Missing protocol features that could help Linux

[Jeremy Allison]

On Fri, Apr 19, 2024 at 06:53:01PM +0200, Ralph Boehme wrote:
>On 4/18/24 22:21, Steve French via samba-technical wrote:
>>Was following up on a recent question about support for Linux features
>>that are missing that could help us pass more xfstests
>>
>>Looking at the standard fstests for Linux (xfstests that are skipped
>>or fail for cifs.ko) to find 'features' that would help, perhaps
>>extending the current POSIX Extensions or adding a couple of SMB3.1.1
>>FSCTLs, I spotted a few obvious ones:
>>
>>  1) renameat2 (RENAME_EXCHANGE) and renameat2(WHITEOUT)  2) FITRIM
>>support 3) trusted namespace (perhaps xattr/EA extension) 4) attr
>>namespace 5) deduplication 6) chattr -i 7) unshare (namespace command)
>>8) delayed allocation 9) dax 10) attr namespace security 11) fstrim
>>12) chattr +s 13) exchange range
>>
>>Any thoughts on which of these which would be 'easy' for samba and/or
>>ksmbd server to implement (e.g. as new fsctls)?
>
>well, I guess none of these will be really "easy".
>
>Iirc when I last brough up file attributes, we vetted towards 
>postponing this kind of stuff until we have full support for the core 
>SMB3 POSIX features in Samba. Iirc the only real thing missing there 
>is symlink/reparse point handling and for that we need to settle on 
>which reparse type to use (WSL vs NFS) as discussed yesterday. It 
>would be a *huge* help Steve, if you can pursue this internally, this 
>has been a blocker for the whole project since quite some time...

renameat2 (RENAME_EXCHANGE) and renameat2(WHITEOUT) need to be
mapped into Windows SMB3 operations. We should not (IMHO) add new
SMB3 operation semantics into POSIX that overlap existing Windows
SMB3 operations.