target: Allow sbc_ops->execute_rw() to accept SGLs + data_direction

COMPARE_AND_WRITE expects to be able to send down a DMA_FROM_DEVICE
to obtain the necessary READ payload for comparision against the
first half of the WRITE payload containing the verify user data.

Currently virtual backends expect to internally reference SGLs,
SGL nents, and data_direction, so change IBLOCK, FILEIO and RD
sbc_ops->execute_rw() to accept this values as function parameters.

Also add default sbc_execute_rw() handler for the typical case for
cmd->execute_rw() submission using cmd->t_data_sg, cmd->t_data_nents,
and cmd->data_direction).

v2 Changes:
  - Add SCF_COMPARE_AND_WRITE command flag
  - Use sbc_execute_rw() for normal cmd->execute_rw() submission
    with expected se_cmd members.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Martin Petersen <martin.petersen@oracle.com>
Cc: Chris Mason <chris.mason@fusionio.com>
Cc: James Bottomley <JBottomley@Parallels.com>
Cc: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Nicholas Bellinger <nab@daterainc.com>

drivers/target/target_core_file.c

@@ -547,11 +547,9 @@ fd_execute_unmap(struct se_cmd *cmd)
 }
 
 static sense_reason_t
-fd_execute_rw(struct se_cmd *cmd)
+fd_execute_rw(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
+	      enum dma_data_direction data_direction)
 {
-	struct scatterlist *sgl = cmd->t_data_sg;
-	u32 sgl_nents = cmd->t_data_nents;
-	enum dma_data_direction data_direction = cmd->data_direction;
 	struct se_device *dev = cmd->se_dev;
 	int ret = 0;
 

drivers/target/target_core_iblock.c

@@ -587,11 +587,9 @@ static ssize_t iblock_show_configfs_dev_params(struct se_device *dev, char *b)
 }
 
 static sense_reason_t
-iblock_execute_rw(struct se_cmd *cmd)
+iblock_execute_rw(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
+		  enum dma_data_direction data_direction)
 {
-	struct scatterlist *sgl = cmd->t_data_sg;
-	u32 sgl_nents = cmd->t_data_nents;
-	enum dma_data_direction data_direction = cmd->data_direction;
 	struct se_device *dev = cmd->se_dev;
 	struct iblock_req *ibr;
 	struct bio *bio;

drivers/target/target_core_rd.c

@@ -280,11 +280,9 @@ static struct rd_dev_sg_table *rd_get_sg_table(struct rd_dev *rd_dev, u32 page)
 }
 
 static sense_reason_t
-rd_execute_rw(struct se_cmd *cmd)
+rd_execute_rw(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
+	      enum dma_data_direction data_direction)
 {
-	struct scatterlist *sgl = cmd->t_data_sg;
-	u32 sgl_nents = cmd->t_data_nents;
-	enum dma_data_direction data_direction = cmd->data_direction;
 	struct se_device *se_dev = cmd->se_dev;
 	struct rd_dev *dev = RD_DEV(se_dev);
 	struct rd_dev_sg_table *table;

drivers/target/target_core_sbc.c

@@ -337,6 +337,13 @@ static sense_reason_t xdreadwrite_callback(struct se_cmd *cmd)
 	return ret;
 }
 
+static sense_reason_t
+sbc_execute_rw(struct se_cmd *cmd)
+{
+	return cmd->execute_rw(cmd, cmd->t_data_sg, cmd->t_data_nents,
+			       cmd->data_direction);
+}
+
 sense_reason_t
 sbc_parse_cdb(struct se_cmd *cmd, struct sbc_ops *ops)
 {
@@ -351,31 +358,36 @@ sbc_parse_cdb(struct se_cmd *cmd, struct sbc_ops *ops)
 		sectors = transport_get_sectors_6(cdb);
 		cmd->t_task_lba = transport_lba_21(cdb);
 		cmd->se_cmd_flags |= SCF_SCSI_DATA_CDB;
-		cmd->execute_cmd = ops->execute_rw;
+		cmd->execute_rw = ops->execute_rw;
+		cmd->execute_cmd = sbc_execute_rw;
 		break;
 	case READ_10:
 		sectors = transport_get_sectors_10(cdb);
 		cmd->t_task_lba = transport_lba_32(cdb);
 		cmd->se_cmd_flags |= SCF_SCSI_DATA_CDB;
-		cmd->execute_cmd = ops->execute_rw;
+		cmd->execute_rw = ops->execute_rw;
+		cmd->execute_cmd = sbc_execute_rw;
 		break;
 	case READ_12:
 		sectors = transport_get_sectors_12(cdb);
 		cmd->t_task_lba = transport_lba_32(cdb);
 		cmd->se_cmd_flags |= SCF_SCSI_DATA_CDB;
-		cmd->execute_cmd = ops->execute_rw;
+		cmd->execute_rw = ops->execute_rw;
+		cmd->execute_cmd = sbc_execute_rw;
 		break;
 	case READ_16:
 		sectors = transport_get_sectors_16(cdb);
 		cmd->t_task_lba = transport_lba_64(cdb);
 		cmd->se_cmd_flags |= SCF_SCSI_DATA_CDB;
-		cmd->execute_cmd = ops->execute_rw;
+		cmd->execute_rw = ops->execute_rw;
+		cmd->execute_cmd = sbc_execute_rw;
 		break;
 	case WRITE_6:
 		sectors = transport_get_sectors_6(cdb);
 		cmd->t_task_lba = transport_lba_21(cdb);
 		cmd->se_cmd_flags |= SCF_SCSI_DATA_CDB;
-		cmd->execute_cmd = ops->execute_rw;
+		cmd->execute_rw = ops->execute_rw;
+		cmd->execute_cmd = sbc_execute_rw;
 		break;
 	case WRITE_10:
 	case WRITE_VERIFY:
@@ -384,23 +396,26 @@ sbc_parse_cdb(struct se_cmd *cmd, struct sbc_ops *ops)
 		if (cdb[1] & 0x8)
 			cmd->se_cmd_flags |= SCF_FUA;
 		cmd->se_cmd_flags |= SCF_SCSI_DATA_CDB;
-		cmd->execute_cmd = ops->execute_rw;
+		cmd->execute_rw = ops->execute_rw;
+		cmd->execute_cmd = sbc_execute_rw;
 		break;
 	case WRITE_12:
 		sectors = transport_get_sectors_12(cdb);
 		cmd->t_task_lba = transport_lba_32(cdb);
 		if (cdb[1] & 0x8)
 			cmd->se_cmd_flags |= SCF_FUA;
 		cmd->se_cmd_flags |= SCF_SCSI_DATA_CDB;
-		cmd->execute_cmd = ops->execute_rw;
+		cmd->execute_rw = ops->execute_rw;
+		cmd->execute_cmd = sbc_execute_rw;
 		break;
 	case WRITE_16:
 		sectors = transport_get_sectors_16(cdb);
 		cmd->t_task_lba = transport_lba_64(cdb);
 		if (cdb[1] & 0x8)
 			cmd->se_cmd_flags |= SCF_FUA;
 		cmd->se_cmd_flags |= SCF_SCSI_DATA_CDB;
-		cmd->execute_cmd = ops->execute_rw;
+		cmd->execute_rw = ops->execute_rw;
+		cmd->execute_cmd = sbc_execute_rw;
 		break;
 	case XDWRITEREAD_10:
 		if (cmd->data_direction != DMA_TO_DEVICE ||
@@ -414,7 +429,8 @@ sbc_parse_cdb(struct se_cmd *cmd, struct sbc_ops *ops)
 		/*
 		 * Setup BIDI XOR callback to be run after I/O completion.
 		 */
-		cmd->execute_cmd = ops->execute_rw;
+		cmd->execute_rw = ops->execute_rw;
+		cmd->execute_cmd = sbc_execute_rw;
 		cmd->transport_complete_callback = &xdreadwrite_callback;
 		if (cdb[1] & 0x8)
 			cmd->se_cmd_flags |= SCF_FUA;
@@ -437,7 +453,8 @@ sbc_parse_cdb(struct se_cmd *cmd, struct sbc_ops *ops)
 			 * Setup BIDI XOR callback to be run during after I/O
 			 * completion.
 			 */
-			cmd->execute_cmd = ops->execute_rw;
+			cmd->execute_rw = ops->execute_rw;
+			cmd->execute_cmd = sbc_execute_rw;
 			cmd->transport_complete_callback = &xdreadwrite_callback;
 			if (cdb[1] & 0x8)
 				cmd->se_cmd_flags |= SCF_FUA;

include/target/target_core_backend.h

@@ -39,7 +39,8 @@ struct se_subsystem_api {
 };
 
 struct sbc_ops {
-	sense_reason_t (*execute_rw)(struct se_cmd *cmd);
+	sense_reason_t (*execute_rw)(struct se_cmd *cmd, struct scatterlist *,
+				     u32, enum dma_data_direction);
 	sense_reason_t (*execute_sync_cache)(struct se_cmd *cmd);
 	sense_reason_t (*execute_write_same)(struct se_cmd *cmd);
 	sense_reason_t (*execute_write_same_unmap)(struct se_cmd *cmd);

include/target/target_core_base.h

@@ -159,6 +159,8 @@ enum se_cmd_flags_table {
 	SCF_ALUA_NON_OPTIMIZED		= 0x00008000,
 	SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC = 0x00020000,
 	SCF_ACK_KREF			= 0x00040000,
+	SCF_COMPARE_AND_WRITE		= 0x00080000,
+	SCF_COMPARE_AND_WRITE_POST	= 0x00100000,
 };
 
 /* struct se_dev_entry->lun_flags and struct se_lun->lun_access */
@@ -448,11 +450,14 @@ struct se_cmd {
 	struct kref		cmd_kref;
 	struct target_core_fabric_ops *se_tfo;
 	sense_reason_t		(*execute_cmd)(struct se_cmd *);
+	sense_reason_t		(*execute_rw)(struct se_cmd *, struct scatterlist *,
+					      u32, enum dma_data_direction);
 	sense_reason_t (*transport_complete_callback)(struct se_cmd *);
 
 	unsigned char		*t_task_cdb;
 	unsigned char		__t_task_cdb[TCM_MAX_COMMAND_SIZE];
 	unsigned long long	t_task_lba;
+	unsigned int		t_task_nolb;
 	unsigned int		transport_state;
 #define CMD_T_ABORTED		(1 << 0)
 #define CMD_T_ACTIVE		(1 << 1)