util: add 'unique' parameter to spdk_get_io_channel

Some subsystems may wish to create unique I/O channels
which are not shared across all users of the same I/O
device on the same thread.

Signed-off-by: Jim Harris <james.r.harris@intel.com>
Change-Id: I3ade3675d57338cf85b6a301285e6f392bd6cd2e

include/spdk/io_channel.h

@@ -96,8 +96,11 @@ void spdk_io_device_unregister(void *io_device);
  * The priority parameter allows callers to create different I/O channels to the same
  *  I/O device with varying priorities.  Currently this value must be set to
  *  SPDK_IO_PRIORITY_DEFAULT.
+ *
+ * The unique parameter allows callers to specify that an existing channel should not
+ *  be used to satisfy this request, even if the io_device and priority fields match.
  */
-struct spdk_io_channel *spdk_get_io_channel(void *io_device, uint32_t priority);
+struct spdk_io_channel *spdk_get_io_channel(void *io_device, uint32_t priority, bool unique);
 
 /**
  * \brief Releases a reference to an I/O channel.

lib/bdev/aio/blockdev_aio.c

@@ -336,7 +336,7 @@ blockdev_aio_destroy_cb(void *io_device, void *ctx_buf)
 static struct spdk_io_channel *
 blockdev_aio_get_io_channel(struct spdk_bdev *bdev, uint32_t priority)
 {
-	return spdk_get_io_channel(bdev, priority);
+	return spdk_get_io_channel(bdev, priority, false);
 }
 
 static const struct spdk_bdev_fn_table aio_fn_table = {

lib/bdev/nvme/blockdev_nvme.c

@@ -336,7 +336,7 @@ blockdev_nvme_get_io_channel(struct spdk_bdev *bdev, uint32_t priority)
 {
 	struct nvme_blockdev *nvme_bdev = (struct nvme_blockdev *)bdev;
 
-	return spdk_get_io_channel(nvme_bdev->ctrlr, priority);
+	return spdk_get_io_channel(nvme_bdev->ctrlr, priority, false);
 }
 
 static const struct spdk_bdev_fn_table nvmelib_fn_table = {

lib/copy/copy_engine.c

@@ -151,7 +151,7 @@ memcpy_destroy_cb(void *io_device, void *ctx_buf)
 
 static struct spdk_io_channel *mem_get_io_channel(uint32_t priority)
 {
-	return spdk_get_io_channel(&memcpy_copy_engine, priority);
+	return spdk_get_io_channel(&memcpy_copy_engine, priority, false);
 }
 
 static int
@@ -208,7 +208,7 @@ copy_destroy_cb(void *io_device, void *ctx_buf)
 struct spdk_io_channel *
 spdk_copy_engine_get_io_channel(uint32_t priority)
 {
-	return spdk_get_io_channel(&spdk_copy_module_list, priority);
+	return spdk_get_io_channel(&spdk_copy_module_list, priority, false);
 }
 
 static int

lib/copy/ioat/copy_engine_ioat.c

@@ -236,7 +236,7 @@ ioat_destroy_cb(void *io_device, void *ctx_buf)
 static struct spdk_io_channel *
 ioat_get_io_channel(uint32_t priority)
 {
-	return spdk_get_io_channel(&ioat_copy_engine, priority);
+	return spdk_get_io_channel(&ioat_copy_engine, priority, false);
 }
 
 struct ioat_probe_ctx {

lib/util/io_channel.c

@@ -130,7 +130,7 @@ spdk_io_device_unregister(void *io_device)
 }
 
 struct spdk_io_channel *
-spdk_get_io_channel(void *io_device, uint32_t priority)
+spdk_get_io_channel(void *io_device, uint32_t priority, bool unique)
 {
 	struct spdk_io_channel *ch;
 	struct io_device *dev;
@@ -154,14 +154,16 @@ spdk_get_io_channel(void *io_device, uint32_t priority)
 	}
 	pthread_mutex_unlock(&g_devlist_mutex);
 
-	TAILQ_FOREACH(ch, &g_io_channels, tailq) {
+	if (unique == false) {
-		if (ch->io_device == io_device && ch->priority == priority) {
+		TAILQ_FOREACH(ch, &g_io_channels, tailq) {
-			ch->ref++;
+			if (ch->io_device == io_device && ch->priority == priority) {
-			/*
+				ch->ref++;
-			 * An I/O channel already exists for this device on this
+				/*
-			 *  thread, so return it.
+				 * An I/O channel already exists for this device on this
-			 */
+				 *  thread, so return it.
-			return ch;
+				 */
+				return ch;
+			}
 		}
 	}
 

test/lib/util/io_channel/io_channel_ut.c

@@ -101,7 +101,7 @@ create_cb_null(void *io_device, uint32_t priority, void *ctx_buf)
 static void
 channel(void)
 {
-	struct spdk_io_channel *ch1, *ch2;
+	struct spdk_io_channel *ch1, *ch2, *ch3;
 	void *ctx;
 
 	spdk_allocate_thread();
@@ -110,12 +110,12 @@ channel(void)
 	spdk_io_device_register(&device3, create_cb_null, NULL, 0);
 
 	g_create_cb_calls = 0;
-	ch1 = spdk_get_io_channel(&device1, SPDK_IO_PRIORITY_DEFAULT);
+	ch1 = spdk_get_io_channel(&device1, SPDK_IO_PRIORITY_DEFAULT, false);
 	CU_ASSERT(g_create_cb_calls == 1);
 	SPDK_CU_ASSERT_FATAL(ch1 != NULL);
 
 	g_create_cb_calls = 0;
-	ch2 = spdk_get_io_channel(&device1, SPDK_IO_PRIORITY_DEFAULT);
+	ch2 = spdk_get_io_channel(&device1, SPDK_IO_PRIORITY_DEFAULT, false);
 	CU_ASSERT(g_create_cb_calls == 0);
 	CU_ASSERT(ch1 == ch2);
 	SPDK_CU_ASSERT_FATAL(ch2 != NULL);
@@ -125,7 +125,7 @@ channel(void)
 	CU_ASSERT(g_destroy_cb_calls == 0);
 
 	g_create_cb_calls = 0;
-	ch2 = spdk_get_io_channel(&device2, SPDK_IO_PRIORITY_DEFAULT);
+	ch2 = spdk_get_io_channel(&device2, SPDK_IO_PRIORITY_DEFAULT, false);
 	CU_ASSERT(g_create_cb_calls == 1);
 	CU_ASSERT(ch1 != ch2);
 	SPDK_CU_ASSERT_FATAL(ch2 != NULL);
@@ -133,6 +133,16 @@ channel(void)
 	ctx = spdk_io_channel_get_ctx(ch2);
 	CU_ASSERT(*(uint64_t *)ctx == ctx2);
 
+	/*
+	 * Confirm that specifying unique==true will generate a new I/O channel,
+	 *  and reuse ch2.
+	 */
+	g_create_cb_calls = 0;
+	ch3 = spdk_get_io_channel(&device2, SPDK_IO_PRIORITY_DEFAULT, true);
+	CU_ASSERT(g_create_cb_calls == 1);
+	CU_ASSERT(ch2 != ch3);
+	CU_ASSERT(ch3 != NULL);
+
 	g_destroy_cb_calls = 0;
 	spdk_put_io_channel(ch1);
 	CU_ASSERT(g_destroy_cb_calls == 1);
@@ -141,11 +151,15 @@ channel(void)
 	spdk_put_io_channel(ch2);
 	CU_ASSERT(g_destroy_cb_calls == 1);
 
-	ch1 = spdk_get_io_channel(&device3, SPDK_IO_PRIORITY_DEFAULT);
+	g_destroy_cb_calls = 0;
+	spdk_put_io_channel(ch3);
+	CU_ASSERT(g_destroy_cb_calls == 1);
+
+	ch1 = spdk_get_io_channel(&device3, SPDK_IO_PRIORITY_DEFAULT, false);
 	CU_ASSERT(ch1 == NULL);
 
 	/* Confirm failure if user specifies an invalid I/O priority. */
-	ch1 = spdk_get_io_channel(&device1, SPDK_IO_PRIORITY_DEFAULT + 1);
+	ch1 = spdk_get_io_channel(&device1, SPDK_IO_PRIORITY_DEFAULT + 1, false);
 	CU_ASSERT(ch1 == NULL);
 
 	spdk_io_device_unregister(&device1);