scsi: target: use the stack for XCOPY passthrough cmds

Reads and writes in the XCOPY loop are synchronous, so needn't be heap
allocated / freed with each loop.

Link: https://lore.kernel.org/r/20200327141954.955-6-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>

diff --git a/drivers/target/target_core_xcopy.c b/drivers/target/target_core_xcopy.c
index d61c41f..bd3ed6c 100644 (file)
--- a/drivers/target/target_core_xcopy.c
+++ b/drivers/target/target_core_xcopy.c
@@ -410,7 +410,8 @@ static void xcopy_pt_release_cmd(struct se_cmd *se_cmd)
        struct xcopy_pt_cmd *xpt_cmd = container_of(se_cmd,
                                struct xcopy_pt_cmd, se_cmd);
 
-       kfree(xpt_cmd);
+       /* xpt_cmd is on the stack, nothing to free here */
+       pr_debug("xpt_cmd done: %p\n", xpt_cmd);
 }
 
 static int xcopy_pt_check_stop_free(struct se_cmd *se_cmd)
@@ -566,20 +567,15 @@ static int target_xcopy_read_source(
        sector_t src_lba,
        u32 src_sectors)
 {
-       struct xcopy_pt_cmd *xpt_cmd;
-       struct se_cmd *se_cmd;
+       struct xcopy_pt_cmd xpt_cmd;
+       struct se_cmd *se_cmd = &xpt_cmd.se_cmd;
        u32 length = (src_sectors * src_dev->dev_attrib.block_size);
        int rc;
        unsigned char cdb[16];
        bool remote_port = (xop->op_origin == XCOL_DEST_RECV_OP);
 
-       xpt_cmd = kzalloc(sizeof(struct xcopy_pt_cmd), GFP_KERNEL);
-       if (!xpt_cmd) {
-               pr_err("Unable to allocate xcopy_pt_cmd\n");
-               return -ENOMEM;
-       }
-       init_completion(&xpt_cmd->xpt_passthrough_sem);
-       se_cmd = &xpt_cmd->se_cmd;
+       memset(&xpt_cmd, 0, sizeof(xpt_cmd));
+       init_completion(&xpt_cmd.xpt_passthrough_sem);
 
        memset(&cdb[0], 0, 16);
        cdb[0] = READ_16;
@@ -589,28 +585,24 @@ static int target_xcopy_read_source(
                (unsigned long long)src_lba, src_sectors, length);
 
        transport_init_se_cmd(se_cmd, &xcopy_pt_tfo, &xcopy_pt_sess, length,
-                             DMA_FROM_DEVICE, 0, &xpt_cmd->sense_buffer[0]);
-       xop->src_pt_cmd = xpt_cmd;
+                             DMA_FROM_DEVICE, 0, &xpt_cmd.sense_buffer[0]);
 
-       rc = target_xcopy_setup_pt_cmd(xpt_cmd, xop, src_dev, &cdb[0],
+       rc = target_xcopy_setup_pt_cmd(&xpt_cmd, xop, src_dev, &cdb[0],
                                remote_port);
        if (rc < 0) {
-               ec_cmd->scsi_status = xpt_cmd->se_cmd.scsi_status;
-               transport_generic_free_cmd(se_cmd, 0);
-               return rc;
+               ec_cmd->scsi_status = se_cmd->scsi_status;
+               goto out;
        }
 
        pr_debug("XCOPY-READ: Saved xop->xop_data_sg: %p, num: %u for READ"
                " memory\n", xop->xop_data_sg, xop->xop_data_nents);
 
-       rc = target_xcopy_issue_pt_cmd(xpt_cmd);
-       if (rc < 0) {
-               ec_cmd->scsi_status = xpt_cmd->se_cmd.scsi_status;
-               transport_generic_free_cmd(se_cmd, 0);
-               return rc;
-       }
-
-       return 0;
+       rc = target_xcopy_issue_pt_cmd(&xpt_cmd);
+       if (rc < 0)
+               ec_cmd->scsi_status = se_cmd->scsi_status;
+out:
+       transport_generic_free_cmd(se_cmd, 0);
+       return rc;
 }
 
 static int target_xcopy_write_destination(
@@ -620,20 +612,15 @@ static int target_xcopy_write_destination(
        sector_t dst_lba,
        u32 dst_sectors)
 {
-       struct xcopy_pt_cmd *xpt_cmd;
-       struct se_cmd *se_cmd;
+       struct xcopy_pt_cmd xpt_cmd;
+       struct se_cmd *se_cmd = &xpt_cmd.se_cmd;
        u32 length = (dst_sectors * dst_dev->dev_attrib.block_size);
        int rc;
        unsigned char cdb[16];
        bool remote_port = (xop->op_origin == XCOL_SOURCE_RECV_OP);
 
-       xpt_cmd = kzalloc(sizeof(struct xcopy_pt_cmd), GFP_KERNEL);
-       if (!xpt_cmd) {
-               pr_err("Unable to allocate xcopy_pt_cmd\n");
-               return -ENOMEM;
-       }
-       init_completion(&xpt_cmd->xpt_passthrough_sem);
-       se_cmd = &xpt_cmd->se_cmd;
+       memset(&xpt_cmd, 0, sizeof(xpt_cmd));
+       init_completion(&xpt_cmd.xpt_passthrough_sem);
 
        memset(&cdb[0], 0, 16);
        cdb[0] = WRITE_16;
@@ -643,25 +630,21 @@ static int target_xcopy_write_destination(
                (unsigned long long)dst_lba, dst_sectors, length);
 
        transport_init_se_cmd(se_cmd, &xcopy_pt_tfo, &xcopy_pt_sess, length,
-                             DMA_TO_DEVICE, 0, &xpt_cmd->sense_buffer[0]);
-       xop->dst_pt_cmd = xpt_cmd;
+                             DMA_TO_DEVICE, 0, &xpt_cmd.sense_buffer[0]);
 
-       rc = target_xcopy_setup_pt_cmd(xpt_cmd, xop, dst_dev, &cdb[0],
+       rc = target_xcopy_setup_pt_cmd(&xpt_cmd, xop, dst_dev, &cdb[0],
                                remote_port);
        if (rc < 0) {
-               ec_cmd->scsi_status = xpt_cmd->se_cmd.scsi_status;
-               transport_generic_free_cmd(se_cmd, 0);
-               return rc;
-       }
-
-       rc = target_xcopy_issue_pt_cmd(xpt_cmd);
-       if (rc < 0) {
-               ec_cmd->scsi_status = xpt_cmd->se_cmd.scsi_status;
-               transport_generic_free_cmd(se_cmd, 0);
-               return rc;
+               ec_cmd->scsi_status = se_cmd->scsi_status;
+               goto out;
        }
 
-       return 0;
+       rc = target_xcopy_issue_pt_cmd(&xpt_cmd);
+       if (rc < 0)
+               ec_cmd->scsi_status = se_cmd->scsi_status;
+out:
+       transport_generic_free_cmd(se_cmd, 0);
+       return rc;
 }
 
 static void target_xcopy_do_work(struct work_struct *work)
@@ -736,10 +719,8 @@ static void target_xcopy_do_work(struct work_struct *work)
 
                rc = target_xcopy_write_destination(ec_cmd, xop, dst_dev,
                                                dst_lba, cur_nolb);
-               if (rc < 0) {
-                       transport_generic_free_cmd(&xop->src_pt_cmd->se_cmd, 0);
+               if (rc < 0)
                        goto out;
-               }
 
                dst_lba += cur_nolb;
                pr_debug("target_xcopy_do_work: Incremented WRITE dst_lba to %llu\n",
@@ -747,9 +728,6 @@ static void target_xcopy_do_work(struct work_struct *work)
 
                copied_nolb += cur_nolb;
                nolb -= cur_nolb;
-
-               transport_generic_free_cmd(&xop->src_pt_cmd->se_cmd, 0);
-               transport_generic_free_cmd(&xop->dst_pt_cmd->se_cmd, 0);
        }
 
        xcopy_pt_undepend_remotedev(xop);

diff --git a/drivers/target/target_core_xcopy.h b/drivers/target/target_core_xcopy.h
index f1aaf71..c56a1bd 100644 (file)
--- a/drivers/target/target_core_xcopy.h
+++ b/drivers/target/target_core_xcopy.h
@@ -18,8 +18,6 @@ enum xcopy_origin_list {
        XCOL_DEST_RECV_OP = 0x02,
 };
 
-struct xcopy_pt_cmd;
-
 struct xcopy_op {
        int op_origin;
 
@@ -36,9 +34,6 @@ struct xcopy_op {
        unsigned short dtdi;
        unsigned short nolb;
 
-       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;