fs/aufs/dcsub.h

   1 /*
   2  * Copyright (C) 2005-2017 Junjiro R. Okajima
   3  *
   4  * This program, aufs is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 /*
  19  * sub-routines for dentry cache
  20  */
  21
  22 #ifndef __AUFS_DCSUB_H__
  23 #define __AUFS_DCSUB_H__
  24
  25 #ifdef __KERNEL__
  26
  27 #include <linux/dcache.h>
  28 #include <linux/fs.h>
  29
  30 struct au_dpage {
  31         int ndentry;
  32         struct dentry **dentries;
  33 };
  34
  35 struct au_dcsub_pages {
  36         int ndpage;
  37         struct au_dpage *dpages;
  38 };
  39
  40 /* ---------------------------------------------------------------------- */
  41
  42 /* dcsub.c */
  43 int au_dpages_init(struct au_dcsub_pages *dpages, gfp_t gfp);
  44 void au_dpages_free(struct au_dcsub_pages *dpages);
  45 typedef int (*au_dpages_test)(struct dentry *dentry, void *arg);
  46 int au_dcsub_pages(struct au_dcsub_pages *dpages, struct dentry *root,
  47                    au_dpages_test test, void *arg);
  48 int au_dcsub_pages_rev(struct au_dcsub_pages *dpages, struct dentry *dentry,
  49                        int do_include, au_dpages_test test, void *arg);
  50 int au_dcsub_pages_rev_aufs(struct au_dcsub_pages *dpages,
  51                             struct dentry *dentry, int do_include);
  52 int au_test_subdir(struct dentry *d1, struct dentry *d2);
  53
  54 /* ---------------------------------------------------------------------- */
  55
  56 /*
  57  * todo: in linux-3.13, several similar (but faster) helpers are added to
  58  * include/linux/dcache.h. Try them (in the future).
  59  */
  60
  61 static inline int au_d_hashed_positive(struct dentry *d)
  62 {
  63         int err;
  64         struct inode *inode = d_inode(d);
  65
  66         err = 0;
  67         if (unlikely(d_unhashed(d)
  68                      || d_is_negative(d)
  69                      || !inode->i_nlink))
  70                 err = -ENOENT;
  71         return err;
  72 }
  73
  74 static inline int au_d_linkable(struct dentry *d)
  75 {
  76         int err;
  77         struct inode *inode = d_inode(d);
  78
  79         err = au_d_hashed_positive(d);
  80         if (err
  81             && d_is_positive(d)
  82             && (inode->i_state & I_LINKABLE))
  83                 err = 0;
  84         return err;
  85 }
  86
  87 static inline int au_d_alive(struct dentry *d)
  88 {
  89         int err;
  90         struct inode *inode;
  91
  92         err = 0;
  93         if (!IS_ROOT(d))
  94                 err = au_d_hashed_positive(d);
  95         else {
  96                 inode = d_inode(d);
  97                 if (unlikely(d_unlinked(d)
  98                              || d_is_negative(d)
  99                              || !inode->i_nlink))
 100                         err = -ENOENT;
 101         }
 102         return err;
 103 }
 104
 105 static inline int au_alive_dir(struct dentry *d)
 106 {
 107         int err;
 108
 109         err = au_d_alive(d);
 110         if (unlikely(err || IS_DEADDIR(d_inode(d))))
 111                 err = -ENOENT;
 112         return err;
 113 }
 114
 115 static inline int au_qstreq(struct qstr *a, struct qstr *b)
 116 {
 117         return a->len == b->len
 118                 && !memcmp(a->name, b->name, a->len);
 119 }
 120
 121 /*
 122  * by the commit
 123  * 360f547 2015-01-25 dcache: let the dentry count go down to zero without
 124  *                      taking d_lock
 125  * the type of d_lockref.count became int, but the inlined function d_count()
 126  * still returns unsigned int.
 127  * I don't know why. Maybe it is for every d_count() users?
 128  * Anyway au_dcount() lives on.
 129  */
 130 static inline int au_dcount(struct dentry *d)
 131 {
 132         return (int)d_count(d);
 133 }
 134
 135 #endif /* __KERNEL__ */
 136 #endif /* __AUFS_DCSUB_H__ */