[LU-14286] fallocate() does not zero on-disk data

• Type: Bug
• Resolution: Fixed
• Priority: Blocker
• Fix Version/s: Lustre 2.14.0
• Affects Version/s: Lustre 2.14.0
• Severity: 3
• Assignee: Arshad Hussain
• Reporter: Arshad Hussain

Description

The ldiskfs osd_fallocate() does not correctly zero the allocated blocks. This is not noticed during autotest and local developer testing because the underlying storage is zero-filled due to using a sparse backing file and will usually read back as zero. Also, the fsx data correctness test was not properly detecting fallocate() support, and as a result this behavior was not detected until after fsx was fixed.

fsx uses test_fallocate() to determine if fallocate() along with its various FLAGS is enabled and could be called. This was discovered while working on LU-14160 that test_fallocate() always returned false as a bug. Resulting is fallocate() being skipped always for fsx runs.

Issue Links

• is related to: LU-14326 sanity-dom test_fsx: crash in osc_extent_make_ready()
• is related to: LU-14333 ASSERTION( oinfo->loi_lvb.lvb_size >= oinfo->loi_kms ) failed
• is related to: LU-14324 fsx fallocate detection is buggy
• is related to: LUDOC-487 Document llite.*.fallocate_zero_blocks tunable