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    SubjectRe: [PATCH 03/11] block: add rq->resid_len
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    On Mon, 11 May 2009 14:31:41 +0300
    Boaz Harrosh <bharrosh@panasas.com> wrote:

    > >>> diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c
    > >>> index 3da02e4..6605ec9 100644
    > >>> --- a/drivers/scsi/libsas/sas_expander.c
    > >>> +++ b/drivers/scsi/libsas/sas_expander.c
    > >>> @@ -1936,12 +1936,8 @@ int sas_smp_handler(struct Scsi_Host *shost, struct sas_rphy *rphy,
    > >>> bio_data(rsp->bio), rsp->data_len);
    > >>> if (ret > 0) {
    > >>> /* positive number is the untransferred residual */
    > >>> - rsp->data_len = ret;
    > >>> - req->data_len = 0;
    > >>> + rsp->resid_len = ret;
    > >>> ret = 0;
    > >>> - } else if (ret == 0) {
    > >>> - rsp->data_len = 0;
    > >>> - req->data_len = 0;
    > >>> }
    > >>>
    > >>> return ret;
    > >> This is actually a bug fix, as well as a strait conversion
    > >
    > > Can you elaborate a bit about the bug fix part?
    > >
    >
    > Nothing big really, just that before (according to the comment), the theoretical
    > negative case would be full-residual. and now it is zero (untouched).
    >
    > I know that in iscsi a negative residual is possible which means over-flow. That is:
    > the target had more data to give then the buffer had space for. (which is not an error at all)

    Hmm, iSCSI? This code is for SAS management Protocol.

    smp_execute_task returns a negative value for some errors (ENOMEM, the
    hardware doesn't respond, etc). It's not related with 'transferred
    buffer length' at all.


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