[LU-15686] loopdev: op 0x9:(WRITE_ZEROES) not supported on Lustre / ZFS

• Type: Bug
• Resolution: Unresolved
• Priority: Minor
• Labels: e2fsprogs
• Environment: Lustre 2.15.0RC2 + ZFS 2.0.7
• Severity: 3
• Assignee: WC Triage
• Reporter: Lukasz Flis

Description

Dear WC Team,

To mitigate high cost of calling ftruncate on ZFS Lustre (call used by fortran programs to extend the file size by certain chunk) - we are using localy mounted loop devices from Lustre.

Underlying file is created as a sparse file, initialized as journal-less ext4 with lazy_itable_init=1,stride=32,stripe-width=256 parameters and mounted as temporary job storage.

This solution works well with LDISKFS based OST. In the ZFS environment we are seeing a lots of op not supported errors:

[1118332.841747] blk_update_request: operation not supported error, dev loop0, sector 457191680 op 0x9:(WRITE_ZEROES) flags 0x800 phys_seg 0 prio class 0
[1118349.509300] blk_update_request: operation not supported error, dev loop0, sector 457195776 op 0x9:(WRITE_ZEROES) flags 0x800 phys_seg 0 prio class 0

Except of significant amount of logs we haven't seen application instability so far.

This happens regardless of nodiscard,discard mount flags

 

 

Issue Links

• is related to: LU-15607 update e2fsprogs to 1.46.5