percpu: setup_first_chunk remove dyn_size and consolidate logic

There is logic for setting variables in the static chunk init code that
could be consolidated with the dynamic chunk init code. This combines
this logic to setup for combining the allocation paths. reserved_size is
used as the conditional as a dynamic region will always exist.

Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

mm/percpu.c

@@ -1562,8 +1562,7 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
 {
 	static int smap[PERCPU_DYNAMIC_EARLY_SLOTS] __initdata;
 	static int dmap[PERCPU_DYNAMIC_EARLY_SLOTS] __initdata;
-	size_t dyn_size = ai->dyn_size;
-	size_t size_sum = ai->static_size + ai->reserved_size + dyn_size;
+	size_t size_sum = ai->static_size + ai->reserved_size + ai->dyn_size;
 	struct pcpu_chunk *schunk, *dchunk = NULL;
 	unsigned long *group_offsets;
 	size_t *group_sizes;
@@ -1690,14 +1689,7 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
 	bitmap_fill(schunk->populated, pcpu_unit_pages);
 	schunk->nr_populated = pcpu_unit_pages;
 
-	if (ai->reserved_size) {
-		schunk->free_size = ai->reserved_size;
-		pcpu_reserved_chunk = schunk;
-	} else {
-		schunk->free_size = dyn_size;
-		dyn_size = 0;			/* dynamic area covered */
-	}
-
+	schunk->free_size = ai->reserved_size ?: ai->dyn_size;
 	schunk->contig_hint = schunk->free_size;
 	schunk->map[0] = 1;
 	schunk->map[1] = schunk->start_offset;
@@ -1705,7 +1697,9 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
 	schunk->map_used = 2;
 
 	/* init dynamic chunk if necessary */
-	if (dyn_size) {
+	if (ai->reserved_size) {
+		pcpu_reserved_chunk = schunk;
+
 		dchunk = memblock_virt_alloc(pcpu_chunk_struct_size, 0);
 		INIT_LIST_HEAD(&dchunk->list);
 		INIT_LIST_HEAD(&dchunk->map_extend_list);
@@ -1717,7 +1711,7 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
 		bitmap_fill(dchunk->populated, pcpu_unit_pages);
 		dchunk->nr_populated = pcpu_unit_pages;
 
-		dchunk->contig_hint = dchunk->free_size = dyn_size;
+		dchunk->contig_hint = dchunk->free_size = ai->dyn_size;
 		dchunk->map[0] = 1;
 		dchunk->map[1] = dchunk->start_offset;
 		dchunk->map[2] = (dchunk->start_offset + dchunk->free_size) | 1;