scsi-disk: Add warning comments that host_status errors take a shortcut

scsi-disk: Add warning comments that host_status errors take a shortcut

scsi_block_sgio_complete() has surprising behaviour in that there are
error cases in which it directly completes the request and never calls
the passed callback. In the current state of the code, this doesn't seem
to result in bugs, but with future code changes, we must be careful to
never rely on the callback doing some cleanup until this code smell is
fixed. For now, just add warnings to make people aware of the trap.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20240731123207.27636-4-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit 8a0495624f23f8f01dfb1484f367174f3b3572e8)
(Mjt: fix for e7fc3c4a8cc "scsi: remove outdated AioContext lock comment")
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>