Expose major and minor device numbers

kbdus/include-private/kbdus/device.h

@@ -86,8 +86,8 @@ int kbdus_device_validate_and_adjust_config(struct kbdus_device_config *config);
  *
  * SLEEPING: This function might sleep.
  */
-struct kbdus_device *kbdus_device_create(
- const struct kbdus_device_config *config, int first_minor);
+struct kbdus_device *
+ kbdus_device_create(const struct kbdus_device_config *config);
 
 /**
  * \brief Destroys a device.

kbdus/include/kbdus.h

@@ -327,7 +327,25 @@ struct kbdus_device_config
  uint8_t recoverable;
 
  /** \cond PRIVATE */
- uint8_t reserved_[71];
+ uint8_t reserved_1_[3];
+ /** \endcond */
+
+ /**
+ * \brief The device's major number.
+ *
+ * Directionality: OUT on create.
+ */
+ uint32_t major;
+
+ /**
+ * \brief The device's minor number.
+ *
+ * Directionality: OUT on create.
+ */
+ uint32_t minor;
+
+ /** \cond PRIVATE */
+ uint8_t reserved_2_[60];
  /** \endcond */
 };
 

kbdus/src/control.c

@@ -432,6 +432,9 @@ static int __kbdus_control_ioctl_create_device_(
 
  config->device.id = kbdus_control_next_id_;
 
+ config->device.major = kbdus_device_get_major();
+ config->device.minor = (u32)(index * DISK_MAX_PARTS);
+
  // copy modified configuration back to user space
 
  if (copy_to_user(config_usrptr, config, sizeof(*config)) != 0)
@@ -456,8 +459,7 @@ static int __kbdus_control_ioctl_create_device_(
 
  // create device
 
- device_wrapper->device =
- kbdus_device_create(&config->device, index * DISK_MAX_PARTS);
+ device_wrapper->device = kbdus_device_create(&config->device);
 
  if (IS_ERR(device_wrapper->device))
  {

kbdus/src/device.c

@@ -114,9 +114,11 @@ static bool
 
  // ensure that reserved space is zeroed out
 
- static const char zero[sizeof(config->reserved_)];
+ static const char zero_1[sizeof(config->reserved_1_)];
+ static const char zero_2[sizeof(config->reserved_2_)];
 
- valid = memcmp(config->reserved_, zero, sizeof(zero)) == 0;
+ valid = (memcmp(config->reserved_1_, zero_1, sizeof(zero_1)) == 0)
+ && (memcmp(config->reserved_2_, zero_2, sizeof(zero_2)) == 0);
 
  // operations -- supports_fua_write implies supports_flush
 
@@ -686,8 +688,8 @@ int kbdus_device_validate_and_adjust_config(struct kbdus_device_config *config)
  return 0;
 }
 
-struct kbdus_device *kbdus_device_create(
- const struct kbdus_device_config *config, int first_minor)
+struct kbdus_device *
+ kbdus_device_create(const struct kbdus_device_config *config)
 {
  struct kbdus_device *device;
  int ret_error;
@@ -769,7 +771,7 @@ struct kbdus_device *kbdus_device_create(
  device->disk->flags |= GENHD_FL_NO_PART_SCAN;
 
  device->disk->major = kbdus_device_major_;
- device->disk->first_minor = (int)first_minor;
+ device->disk->first_minor = (int)config->minor;
  device->disk->fops = &kbdus_device_ops_;
  device->disk->queue = device->queue;
 

libbdus/include/bdus.h

@@ -103,6 +103,12 @@ struct bdus_ctx
  * value of this field.
  */
  void *private_data;
+
+ /** \brief The device's major number. */
+ const uint32_t major;
+
+ /** \brief The device's minor number. */
+ const uint32_t minor;
 };
 
 /**
@@ -790,6 +796,10 @@ bool bdus_run_0_1_0_(
  const struct bdus_ops *ops, const struct bdus_attrs *attrs,
  void *private_data);
 
+bool bdus_run_0_1_1_(
+ const struct bdus_ops *ops, const struct bdus_attrs *attrs,
+ void *private_data);
+
 /**
  * \brief Runs a driver for a new block device with the specified callbacks and
  * attributes.
@@ -815,13 +825,17 @@ static inline bool bdus_run(
  const struct bdus_ops *ops, const struct bdus_attrs *attrs,
  void *private_data)
 {
- return bdus_run_0_1_0_(ops, attrs, private_data);
+ return bdus_run_0_1_1_(ops, attrs, private_data);
 }
 
 bool bdus_rerun_0_1_0_(
  uint64_t dev_id, const struct bdus_ops *ops, const struct bdus_attrs *attrs,
  void *private_data);
 
+bool bdus_rerun_0_1_1_(
+ uint64_t dev_id, const struct bdus_ops *ops, const struct bdus_attrs *attrs,
+ void *private_data);
+
 /**
  * \brief Runs a driver for an *existing* block device with the specified
  * callbacks and attributes.
@@ -869,7 +883,7 @@ static inline bool bdus_rerun(
  uint64_t dev_id, const struct bdus_ops *ops, const struct bdus_attrs *attrs,
  void *private_data)
 {
- return bdus_rerun_0_1_0_(dev_id, ops, attrs, private_data);
+ return bdus_rerun_0_1_1_(dev_id, ops, attrs, private_data);
 }
 
 /* -------------------------------------------------------------------------- */

libbdus/src/bdus.c

@@ -327,6 +327,8 @@ static bool bdus_execute_driver_(
  .attrs = attrs,
  .is_rerun = is_rerun,
  .private_data = private_data,
+ .major = device_config->major,
+ .minor = device_config->minor,
  };
 
  // log attribute adjustment
@@ -685,6 +687,13 @@ BDUS_EXPORT_ bool bdus_run_0_1_0_(
  return success;
 }
 
+BDUS_EXPORT_ bool bdus_run_0_1_1_(
+ const struct bdus_ops *ops, const struct bdus_attrs *attrs,
+ void *private_data)
+{
+ return bdus_run_0_1_0_(ops, attrs, private_data);
+}
+
 /* -------------------------------------------------------------------------- */
 /* driver development -- bdus_rerun() */
 
@@ -1060,6 +1069,13 @@ BDUS_EXPORT_ bool bdus_rerun_0_1_0_(
  return success;
 }
 
+BDUS_EXPORT_ bool bdus_rerun_0_1_1_(
+ uint64_t dev_id, const struct bdus_ops *ops, const struct bdus_attrs *attrs,
+ void *private_data)
+{
+ return bdus_rerun_0_1_0_(dev_id, ops, attrs, private_data);
+}
+
 /* -------------------------------------------------------------------------- */
 /* device management */
 

tests/c/major-minor.c

@@ -0,0 +1,58 @@
+/* SPDX-License-Identifier: MIT */
+/* -------------------------------------------------------------------------- */
+
+// This test ensures that the major and minor device numbers available through
+// struct bdus_ctx match those of the device's block special file.
+
+/* -------------------------------------------------------------------------- */
+
+#include <bdus.h>
+
+#include <errno.h>
+#include <stdbool.h>
+#include <sys/stat.h>
+#include <sys/sysmacros.h>
+
+/* -------------------------------------------------------------------------- */
+
+static int device_on_device_available(struct bdus_ctx *ctx)
+{
+ struct stat st;
+
+ if (stat(ctx->path, &st) != 0)
+ return errno;
+
+ if (ctx->major == major(st.st_rdev) && ctx->minor == minor(st.st_rdev))
+ *(bool *)ctx->private_data = true;
+
+ return EIO;
+}
+
+static const struct bdus_ops device_ops = {
+ .on_device_available = device_on_device_available,
+};
+
+static const struct bdus_attrs device_attrs = {
+ .size = 1 << 30,
+ .logical_block_size = 512,
+ .dont_daemonize = true,
+};
+
+/* -------------------------------------------------------------------------- */
+
+int main(void)
+{
+ for (int iteration = 0; iteration < 10; ++iteration)
+ {
+ bool matches = false;
+
+ bdus_run(&device_ops, &device_attrs, &matches);
+
+ if (!matches)
+ return 1;
+ }
+
+ return 0;
+}
+
+/* -------------------------------------------------------------------------- */