I'm not very familiar with SMB but overall this looks good. I just had a few small comments.
smbfs_client.c
453 I'm not familiar with review board. Is this a line with trailing white space?
517 Normally 'XXX' is used to denote work TBD. Is there more to do here? If not can this comment be improved?
smbfs_vnops.c
1092 Does this comment need to be fixed up now that you are handling DOS attrs?
Yes, white space fixed.
XXX was a reminer to take that out (thanks!;)
Correct re. comment in vnops (we may set dosattr now:)
All good caches.