[LU-5389] llite: optimize ll_fid2path()

• Type: Bug
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.7.0
• Affects Version/s: Lustre 2.6.0, Lustre 2.5.2, Lustre 2.4.3
• Labels: patch
• Severity: 3
• Assignee: James Nunez (Inactive)
• Reporter: Frank Zago (Inactive)

Description

The only parameter from userspace that matters is the length of the
buffer. We don't need to allocate then import the whole structure. By
importing only that length, we can save a memory allocation.

Add sparse annotations to that function.