fs/aufs/finfo.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  * file private data
  20  */
  21
  22 #include "aufs.h"
  23
  24 void au_hfput(struct au_hfile *hf, int execed)
  25 {
  26         if (execed)
  27                 allow_write_access(hf->hf_file);
  28         fput(hf->hf_file);
  29         hf->hf_file = NULL;
  30         au_br_put(hf->hf_br);
  31         hf->hf_br = NULL;
  32 }
  33
  34 void au_set_h_fptr(struct file *file, aufs_bindex_t bindex, struct file *val)
  35 {
  36         struct au_finfo *finfo = au_fi(file);
  37         struct au_hfile *hf;
  38         struct au_fidir *fidir;
  39
  40         fidir = finfo->fi_hdir;
  41         if (!fidir) {
  42                 AuDebugOn(finfo->fi_btop != bindex);
  43                 hf = &finfo->fi_htop;
  44         } else
  45                 hf = fidir->fd_hfile + bindex;
  46
  47         if (hf && hf->hf_file)
  48                 au_hfput(hf, vfsub_file_execed(file));
  49         if (val) {
  50                 FiMustWriteLock(file);
  51                 AuDebugOn(IS_ERR_OR_NULL(file->f_path.dentry));
  52                 hf->hf_file = val;
  53                 hf->hf_br = au_sbr(file->f_path.dentry->d_sb, bindex);
  54         }
  55 }
  56
  57 void au_update_figen(struct file *file)
  58 {
  59         atomic_set(&au_fi(file)->fi_generation, au_digen(file->f_path.dentry));
  60         /* smp_mb(); */ /* atomic_set */
  61 }
  62
  63 /* ---------------------------------------------------------------------- */
  64
  65 struct au_fidir *au_fidir_alloc(struct super_block *sb)
  66 {
  67         struct au_fidir *fidir;
  68         int nbr;
  69
  70         nbr = au_sbbot(sb) + 1;
  71         if (nbr < 2)
  72                 nbr = 2; /* initial allocate for 2 branches */
  73         fidir = kzalloc(au_fidir_sz(nbr), GFP_NOFS);
  74         if (fidir) {
  75                 fidir->fd_bbot = -1;
  76                 fidir->fd_nent = nbr;
  77         }
  78
  79         return fidir;
  80 }
  81
  82 int au_fidir_realloc(struct au_finfo *finfo, int nbr, int may_shrink)
  83 {
  84         int err;
  85         struct au_fidir *fidir, *p;
  86
  87         AuRwMustWriteLock(&finfo->fi_rwsem);
  88         fidir = finfo->fi_hdir;
  89         AuDebugOn(!fidir);
  90
  91         err = -ENOMEM;
  92         p = au_kzrealloc(fidir, au_fidir_sz(fidir->fd_nent), au_fidir_sz(nbr),
  93                          GFP_NOFS, may_shrink);
  94         if (p) {
  95                 p->fd_nent = nbr;
  96                 finfo->fi_hdir = p;
  97                 err = 0;
  98         }
  99
 100         return err;
 101 }
 102
 103 /* ---------------------------------------------------------------------- */
 104
 105 void au_finfo_fin(struct file *file)
 106 {
 107         struct au_finfo *finfo;
 108
 109         au_nfiles_dec(file->f_path.dentry->d_sb);
 110
 111         finfo = au_fi(file);
 112         AuDebugOn(finfo->fi_hdir);
 113         AuRwDestroy(&finfo->fi_rwsem);
 114         au_cache_free_finfo(finfo);
 115 }
 116
 117 void au_fi_init_once(void *_finfo)
 118 {
 119         struct au_finfo *finfo = _finfo;
 120
 121         au_rw_init(&finfo->fi_rwsem);
 122 }
 123
 124 int au_finfo_init(struct file *file, struct au_fidir *fidir)
 125 {
 126         int err;
 127         struct au_finfo *finfo;
 128         struct dentry *dentry;
 129
 130         err = -ENOMEM;
 131         dentry = file->f_path.dentry;
 132         finfo = au_cache_alloc_finfo();
 133         if (unlikely(!finfo))
 134                 goto out;
 135
 136         err = 0;
 137         au_nfiles_inc(dentry->d_sb);
 138         au_rw_write_lock(&finfo->fi_rwsem);
 139         finfo->fi_btop = -1;
 140         finfo->fi_hdir = fidir;
 141         atomic_set(&finfo->fi_generation, au_digen(dentry));
 142         /* smp_mb(); */ /* atomic_set */
 143
 144         file->private_data = finfo;
 145
 146 out:
 147         return err;
 148 }