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scsi: megaraid_sas: Remove IO buffer hole detection logic
As blk_queue_virt_boundary() API in slave_configure ensures that no IOs will come with holes/gaps. Hence, code logic to detect the holes/gaps in IO buffer is not required. Link: https://lore.kernel.org/r/20200508083838.22778-3-chandrakanth.patil@broadcom.com Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com> Signed-off-by: Chandrakanth Patil <chandrakanth.patil@broadcom.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
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1 changed files with 0 additions and 58 deletions
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@ -2070,7 +2070,6 @@ static bool
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megasas_is_prp_possible(struct megasas_instance *instance,
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megasas_is_prp_possible(struct megasas_instance *instance,
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struct scsi_cmnd *scmd, int sge_count)
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struct scsi_cmnd *scmd, int sge_count)
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{
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{
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int i;
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u32 data_length = 0;
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u32 data_length = 0;
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struct scatterlist *sg_scmd;
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struct scatterlist *sg_scmd;
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bool build_prp = false;
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bool build_prp = false;
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@ -2099,63 +2098,6 @@ megasas_is_prp_possible(struct megasas_instance *instance,
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build_prp = true;
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build_prp = true;
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}
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}
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/*
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* Below code detects gaps/holes in IO data buffers.
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* What does holes/gaps mean?
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* Any SGE except first one in a SGL starts at non NVME page size
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* aligned address OR Any SGE except last one in a SGL ends at
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* non NVME page size boundary.
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*
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* Driver has already informed block layer by setting boundary rules for
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* bio merging done at NVME page size boundary calling kernel API
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* blk_queue_virt_boundary inside slave_config.
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* Still there is possibility of IO coming with holes to driver because of
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* IO merging done by IO scheduler.
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*
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* With SCSI BLK MQ enabled, there will be no IO with holes as there is no
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* IO scheduling so no IO merging.
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*
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* With SCSI BLK MQ disabled, IO scheduler may attempt to merge IOs and
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* then sending IOs with holes.
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*
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* Though driver can request block layer to disable IO merging by calling-
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* blk_queue_flag_set(QUEUE_FLAG_NOMERGES, sdev->request_queue) but
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* user may tune sysfs parameter- nomerges again to 0 or 1.
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*
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* If in future IO scheduling is enabled with SCSI BLK MQ,
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* this algorithm to detect holes will be required in driver
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* for SCSI BLK MQ enabled case as well.
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*
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*
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*/
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scsi_for_each_sg(scmd, sg_scmd, sge_count, i) {
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if ((i != 0) && (i != (sge_count - 1))) {
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if (mega_mod64(sg_dma_len(sg_scmd), mr_nvme_pg_size) ||
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mega_mod64(sg_dma_address(sg_scmd),
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mr_nvme_pg_size)) {
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build_prp = false;
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break;
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}
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}
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if ((sge_count > 1) && (i == 0)) {
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if ((mega_mod64((sg_dma_address(sg_scmd) +
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sg_dma_len(sg_scmd)),
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mr_nvme_pg_size))) {
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build_prp = false;
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break;
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}
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}
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if ((sge_count > 1) && (i == (sge_count - 1))) {
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if (mega_mod64(sg_dma_address(sg_scmd),
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mr_nvme_pg_size)) {
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build_prp = false;
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break;
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}
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}
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}
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return build_prp;
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return build_prp;
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}
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}
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