Missing protocol features that could help Linux

[Steve French]

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)?
-- 
Thanks,

Steve