Re: Additional SMB3.1.1 FSCTLs

On 7/1/2026 6:41 PM, Steve French wrote:
> Looking at MS-FSCC, I noticed some FSCTLs we don't use in current
> cifs.ko but Windows supports:
> 2.3.13 FSCTL_FILE_LEVEL_TRIM
> 2.3.29 FSCTL_GET_RETRIEVAL_POINTER_COUNT
> 2.3.41 FSCTL_OFFLOAD_READ Request
> 2.3.43 FSCTL_OFFLOAD_WRITE
> 2.3.55 FSCTL_QUERY_FILE_REGIONS
> 2.3.63 FSCTL_RECALL_FILE (maybe add an smbinfo command for this?)
> 2.3.87 FSCTL_SET_ZERO_ON_DEALLOCATION (maybe add an smbinfo command for this?)
> 
> Do you see any of these that we should be using in cifs.ko or userspace tools?
> 

I'd be careful with these. They're whitelisted by SMB3.1.1 but they
are implemented by the server's backend filesystem and storage. I would
not expect third-party servers to support them routinely. Also they
are somewhat exotic, that is, specific to narrow scenarios and apps.
What Linux API would we expect to use/support them?

Tom.