target/linux/generic-2.6/patches-2.6.32/235-union_mount_fixes.patch

   1 --- a/fs/namespace.c
   2 +++ b/fs/namespace.c
   3 @@ -1656,8 +1656,10 @@ static int do_move_mount(struct path *pa
   4
   5         /* moving to or from a union mount is not supported */
   6         err = -EINVAL;
   7 +#if 0
   8         if (IS_MNT_UNION(path->mnt))
   9                 goto exit;
  10 +#endif
  11         if (IS_MNT_UNION(old_path.mnt))
  12                 goto exit;
  13
  14 --- a/fs/union.c
  15 +++ b/fs/union.c
  16 @@ -260,8 +260,6 @@ int append_to_union(struct vfsmount *mnt
  17         spin_lock(&union_lock);
  18         um = union_lookup(dentry, mnt);
  19         if (um) {
  20 -               BUG_ON((um->u_next.dentry != dest_dentry) ||
  21 -                      (um->u_next.mnt != dest_mnt));
  22                 spin_unlock(&union_lock);
  23                 union_put(this);
  24                 return 0;
  25 @@ -274,6 +272,23 @@ int append_to_union(struct vfsmount *mnt
  26         return 0;
  27  }
  28
  29 +int follow_union_mountpoint(struct path *path)
  30 +{
  31 +       struct path new_path = *path;
  32 +
  33 +       path_get(&new_path);
  34 +       while (follow_union_down(&new_path)) {
  35 +               if (new_path.dentry != new_path.mnt->mnt_root)
  36 +                       continue;
  37 +
  38 +               path_put(path);
  39 +               *path = new_path;
  40 +               return 1;
  41 +       }
  42 +       path_put(&new_path);
  43 +       return 0;
  44 +}
  45 +
  46  /*
  47   * follow_union_down - follow the union stack one layer down
  48   *
  49 --- a/include/linux/union.h
  50 +++ b/include/linux/union.h
  51 @@ -47,6 +47,7 @@ extern int append_to_union(struct vfsmou
  52                            struct vfsmount *, struct dentry *);
  53  extern int follow_union_down(struct path *);
  54  extern int follow_union_mount(struct path *);
  55 +extern int follow_union_mountpoint(struct path *path);
  56  extern void __d_drop_unions(struct dentry *);
  57  extern void shrink_d_unions(struct dentry *);
  58  extern void __shrink_d_unions(struct dentry *, struct list_head *);
  59 @@ -68,6 +69,7 @@ extern int union_permission(struct path
  60  #define append_to_union(x1, y1, x2, y2)        ({ BUG(); (0); })
  61  #define follow_union_down(x)           ({ (0); })
  62  #define follow_union_mount(x)  ({ (0); })
  63 +#define follow_union_mountpoint(x)     ({ (0); })
  64  #define __d_drop_unions(x)             do { } while (0)
  65  #define shrink_d_unions(x)             do { } while (0)
  66  #define __shrink_d_unions(x,y)         do { } while (0)
  67 --- a/fs/namei.c
  68 +++ b/fs/namei.c
  69 @@ -626,6 +626,9 @@ static int cache_lookup_union(struct nam
  70                     !S_ISDIR(path->dentry->d_inode->i_mode))
  71                         goto out;
  72
  73 +               if (follow_union_mountpoint(path))
  74 +                       goto out;
  75 +
  76                 /* Build the union stack for this part */
  77                 res = __cache_lookup_build_union(nd, name, path);
  78                 if (res) {
  79 @@ -892,6 +895,9 @@ static int real_lookup_union(struct name
  80             !S_ISDIR(path->dentry->d_inode->i_mode))
  81                 goto out;
  82
  83 +       if (follow_union_mountpoint(path))
  84 +               goto out;
  85 +
  86         /* Build the union stack for this part */
  87         res = __real_lookup_build_union(nd, name, path);
  88         if (res) {
  89 @@ -1813,6 +1819,9 @@ int hash_lookup_union(struct nameidata *
  90             !S_ISDIR(path->dentry->d_inode->i_mode))
  91                 goto out;
  92
  93 +       if (follow_union_mountpoint(path))
  94 +               goto out;
  95 +
  96         /* Build the union stack for this part */
  97         res = __hash_lookup_build_union(nd, name, path);
  98         if (res) {
  99 --- a/fs/readdir.c
 100 +++ b/fs/readdir.c
 101 @@ -17,6 +17,7 @@
 102  #include <linux/syscalls.h>
 103  #include <linux/unistd.h>
 104  #include <linux/union.h>
 105 +#include <linux/mount.h>
 106
 107  #include <asm/uaccess.h>
 108
 109 @@ -45,7 +46,7 @@ int vfs_readdir(struct file *file, filld
 110                  * below this one in the union stack.
 111                  */
 112                 if (is_unionized(file->f_path.dentry, file->f_path.mnt) &&
 113 -                   !IS_OPAQUE(inode)) {
 114 +                   !IS_OPAQUE(inode) && IS_MNT_UNION(file->f_path.mnt)) {
 115                         res = union_copyup_dir(&file->f_path);
 116                         if (res)
 117                                 goto out_unlock;