summaryrefslogtreecommitdiffstats
path: root/drivers/block/zram/zram_drv.h
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/block/zram/zram_drv.h')
-rw-r--r--drivers/block/zram/zram_drv.h109
1 files changed, 109 insertions, 0 deletions
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
new file mode 100644
index 000000000000..ad8aa35bae00
--- /dev/null
+++ b/drivers/block/zram/zram_drv.h
@@ -0,0 +1,109 @@
+/*
+ * Compressed RAM block device
+ *
+ * Copyright (C) 2008, 2009, 2010 Nitin Gupta
+ * 2012, 2013 Minchan Kim
+ *
+ * This code is released using a dual license strategy: BSD/GPL
+ * You can choose the licence that better fits your requirements.
+ *
+ * Released under the terms of 3-clause BSD License
+ * Released under the terms of GNU General Public License Version 2.0
+ *
+ */
+
+#ifndef _ZRAM_DRV_H_
+#define _ZRAM_DRV_H_
+
+#include <linux/spinlock.h>
+#include <linux/mutex.h>
+#include <linux/zsmalloc.h>
+
+/*
+ * Some arbitrary value. This is just to catch
+ * invalid value for num_devices module parameter.
+ */
+static const unsigned max_num_devices = 32;
+
+/*-- Configurable parameters */
+
+/*
+ * Pages that compress to size greater than this are stored
+ * uncompressed in memory.
+ */
+static const size_t max_zpage_size = PAGE_SIZE / 4 * 3;
+
+/*
+ * NOTE: max_zpage_size must be less than or equal to:
+ * ZS_MAX_ALLOC_SIZE. Otherwise, zs_malloc() would
+ * always return failure.
+ */
+
+/*-- 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
+#define ZRAM_LOGICAL_BLOCK_SIZE (1 << ZRAM_LOGICAL_BLOCK_SHIFT)
+#define ZRAM_SECTOR_PER_LOGICAL_BLOCK \
+ (1 << (ZRAM_LOGICAL_BLOCK_SHIFT - SECTOR_SHIFT))
+
+/* Flags for zram pages (table[page_no].flags) */
+enum zram_pageflags {
+ /* Page consists entirely of zeros */
+ ZRAM_ZERO,
+
+ __NR_ZRAM_PAGEFLAGS,
+};
+
+/*-- Data structures */
+
+/* Allocated for each disk page */
+struct table {
+ unsigned long handle;
+ u16 size; /* object size (excluding header) */
+ u8 count; /* object ref count (not yet used) */
+ u8 flags;
+} __aligned(4);
+
+struct zram_stats {
+ atomic64_t compr_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_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 */
+ atomic_t pages_zero; /* no. of zero filled pages */
+ atomic_t pages_stored; /* no. of pages currently stored */
+ atomic_t good_compress; /* % of pages with compression ratio<=50% */
+ atomic_t bad_compress; /* % of pages with compression ratio>=75% */
+};
+
+struct zram_meta {
+ rwlock_t tb_lock; /* protect table */
+ void *compress_workmem;
+ void *compress_buffer;
+ struct table *table;
+ struct zs_pool *mem_pool;
+ struct mutex buffer_lock; /* protect compress buffers */
+};
+
+struct zram {
+ struct zram_meta *meta;
+ struct request_queue *queue;
+ struct gendisk *disk;
+ int init_done;
+ /* Prevent concurrent execution of device init, reset and R/W request */
+ struct rw_semaphore init_lock;
+ /*
+ * This is the limit on amount of *uncompressed* worth of data
+ * we can store in a disk.
+ */
+ u64 disksize; /* bytes */
+
+ struct zram_stats stats;
+};
+#endif