mailing list.
When initiating a write, ccdbuffer() returns two "struct ccdbuf *"s
linked together by the cb_mirror field. "cb_pflags &
CCDPF_MIRROR_DONE" is set to 0 on both of them.
When a component returns to ccdiodone(), it checks if "cb_pflags &
CCDPF_MIRROR_DONE" is set or not. If not, it sets the partner's
flag and returns. If it is, it means its partner has already
returned, so it will go to the regular cleanup (which is in the
fallthrough code).
There should be no performance or functionality changes unless the
higher-level scsi driver does something with the resid value. The change
is purely aesthetical and prepares us for the parity implementation.
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