zsmalloc: use accessor

Upcoming patch will change how to encode zspage meta so for easy review,
this patch wraps code to access metadata as accessor.

Link: http://lkml.kernel.org/r/1464736881-24886-7-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 39f29ae..5da8096 100644 (file)
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -268,10 +268,14 @@ struct zs_pool {
  * A zspage's class index and fullness group
  * are encoded in its (first)page->mapping
  */
-#define CLASS_IDX_BITS 28
 #define FULLNESS_BITS  4
-#define CLASS_IDX_MASK ((1 << CLASS_IDX_BITS) - 1)
-#define FULLNESS_MASK  ((1 << FULLNESS_BITS) - 1)
+#define CLASS_BITS     28
+
+#define FULLNESS_SHIFT 0
+#define CLASS_SHIFT    (FULLNESS_SHIFT + FULLNESS_BITS)
+
+#define FULLNESS_MASK  ((1UL << FULLNESS_BITS) - 1)
+#define CLASS_MASK     ((1UL << CLASS_BITS) - 1)
 
 struct mapping_area {
 #ifdef CONFIG_PGTABLE_MAPPING
@@ -418,6 +422,41 @@ static int is_last_page(struct page *page)
        return PagePrivate2(page);
 }
 
+static inline int get_zspage_inuse(struct page *first_page)
+{
+       return first_page->inuse;
+}
+
+static inline void set_zspage_inuse(struct page *first_page, int val)
+{
+       first_page->inuse = val;
+}
+
+static inline void mod_zspage_inuse(struct page *first_page, int val)
+{
+       first_page->inuse += val;
+}
+
+static inline int get_first_obj_offset(struct page *page)
+{
+       return page->index;
+}
+
+static inline void set_first_obj_offset(struct page *page, int offset)
+{
+       page->index = offset;
+}
+
+static inline unsigned long get_freeobj(struct page *first_page)
+{
+       return (unsigned long)first_page->freelist;
+}
+
+static inline void set_freeobj(struct page *first_page, unsigned long obj)
+{
+       first_page->freelist = (void *)obj;
+}
+
 static void get_zspage_mapping(struct page *first_page,
                                unsigned int *class_idx,
                                enum fullness_group *fullness)
@@ -426,8 +465,8 @@ static void get_zspage_mapping(struct page *first_page,
        VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
 
        m = (unsigned long)first_page->mapping;
-       *fullness = m & FULLNESS_MASK;
-       *class_idx = (m >> FULLNESS_BITS) & CLASS_IDX_MASK;
+       *fullness = (m >> FULLNESS_SHIFT) & FULLNESS_MASK;
+       *class_idx = (m >> CLASS_SHIFT) & CLASS_MASK;
 }
 
 static void set_zspage_mapping(struct page *first_page,
@@ -437,8 +476,7 @@ static void set_zspage_mapping(struct page *first_page,
        unsigned long m;
        VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
 
-       m = ((class_idx & CLASS_IDX_MASK) << FULLNESS_BITS) |
-                       (fullness & FULLNESS_MASK);
+       m = (class_idx << CLASS_SHIFT) | (fullness << FULLNESS_SHIFT);
        first_page->mapping = (struct address_space *)m;
 }
 
@@ -638,7 +676,7 @@ static enum fullness_group get_fullness_group(struct size_class *class,
 
        VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
 
-       inuse = first_page->inuse;
+       inuse = get_zspage_inuse(first_page);
        objs_per_zspage = class->objs_per_zspage;
 
        if (inuse == 0)
@@ -684,7 +722,7 @@ static void insert_zspage(struct size_class *class,
         * empty/full. Put pages with higher ->inuse first.
         */
        list_add_tail(&first_page->lru, &(*head)->lru);
-       if (first_page->inuse >= (*head)->inuse)
+       if (get_zspage_inuse(first_page) >= get_zspage_inuse(*head))
                *head = first_page;
 }
 
@@ -861,7 +899,7 @@ static unsigned long obj_idx_to_offset(struct page *page,
        unsigned long off = 0;
 
        if (!is_first_page(page))
-               off = page->index;
+               off = get_first_obj_offset(page);
 
        return off + obj_idx * class_size;
 }
@@ -896,7 +934,7 @@ static void free_zspage(struct page *first_page)
        struct page *nextp, *tmp, *head_extra;
 
        VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
-       VM_BUG_ON_PAGE(first_page->inuse, first_page);
+       VM_BUG_ON_PAGE(get_zspage_inuse(first_page), first_page);
 
        head_extra = (struct page *)page_private(first_page);
 
@@ -937,7 +975,7 @@ static void init_zspage(struct size_class *class, struct page *first_page)
                 * head of corresponding zspage's freelist.
                 */
                if (page != first_page)
-                       page->index = off;
+                       set_first_obj_offset(page, off);
 
                vaddr = kmap_atomic(page);
                link = (struct link_free *)vaddr + off / sizeof(*link);
@@ -992,7 +1030,7 @@ static struct page *alloc_zspage(struct size_class *class, gfp_t flags)
                        SetPagePrivate(page);
                        set_page_private(page, 0);
                        first_page = page;
-                       first_page->inuse = 0;
+                       set_zspage_inuse(first_page, 0);
                }
                if (i == 1)
                        set_page_private(first_page, (unsigned long)page);
@@ -1007,7 +1045,7 @@ static struct page *alloc_zspage(struct size_class *class, gfp_t flags)
 
        init_zspage(class, first_page);
 
-       first_page->freelist = location_to_obj(first_page, 0);
+       set_freeobj(first_page, (unsigned long)location_to_obj(first_page, 0));
        error = 0; /* Success */
 
 cleanup:
@@ -1239,7 +1277,7 @@ static bool zspage_full(struct size_class *class, struct page *first_page)
 {
        VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
 
-       return first_page->inuse == class->objs_per_zspage;
+       return get_zspage_inuse(first_page) == class->objs_per_zspage;
 }
 
 unsigned long zs_get_total_pages(struct zs_pool *pool)
@@ -1358,13 +1396,13 @@ static unsigned long obj_malloc(struct size_class *class,
        void *vaddr;
 
        handle |= OBJ_ALLOCATED_TAG;
-       obj = (unsigned long)first_page->freelist;
+       obj = get_freeobj(first_page);
        obj_to_location(obj, &m_page, &m_objidx);
        m_offset = obj_idx_to_offset(m_page, m_objidx, class->size);
 
        vaddr = kmap_atomic(m_page);
        link = (struct link_free *)vaddr + m_offset / sizeof(*link);
-       first_page->freelist = link->next;
+       set_freeobj(first_page, (unsigned long)link->next);
        if (!class->huge)
                /* record handle in the header of allocated chunk */
                link->handle = handle;
@@ -1372,7 +1410,7 @@ static unsigned long obj_malloc(struct size_class *class,
                /* record handle in first_page->private */
                set_page_private(first_page, handle);
        kunmap_atomic(vaddr);
-       first_page->inuse++;
+       mod_zspage_inuse(first_page, 1);
        zs_stat_inc(class, OBJ_USED, 1);
 
        return obj;
@@ -1452,12 +1490,12 @@ static void obj_free(struct size_class *class, unsigned long obj)
 
        /* Insert this object in containing zspage's freelist */
        link = (struct link_free *)(vaddr + f_offset);
-       link->next = first_page->freelist;
+       link->next = (void *)get_freeobj(first_page);
        if (class->huge)
                set_page_private(first_page, 0);
        kunmap_atomic(vaddr);
-       first_page->freelist = (void *)obj;
-       first_page->inuse--;
+       set_freeobj(first_page, obj);
+       mod_zspage_inuse(first_page, -1);
        zs_stat_dec(class, OBJ_USED, 1);
 }
 
@@ -1573,7 +1611,7 @@ static unsigned long find_alloced_obj(struct size_class *class,
        void *addr = kmap_atomic(page);
 
        if (!is_first_page(page))
-               offset = page->index;
+               offset = get_first_obj_offset(page);
        offset += class->size * index;
 
        while (offset < PAGE_SIZE) {