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由 Chuck Lever 提交于
The use of DMA_BIDIRECTIONAL is discouraged by DMA-API.txt. Fortunately, xprtrdma now knows which direction I/O is going as soon as it allocates each regbuf. The RPC Call and Reply buffers are no longer the same regbuf. They can each be labeled correctly now. The RPC Reply buffer is never part of either a Send or Receive WR, but it can be part of Reply chunk, which is mapped and registered via ->ro_map . So it is not DMA mapped when it is allocated (DMA_NONE), to avoid a double- mapping. Since Receive buffers are no longer DMA_BIDIRECTIONAL and their contents are never modified by the host CPU, DMA-API-HOWTO.txt suggests that a DMA sync before posting each buffer should be unnecessary. (See my_card_interrupt_handler). Signed-off-by: NChuck Lever <chuck.lever@oracle.com> Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>
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