On Wed, 2023-06-28 at 19:36 -0700, Dai Ngo wrote: > The NFSv4 server currently supports read delegation using VFS lease > which is implemented using file_lock. > > This patch series add write delegation support for NFSv4.1+ client 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. > > The write delegation support is for NFSv4.1+ client only since the NFSv4.0 > Linux client behavior is not compliant with RFC 7530 Section 16.7.5. It > expects the server to look ahead in the compound to find a stateid in order > to determine whether the client that sends the GETATTR is the same client > that holds the write delegation. RFC 7530 spec does not call for the server > to look ahead in order to service the GETATTR op. > > 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 these patches > > Changes since v3: > > - recall write delegation when there is GETATTR from 2nd client > - add trace point to track when write delegation is granted > > Changes since v4: > - squash 4/4 into 2/4 > - apply 1/4 last instead of first > - combine nfs4_wrdeleg_filelock and nfs4_handle_wrdeleg_conflict to > nfsd4_deleg_getattr_conflict and move it to fs/nfsd/nfs4state.c > - check for lock belongs to delegation before proceed and do it > under the fl_lock > - check and skip FL_LAYOUT file_locks > > Changes since v5: > - [patch 2/5] disable write delegation for NFSv4.0 client > > - [patch 4/5] allow client to use write delegation stateid for READ (same > behavior as Solaris server) > > When the server receives a READ request with write delegation stateid > the server may returns the NFS4ERR_OPENMODE or allows the READ to proceed > to accommodate clients whose WRITE implementation may unavoidably do reads > (e.g., due to buffer cache constraints). Per RFC 8881 section 9.1.2. Use > of the Stateid and Locking > > Returning NFS4ERR_OPENMODE causes the client and server to enter an infinite > loop of READ, NFS4ERR_OPENMODE, TEST_STATEID, READs, NFS4ERR_OPENMODEs, > TEST_STATEID, READs, NFS4ERR_OPENMODEs. The Linux NFS client can not recover > from NFS4ERR_OPENMODE for READ request if the file was opened with > OPEN4_SHARE_ACCESS_WRITE. This READ was initiated internally from the NFS > client and not from the read(2) system call. > > - pass git regression test with 40 threads > Nice work, Dai! This all looks good to me. You can add: Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
