Re: booting btrfs

[Vladimir 'φ-coder/phcoder' Serbinenko]

On 14.10.2013 22:45, Chris Murphy wrote:
> 
> On Oct 14, 2013, at 1:29 PM, Vladimir 'φ-coder/phcoder' Serbinenko 
> <address@hidden> wrote:
> 
>>> So it seems that GRUB is using relative pathnames to the default subvolume.
>> This is not intentional. When this part of code was written there was no
>> set-default available at all so this couldn't be tested and I simply
>> followed the specification. It told to take root_tree and
>> root_dir_objectid from superblock then go to "default" directory. What
>> of this needs to be changed? Just remove "default" and make it part of
>> path? We would need to change grub-mkrelpath to match runtime behaviour.
>> Is there a way to detect that mountinfo gives garbage and somehow get
>> where the real root points?
> 
> Here's the response. It seems similar but not identical to what you described 
> above.
> 
> http://www.mail-archive.com/address@hidden/msg27955.html
> 
Possibly this is the answer:
=== modified file 'grub-core/fs/btrfs.c'
--- grub-core/fs/btrfs.c        2013-01-21 01:33:46 +0000
+++ grub-core/fs/btrfs.c        2013-10-14 21:00:53 +0000
@@ -1217,7 +1217,7 @@

   *type = GRUB_BTRFS_DIR_ITEM_TYPE_DIRECTORY;
   *tree = data->sblock.root_tree;
-  key->object_id = data->sblock.root_dir_objectid;
+  key->object_id = grub_cpu_to_le64_compile_time (5);
   key->type = GRUB_BTRFS_ITEM_TYPE_DIR_ITEM;
   key->offset = 0;
   skip_default = 1;

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