Mount by filesystem label

[andrewbaxter]

Issue #1 discussed mounting by UUID and label. Mounting by UUID is done, and I'm making this new issue to track the latter.

[jpsollie]

guess you'd better request this from libblkid, right? isn't this due to libblkid not mapping to partlabel variable?

[Komzpa]

Opened koverstreet/bcachefs-tools#664 for this.

The patch adds LABEL=<label> to the userspace mount/device scanner. It scans bcachefs superblocks for the filesystem label, rejects ambiguous duplicate labels across different filesystem UUIDs, then reuses the existing UUID-based all-member discovery path so multi-device behavior stays shared with UUID=<uuid> mounts.

It also updates bcachefs mount --help and the checked-in manpage to advertise LABEL=<label>.

Companion ktest regression:
koverstreet/ktest#76

Current status:

• mount: support filesystem label lookup bcachefs-tools#664 is CLEAN and the GitHub Actions Nix flake matrix is green on head 3fe24f146a9c6ecf2ccb3adb56501168f256ab3c.
• bcachefs: test filesystem label mounts ktest#76 is CLEAN and build-and-format is green on head 20c72d442b4e3265835c1f21146f1bdfb40d290d.

Validation for koverstreet/bcachefs-tools#664:

• git diff --check
• BINDGEN=/home/kom/.cargo/bin/bindgen make -j32 bcachefs
• ./target/release/bcachefs mount --help | rg -C 2 'LABEL|UUID'

[koverstreet]

Implemented — bcachefs mount now supports mounting by filesystem label (mount: support filesystem label lookup), in the upcoming v1.38.7 release. Closing as resolved; please reopen if it doesn't cover your use case. Thanks!