[LU-3606] Implement fallocate() support for ldiskfs Lustre

• Type: New Feature
• Resolution: Fixed
• Priority: Major
• Fix Version/s: Lustre 2.14.0
• Labels: medium patch
• Assignee: Arshad Hussain
• Reporter: Andreas Dilger

Description

The sys_fallocate() syscall was introduced to the linux kernel in the 2.6.24 kernel. There is also an ext4_fallocate() method added in this same kernel release. This has been available in vendor kernels since RHEL 5.4.

We need to implement an fallocate() method for llite, and transport this to the OSTs to interface with the underlying OSD's fallocate() code (for ldiskfs, ZFS has no such method).

The FALLOC_FL_PUNCH_HOLE functionality of fallocate() fits very nicely with the OST_PUNCH RPC, since this was anticipated in Lustre from the beginning. The actual space reservation might also use OST_PUNCH or OST_WRITE, or we might consider a new OST_PREALLOC RPC, depending on what fits best.

Issue Links

• is cloned by: LU-14157 Implement fallocate() support for zfs Lustre
• is related to: LU-14333 ASSERTION( oinfo->loi_lvb.lvb_size >= oinfo->loi_kms ) failed
• is related to: LU-15167 fallocate does not increase quota usage
• is related to: LU-15519 fallocate does not increase projid quota usage
• is related to: LU-10370 "truncate" does not update blocks count on client
• is related to: LU-8699 Further fsx improvements
• is related to: LU-13155 "lfs migrate" and "lfs mirror" should fallocate() the target file
• is related to: LU-17055 Implement FALLOC_FL_ZERO_RANGE
• is related to: 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-14382 Implement fallocate() support at MDT
• is related to: LU-10810 SEEK_HOLE and SEEK_DATA support for lseek
• is related to: LU-14287 Add 'fallocate' to racer
• is related to: LU-14160 Implement fallocate FALLOCATE_FL_PUNCH_HOLE support