btrfs-progs: Create uuid tree with proper contents
Commit 2a496a5b8b ("btrfs-progs: mkfs: precreate the uuid tree")
creates uuid tree at mkfs time. However it doesn't populate uuid tree
correctly nor creates an empty root.
It uses create_tree(), which just
copies the content of fs root, containing a 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:
(NOTE: due to tree-checker, kernel doesn't accept empty uuid tree, so we
can only fix it by populating uuid tree correctly)
With 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
For kernel, except tree-checker needs an non-empty uuid tree, both of
the above behavior won't cause problem, but it's always better to keep a
good standardized behavior.
Fixes: 2a496a5b8b ("btrfs-progs: mkfs: precreate the uuid tree")
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
8addcab0d0