scsi: lpfc: use sg helper to iterate over scatterlist

Unlike the legacy I/O path, scsi-mq preallocates a large array to hold
the scatterlist for each request. This static allocation can consume
substantial amounts of memory on modern controllers which support a
large number of concurrently outstanding requests.

To facilitate a switch to a smaller static allocation combined with a
dynamic allocation for requests that need it, we need to make sure all
SCSI drivers handle chained scatterlists correctly.

Convert remaining drivers that directly dereference the scatterlist
array to using the iterator functions.

[mkp: clarified commit message]

Reviewed by: Ewan D. Milne <emilne@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/lpfc/lpfc_nvmet.c b/drivers/scsi/lpfc/lpfc_nvmet.c
index d74bfd2644950804da7c8c6023c5b6537e3e9138..877d1fb92754551d947ade8b872c050fb5515ef7 100644 (file)
--- a/drivers/scsi/lpfc/lpfc_nvmet.c
+++ b/drivers/scsi/lpfc/lpfc_nvmet.c
@@ -2662,8 +2662,7 @@ lpfc_nvmet_prep_fcp_wqe(struct lpfc_hba *phba,
        nvmewqe->drvrTimeout = (phba->fc_ratov * 3) + LPFC_DRVR_TIMEOUT;
        nvmewqe->context1 = ndlp;
 
-       for (i = 0; i < rsp->sg_cnt; i++) {
-               sgel = &rsp->sg[i];
+       for_each_sg(rsp->sg, sgel, rsp->sg_cnt, i) {
                physaddr = sg_dma_address(sgel);
                cnt = sg_dma_len(sgel);
                sgl->addr_hi = putPaddrHigh(physaddr);