zram: replace global tb_lock with fine grain lock

[cascardo/linux.git] / drivers / block / zram / zram_drv.h

diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index 7f21c14..5b0afde 100644 (file)
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -43,7 +43,6 @@ static const size_t max_zpage_size = PAGE_SIZE / 4 * 3;
 /*-- End of configurable params */
 
 #define SECTOR_SHIFT           9
-#define SECTOR_SIZE            (1 << SECTOR_SHIFT)
 #define SECTORS_PER_PAGE_SHIFT (PAGE_SHIFT - SECTOR_SHIFT)
 #define SECTORS_PER_PAGE       (1 << SECTORS_PER_PAGE_SHIFT)
 #define ZRAM_LOGICAL_BLOCK_SHIFT 12
@@ -51,10 +50,24 @@ static const size_t max_zpage_size = PAGE_SIZE / 4 * 3;
 #define ZRAM_SECTOR_PER_LOGICAL_BLOCK  \
        (1 << (ZRAM_LOGICAL_BLOCK_SHIFT - SECTOR_SHIFT))
 
-/* Flags for zram pages (table[page_no].flags) */
+
+/*
+ * The lower ZRAM_FLAG_SHIFT bits of table.value is for
+ * object size (excluding header), the higher bits is for
+ * zram_pageflags.
+ *
+ * zram is mainly used for memory efficiency so we want to keep memory
+ * footprint small so we can squeeze size and flags into a field.
+ * The lower ZRAM_FLAG_SHIFT bits is for object size (excluding header),
+ * the higher bits is for zram_pageflags.
+ */
+#define ZRAM_FLAG_SHIFT 24
+
+/* Flags for zram pages (table[page_no].value) */
 enum zram_pageflags {
        /* Page consists entirely of zeros */
-       ZRAM_ZERO,
+       ZRAM_ZERO = ZRAM_FLAG_SHIFT + 1,
+       ZRAM_ACCESS,    /* page in now accessed */
 
        __NR_ZRAM_PAGEFLAGS,
 };
@@ -62,11 +75,10 @@ enum zram_pageflags {
 /*-- Data structures */
 
 /* Allocated for each disk page */
-struct table {
+struct zram_table_entry {
        unsigned long handle;
-       u16 size;       /* object size (excluding header) */
-       u8 flags;
-} __aligned(4);
+       unsigned long value;
+};
 
 struct zram_stats {
        atomic64_t compr_data_size;     /* compressed size of pages stored */
@@ -81,8 +93,7 @@ struct zram_stats {
 };
 
 struct zram_meta {
-       rwlock_t tb_lock;       /* protect table */
-       struct table *table;
+       struct zram_table_entry *table;
        struct zs_pool *mem_pool;
 };