[LU-17055] Implement FALLOC_FL_ZERO_RANGE

• Type: Improvement
• Resolution: Unresolved
• Priority: Minor
• Labels: easy lad23dd
• Severity: 3
• Assignee: Keguang Xu
• Reporter: Andreas Dilger

Description

It would be possible to implement the fallocate(FALLOC_FL_ZERO_RANGE) option for Lustre. This would need the OST thread performing the operation to get PW extent locks (and possibly the PW lock on the MDT for DOM files) in order to ensure the client cache is flushed, since it is modifying the file's data.

For ldiskfs this would be passed down to the ldiskfs fallocate() call. I'm not sure whether ZFS supports zeroing blocks or not, but it could also be mapped to FALLOC_FL_PUNCH_HOLE on ZFS to provide functionally equivalent behavior (due to COW needing to allocate new blocks anyway).
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Issue Links

• is cloned by: LU-17326 Implement FALLOC_FL_COLLAPSE_RANGE and FALLOC_FL_INSERT_RANGE
• is related to: LUDOC-487 Document llite.*.fallocate_zero_blocks tunable
• is related to: LU-3606 Implement fallocate() support for ldiskfs Lustre
• is related to: LU-14160 Implement fallocate FALLOCATE_FL_PUNCH_HOLE support

Comments

[Gerrit Updater]

"Oleg Drokin <[e-mail]>" merged in patch https://review.whamcloud.com/c/fs/lustre-release/+/57763/
Subject: LU-17055 ldiskfs: add falloc(zero) for OST/ext
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: f57455ffa2871ab31a3e8f3a78e0f5e3b9110586

[Gerrit Updater]

"kg.xu <[e-mail]>" uploaded a new patch: https://review.whamcloud.com/c/fs/lustre-release/+/57763
Subject: LU-17055 ldiskfs: add falloc(zero) for OST/ext
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: e839f0087309356906342930f1d0df18f7cbb139

[Gerrit Updater]

"kg.xu <[e-mail]>" uploaded a new patch: https://review.whamcloud.com/c/fs/lustre-release/+/57246
Subject: LU-17055 ldiskfs: add Zero-Range mode to fallocate
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: e2b2f8b6b49843f7e2e76a74815a83ca6e85b01d