From: Kyungchan Koh <kkc6196@xxxxxx>
The testb block device driver is intended for testing, so configuration
should be easy. We are using configfs here, which can be configured with
a shell script. Basically the the testb will be configured as:
mount the configfs fs as usual:
mount -t configfs none /mnt
Checking which features the driver supports:
cat /mnt/testb/features
The 'features' attribute is for future extension. We probably will add
new features into the driver, userspace can check this attribute to find
the supported features.
Create a device:
mkdir /mnt/testb/a
Then configure the device by setting attributes under /mnt/testb/a
size: disk size in bytes
blocksize: sector size, mush be multiples of 512, and maximum is 4k
discard: if the disk supports discard
nr_queues: how many queues supported in the disk
q_depth: queue depth of the disk
Then power on the device:
echo 1 > /mnt/testb/a/power
this will create a disk, which should be /dev/testb_a
We don't allow change attributes after the device poweron once so far
We can remove the disk by writing 0 to the 'power' attribute. 'rmdir
/mnt/testb/a' will delete the device, which also remove the disk if the
disk isn't removed yet.
Signed-off-by: Kyungchan Koh <kkc6196@xxxxxx>
Signed-off-by: Shaohua Li <shli@xxxxxx>
---
drivers/block/Kconfig | 8 ++
drivers/block/Makefile | 2 +
drivers/block/test_blk.c | 261 +++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 271 insertions(+)
create mode 100644 drivers/block/test_blk.c
diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig
index 8ddc982..2da5d02 100644
--- a/drivers/block/Kconfig
+++ b/drivers/block/Kconfig
@@ -15,6 +15,14 @@ menuconfig BLK_DEV
if BLK_DEV
+config BLK_DEV_TEST_BLK
+ tristate "A test block driver"
+ depends on CONFIGFS_FS
+ help
+ A memory-based block device driver for testing purposes. Configurable
+ through configFS. Useful features such as bandwidth throttling,
+ writeback cache, and power loss emulation.
+
config BLK_DEV_NULL_BLK
tristate "Null test block driver"
diff --git a/drivers/block/Makefile b/drivers/block/Makefile
index ec8c368..f0f0d21 100644
--- a/drivers/block/Makefile
+++ b/drivers/block/Makefile
@@ -29,6 +29,8 @@ obj-$(CONFIG_VIRTIO_BLK) += virtio_blk.o
obj-$(CONFIG_BLK_DEV_SX8) += sx8.o
+obj-$(CONFIG_BLK_DEV_TEST_BLK) += test_blk.o
+
obj-$(CONFIG_XEN_BLKDEV_FRONTEND) += xen-blkfront.o
obj-$(CONFIG_XEN_BLKDEV_BACKEND) += xen-blkback/
obj-$(CONFIG_BLK_DEV_DRBD) += drbd/
diff --git a/drivers/block/test_blk.c b/drivers/block/test_blk.c
new file mode 100644
index 0000000..93e8ec2
--- /dev/null
+++ b/drivers/block/test_blk.c
@@ -0,0 +1,261 @@
+/*
+ * test_blk.c - A memory-based test block device driver.
+ *
+ * Copyright (c) 2017 Facebook, Inc.
+ *
+ * Parts derived from drivers/block/null_blk.c and drivers/block/brd.c,
+ * copyright to respective owners.
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/blkdev.h>
+#include <linux/configfs.h>
+#include <linux/radix-tree.h>
+
+/*
+ * Status flags for testb_device.
+ *
+ * CONFIGURED: Device has been configured and turned on. Cannot reconfigure.
+ * UP: Device is currently on and visible in userspace.
+ */
+enum testb_device_flags {
+ TESTB_DEV_FL_CONFIGURED = 0,
+ TESTB_DEV_FL_UP = 1,
+};
+
+/*
+ * testb_device represents the characteristics of a virtual device.
+ *
+ * @item: The struct used by configfs to represent items in fs.
+ * @lock: Protect data of the device
+ * @pages: The storage of the device.
+ * @flags: TEST_DEV_FL_ flags to indicate various status.
+ *
+ * @power: 1 means on; 0 means off.
+ * @size: The size of the disk (in bytes).
+ * @blocksize: The block size for the request queue.
+ * @nr_queues: The number of queues.
+ * @q_depth: The depth of each queue.
+ * @discard: If enable discard
+ */
+struct testb_device {
+ struct config_item item;
+ spinlock_t lock;
+ struct radix_tree_root pages;
+ unsigned long flags;
+
+ uint power;
+ u64 size;
+ uint blocksize;
+ uint nr_queues;
+ uint q_depth;
+ uint discard;
+};
+
+static inline struct testb_device *to_testb_device(struct config_item *item)
+{
+ return item ? container_of(item, struct testb_device, item) : NULL;
+}
+
+static inline ssize_t testb_device_uint_attr_show(uint val, char *page)
+{
+ return snprintf(page, PAGE_SIZE, "%u\n", val);
+}
+
+static ssize_t
+testb_device_uint_attr_store(uint *val, const char *page, size_t count)
+{
+ uint tmp;
+ int result;
+
+ result = kstrtouint(page, 0, &tmp);
+ if (result)
+ return result;
+
+ *val = tmp;
+ return count;
+}
+
+static inline ssize_t testb_device_u64_attr_show(u64 val, char *page)
+{
+ return snprintf(page, PAGE_SIZE, "%llu\n", val);
+}
+
+static ssize_t
+testb_device_u64_attr_store(u64 *val, const char *page, size_t count)
+{
+ int result;
+ u64 tmp;
+
+ result = kstrtoull(page, 0, &tmp);
+ if (result)
+ return result;
+
+ *val = tmp;
+ return count;
+}
+
+/* The following macro should only be used with TYPE = {uint, u64}. */
+#define TESTB_DEVICE_ATTR(NAME, TYPE) \
+static ssize_t \
+testb_device_##NAME##_show(struct config_item *item, char *page) \
+{ \
+ return testb_device_##TYPE##_attr_show( \
+ to_testb_device(item)->NAME, page); \
+} \
+static ssize_t \
+testb_device_##NAME##_store(struct config_item *item, const char *page, \
+ size_t count) \
+{ \
+ if (test_bit(TESTB_DEV_FL_CONFIGURED, &to_testb_device(item)->flags)) \
+ return -EBUSY; \
+ return testb_device_##TYPE##_attr_store( \
+ &to_testb_device(item)->NAME, page, count); \
+} \
+CONFIGFS_ATTR(testb_device_, NAME);
+
+TESTB_DEVICE_ATTR(size, u64);
+TESTB_DEVICE_ATTR(blocksize, uint);
+TESTB_DEVICE_ATTR(nr_queues, uint);
+TESTB_DEVICE_ATTR(q_depth, uint);
+TESTB_DEVICE_ATTR(discard, uint);
+
+static ssize_t testb_device_power_show(struct config_item *item, char *page)
+{
+ return testb_device_uint_attr_show(to_testb_device(item)->power, page);
+}
+
+static ssize_t testb_device_power_store(struct config_item *item,
+ const char *page, size_t count)
+{
+ struct testb_device *t_dev = to_testb_device(item);
+ uint newp = 0;
+ ssize_t ret;
+
+ ret = testb_device_uint_attr_store(&newp, page, count);
+ if (ret < 0)
+ return ret;
+
+ if (!t_dev->power && newp) {
+ if (test_and_set_bit(TESTB_DEV_FL_UP, &t_dev->flags))
+ return count;
+
+ set_bit(TESTB_DEV_FL_CONFIGURED, &t_dev->flags);
+ t_dev->power = newp;
+ } else if (to_testb_device(item)->power && !newp) {
+ t_dev->power = newp;
+ clear_bit(TESTB_DEV_FL_UP, &t_dev->flags);
+ }
+
+ return count;
+}
+
+CONFIGFS_ATTR(testb_device_, power);
+
+static struct configfs_attribute *testb_device_attrs[] = {
+ &testb_device_attr_power,
+ &testb_device_attr_size,
+ &testb_device_attr_blocksize,
+ &testb_device_attr_nr_queues,
+ &testb_device_attr_q_depth,
+ &testb_device_attr_discard,
+ NULL,
+};
+
+static void testb_device_release(struct config_item *item)
+{
+ kfree(to_testb_device(item));
+}
+
+static struct configfs_item_operations testb_device_ops = {
+ .release = testb_device_release,
+};
+
+static struct config_item_type testb_device_type = {
+ .ct_item_ops = &testb_device_ops,
+ .ct_attrs = testb_device_attrs,
+ .ct_owner = THIS_MODULE,
+};
+
+static struct
+config_item *testb_group_make_item(struct config_group *group, const char *name)
+{
+ struct testb_device *t_dev;
+
+ t_dev = kzalloc(sizeof(struct testb_device), GFP_KERNEL);
+ if (!t_dev)
+ return ERR_PTR(-ENOMEM);
+
+ config_item_init_type_name(&t_dev->item, name, &testb_device_type);
+
+ /* Initialize attributes with default values. */
+ t_dev->size = 1024 * 1024 * 1024ULL;
+ t_dev->blocksize = 512;
+ t_dev->nr_queues = 2;
+ t_dev->q_depth = 64;
+ t_dev->discard = 1;
+
+ return &t_dev->item;
+}
+
+static void
+testb_group_drop_item(struct config_group *group, struct config_item *item)
+{
+ config_item_put(item);
+}
+
+static ssize_t memb_group_features_show(struct config_item *item, char *page)
+{
+ return snprintf(page, PAGE_SIZE, "\n");
+}
+
+CONFIGFS_ATTR_RO(memb_group_, features);
+
+static struct configfs_attribute *testb_group_attrs[] = {
+ &memb_group_attr_features,
+ NULL,
+};
+
+static struct configfs_group_operations testb_group_ops = {
+ .make_item = testb_group_make_item,
+ .drop_item = testb_group_drop_item,
+};
+
+static struct config_item_type testb_group_type = {
+ .ct_group_ops = &testb_group_ops,
+ .ct_attrs = testb_group_attrs,
+ .ct_owner = THIS_MODULE,
+};
+
+static struct configfs_subsystem testb_subsys = {
+ .su_group = {
+ .cg_item = {
+ .ci_namebuf = "testb",
+ .ci_type = &testb_group_type,
+ },
+ },
+};
+
+static int __init testb_init(void)
+{
+ int ret = 0;
+ struct configfs_subsystem *subsys = &testb_subsys;
+
+ config_group_init(&subsys->su_group);
+ mutex_init(&subsys->su_mutex);
+
+ ret = configfs_register_subsystem(subsys);
+ return ret;
+}
+
+static void __exit testb_exit(void)
+{
+ configfs_unregister_subsystem(&testb_subsys);
+}
+
+module_init(testb_init);
+module_exit(testb_exit);
+
+MODULE_AUTHOR("Will Koh <kkc6196@xxxxxx>, Shaohua Li <shli@xxxxxx>");
+MODULE_LICENSE("GPL");
--
2.9.3
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