percpu: add an indirection ptr for chunk page map access

Impact: allow sharing page map, no functional difference yet

Make chunk->page access indirect by adding a pointer and renaming the
actual array to page_ar.  This will be used by future changes.

Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 4 insertions, 1 deletions

diff --git a/mm/percpu.c b/mm/percpu.c
index a84cf9977faf..5b47d9fe65f5 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -80,7 +80,8 @@ struct pcpu_chunk {
         int                     map_alloc;      /* # of map entries allocated */
         int                     *map;           /* allocation map */
         bool                    immutable;      /* no [de]population allowed */
-        struct page             *page[];        /* #cpus * UNIT_PAGES */
+        struct page             **page;         /* points to page array */
+        struct page             *page_ar[];     /* #cpus * UNIT_PAGES */
 };
 
 static int pcpu_unit_pages __read_mostly;
@@ -696,6 +697,7 @@ static struct pcpu_chunk *alloc_pcpu_chunk(void)
                                   PCPU_DFL_MAP_ALLOC * sizeof(chunk->map[0]));
         chunk->map_alloc = PCPU_DFL_MAP_ALLOC;
         chunk->map[chunk->map_used++] = pcpu_unit_size;
+        chunk->page = chunk->page_ar;
 
         chunk->vm = get_vm_area(pcpu_chunk_size, GFP_KERNEL);
         if (!chunk->vm) {
@@ -918,6 +920,7 @@ size_t __init pcpu_setup_first_chunk(pcpu_get_page_fn_t get_page_fn,
         schunk->vm = &first_vm;
         schunk->map = smap;
         schunk->map_alloc = ARRAY_SIZE(smap);
+        schunk->page = schunk->page_ar;
         schunk->free_size = dyn_size;
         schunk->contig_hint = schunk->free_size;