[PATCH 4/4] scsi: target: Detect unmap support post configuration

[Mike Christie <michael.christie@oracle.com>]

On our backend we can do something similar to LIO where we can enable and
disable unmap support on the fly. In the scsi/block layer we can detect
this by just doing a rescan. However, LIO cannot detect this change
because we only check during the initial configuration. This patch
allows unmap detection to also happen when the user tries to turn it on.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
---
 drivers/target/target_core_configfs.c | 27 +++++++++++++++++++--------
 drivers/target/target_core_file.c     | 15 ++++++++++++++-
 drivers/target/target_core_iblock.c   | 11 ++++++++++-
 include/target/target_core_backend.h  |  1 +
 4 files changed, 44 insertions(+), 10 deletions(-)

diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c
index bbcbbfa72b07..416514c5c7ac 100644
--- a/drivers/target/target_core_configfs.c
+++ b/drivers/target/target_core_configfs.c
@@ -732,6 +732,7 @@ static ssize_t emulate_tpu_store(struct config_item *item,
 		const char *page, size_t count)
 {
 	struct se_dev_attrib *da = to_attrib(item);
+	struct se_device *dev = da->da_dev;
 	bool flag;
 	int ret;
 
@@ -744,8 +745,11 @@ static ssize_t emulate_tpu_store(struct config_item *item,
 	 * Discard supported is detected iblock_create_virtdevice().
 	 */
 	if (flag && !da->max_unmap_block_desc_count) {
-		pr_err("Generic Block Discard not supported\n");
-		return -ENOSYS;
+		if (!dev->transport->configure_unmap ||
+		    !dev->transport->configure_unmap(dev)) {
+			pr_err("Generic Block Discard not supported\n");
+			return -ENOSYS;
+		}
 	}
 
 	da->emulate_tpu = flag;
@@ -758,6 +762,7 @@ static ssize_t emulate_tpws_store(struct config_item *item,
 		const char *page, size_t count)
 {
 	struct se_dev_attrib *da = to_attrib(item);
+	struct se_device *dev = da->da_dev;
 	bool flag;
 	int ret;
 
@@ -770,8 +775,11 @@ static ssize_t emulate_tpws_store(struct config_item *item,
 	 * Discard supported is detected iblock_create_virtdevice().
 	 */
 	if (flag && !da->max_unmap_block_desc_count) {
-		pr_err("Generic Block Discard not supported\n");
-		return -ENOSYS;
+		if (!dev->transport->configure_unmap ||
+		    !dev->transport->configure_unmap(dev)) {
+			pr_err("Generic Block Discard not supported\n");
+			return -ENOSYS;
+		}
 	}
 
 	da->emulate_tpws = flag;
@@ -964,6 +972,7 @@ static ssize_t unmap_zeroes_data_store(struct config_item *item,
 		const char *page, size_t count)
 {
 	struct se_dev_attrib *da = to_attrib(item);
+	struct se_device *dev = da->da_dev;
 	bool flag;
 	int ret;
 
@@ -982,10 +991,12 @@ static ssize_t unmap_zeroes_data_store(struct config_item *item,
 	 * Discard supported is detected iblock_configure_device().
 	 */
 	if (flag && !da->max_unmap_block_desc_count) {
-		pr_err("dev[%p]: Thin Provisioning LBPRZ will not be set"
-		       " because max_unmap_block_desc_count is zero\n",
-		       da->da_dev);
-		return -ENOSYS;
+		if (!dev->transport->configure_unmap ||
+		    !dev->transport->configure_unmap(dev)) {
+			pr_err("dev[%p]: Thin Provisioning LBPRZ will not be set because max_unmap_block_desc_count is zero\n",
+			       da->da_dev);
+			return -ENOSYS;
+		}
 	}
 	da->unmap_zeroes_data = flag;
 	pr_debug("dev[%p]: SE Device Thin Provisioning LBPRZ bit: %d\n",
diff --git a/drivers/target/target_core_file.c b/drivers/target/target_core_file.c
index 2011836ab7f4..a7c6df01d554 100644
--- a/drivers/target/target_core_file.c
+++ b/drivers/target/target_core_file.c
@@ -86,6 +86,18 @@ static struct se_device *fd_alloc_device(struct se_hba *hba, const char *name)
 	return &fd_dev->dev;
 }
 
+static bool fd_configure_unmap(struct se_device *dev)
+{
+	struct file *file = FD_DEV(dev)->fd_file;
+	struct inode *inode = file->f_mapping->host;
+
+	if (!S_ISBLK(inode->i_mode))
+		return true;
+
+	return target_configure_unmap_from_queue(&dev->dev_attrib,
+						 I_BDEV(inode));
+}
+
 static int fd_configure_device(struct se_device *dev)
 {
 	struct fd_dev *fd_dev = FD_DEV(dev);
@@ -150,7 +162,7 @@ static int fd_configure_device(struct se_device *dev)
 			dev_size, div_u64(dev_size, fd_dev->fd_block_size),
 			fd_dev->fd_block_size);
 
-		if (target_configure_unmap_from_queue(&dev->dev_attrib, bdev))
+		if (fd_configure_unmap(dev))
 			pr_debug("IFILE: BLOCK Discard support available,"
 				 " disabled by default\n");
 		/*
@@ -944,6 +956,7 @@ static const struct target_backend_ops fileio_ops = {
 	.configure_device	= fd_configure_device,
 	.destroy_device		= fd_destroy_device,
 	.free_device		= fd_free_device,
+	.configure_unmap	= fd_configure_unmap,
 	.parse_cdb		= fd_parse_cdb,
 	.set_configfs_dev_params = fd_set_configfs_dev_params,
 	.show_configfs_dev_params = fd_show_configfs_dev_params,
diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c
index 767ed2e9474b..c435b6dd3ae2 100644
--- a/drivers/target/target_core_iblock.c
+++ b/drivers/target/target_core_iblock.c
@@ -76,6 +76,14 @@ static struct se_device *iblock_alloc_device(struct se_hba *hba, const char *nam
 	return NULL;
 }
 
+static bool iblock_configure_unmap(struct se_device *dev)
+{
+	struct iblock_dev *ib_dev = IBLOCK_DEV(dev);
+
+	return target_configure_unmap_from_queue(&dev->dev_attrib,
+						 ib_dev->ibd_bd);
+}
+
 static int iblock_configure_device(struct se_device *dev)
 {
 	struct iblock_dev *ib_dev = IBLOCK_DEV(dev);
@@ -119,7 +127,7 @@ static int iblock_configure_device(struct se_device *dev)
 	dev->dev_attrib.hw_max_sectors = queue_max_hw_sectors(q);
 	dev->dev_attrib.hw_queue_depth = q->nr_requests;
 
-	if (target_configure_unmap_from_queue(&dev->dev_attrib, bd))
+	if (iblock_configure_unmap(dev))
 		pr_debug("IBLOCK: BLOCK Discard support available,"
 			 " disabled by default\n");
 
@@ -923,6 +931,7 @@ static const struct target_backend_ops iblock_ops = {
 	.configure_device	= iblock_configure_device,
 	.destroy_device		= iblock_destroy_device,
 	.free_device		= iblock_free_device,
+	.configure_unmap	= iblock_configure_unmap,
 	.plug_device		= iblock_plug_device,
 	.unplug_device		= iblock_unplug_device,
 	.parse_cdb		= iblock_parse_cdb,
diff --git a/include/target/target_core_backend.h b/include/target/target_core_backend.h
index 773963a1e0b5..a3c193df25b3 100644
--- a/include/target/target_core_backend.h
+++ b/include/target/target_core_backend.h
@@ -37,6 +37,7 @@ struct target_backend_ops {
 	struct se_dev_plug *(*plug_device)(struct se_device *se_dev);
 	void (*unplug_device)(struct se_dev_plug *se_plug);
 
+	bool (*configure_unmap)(struct se_device *se_dev);
 	ssize_t (*set_configfs_dev_params)(struct se_device *,
 					   const char *, ssize_t);
 	ssize_t (*show_configfs_dev_params)(struct se_device *, char *);
-- 
2.25.1