Btrfs-progs: fsck: disallow partial opening if critical roots corrupted

Btrfs-progs: fsck: disallow partial opening if critical roots corrupted

If btrfs tree root is corrupted, fsck will hit the following segmentation.

enabling repair mode
Check tree block failed, want=29376512, have=0
Check tree block failed, want=29376512, have=0
Check tree block failed, want=29376512, have=0
Check tree block failed, want=29376512, have=0
Check tree block failed, want=29376512, have=0
read block failed check_tree_block
Couldn't read tree root
Checking filesystem on /dev/sda9
UUID: 0e1a754d-04a5-4256-ae79-0f769751803e
Critical roots corrupted, unable to fsck the FS
Segmentation fault (core dumped)

In btrfs_setup_all_roots(), we could tolerate some trees(extent tree, csum tree)
corrupted, and we have did careful check inside that function, it will
return NULL if critial roots corrupt(for example tree root).

The problem is that we check @OPEN_CTREE_PARTIAL flag again after
calling btrfs_setup_all_roots() which will successfully return
@fs_info though critial roots corrupted.

Fix this problem by removing @OPEN_CTREE_PARTIAL flag check outsize
btrfs_setup_all_roots().

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>