target/linux/generic/patches-2.6.37/212-overlayfs_fix_readdir_unlink_deadlock.patch

   1 --- a/fs/overlayfs/overlayfs.c
   2 +++ b/fs/overlayfs/overlayfs.c
   3 @@ -1686,37 +1686,56 @@ static int ovl_check_empty_dir(struct de
   4         return err;
   5  }
   6
   7 -static int ovl_unlink_whiteout(void *buf, const char *name, int namelen,
   8 -                                loff_t offset, u64 ino, unsigned int d_type)
   9 +static int ovl_fill_links(void *buf, const char *name, int namelen,
  10 +                          loff_t offset, u64 ino, unsigned int d_type)
  11  {
  12         struct ovl_readdir_data *rdd = buf;
  13 +       struct ovl_cache_entry *p;
  14
  15 -       rdd->count++;
  16 -       /* check d_type to filter out "." and ".." */
  17 -       if (d_type == DT_LNK) {
  18 -               struct dentry *dentry;
  19 +       if (d_type != DT_LNK)
  20 +               return 0;
  21
  22 -               dentry = lookup_one_len(name, rdd->dir, namelen);
  23 -               if (IS_ERR(dentry)) {
  24 -                       rdd->err = PTR_ERR(dentry);
  25 -               } else {
  26 -                       rdd->err = vfs_unlink(rdd->dir->d_inode, dentry);
  27 -                       dput(dentry);
  28 -               }
  29 -       }
  30 +       p = ovl_cache_entry_new(name, namelen, ino, d_type);
  31 +       if (!p)
  32 +               return -ENOMEM;
  33
  34 -       return rdd->err;
  35 +       list_add(&p->l_node, rdd->list);
  36 +       return 0;
  37  }
  38
  39  static int ovl_remove_whiteouts(struct dentry *dentry)
  40  {
  41         struct path upperpath;
  42 -       struct ovl_readdir_data rdd = { .list = NULL };
  43 +       LIST_HEAD(list);
  44 +       struct ovl_readdir_data rdd = { .list = &list };
  45 +       struct ovl_cache_entry *p, *t;
  46 +       int ret;
  47
  48         ovl_path_upper(dentry, &upperpath);
  49         rdd.dir = upperpath.dentry;
  50
  51 -       return ovl_dir_read(&upperpath, &rdd, ovl_unlink_whiteout);
  52 +       ret = ovl_dir_read(&upperpath, &rdd, ovl_fill_links);
  53 +
  54 +       mutex_lock(&rdd.dir->d_inode->i_mutex);
  55 +       list_for_each_entry_safe(p, t, &list, l_node) {
  56 +               struct dentry *dentry;
  57 +
  58 +               if (!ret) {
  59 +                       dentry = lookup_one_len(p->name, rdd.dir, p->len);
  60 +                       if (IS_ERR(dentry)) {
  61 +                               ret = PTR_ERR(dentry);
  62 +                       } else {
  63 +                               ret = vfs_unlink(rdd.dir->d_inode, dentry);
  64 +                               dput(dentry);
  65 +                       }
  66 +               }
  67 +
  68 +               list_del(&p->l_node);
  69 +               kfree(p);
  70 +       }
  71 +       mutex_unlock(&rdd.dir->d_inode->i_mutex);
  72 +
  73 +       return ret;
  74  }
  75
  76  static int ovl_rmdir(struct inode *dir, struct dentry *dentry)