[LU-19743] debugfs: decode LOV attribute

• Type: Improvement
• Resolution: Unresolved
• Priority: Medium
• Severity: 3
• Assignee: Aurélien Cedeyn
• Reporter: Aurélien Cedeyn

Description

Current code only display size or binary output for lov xattr:

# debugfs -c -R "ea_list ROOT/file" /dev/mdt0000
debugfs 1.47.2-wc2 (25-Jun-2025)
Extended attributes:
  lma: fid=[0x20000a042:0x1:0x0] compat=0 incompat=0
  trusted.lov (56) = d0 0b d1 0b 01 00 00 00 01 00 00 [...]
  security.selinux (37) = "unconfined_u:object_r:unlabeled_t:s0\000"
  linkea: idx=0 parent=[0x200000007:0x1:0x0] name='file'
  trusted.som (24) = 04 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

To provide easier debugging facility, debugfs should decode LOV attribute.

It will provide data layout from MDTs without the need to mount the filesystem and use lfs getstripe.

Work on this feature already started here:

https://review.whamcloud.com/c/tools/e2fsprogs/+/62505

Some improvement will change FID output format for the stat command.

This LU aims to track any needed changes in lustre code to merge this change smoothly.