1 files changed, 27 insertions, 10 deletions

diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index 7f21c145e317..c6ee271317f5 100644
--- 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,
 };
@@ -62,27 +75,26 @@ 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 */
 	atomic64_t num_reads;	/* failed + successful */
 	atomic64_t num_writes;	/* --do-- */
-	atomic64_t failed_reads;	/* should NEVER! happen */
+	atomic64_t failed_reads;	/* can happen when memory is too low */
 	atomic64_t failed_writes;	/* can happen when memory is too low */
 	atomic64_t invalid_io;	/* non-page-aligned I/O requests */
 	atomic64_t notify_free;	/* no. of swap slot free notifications */
 	atomic64_t zero_pages;		/* no. of zero filled pages */
 	atomic64_t pages_stored;	/* no. of pages currently stored */
+	atomic_long_t max_used_pages;	/* no. of maximum pages stored */
 };
 
 struct zram_meta {
-	rwlock_t tb_lock;	/* protect table */
-	struct table *table;
+	struct zram_table_entry *table;
 	struct zs_pool *mem_pool;
 };
 
@@ -101,6 +113,11 @@ struct zram {
 	u64 disksize;	/* bytes */
 	int max_comp_streams;
 	struct zram_stats stats;
+	/*
+	 * the number of pages zram can consume for storing compressed data
+	 */
+	unsigned long limit_pages;
+
 	char compressor[10];
 };
 #endif