Line data    Source code

       1             : /* SPDX-License-Identifier: GPL-2.0-or-later */
       2             : /*
       3             :  * Copyright (C) 2021-2023 Oracle.  All Rights Reserved.
       4             :  * Author: Darrick J. Wong <djwong@kernel.org>
       5             :  */
       6             : #ifndef __XFS_SCRUB_NLINKS_H__
       7             : #define __XFS_SCRUB_NLINKS_H__
       8             : 
       9             : /* Live link count control structure. */
      10             : struct xchk_nlink_ctrs {
      11             :         struct xfs_scrub        *sc;
      12             : 
      13             :         /* Shadow link count data and its mutex. */
      14             :         struct xfarray          *nlinks;
      15             :         struct mutex            lock;
      16             : 
      17             :         /*
      18             :          * The collection step uses a separate iscan context from the compare
      19             :          * step because the collection iscan coordinates live updates to the
      20             :          * observation data while this scanner is running.  The compare iscan
      21             :          * is secondary and can be reinitialized as needed.
      22             :          */
      23             :         struct xchk_iscan       collect_iscan;
      24             :         struct xchk_iscan       compare_iscan;
      25             : 
      26             :         /* Parent pointer for finding backrefs. */
      27             :         struct xfs_parent_name_irec pptr;
      28             : 
      29             :         /*
      30             :          * Hook into directory updates so that we can receive live updates
      31             :          * from other writer threads.
      32             :          */
      33             :         struct xfs_dir_hook     hooks;
      34             : 
      35             :         /* Orphanage reparenting request. */
      36             :         struct xrep_adoption    adoption;
      37             : 
      38             :         /* Directory entry name, plus the trailing null. */
      39             :         char                    namebuf[MAXNAMELEN];
      40             : };
      41             : 
      42             : /*
      43             :  * In-core link counts for a given inode in the filesystem.
      44             :  *
      45             :  * For an empty rootdir, the directory entries and the field to which they are
      46             :  * accounted are as follows:
      47             :  *
      48             :  * Root directory:
      49             :  *
      50             :  * . points to self             (root.child)
      51             :  * .. points to self            (root.parent)
      52             :  * f1 points to a child file    (f1.parent)
      53             :  * d1 points to a child dir     (d1.parent, root.child)
      54             :  *
      55             :  * Subdirectory d1:
      56             :  *
      57             :  * . points to self             (d1.child)
      58             :  * .. points to root dir        (root.backref)
      59             :  * f2 points to child file      (f2.parent)
      60             :  * f3 points to root.f1         (f1.parent)
      61             :  *
      62             :  * root.nlink == 3 (root.dot, root.dotdot, root.d1)
      63             :  * d1.nlink == 2 (root.d1, d1.dot)
      64             :  * f1.nlink == 2 (root.f1, d1.f3)
      65             :  * f2.nlink == 1 (d1.f2)
      66             :  */
      67             : struct xchk_nlink {
      68             :         /* Count of forward links from parent directories to this file. */
      69             :         xfs_nlink_t             parents;
      70             : 
      71             :         /*
      72             :          * Count of back links to this parent directory from child
      73             :          * subdirectories.
      74             :          */
      75             :         xfs_nlink_t             backrefs;
      76             : 
      77             :         /*
      78             :          * Count of forward links from this directory to all child files and
      79             :          * the number of dot entries.  Should be zero for non-directories.
      80             :          */
      81             :         xfs_nlink_t             children;
      82             : 
      83             :         /* Record state flags */
      84             :         unsigned int            flags;
      85             : };
      86             : 
      87             : /*
      88             :  * This incore link count has been written at least once.  We never want to
      89             :  * store an xchk_nlink that looks uninitialized.
      90             :  */
      91             : #define XCHK_NLINK_WRITTEN              (1U << 0)
      92             : 
      93             : /* Already checked this link count record. */
      94             : #define XCHK_NLINK_COMPARE_SCANNED      (1U << 1)
      95             : 
      96             : /* Already made a repair with this link count record. */
      97             : #define XREP_NLINK_DIRTY                (1U << 2)
      98             : 
      99             : /* Compute total link count, using large enough variables to detect overflow. */
     100             : static inline uint64_t
     101   570773978 : xchk_nlink_total(struct xfs_inode *ip, const struct xchk_nlink *live)
     102             : {
     103   570774324 :         uint64_t        ret = live->parents;
     104             : 
     105             :         /* Add one link count for the dot entry of any linked directory. */
     106   570773978 :         if (ip && S_ISDIR(VFS_I(ip)->i_mode) && VFS_I(ip)->i_nlink)
     107   202289189 :                 ret++;
     108    91362856 :         return ret + live->children;
     109             : }
     110             : 
     111             : #endif /* __XFS_SCRUB_NLINKS_H__ */