[PATCH 0/2] btrfs-progs: mkfs: extent-tree-v2 related fixes

[Qu Wenruo <wqu@suse.com>]

Although recently we still have some uncertainty around the on-disk
format for extent-tree-v2, related to how to determine the number
of global roots, most of the on-disk format is fixed.

And even with the uncertain part involved, mkfs.btrfs should not crash
for extent-tree-v2 feature (hidden behind the experimental builds).

There are two bugs involved:

- A crash caused by incorrectly set chunk_objectid for block group item
  As extent-tree-v2 feature reuse that member to indicate which extent
  tree a block group belongs to.

  But the regular fs uses a fixed 256 for that chunk_objectid, and no
  extent-tree-v2 btrfs would have that many global roots.

  This leads to btrfs_extent_root() to return NULL, and cause later
  segfault.

  Fix it by properly setting chunk_objectid.
  This is a regression caused by 1430b41427b5 ("btrfs-progs: separate
  block group tree from extent tree v2").

- A stack-over-flow caused by too long feature string
  With extent-tree-v2 enabled, we have at least 84 bytes long feature
  string (unified features, including compat_ro features likle fst).

  This is beyond the hard-coded 64 bytes limit.

  Fix it by introducing a new macro to indicate a minimal safe buf size,
  and a sanity check to make sure that macro is really large enough.

Qu Wenruo (2):
  btrfs-progs: mkfs: fix a crash when enabling extent-tree-v2
  btrfs-progs: mkfs: fix a stack over-flow when features string are too
    long

 common/fsfeatures.c | 26 ++++++++++++++++++++++++++
 common/fsfeatures.h |  7 +++++++
 convert/main.c      |  3 ++-
 mkfs/common.c       | 14 ++++++++++++--
 mkfs/main.c         |  3 ++-
 5 files changed, 49 insertions(+), 4 deletions(-)

-- 
2.37.3