target: clean up the backend interface to caching parameters

Remove the dpo_emulated, fua_write_emulated, fua_read_emulated and
write_cache_emulated methods, and replace them with a simple bitfields in
se_subsystem_api in those cases where they ever returned one.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/target_core_device.c

@@ -972,36 +972,24 @@ int se_dev_set_unmap_granularity_alignment(
 
 int se_dev_set_emulate_dpo(struct se_device *dev, int flag)
 {
-	if ((flag != 0) && (flag != 1)) {
+	if (flag != 0 && flag != 1) {
 		pr_err("Illegal value %d\n", flag);
 		return -EINVAL;
 	}
-	if (dev->transport->dpo_emulated == NULL) {
-		pr_err("dev->transport->dpo_emulated is NULL\n");
-		return -EINVAL;
-	}
-	if (dev->transport->dpo_emulated(dev) == 0) {
-		pr_err("dev->transport->dpo_emulated not supported\n");
+
+	pr_err("dpo_emulated not supported\n");
 	return -EINVAL;
-	}
-	dev->se_sub_dev->se_dev_attrib.emulate_dpo = flag;
-	pr_debug("dev[%p]: SE Device Page Out (DPO) Emulation"
-			" bit: %d\n", dev, dev->se_sub_dev->se_dev_attrib.emulate_dpo);
-	return 0;
 }
 
 int se_dev_set_emulate_fua_write(struct se_device *dev, int flag)
 {
-	if ((flag != 0) && (flag != 1)) {
+	if (flag != 0 && flag != 1) {
 		pr_err("Illegal value %d\n", flag);
 		return -EINVAL;
 	}
-	if (dev->transport->fua_write_emulated == NULL) {
-		pr_err("dev->transport->fua_write_emulated is NULL\n");
-		return -EINVAL;
-	}
-	if (dev->transport->fua_write_emulated(dev) == 0) {
-		pr_err("dev->transport->fua_write_emulated not supported\n");
+
+	if (dev->transport->fua_write_emulated == 0) {
+		pr_err("fua_write_emulated not supported\n");
 		return -EINVAL;
 	}
 	dev->se_sub_dev->se_dev_attrib.emulate_fua_write = flag;
@@ -1012,36 +1000,23 @@ int se_dev_set_emulate_fua_write(struct se_device *dev, int flag)
 
 int se_dev_set_emulate_fua_read(struct se_device *dev, int flag)
 {
-	if ((flag != 0) && (flag != 1)) {
+	if (flag != 0 && flag != 1) {
 		pr_err("Illegal value %d\n", flag);
 		return -EINVAL;
 	}
-	if (dev->transport->fua_read_emulated == NULL) {
-		pr_err("dev->transport->fua_read_emulated is NULL\n");
-		return -EINVAL;
-	}
-	if (dev->transport->fua_read_emulated(dev) == 0) {
-		pr_err("dev->transport->fua_read_emulated not supported\n");
+
+	pr_err("ua read emulated not supported\n");
 	return -EINVAL;
-	}
-	dev->se_sub_dev->se_dev_attrib.emulate_fua_read = flag;
-	pr_debug("dev[%p]: SE Device Forced Unit Access READs: %d\n",
-			dev, dev->se_sub_dev->se_dev_attrib.emulate_fua_read);
-	return 0;
 }
 
 int se_dev_set_emulate_write_cache(struct se_device *dev, int flag)
 {
-	if ((flag != 0) && (flag != 1)) {
+	if (flag != 0 && flag != 1) {
 		pr_err("Illegal value %d\n", flag);
 		return -EINVAL;
 	}
-	if (dev->transport->write_cache_emulated == NULL) {
-		pr_err("dev->transport->write_cache_emulated is NULL\n");
-		return -EINVAL;
-	}
-	if (dev->transport->write_cache_emulated(dev) == 0) {
-		pr_err("dev->transport->write_cache_emulated not supported\n");
+	if (dev->transport->write_cache_emulated == 0) {
+		pr_err("write_cache_emulated not supported\n");
 		return -EINVAL;
 	}
 	dev->se_sub_dev->se_dev_attrib.emulate_write_cache = flag;

drivers/target/target_core_file.c

@@ -399,33 +399,6 @@ static void fd_emulate_sync_cache(struct se_task *task)
 		transport_complete_sync_cache(cmd, ret == 0);
 }
 
-/*
- * Tell TCM Core that we are capable of WriteCache emulation for
- * an underlying struct se_device.
- */
-static int fd_emulated_write_cache(struct se_device *dev)
-{
-	return 1;
-}
-
-static int fd_emulated_dpo(struct se_device *dev)
-{
-	return 0;
-}
-/*
- * Tell TCM Core that we will be emulating Forced Unit Access (FUA) for WRITEs
- * for TYPE_DISK.
- */
-static int fd_emulated_fua_write(struct se_device *dev)
-{
-	return 1;
-}
-
-static int fd_emulated_fua_read(struct se_device *dev)
-{
-	return 0;
-}
-
 /*
  * WRITE Force Unit Access (FUA) emulation on a per struct se_task
  * LBA range basis..
@@ -640,15 +613,13 @@ static struct se_subsystem_api fileio_template = {
 	.name			= "fileio",
 	.owner			= THIS_MODULE,
 	.transport_type		= TRANSPORT_PLUGIN_VHBA_PDEV,
+	.write_cache_emulated	= 1,
+	.fua_write_emulated	= 1,
 	.attach_hba		= fd_attach_hba,
 	.detach_hba		= fd_detach_hba,
 	.allocate_virtdevice	= fd_allocate_virtdevice,
 	.create_virtdevice	= fd_create_virtdevice,
 	.free_device		= fd_free_device,
-	.dpo_emulated		= fd_emulated_dpo,
-	.fua_write_emulated	= fd_emulated_fua_write,
-	.fua_read_emulated	= fd_emulated_fua_read,
-	.write_cache_emulated	= fd_emulated_write_cache,
 	.alloc_task		= fd_alloc_task,
 	.do_task		= fd_do_task,
 	.do_sync_cache		= fd_emulate_sync_cache,

drivers/target/target_core_iblock.c

@@ -351,34 +351,6 @@ static void iblock_emulate_sync_cache(struct se_task *task)
 	submit_bio(WRITE_FLUSH, bio);
 }
 
-/*
- * Tell TCM Core that we are capable of WriteCache emulation for
- * an underlying struct se_device.
- */
-static int iblock_emulated_write_cache(struct se_device *dev)
-{
-	return 1;
-}
-
-static int iblock_emulated_dpo(struct se_device *dev)
-{
-	return 0;
-}
-
-/*
- * Tell TCM Core that we will be emulating Forced Unit Access (FUA) for WRITEs
- * for TYPE_DISK.
- */
-static int iblock_emulated_fua_write(struct se_device *dev)
-{
-	return 1;
-}
-
-static int iblock_emulated_fua_read(struct se_device *dev)
-{
-	return 0;
-}
-
 static int iblock_do_discard(struct se_device *dev, sector_t lba, u32 range)
 {
 	struct iblock_dev *ibd = dev->dev_ptr;
@@ -679,15 +651,13 @@ static struct se_subsystem_api iblock_template = {
 	.name			= "iblock",
 	.owner			= THIS_MODULE,
 	.transport_type		= TRANSPORT_PLUGIN_VHBA_PDEV,
+	.write_cache_emulated	= 1,
+	.fua_write_emulated	= 1,
 	.attach_hba		= iblock_attach_hba,
 	.detach_hba		= iblock_detach_hba,
 	.allocate_virtdevice	= iblock_allocate_virtdevice,
 	.create_virtdevice	= iblock_create_virtdevice,
 	.free_device		= iblock_free_device,
-	.dpo_emulated		= iblock_emulated_dpo,
-	.fua_write_emulated	= iblock_emulated_fua_write,
-	.fua_read_emulated	= iblock_emulated_fua_read,
-	.write_cache_emulated	= iblock_emulated_write_cache,
 	.alloc_task		= iblock_alloc_task,
 	.do_task		= iblock_do_task,
 	.do_discard		= iblock_do_discard,

include/target/target_core_transport.h

@@ -218,6 +218,10 @@ struct se_subsystem_api {
 	 * Transport Type.
 	 */
 	u8 transport_type;
+
+	unsigned int fua_write_emulated : 1;
+	unsigned int write_cache_emulated : 1;
+
 	/*
 	 * struct module for struct se_hba references
 	 */
@@ -253,22 +257,6 @@ struct se_subsystem_api {
 	 */
 	void (*free_device)(void *);
 
-	/*
-	 * dpo_emulated():
-	 */
-	int (*dpo_emulated)(struct se_device *);
-	/*
-	 * fua_write_emulated():
-	 */
-	int (*fua_write_emulated)(struct se_device *);
-	/*
-	 * fua_read_emulated():
-	 */
-	int (*fua_read_emulated)(struct se_device *);
-	/*
-	 * write_cache_emulated():
-	 */
-	int (*write_cache_emulated)(struct se_device *);
 	/*
 	 * transport_complete():
 	 *