xprtrdma: Provide a buffer to pad Write chunks of unaligned length
This is a buffer to be left persistently registered while a
connection is up. Connection tear-down will automatically DMA-unmap,
invalidate, and dereg the MR. A persistently registered buffer is
lower in cost to provide, and it can never be coalesced into the
RDMA segment that carries the data payload.
An RPC that provisions a Write chunk with a non-aligned length now
uses this MR rather than the tail buffer of the RPC's rq_rcv_buf.
Reviewed-By: Tom Talpey <tom@talpey.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
5 files changed