scsi: target: avoid per-loop XCOPY buffer allocations
The main target_xcopy_do_work() loop unnecessarily allocates an I/O buffer with each synchronous READ / WRITE pair. This commit significantly reduces allocations by reusing the XCOPY I/O buffer when possible. Link: https://lore.kernel.org/r/20200327141954.955-4-ddiss@suse.de Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: David Disseldorp <ddiss@suse.de> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
David Disseldorp
Martin K. Petersen
parent
267fc83f88
commit
0ad08996da
@ -499,7 +499,6 @@ void target_xcopy_release_pt(void)
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* @cdb: SCSI CDB to be copied into @xpt_cmd.
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* @remote_port: If false, use the LUN through which the XCOPY command has
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* been received. If true, use @se_dev->xcopy_lun.
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* @alloc_mem: Whether or not to allocate an SGL list.
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*
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* Set up a SCSI command (READ or WRITE) that will be used to execute an
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* XCOPY command.
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@ -509,12 +508,9 @@ static int target_xcopy_setup_pt_cmd(
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struct xcopy_op *xop,
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struct se_device *se_dev,
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unsigned char *cdb,
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bool remote_port,
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bool alloc_mem)
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bool remote_port)
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{
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struct se_cmd *cmd = &xpt_cmd->se_cmd;
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sense_reason_t sense_rc;
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int ret = 0, rc;
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/*
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* Setup LUN+port to honor reservations based upon xop->op_origin for
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@ -530,46 +526,17 @@ static int target_xcopy_setup_pt_cmd(
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cmd->se_cmd_flags |= SCF_SE_LUN_CMD;
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cmd->tag = 0;
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sense_rc = target_setup_cmd_from_cdb(cmd, cdb);
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if (sense_rc) {
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ret = -EINVAL;
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goto out;
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}
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if (target_setup_cmd_from_cdb(cmd, cdb))
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return -EINVAL;
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if (alloc_mem) {
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rc = target_alloc_sgl(&cmd->t_data_sg, &cmd->t_data_nents,
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cmd->data_length, false, false);
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if (rc < 0) {
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ret = rc;
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goto out;
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}
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/*
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* Set this bit so that transport_free_pages() allows the
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* caller to release SGLs + physical memory allocated by
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* transport_generic_get_mem()..
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*/
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cmd->se_cmd_flags |= SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC;
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} else {
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/*
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* Here the previously allocated SGLs for the internal READ
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* are mapped zero-copy to the internal WRITE.
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*/
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sense_rc = transport_generic_map_mem_to_cmd(cmd,
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xop->xop_data_sg, xop->xop_data_nents,
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NULL, 0);
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if (sense_rc) {
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ret = -EINVAL;
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goto out;
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}
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if (transport_generic_map_mem_to_cmd(cmd, xop->xop_data_sg,
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xop->xop_data_nents, NULL, 0))
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return -EINVAL;
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pr_debug("Setup PASSTHROUGH_NOALLOC t_data_sg: %p t_data_nents:"
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" %u\n", cmd->t_data_sg, cmd->t_data_nents);
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}
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pr_debug("Setup PASSTHROUGH_NOALLOC t_data_sg: %p t_data_nents:"
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" %u\n", cmd->t_data_sg, cmd->t_data_nents);
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return 0;
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out:
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return ret;
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}
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static int target_xcopy_issue_pt_cmd(struct xcopy_pt_cmd *xpt_cmd)
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@ -626,15 +593,13 @@ static int target_xcopy_read_source(
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xop->src_pt_cmd = xpt_cmd;
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rc = target_xcopy_setup_pt_cmd(xpt_cmd, xop, src_dev, &cdb[0],
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remote_port, true);
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remote_port);
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if (rc < 0) {
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ec_cmd->scsi_status = xpt_cmd->se_cmd.scsi_status;
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transport_generic_free_cmd(se_cmd, 0);
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return rc;
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}
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xop->xop_data_sg = se_cmd->t_data_sg;
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xop->xop_data_nents = se_cmd->t_data_nents;
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pr_debug("XCOPY-READ: Saved xop->xop_data_sg: %p, num: %u for READ"
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" memory\n", xop->xop_data_sg, xop->xop_data_nents);
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@ -644,12 +609,6 @@ static int target_xcopy_read_source(
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transport_generic_free_cmd(se_cmd, 0);
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return rc;
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}
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/*
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* Clear off the allocated t_data_sg, that has been saved for
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* zero-copy WRITE submission reuse in struct xcopy_op..
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*/
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se_cmd->t_data_sg = NULL;
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se_cmd->t_data_nents = 0;
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return 0;
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}
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@ -688,19 +647,9 @@ static int target_xcopy_write_destination(
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xop->dst_pt_cmd = xpt_cmd;
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rc = target_xcopy_setup_pt_cmd(xpt_cmd, xop, dst_dev, &cdb[0],
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remote_port, false);
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remote_port);
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if (rc < 0) {
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struct se_cmd *src_cmd = &xop->src_pt_cmd->se_cmd;
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ec_cmd->scsi_status = xpt_cmd->se_cmd.scsi_status;
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/*
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* If the failure happened before the t_mem_list hand-off in
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* target_xcopy_setup_pt_cmd(), Reset memory + clear flag so that
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* core releases this memory on error during X-COPY WRITE I/O.
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*/
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src_cmd->se_cmd_flags &= ~SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC;
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src_cmd->t_data_sg = xop->xop_data_sg;
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src_cmd->t_data_nents = xop->xop_data_nents;
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transport_generic_free_cmd(se_cmd, 0);
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return rc;
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}
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@ -708,7 +657,6 @@ static int target_xcopy_write_destination(
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rc = target_xcopy_issue_pt_cmd(xpt_cmd);
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if (rc < 0) {
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ec_cmd->scsi_status = xpt_cmd->se_cmd.scsi_status;
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se_cmd->se_cmd_flags &= ~SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC;
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transport_generic_free_cmd(se_cmd, 0);
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return rc;
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}
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@ -724,7 +672,7 @@ static void target_xcopy_do_work(struct work_struct *work)
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sector_t src_lba, dst_lba, end_lba;
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unsigned int max_sectors;
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int rc = 0;
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unsigned short nolb, cur_nolb, max_nolb, copied_nolb = 0;
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unsigned short nolb, max_nolb, copied_nolb = 0;
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if (target_parse_xcopy_cmd(xop) != TCM_NO_SENSE)
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goto err_free;
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@ -754,7 +702,23 @@ static void target_xcopy_do_work(struct work_struct *work)
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(unsigned long long)src_lba, (unsigned long long)dst_lba);
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while (src_lba < end_lba) {
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cur_nolb = min(nolb, max_nolb);
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unsigned short cur_nolb = min(nolb, max_nolb);
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u32 cur_bytes = cur_nolb * src_dev->dev_attrib.block_size;
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if (cur_bytes != xop->xop_data_bytes) {
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/*
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* (Re)allocate a buffer large enough to hold the XCOPY
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* I/O size, which can be reused each read / write loop.
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*/
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target_free_sgl(xop->xop_data_sg, xop->xop_data_nents);
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rc = target_alloc_sgl(&xop->xop_data_sg,
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&xop->xop_data_nents,
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cur_bytes,
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false, false);
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if (rc < 0)
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goto out;
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xop->xop_data_bytes = cur_bytes;
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}
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pr_debug("target_xcopy_do_work: Calling read src_dev: %p src_lba: %llu,"
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" cur_nolb: %hu\n", src_dev, (unsigned long long)src_lba, cur_nolb);
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@ -785,12 +749,11 @@ static void target_xcopy_do_work(struct work_struct *work)
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nolb -= cur_nolb;
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transport_generic_free_cmd(&xop->src_pt_cmd->se_cmd, 0);
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xop->dst_pt_cmd->se_cmd.se_cmd_flags &= ~SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC;
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transport_generic_free_cmd(&xop->dst_pt_cmd->se_cmd, 0);
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}
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xcopy_pt_undepend_remotedev(xop);
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target_free_sgl(xop->xop_data_sg, xop->xop_data_nents);
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kfree(xop);
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pr_debug("target_xcopy_do_work: Final src_lba: %llu, dst_lba: %llu\n",
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@ -804,6 +767,7 @@ static void target_xcopy_do_work(struct work_struct *work)
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out:
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xcopy_pt_undepend_remotedev(xop);
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target_free_sgl(xop->xop_data_sg, xop->xop_data_nents);
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err_free:
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kfree(xop);
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@ -39,6 +39,7 @@ struct xcopy_op {
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struct xcopy_pt_cmd *src_pt_cmd;
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struct xcopy_pt_cmd *dst_pt_cmd;
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u32 xop_data_bytes;
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u32 xop_data_nents;
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struct scatterlist *xop_data_sg;
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struct work_struct xop_work;
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