ACL_FILE)-1) >> #define SGI_ACL_DEFAULT_SIZE (sizeof(SGI_ACL_DEFAULT)-1) >> >> +/* >> + * 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 { >> + uint64_t p_ino; > Should use incore xfs types, i.e. xfs_ino_t. Ok, will fix >> + uint32_t p_gen; >> + xfs_dir2_dataptr_t p_diroffset; >> + const char *p_name; >> + uint32_t p_namelen; > Pathname components are at most 255 bytes long, though I guess that > doesn't save us any space here. Ok, I'll update it to use a uint8_t, parameters get shifted around all the time. Allison > --D > >> +}; >> + >> #endif /* __XFS_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