[PATCH for-4.20 0/3] Fix incorrectly created uuid tree

[Qu Wenruo <wqu@suse.com>]

This patchset can be fetched from github:
https://github.com/adam900710/btrfs-progs/tree/uuid_tree_support
Which is based on v4.19.1 tag.

Commit 2a496a5b8b74 ("btrfs-progs: mkfs: precreate the uuid tree")
creates uuid tree at mkfs time.

However it doesn't populate uuid tree correctly nor just create an empty
root.
It uses create_tree(), which just copies the content of fs root,
containing meaningless INODE_ITEM:

v4.15 mkfs (no uuid tree creation) + kernel mount:
  uuid tree key (UUID_TREE ROOT_ITEM 0)
  leaf 30572544 items 1 free space 16250 generation 7 owner UUID_TREE
  leaf 30572544 flags 0x1(WRITTEN) backref revision 1
  fs uuid 33ecddef-fc86-481a-93ce-846b01c11376
  chunk uuid 9e58f646-b0da-43ca-9c7d-8bbe3e120246
	item 0 key (0x92457c59d31491be UUID_KEY_SUBVOL 0xef908b5e79aa76a1) itemoff 16275 itemsize 8
		subvol_id 5

v4.19.1 mkfs (incorrect one), no kernel mount:
  uuid tree key (UUID_TREE ROOT_ITEM 0)
  leaf 30507008 items 2 free space 16061 generation 4 owner UUID_TREE
  leaf 30507008 flags 0x1(WRITTEN) backref revision 1
  fs uuid 162f5333-9b5d-4217-877c-ddaeaa79398e
  chunk uuid 7bc2c5c6-a6d2-4eec-a513-142b549c6541
	item 0 key (256 INODE_ITEM 0) itemoff 16123 itemsize 160
		generation 3 transid 0 size 0 nbytes 16384
		block group 0 mode 40755 links 1 uid 0 gid 0 rdev 0
		sequence 0 flags 0x0(none)
	item 1 key (256 INODE_REF 256) itemoff 16111 itemsize 12
		index 0 namelen 2 name: ..

This patchset will fix it by populuating uuid tree properly, as kernel
tree checker now doesn't accept empty uuid tree.

w/ this patchset, no kernel mount:
  uuid tree key (UUID_TREE ROOT_ITEM 0)
  leaf 30507008 items 1 free space 16250 generation 4 owner UUID_TREE
  leaf 30507008 flags 0x1(WRITTEN) backref revision 1
  fs uuid ae53079e-dbbc-409b-a565-5326c7b27731
  chunk uuid b5fb1bea-f20d-4af1-80f8-6ca3f0038d67
	item 0 key (0x334ba6b032d89c07 UUID_KEY_SUBVOL 0x86cde09cb78bcca0) itemoff 16275 itemsize 8
		subvol_id 5

Qu Wenruo (3):
  btrfs-progs: uuid: Port kernel btrfs_uuid_tree_lookup()
  btrfs-progs: uuid: Port btrfs_uuid_tree_add() function
  btrfs-progs: Create uuid tree with proper contents

 ctree.h       |   7 ++-
 disk-io.c     |   4 ++
 mkfs/common.c | 103 ++++++++++++++++++++++++++++++++++++++
 mkfs/common.h |   3 ++
 mkfs/main.c   |  36 +------------
 uuid-tree.c   | 136 +++++++++++++++++++++++++++++++++++++++++++++++++-
 6 files changed, 252 insertions(+), 37 deletions(-)

-- 
2.20.1