Btrfs: add a new "type" field into the block reservation structure

Sometimes we need choose the method of the reservation according to the type
of the block reservation, such as the reservation for the delayed inode update.
Now we identify the type just by comparing the address of the reservation
variants, it is very ugly if it is a temporary one because we need compare it
with all the common reservation variants. So we add a new "type" field to keep
the type the reservation variants.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index ee51b7a..36e0331 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -4108,13 +4108,15 @@
 	return 0;
 }
 
-void btrfs_init_block_rsv(struct btrfs_block_rsv *rsv)
+void btrfs_init_block_rsv(struct btrfs_block_rsv *rsv, unsigned short type)
 {
 	memset(rsv, 0, sizeof(*rsv));
 	spin_lock_init(&rsv->lock);
+	rsv->type = type;
 }
 
-struct btrfs_block_rsv *btrfs_alloc_block_rsv(struct btrfs_root *root)
+struct btrfs_block_rsv *btrfs_alloc_block_rsv(struct btrfs_root *root,
+					      unsigned short type)
 {
 	struct btrfs_block_rsv *block_rsv;
 	struct btrfs_fs_info *fs_info = root->fs_info;
@@ -4123,7 +4125,7 @@
 	if (!block_rsv)
 		return NULL;
 
-	btrfs_init_block_rsv(block_rsv);
+	btrfs_init_block_rsv(block_rsv, type);
 	block_rsv->space_info = __find_space_info(fs_info,
 						  BTRFS_BLOCK_GROUP_METADATA);
 	return block_rsv;