Re: [PATCH v3 0/2] NFSD: add support for NFSv4 write delegation

[Jeff Layton <jlayton@kernel.org>]

On Wed, 2023-05-17 at 16:38 -0700, Dai Ngo wrote:
> NFSD: add support for NFSv4 write delegation
> 
> The NFSv4 server currently supports read delegation using VFS lease
> which is implemented using file_lock. 
> 
> This patch series add write delegation support for NFSv4 server by:
> 
>     . remove the check for F_WRLCK in generic_add_lease to allow
>       file_lock to be used for write delegation.  
> 
>     . grant write delegation for OPEN with NFS4_SHARE_ACCESS_WRITE
>       if there is no conflict with other OPENs.
> 
> Write delegation conflict with another OPEN, REMOVE, RENAME and SETATTR
> are handled the same as read delegation using notify_change, try_break_deleg.
> 
> Changes since v1:
> 
> [PATCH 3/4] NFSD: add supports for CB_GETATTR callback
> - remove WARN_ON_ONCE from encode_bitmap4
> - replace decode_bitmap4 with xdr_stream_decode_uint32_array
> - replace xdr_inline_decode and xdr_decode_hyper in decode_cb_getattr
>    with xdr_stream_decode_u64. Also remove the un-needed likely().
> - modify signature of encode_cb_getattr4args to take pointer to
>    nfs4_cb_fattr
> - replace decode_attr_length with xdr_stream_decode_u32
> - rename decode_cb_getattr to decode_cb_fattr4
> - fold the initialization of cb_cinfo and cb_fsize into decode_cb_fattr4
> - rename ncf_cb_cinfo to ncf_cb_change to avoid confusion of cindo usage
>   in fs/nfsd/nfs4xdr.c
> - correct NFS4_dec_cb_getattr_sz and update size description
> 
> [PATCH 4/4] NFSD: handle GETATTR conflict with write delegation
> - change nfs4_handle_wrdeleg_conflict returns __be32 to fix test robot
> - change ncf_cb_cinfo to ncf_cb_change to avoid confusion of cindo usage
>   in fs/nfsd/nfs4xdr.c
> 
> Changes since v2:
> 
> [PATCH 2/4] NFSD: enable support for write delegation
> - rename 'deleg' to 'dl_type' in nfs4_set_delegation
> - remove 'wdeleg' in nfs4_open_delegation
> 
> - drop [PATCH 3/4] NFSD: add supports for CB_GETATTR callback
>   and [PATCH 4/4] NFSD: handle GETATTR conflict with write delegation
>   for futher clarification of the benefits of using CB_GETATTR
>   for handling GETATTR from the 2nd client
> 

Pretty straightforward. Not as useful (IMO) without CB_GETATTR, since
even a stray 'ls -l' in the parent directory will cause the delegation
to be recalled, but it's a reasonable first step.

Reviewed-by: Jeff Layton <jlayton@kernel.org>