[v2,0/5] btrfs-progs: rework how we traverse rootdir

Message

Qu Wenruo Aug. 1, 2024, 6:12 a.m. UTC

[CHANGELOG]
v2:
- Change the current_path.level, so that 0 means uninitialized
  This makes the current_path level to match the ftwbuf level.

- Add a comment explaining how the current_path stack works
  With an example layout and stack changes.

- Add two new test cases
  Both test cases are for the old rootdir bugs:
  * Extra hard link are out of the rootdir
    Old --rootdir will create a corrupted fs with incorrect nlink.
    This is because we use st_nlink without any extra verification

  * Conflicting inode numbers caused by different mount points
    Old --rootdir will fail gracefully, but still not ideal as the error
    message doesn't explain it at all.
    This is because we use st_inode without any extra verification

- Newline and typo fixes

Thanks to Mark's recent work, I finally get some time to rework rootdir
traversal.

All the problems are described inside the second patch.
While the last patch is a small enhancement to --rootdir to reject hard
links.

With this change, it's much easier to support subvolume creations at
mkfs time:

- Create a hashmap (or other similar structure) to record all the
  directories that should be subvolume

- Call btrfs_make_subvoume() other than btrfs_insert_inode() if a path
  should be a subvolume

- Call btrfs_link_subvolume() other than btrfs_add_link() for a
  subvolume

Everything like parent directory inode size is properly handled by
btrfs_link_subvolume() and btrfs_add_link() already.


Qu Wenruo (5):
  btrfs-progs: constify the name parameter of btrfs_add_link()
  btrfs-progs: mkfs: rework how we traverse rootdir
  btrfs-progs: rootdir: warn about hard links
  btrfs-progs: mkfs-tests: a new test case to verify handling of hard
    links
  btrfs-progs: mkfs-tests: verify cross mount point behavior for rootdir

 kernel-shared/ctree.h                         |   2 +-
 kernel-shared/inode.c                         |   2 +-
 mkfs/rootdir.c                                | 711 ++++++++----------
 mkfs/rootdir.h                                |   8 -
 .../034-rootdir-extra-hard-links/test.sh      |  24 +
 .../035-rootdir-cross-mount/test.sh           |  46 ++
 6 files changed, 377 insertions(+), 416 deletions(-)
 create mode 100755 tests/mkfs-tests/034-rootdir-extra-hard-links/test.sh
 create mode 100755 tests/mkfs-tests/035-rootdir-cross-mount/test.sh

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2.45.2