From: David Disseldorp ddiss@suse.de
[ Upstream commit 0ad08996da05b6b735d4963dceab7d2a4043607c ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/target/target_core_xcopy.c | 96 ++++++++++-------------------- drivers/target/target_core_xcopy.h | 1 + 2 files changed, 31 insertions(+), 66 deletions(-)
diff --git a/drivers/target/target_core_xcopy.c b/drivers/target/target_core_xcopy.c index 596ad3edec9c..48fabece7644 100644 --- a/drivers/target/target_core_xcopy.c +++ b/drivers/target/target_core_xcopy.c @@ -533,7 +533,6 @@ void target_xcopy_release_pt(void) * @cdb: SCSI CDB to be copied into @xpt_cmd. * @remote_port: If false, use the LUN through which the XCOPY command has * been received. If true, use @se_dev->xcopy_lun. - * @alloc_mem: Whether or not to allocate an SGL list. * * Set up a SCSI command (READ or WRITE) that will be used to execute an * XCOPY command. @@ -543,12 +542,9 @@ static int target_xcopy_setup_pt_cmd( struct xcopy_op *xop, struct se_device *se_dev, unsigned char *cdb, - bool remote_port, - bool alloc_mem) + bool remote_port) { struct se_cmd *cmd = &xpt_cmd->se_cmd; - sense_reason_t sense_rc; - int ret = 0, rc;
/* * Setup LUN+port to honor reservations based upon xop->op_origin for @@ -564,46 +560,17 @@ static int target_xcopy_setup_pt_cmd( cmd->se_cmd_flags |= SCF_SE_LUN_CMD;
cmd->tag = 0; - sense_rc = target_setup_cmd_from_cdb(cmd, cdb); - if (sense_rc) { - ret = -EINVAL; - goto out; - } + if (target_setup_cmd_from_cdb(cmd, cdb)) + return -EINVAL;
- if (alloc_mem) { - rc = target_alloc_sgl(&cmd->t_data_sg, &cmd->t_data_nents, - cmd->data_length, false, false); - if (rc < 0) { - ret = rc; - goto out; - } - /* - * Set this bit so that transport_free_pages() allows the - * caller to release SGLs + physical memory allocated by - * transport_generic_get_mem().. - */ - cmd->se_cmd_flags |= SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC; - } else { - /* - * Here the previously allocated SGLs for the internal READ - * are mapped zero-copy to the internal WRITE. - */ - sense_rc = transport_generic_map_mem_to_cmd(cmd, - xop->xop_data_sg, xop->xop_data_nents, - NULL, 0); - if (sense_rc) { - ret = -EINVAL; - goto out; - } + if (transport_generic_map_mem_to_cmd(cmd, xop->xop_data_sg, + xop->xop_data_nents, NULL, 0)) + return -EINVAL;
- pr_debug("Setup PASSTHROUGH_NOALLOC t_data_sg: %p t_data_nents:" - " %u\n", cmd->t_data_sg, cmd->t_data_nents); - } + pr_debug("Setup PASSTHROUGH_NOALLOC t_data_sg: %p t_data_nents:" + " %u\n", cmd->t_data_sg, cmd->t_data_nents);
return 0; - -out: - return ret; }
static int target_xcopy_issue_pt_cmd(struct xcopy_pt_cmd *xpt_cmd) @@ -660,15 +627,13 @@ static int target_xcopy_read_source( xop->src_pt_cmd = xpt_cmd;
rc = target_xcopy_setup_pt_cmd(xpt_cmd, xop, src_dev, &cdb[0], - remote_port, true); + remote_port); if (rc < 0) { ec_cmd->scsi_status = xpt_cmd->se_cmd.scsi_status; transport_generic_free_cmd(se_cmd, 0); return rc; }
- xop->xop_data_sg = se_cmd->t_data_sg; - xop->xop_data_nents = se_cmd->t_data_nents; pr_debug("XCOPY-READ: Saved xop->xop_data_sg: %p, num: %u for READ" " memory\n", xop->xop_data_sg, xop->xop_data_nents);
@@ -678,12 +643,6 @@ static int target_xcopy_read_source( transport_generic_free_cmd(se_cmd, 0); return rc; } - /* - * Clear off the allocated t_data_sg, that has been saved for - * zero-copy WRITE submission reuse in struct xcopy_op.. - */ - se_cmd->t_data_sg = NULL; - se_cmd->t_data_nents = 0;
return 0; } @@ -722,19 +681,9 @@ static int target_xcopy_write_destination( xop->dst_pt_cmd = xpt_cmd;
rc = target_xcopy_setup_pt_cmd(xpt_cmd, xop, dst_dev, &cdb[0], - remote_port, false); + remote_port); if (rc < 0) { - struct se_cmd *src_cmd = &xop->src_pt_cmd->se_cmd; ec_cmd->scsi_status = xpt_cmd->se_cmd.scsi_status; - /* - * If the failure happened before the t_mem_list hand-off in - * target_xcopy_setup_pt_cmd(), Reset memory + clear flag so that - * core releases this memory on error during X-COPY WRITE I/O. - */ - src_cmd->se_cmd_flags &= ~SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC; - src_cmd->t_data_sg = xop->xop_data_sg; - src_cmd->t_data_nents = xop->xop_data_nents; - transport_generic_free_cmd(se_cmd, 0); return rc; } @@ -742,7 +691,6 @@ static int target_xcopy_write_destination( rc = target_xcopy_issue_pt_cmd(xpt_cmd); if (rc < 0) { ec_cmd->scsi_status = xpt_cmd->se_cmd.scsi_status; - se_cmd->se_cmd_flags &= ~SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC; transport_generic_free_cmd(se_cmd, 0); return rc; } @@ -758,7 +706,7 @@ static void target_xcopy_do_work(struct work_struct *work) sector_t src_lba, dst_lba, end_lba; unsigned int max_sectors; int rc = 0; - unsigned short nolb, cur_nolb, max_nolb, copied_nolb = 0; + unsigned short nolb, max_nolb, copied_nolb = 0;
if (target_parse_xcopy_cmd(xop) != TCM_NO_SENSE) goto err_free; @@ -788,7 +736,23 @@ static void target_xcopy_do_work(struct work_struct *work) (unsigned long long)src_lba, (unsigned long long)dst_lba);
while (src_lba < end_lba) { - cur_nolb = min(nolb, max_nolb); + unsigned short cur_nolb = min(nolb, max_nolb); + u32 cur_bytes = cur_nolb * src_dev->dev_attrib.block_size; + + if (cur_bytes != xop->xop_data_bytes) { + /* + * (Re)allocate a buffer large enough to hold the XCOPY + * I/O size, which can be reused each read / write loop. + */ + target_free_sgl(xop->xop_data_sg, xop->xop_data_nents); + rc = target_alloc_sgl(&xop->xop_data_sg, + &xop->xop_data_nents, + cur_bytes, + false, false); + if (rc < 0) + goto out; + xop->xop_data_bytes = cur_bytes; + }
pr_debug("target_xcopy_do_work: Calling read src_dev: %p src_lba: %llu," " cur_nolb: %hu\n", src_dev, (unsigned long long)src_lba, cur_nolb); @@ -819,12 +783,11 @@ static void target_xcopy_do_work(struct work_struct *work) nolb -= cur_nolb;
transport_generic_free_cmd(&xop->src_pt_cmd->se_cmd, 0); - xop->dst_pt_cmd->se_cmd.se_cmd_flags &= ~SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC; - transport_generic_free_cmd(&xop->dst_pt_cmd->se_cmd, 0); }
xcopy_pt_undepend_remotedev(xop); + target_free_sgl(xop->xop_data_sg, xop->xop_data_nents); kfree(xop);
pr_debug("target_xcopy_do_work: Final src_lba: %llu, dst_lba: %llu\n", @@ -838,6 +801,7 @@ static void target_xcopy_do_work(struct work_struct *work)
out: xcopy_pt_undepend_remotedev(xop); + target_free_sgl(xop->xop_data_sg, xop->xop_data_nents);
err_free: kfree(xop); diff --git a/drivers/target/target_core_xcopy.h b/drivers/target/target_core_xcopy.h index 974bc1e19ff2..a1805a14eea0 100644 --- a/drivers/target/target_core_xcopy.h +++ b/drivers/target/target_core_xcopy.h @@ -41,6 +41,7 @@ struct xcopy_op { struct xcopy_pt_cmd *src_pt_cmd; struct xcopy_pt_cmd *dst_pt_cmd;
+ u32 xop_data_bytes; u32 xop_data_nents; struct scatterlist *xop_data_sg; struct work_struct xop_work;