bdev: add API to query supported I/O types

Some block devices do not support the unmap operation, and we may add
other optional I/O types in the future.  Add a method to check which I/O
types a specific block device supports.

Change-Id: I6e6414bf6b6482ea0224022d8326b252bd363c7f
Signed-off-by: Daniel Verkamp <daniel.verkamp@intel.com>

include/spdk/bdev.h

@@ -154,6 +154,16 @@ struct spdk_bdev {
 	TAILQ_ENTRY(spdk_bdev) link;
 };
 
+/** Blockdev I/O type */
+enum spdk_bdev_io_type {
+	SPDK_BDEV_IO_TYPE_INVALID,
+	SPDK_BDEV_IO_TYPE_READ,
+	SPDK_BDEV_IO_TYPE_WRITE,
+	SPDK_BDEV_IO_TYPE_UNMAP,
+	SPDK_BDEV_IO_TYPE_FLUSH,
+	SPDK_BDEV_IO_TYPE_RESET,
+};
+
 /**
  * Function table for a block device backend.
  *
@@ -173,16 +183,9 @@ struct spdk_bdev_fn_table {
 
 	/** Release buf for read command. */
 	void (*free_request)(struct spdk_bdev_io *);
-};
 
-/** Blockdev I/O type */
+	/** Check if the block device supports a specific I/O type. */
-enum spdk_bdev_io_type {
+	bool (*io_type_supported)(struct spdk_bdev *bdev, enum spdk_bdev_io_type);
-	SPDK_BDEV_IO_TYPE_INVALID,
-	SPDK_BDEV_IO_TYPE_READ,
-	SPDK_BDEV_IO_TYPE_WRITE,
-	SPDK_BDEV_IO_TYPE_UNMAP,
-	SPDK_BDEV_IO_TYPE_FLUSH,
-	SPDK_BDEV_IO_TYPE_RESET,
 };
 
 /** Blockdev I/O completion status */
@@ -369,6 +372,8 @@ struct spdk_bdev *spdk_bdev_get_by_name(const char *bdev_name);
 struct spdk_bdev *spdk_bdev_first(void);
 struct spdk_bdev *spdk_bdev_next(struct spdk_bdev *prev);
 
+bool spdk_bdev_io_type_supported(struct spdk_bdev *bdev, enum spdk_bdev_io_type io_type);
+
 struct spdk_bdev_io *spdk_bdev_read(struct spdk_bdev *bdev,
 				    void *buf, uint64_t nbytes, uint64_t offset,
 				    spdk_bdev_io_completion_cb cb, void *cb_arg);

lib/bdev/aio/blockdev_aio.c

@@ -277,11 +277,27 @@ static void blockdev_aio_free_request(struct spdk_bdev_io *bdev_io)
 {
 }
 
+static bool
+blockdev_aio_io_type_supported(struct spdk_bdev *bdev, enum spdk_bdev_io_type io_type)
+{
+	switch (io_type) {
+	case SPDK_BDEV_IO_TYPE_READ:
+	case SPDK_BDEV_IO_TYPE_WRITE:
+	case SPDK_BDEV_IO_TYPE_FLUSH:
+	case SPDK_BDEV_IO_TYPE_RESET:
+		return true;
+
+	default:
+		return false;
+	}
+}
+
 static struct spdk_bdev_fn_table aio_fn_table = {
-	.destruct	= blockdev_aio_destruct,
+	.destruct		= blockdev_aio_destruct,
-	.check_io	= blockdev_aio_check_io,
+	.check_io		= blockdev_aio_check_io,
-	.submit_request	= blockdev_aio_submit_request,
+	.submit_request		= blockdev_aio_submit_request,
-	.free_request	= blockdev_aio_free_request,
+	.free_request		= blockdev_aio_free_request,
+	.io_type_supported	= blockdev_aio_io_type_supported,
 };
 
 static void aio_free_disk(struct file_disk *fdisk)

lib/bdev/bdev.c

@@ -515,6 +515,12 @@ spdk_bdev_get_child_io(struct spdk_bdev_io *parent,
 	return child;
 }
 
+bool
+spdk_bdev_io_type_supported(struct spdk_bdev *bdev, enum spdk_bdev_io_type io_type)
+{
+	return bdev->fn_table->io_type_supported(bdev, io_type);
+}
+
 struct spdk_bdev_io *
 spdk_bdev_read(struct spdk_bdev *bdev,
 	       void *buf, uint64_t nbytes, uint64_t offset,

lib/bdev/malloc/blockdev_malloc.c

@@ -214,11 +214,27 @@ static void blockdev_malloc_free_request(struct spdk_bdev_io *bdev_io)
 {
 }
 
+static bool
+blockdev_malloc_io_type_supported(struct spdk_bdev *bdev, enum spdk_bdev_io_type io_type)
+{
+	switch (io_type) {
+	case SPDK_BDEV_IO_TYPE_READ:
+	case SPDK_BDEV_IO_TYPE_WRITE:
+	case SPDK_BDEV_IO_TYPE_FLUSH:
+	case SPDK_BDEV_IO_TYPE_RESET:
+		return true;
+
+	default:
+		return false;
+	}
+}
+
 static struct spdk_bdev_fn_table malloc_fn_table = {
-	.destruct	= blockdev_malloc_destruct,
+	.destruct		= blockdev_malloc_destruct,
-	.check_io	= blockdev_malloc_check_io,
+	.check_io		= blockdev_malloc_check_io,
-	.submit_request	= blockdev_malloc_submit_request,
+	.submit_request		= blockdev_malloc_submit_request,
-	.free_request	= blockdev_malloc_free_request,
+	.free_request		= blockdev_malloc_free_request,
+	.io_type_supported	= blockdev_malloc_io_type_supported,
 };
 
 struct malloc_disk *create_malloc_disk(uint64_t num_blocks, uint32_t block_size)

lib/bdev/nvme/blockdev_nvme.c

@@ -274,11 +274,34 @@ static void blockdev_nvme_free_request(struct spdk_bdev_io *bdev_io)
 {
 }
 
+static bool
+blockdev_nvme_io_type_supported(struct spdk_bdev *bdev, enum spdk_bdev_io_type io_type)
+{
+	struct nvme_blockdev *nbdev = (struct nvme_blockdev *)bdev;
+	const struct spdk_nvme_ctrlr_data *cdata;
+
+	switch (io_type) {
+	case SPDK_BDEV_IO_TYPE_READ:
+	case SPDK_BDEV_IO_TYPE_WRITE:
+	case SPDK_BDEV_IO_TYPE_RESET:
+	case SPDK_BDEV_IO_TYPE_FLUSH:
+		return true;
+
+	case SPDK_BDEV_IO_TYPE_UNMAP:
+		cdata = spdk_nvme_ctrlr_get_data(nbdev->ctrlr);
+		return cdata->oncs.dsm;
+
+	default:
+		return false;
+	}
+}
+
 static struct spdk_bdev_fn_table nvmelib_fn_table = {
-	.destruct	= blockdev_nvme_destruct,
+	.destruct		= blockdev_nvme_destruct,
-	.check_io	= blockdev_nvme_check_io,
+	.check_io		= blockdev_nvme_check_io,
-	.submit_request	= blockdev_nvme_submit_request,
+	.submit_request		= blockdev_nvme_submit_request,
-	.free_request	= blockdev_nvme_free_request,
+	.free_request		= blockdev_nvme_free_request,
+	.io_type_supported	= blockdev_nvme_io_type_supported,
 };
 
 struct nvme_probe_ctx {