fs/aufs/dcsub.c

   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 #include "aufs.h"
  23
  24 static void au_dpage_free(struct au_dpage *dpage)
  25 {
  26         int i;
  27         struct dentry **p;
  28
  29         p = dpage->dentries;
  30         for (i = 0; i < dpage->ndentry; i++)
  31                 dput(*p++);
  32         free_page((unsigned long)dpage->dentries);
  33 }
  34
  35 int au_dpages_init(struct au_dcsub_pages *dpages, gfp_t gfp)
  36 {
  37         int err;
  38         void *p;
  39
  40         err = -ENOMEM;
  41         dpages->dpages = kmalloc(sizeof(*dpages->dpages), gfp);
  42         if (unlikely(!dpages->dpages))
  43                 goto out;
  44
  45         p = (void *)__get_free_page(gfp);
  46         if (unlikely(!p))
  47                 goto out_dpages;
  48
  49         dpages->dpages[0].ndentry = 0;
  50         dpages->dpages[0].dentries = p;
  51         dpages->ndpage = 1;
  52         return 0; /* success */
  53
  54 out_dpages:
  55         kfree(dpages->dpages);
  56 out:
  57         return err;
  58 }
  59
  60 void au_dpages_free(struct au_dcsub_pages *dpages)
  61 {
  62         int i;
  63         struct au_dpage *p;
  64
  65         p = dpages->dpages;
  66         for (i = 0; i < dpages->ndpage; i++)
  67                 au_dpage_free(p++);
  68         kfree(dpages->dpages);
  69 }
  70
  71 static int au_dpages_append(struct au_dcsub_pages *dpages,
  72                             struct dentry *dentry, gfp_t gfp)
  73 {
  74         int err, sz;
  75         struct au_dpage *dpage;
  76         void *p;
  77
  78         dpage = dpages->dpages + dpages->ndpage - 1;
  79         sz = PAGE_SIZE / sizeof(dentry);
  80         if (unlikely(dpage->ndentry >= sz)) {
  81                 AuLabel(new dpage);
  82                 err = -ENOMEM;
  83                 sz = dpages->ndpage * sizeof(*dpages->dpages);
  84                 p = au_kzrealloc(dpages->dpages, sz,
  85                                  sz + sizeof(*dpages->dpages), gfp,
  86                                  /*may_shrink*/0);
  87                 if (unlikely(!p))
  88                         goto out;
  89
  90                 dpages->dpages = p;
  91                 dpage = dpages->dpages + dpages->ndpage;
  92                 p = (void *)__get_free_page(gfp);
  93                 if (unlikely(!p))
  94                         goto out;
  95
  96                 dpage->ndentry = 0;
  97                 dpage->dentries = p;
  98                 dpages->ndpage++;
  99         }
 100
 101         AuDebugOn(au_dcount(dentry) <= 0);
 102         dpage->dentries[dpage->ndentry++] = dget_dlock(dentry);
 103         return 0; /* success */
 104
 105 out:
 106         return err;
 107 }
 108
 109 /* todo: BAD approach */
 110 /* copied from linux/fs/dcache.c */
 111 enum d_walk_ret {
 112         D_WALK_CONTINUE,
 113         D_WALK_QUIT,
 114         D_WALK_NORETRY,
 115         D_WALK_SKIP,
 116 };
 117
 118 extern void d_walk(struct dentry *parent, void *data,
 119                    enum d_walk_ret (*enter)(void *, struct dentry *),
 120                    void (*finish)(void *));
 121
 122 struct ac_dpages_arg {
 123         int err;
 124         struct au_dcsub_pages *dpages;
 125         struct super_block *sb;
 126         au_dpages_test test;
 127         void *arg;
 128 };
 129
 130 static enum d_walk_ret au_call_dpages_append(void *_arg, struct dentry *dentry)
 131 {
 132         enum d_walk_ret ret;
 133         struct ac_dpages_arg *arg = _arg;
 134
 135         ret = D_WALK_CONTINUE;
 136         if (dentry->d_sb == arg->sb
 137             && !IS_ROOT(dentry)
 138             && au_dcount(dentry) > 0
 139             && au_di(dentry)
 140             && (!arg->test || arg->test(dentry, arg->arg))) {
 141                 arg->err = au_dpages_append(arg->dpages, dentry, GFP_ATOMIC);
 142                 if (unlikely(arg->err))
 143                         ret = D_WALK_QUIT;
 144         }
 145
 146         return ret;
 147 }
 148
 149 int au_dcsub_pages(struct au_dcsub_pages *dpages, struct dentry *root,
 150                    au_dpages_test test, void *arg)
 151 {
 152         struct ac_dpages_arg args = {
 153                 .err    = 0,
 154                 .dpages = dpages,
 155                 .sb     = root->d_sb,
 156                 .test   = test,
 157                 .arg    = arg
 158         };
 159
 160         d_walk(root, &args, au_call_dpages_append, NULL);
 161
 162         return args.err;
 163 }
 164
 165 int au_dcsub_pages_rev(struct au_dcsub_pages *dpages, struct dentry *dentry,
 166                        int do_include, au_dpages_test test, void *arg)
 167 {
 168         int err;
 169
 170         err = 0;
 171         write_seqlock(&rename_lock);
 172         spin_lock(&dentry->d_lock);
 173         if (do_include
 174             && au_dcount(dentry) > 0
 175             && (!test || test(dentry, arg)))
 176                 err = au_dpages_append(dpages, dentry, GFP_ATOMIC);
 177         spin_unlock(&dentry->d_lock);
 178         if (unlikely(err))
 179                 goto out;
 180
 181         /*
 182          * RCU for vfsmount is unnecessary since this is a traverse in a single
 183          * mount
 184          */
 185         while (!IS_ROOT(dentry)) {
 186                 dentry = dentry->d_parent; /* rename_lock is locked */
 187                 spin_lock(&dentry->d_lock);
 188                 if (au_dcount(dentry) > 0
 189                     && (!test || test(dentry, arg)))
 190                         err = au_dpages_append(dpages, dentry, GFP_ATOMIC);
 191                 spin_unlock(&dentry->d_lock);
 192                 if (unlikely(err))
 193                         break;
 194         }
 195
 196 out:
 197         write_sequnlock(&rename_lock);
 198         return err;
 199 }
 200
 201 static inline int au_dcsub_dpages_aufs(struct dentry *dentry, void *arg)
 202 {
 203         return au_di(dentry) && dentry->d_sb == arg;
 204 }
 205
 206 int au_dcsub_pages_rev_aufs(struct au_dcsub_pages *dpages,
 207                             struct dentry *dentry, int do_include)
 208 {
 209         return au_dcsub_pages_rev(dpages, dentry, do_include,
 210                                   au_dcsub_dpages_aufs, dentry->d_sb);
 211 }
 212
 213 int au_test_subdir(struct dentry *d1, struct dentry *d2)
 214 {
 215         struct path path[2] = {
 216                 {
 217                         .dentry = d1
 218                 },
 219                 {
 220                         .dentry = d2
 221                 }
 222         };
 223
 224         return path_is_under(path + 0, path + 1);
 225 }