btrfs: add flags to give an hint to the chunk allocator (rebased on b6e833567ea12...

Add the following flags to give an hint about which chunk should be
allocated in which a disk.
The following flags are created:

- BTRFS_DEV_ALLOCATION_PREFERRED_DATA
  preferred data chunk, but metadata chunk allowed
- BTRFS_DEV_ALLOCATION_PREFERRED_METADATA
  preferred metadata chunk, but data chunk allowed
- BTRFS_DEV_ALLOCATION_METADATA_ONLY
  only metadata chunk allowed
- BTRFS_DEV_ALLOCATION_DATA_ONLY
  only data chunk allowed

Signed-off-by: Goffredo Baroncelli <kreijack@inwid.it>

diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
index 47ee52859b4589567683785edbfcaec8b24b7af1..726803ce11f0d662f4c9bd4317d3db8ad4c87e2d 100644 (file)
--- a/include/uapi/linux/btrfs_tree.h
+++ b/include/uapi/linux/btrfs_tree.h
@@ -585,6 +585,20 @@ struct btrfs_node {
        struct btrfs_key_ptr ptrs[];
 } __attribute__ ((__packed__));
 
+/* dev_item.type */
+
+/* btrfs chunk allocation hints */
+#define BTRFS_DEV_ALLOCATION_MASK_BIT_COUNT    3
+/* preferred data chunk, but metadata chunk allowed */
+#define BTRFS_DEV_ALLOCATION_PREFERRED_DATA    (0ULL)
+/* preferred metadata chunk, but data chunk allowed */
+#define BTRFS_DEV_ALLOCATION_PREFERRED_METADATA        (1ULL)
+/* only metadata chunk are allowed */
+#define BTRFS_DEV_ALLOCATION_METADATA_ONLY     (2ULL)
+/* only data chunk allowed */
+#define BTRFS_DEV_ALLOCATION_DATA_ONLY         (3ULL)
+/* 5..7 are unused values */
+
 struct btrfs_dev_item {
        /* the internal btrfs device id */
        __le64 devid;