btrfs-progs: zoned: proper "mkfs.btrfs -b" support

[adam900710]

From Naohiro Aota:

mkfs.btrfs -b on a zoned device has several issues listed below.

• The FS size needs to be larger than minimal size that can host a btrfs, but its calculation does not consider non-SINGLE profile
• The calculation also does not ensure tree-log BG and data relocation BG
• It allows creating a FS not aligned to the zone boundary
• It resets all device zones beyond the specified length

This series fixes the issues with some cleanups.

This one passed CI workflow here:

Patches 1 to 3 are clean up patches, so they should not change the behavior.

Patches 4 to 6 address the issues.

Patches 7 to 10 add/modify the test cases. First, patch 7 adds nullb functions to use in later patches. Patch 8 adds a new test for zone resetting. And, patches 9 and 10 rewrites existing tests with the nullb helper.

Changes:

• v4:
  • Fix source directory size alignment.
• v3: https://lore.kernel.org/linux-btrfs/dfd8887b-a2cb-425f-8705-0d6a94cefb9c@gmx.com/
  • Tweak minimum FS size calculation style.
  • Round down the specified byte_count towards sectorsize and zone size, instead of banning unaligned byte_count.
  • Add active zone description in the commit log of patch 6.
  • Add nullb test functions and use them in tests.
• v2: https://lore.kernel.org/linux-btrfs/20240514182227.1197664-1-naohiro.aota@wdc.com/
  • fix function declaration on older distro (non-ZONED setup)
  • fix mkfs test failure
• v1: https://lore.kernel.org/linux-btrfs/20240514005133.44786-1-naohiro.aota@wdc.com/

[kdave]

Thanks, merged to devel. I did a few minor comment or changelog wording fixes.