target/linux/generic/patches-2.6.37/211-overlayfs_fix_readdir_deadlock.patch

   1 --- a/fs/overlayfs/overlayfs.c
   2 +++ b/fs/overlayfs/overlayfs.c
   3 @@ -248,8 +248,7 @@ static struct ovl_cache_entry *ovl_cache
   4  }
   5
   6  static struct ovl_cache_entry *ovl_cache_entry_new(const char *name, int len,
   7 -                                                  u64 ino, unsigned int d_type,
   8 -                                                  bool is_whiteout)
   9 +                                                  u64 ino, unsigned int d_type)
  10  {
  11         struct ovl_cache_entry *p;
  12
  13 @@ -262,7 +261,7 @@ static struct ovl_cache_entry *ovl_cache
  14                 p->len = len;
  15                 p->type = d_type;
  16                 p->ino = ino;
  17 -               p->is_whiteout = is_whiteout;
  18 +               p->is_whiteout = false;
  19         }
  20
  21         return p;
  22 @@ -270,7 +269,7 @@ static struct ovl_cache_entry *ovl_cache
  23
  24  static int ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd,
  25                                   const char *name, int len, u64 ino,
  26 -                                 unsigned int d_type, bool is_whiteout)
  27 +                                 unsigned int d_type)
  28  {
  29         struct rb_node **newp = &rdd->root->rb_node;
  30         struct rb_node *parent = NULL;
  31 @@ -291,11 +290,18 @@ static int ovl_cache_entry_add_rb(struct
  32                         return 0;
  33         }
  34
  35 -       p = ovl_cache_entry_new(name, len, ino, d_type, is_whiteout);
  36 +       p = ovl_cache_entry_new(name, len, ino, d_type);
  37         if (p == NULL)
  38                 return -ENOMEM;
  39
  40 -       list_add_tail(&p->l_node, rdd->list);
  41 +       /*
  42 +        * Add links before other types to be able to quicky mark
  43 +        * any whiteout entries
  44 +        */
  45 +       if (d_type == DT_LNK)
  46 +               list_add(&p->l_node, rdd->list);
  47 +       else
  48 +               list_add_tail(&p->l_node, rdd->list);
  49         rb_link_node(&p->node, parent, newp);
  50         rb_insert_color(&p->node, rdd->root);
  51
  52 @@ -313,7 +319,7 @@ static int ovl_fill_lower(void *buf, con
  53         if (p) {
  54                 list_move_tail(&p->l_node, rdd->middle);
  55         } else {
  56 -               p = ovl_cache_entry_new(name, namelen, ino, d_type, false);
  57 +               p = ovl_cache_entry_new(name, namelen, ino, d_type);
  58                 if (p == NULL)
  59                         rdd->err = -ENOMEM;
  60                 else
  61 @@ -338,26 +344,9 @@ static int ovl_fill_upper(void *buf, con
  62                           loff_t offset, u64 ino, unsigned int d_type)
  63  {
  64         struct ovl_readdir_data *rdd = buf;
  65 -       bool is_whiteout = false;
  66
  67         rdd->count++;
  68 -       if (d_type == DT_LNK) {
  69 -               struct dentry *dentry;
  70 -
  71 -               dentry = lookup_one_len(name, rdd->dir, namelen);
  72 -               if (IS_ERR(dentry)) {
  73 -                       rdd->err = PTR_ERR(dentry);
  74 -                       goto out;
  75 -               }
  76 -               is_whiteout = ovl_is_whiteout(dentry);
  77 -               dput(dentry);
  78 -       }
  79 -
  80 -       rdd->err = ovl_cache_entry_add_rb(rdd, name, namelen, ino, d_type,
  81 -                                         is_whiteout);
  82 -
  83 -out:
  84 -       return rdd->err;
  85 +       return ovl_cache_entry_add_rb(rdd, name, namelen, ino, d_type);
  86  }
  87
  88  static int ovl_dir_read(struct path *realpath, struct ovl_readdir_data *rdd,
  89 @@ -423,6 +412,26 @@ static void ovl_dir_reset(struct file *f
  90         }
  91  }
  92
  93 +static void ovl_dir_mark_whiteouts(struct ovl_readdir_data *rdd)
  94 +{
  95 +       struct ovl_cache_entry *p;
  96 +       struct dentry *dentry;
  97 +
  98 +       mutex_lock(&rdd->dir->d_inode->i_mutex);
  99 +       list_for_each_entry(p, rdd->list, l_node) {
 100 +               if (p->type != DT_LNK)
 101 +                       break;
 102 +
 103 +               dentry = lookup_one_len(p->name, rdd->dir, p->len);
 104 +               if (IS_ERR(dentry))
 105 +                       continue;
 106 +
 107 +               p->is_whiteout = ovl_is_whiteout(dentry);
 108 +               dput(dentry);
 109 +       }
 110 +       mutex_unlock(&rdd->dir->d_inode->i_mutex);
 111 +}
 112 +
 113  static int ovl_dir_read_merged(struct path *upperpath, struct path *lowerpath,
 114                                struct ovl_readdir_data *rdd)
 115  {
 116 @@ -436,6 +445,8 @@ static int ovl_dir_read_merged(struct pa
 117                 err = ovl_dir_read(upperpath, rdd, ovl_fill_upper);
 118                 if (err)
 119                         goto out;
 120 +
 121 +               ovl_dir_mark_whiteouts(rdd);
 122         }
 123         /*
 124          * Insert lowerpath entries before upperpath ones, this allows