[PATCH 1/2] btrfs-progs: add ioctl BTRFS_IOC_DEV_PROPERTIES.

[Goffredo Baroncelli <kreijack@libero.it>]

From: Goffredo Baroncelli <kreijack@inwind.it>

Update the header to add the BTRFS_IOC_DEV_PROPERTIES ioctl:
- add ioctl BTRFS_IOC_DEV_PROPERTIES define
- add struct btrfs_ioctl_dev_properties
- add the BTRFS_DEV_PROPERTY_ define

This ioctl is a base for returning / setting information from / to  the
fields of the btrfs_dev_item object.

For now only the "type" field is returned / set.

Signed-off-by: Goffredo Baroncelli <kreijack@inwind.it>
---
 ioctl.h | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/ioctl.h b/ioctl.h
index ade6dcb9..a4febb95 100644
--- a/ioctl.h
+++ b/ioctl.h
@@ -775,6 +775,44 @@ struct btrfs_ioctl_get_subvol_rootref_args {
 };
 BUILD_ASSERT(sizeof(struct btrfs_ioctl_get_subvol_rootref_args) == 4096);
 
+#define BTRFS_DEV_PROPERTY_TYPE		(1ULL << 0)
+#define BTRFS_DEV_PROPERTY_DEV_GROUP	(1ULL << 1)
+#define BTRFS_DEV_PROPERTY_SEEK_SPEED	(1ULL << 2)
+#define BTRFS_DEV_PROPERTY_BANDWIDTH	(1ULL << 3)
+#define BTRFS_DEV_PROPERTY_READ		(1ULL << 60)
+
+/*
+ * The ioctl BTRFS_IOC_DEV_PROPERTIES can read and write the device properties.
+ *
+ * The properties that the user want to write have to be set
+ * in the 'properties' field using the BTRFS_DEV_PROPERTY_xxxx constants.
+ *
+ * If the ioctl is used to read the device properties, the bit
+ * BTRFS_DEV_PROPERTY_READ has to be set in the 'properties' field.
+ * In this case the properties that the user want have to be set in the
+ * 'properties' field. The kernel doesn't return a property that was not
+ * required, however it may return a subset of the requested properties.
+ * The returned properties have the corrispondent BTRFS_DEV_PROPERTY_xxxx
+ * flag set in the 'properties' field.
+ *
+ * Up to 2020/05/11 the only properties that can be read/write is the 'type'
+ * one.
+ */
+struct btrfs_ioctl_dev_properties {
+	__u64	devid;
+	__u64	properties;
+	__u64	type;
+	__u32	dev_group;
+	__u8	seek_speed;
+	__u8	bandwidth;
+
+	/*
+	 * for future expansion
+	 */
+	__u8	unused1[2];
+	__u64	unused2[4];
+};
+
 /* Error codes as returned by the kernel */
 enum btrfs_err_code {
 	notused,
@@ -949,6 +987,8 @@ static inline char *btrfs_err_str(enum btrfs_err_code err_code)
 				struct btrfs_ioctl_ino_lookup_user_args)
 #define BTRFS_IOC_SNAP_DESTROY_V2 _IOW(BTRFS_IOCTL_MAGIC, 63, \
 				   struct btrfs_ioctl_vol_args_v2)
+#define BTRFS_IOC_DEV_PROPERTIES _IOW(BTRFS_IOCTL_MAGIC, 64, \
+				struct btrfs_ioctl_dev_properties)
 
 #ifdef __cplusplus
 }
-- 
2.30.0