Wei Liu 2fe775fce2 block: use BLKDISCARD/BLKZEROOUT ioctls for block devices ...

Some block devices (ZFS volume) may require BLKDISCARD and BLKZEROOUT
ioctls for discard and write_zeroes operations respectively.

There is no good way to probe whether fallocate is supported on a block
device. Arguably, punch_hole and write_zeroes are rare. Instead of
having a complex scheme for the IO uring backend, we force it to always
use ioctls. The code can be changed if the synchronized ioctls become a
performance issue.

Changes:
- Detect block devices at construction time
- Use BLKDISCARD ioctl for punch_hole (discard) on block devices
- Use BLKZEROOUT ioctl for write_zeroes on block devices
- Add BLKDISCARD/BLKZEROOUT to VirtioBlock seccomp whitelist
- Keep fallocate() path for regular files (no behavior change)
- Consolidate some helper functions to the new sparse module

Signed-off-by: Wei Liu <liuwe@microsoft.com>

2026-05-14 22:35:02 +00:00

..

src

block: use BLKDISCARD/BLKZEROOUT ioctls for block devices

2026-05-14 22:35:02 +00:00

Cargo.toml

block: fix cargo test -p block

2026-05-09 14:10:25 +00:00