[PATCH v3 0/4] erofs-utils: implement the FULLDATA rebuild mode

[Lucas Karpinski <lkarpinski@nvidia.com>]

Currently, erofs-utils supports backing blobs for multi-image setups.  This
implements the FULLDATA import which allows for the merging of multiple
source images into a single self-contained erofs image.

To optimize the rebuild process, erofs_io_xcopy() is used to leverage the
copy_file_range(2) if available. This bypasses userspace buffering and
enables kernel side data transfers.
 
Verification: Built same image with default rebuild and rebuild with
FULLDATA. Then ran F-i-f/tdiff comparing the two.

changes in v3:
- adhere to uniaddress semantics.
- take advantage of existing infrastructure which allows us to drop a
  significant amount of complexity + code.

changes in v2:
- reworked erofs_rebuild_load_trees_full into
  erofs_mkfs_rebuild_load_trees.
- removed --merge option (use --clean=data instead).
- updated man.

Signed-off-by: Lucas Karpinski <lkarpinski@nvidia.com>
---
Lucas Karpinski (4):
      erofs-utils: lib: remove redundant if check
      erofs-utils: lib: add helper function erofs_uuid_unparse_as_tag
      erofs-utils: mfks: add rebuild FULLDATA for combined EROFS images
      erofs-utils: manpages: update to reflect fulldata support

 include/erofs/internal.h |  3 +++
 lib/inode.c              | 39 ++++++++++++++++++++-------
 lib/liberofs_uuid.h      |  1 +
 lib/rebuild.c            | 70 ++++++++++++++++++++++++++++++++++++++++++++++++
 lib/uuid_unparse.c       | 16 ++++++++++-
 man/mkfs.erofs.1         |  7 ++++-
 mkfs/main.c              | 16 ++++-------
 7 files changed, 130 insertions(+), 22 deletions(-)
---
base-commit: 58c3351d5b4b0fc5e4a05d2200c1cf9f85902899
change-id: 20260220-merge-fs-e6231a3a3a1c

Best regards,
-- 
Lucas Karpinski <lkarpinski@nvidia.com>