kernel 6.3 compat: REQ_PREFLUSH without REQ_OP_WRITE returns error

[youzhongyang]

Signed-off-by: Youzhong Yang [email protected]

Motivation and Context

Someone reported the issue when testing #14682. More info available in the comments section of #14682.

The commit "block: add a sanity check for non-write flush/fua bios" in kernel 6.3 introduced a check to make sure that the PREFLUSH and FUA flags are only set on write bios. If it's not the case, an I/O error will be returned when doing flush.

Description

Modify bio_set_flush() so if kernel version is >= 4.10, flags REQ_PREFLUSH and REQ_OP_WRITE are set together.

I've checked a bunch of kernel versions, all of them have these two flags defined.

How Has This Been Tested?

Build and test in an old 5.15 kernel and new 6.3-rc4 kernel.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Breaking change (fix or feature that would cause existing functionality to change)
• Library ABI change (libzfs, libzfs_core, libnvpair, libuutil and libzfsbootenv)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the OpenZFS code style requirements.
• I have updated the documentation accordingly.
• I have read the contributing document.
• I have added tests to cover my changes.
• I have run the ZFS Test Suite with this change applied.
• All commit messages are properly formatted and contain Signed-off-by.