scsi: mvumi: 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 and folded in build fix reported by zeroday]

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

diff --git a/drivers/scsi/mvumi.c b/drivers/scsi/mvumi.c
index a5410615edacf5ad1987c27f9eda200f178fed03..53f3563aca222ca8c3bf1e87352685fc6719e261 100644 (file)
--- a/drivers/scsi/mvumi.c
+++ b/drivers/scsi/mvumi.c
@@ -211,23 +211,22 @@ static int mvumi_make_sgl(struct mvumi_hba *mhba, struct scsi_cmnd *scmd,
        unsigned int sgnum = scsi_sg_count(scmd);
        dma_addr_t busaddr;
 
-       sg = scsi_sglist(scmd);
-       *sg_count = dma_map_sg(&mhba->pdev->dev, sg, sgnum,
+       *sg_count = dma_map_sg(&mhba->pdev->dev, scsi_sglist(scmd), sgnum,
                               scmd->sc_data_direction);
        if (*sg_count > mhba->max_sge) {
                dev_err(&mhba->pdev->dev,
                        "sg count[0x%x] is bigger than max sg[0x%x].\n",
                        *sg_count, mhba->max_sge);
-               dma_unmap_sg(&mhba->pdev->dev, sg, sgnum,
+               dma_unmap_sg(&mhba->pdev->dev, scsi_sglist(scmd), sgnum,
                             scmd->sc_data_direction);
                return -1;
        }
-       for (i = 0; i < *sg_count; i++) {
-               busaddr = sg_dma_address(&sg[i]);
+       scsi_for_each_sg(scmd, sg, *sg_count, i) {
+               busaddr = sg_dma_address(sg);
                m_sg->baseaddr_l = cpu_to_le32(lower_32_bits(busaddr));
                m_sg->baseaddr_h = cpu_to_le32(upper_32_bits(busaddr));
                m_sg->flags = 0;
-               sgd_setsz(mhba, m_sg, cpu_to_le32(sg_dma_len(&sg[i])));
+               sgd_setsz(mhba, m_sg, cpu_to_le32(sg_dma_len(sg)));
                if ((i + 1) == *sg_count)
                        m_sg->flags |= 1U << mhba->eot_flag;