4 files changed, 91 insertions, 11 deletions

diff --git a/drivers/staging/zram/Kconfig b/drivers/staging/zram/Kconfig
index 3bec4db..06f741a 100644
--- a/drivers/staging/zram/Kconfig
+++ b/drivers/staging/zram/Kconfig
@@ -28,3 +28,10 @@ config ZRAM_DEBUG
 	help
 	  This option adds additional debugging code to the compressed
 	  RAM block device driver.
+
+config ZRAM_FOR_ANDROID
+	bool "Optimize zram behavior for android"
+	depends on ZRAM && ANDROID
+	default n
+	help
+	  This option enables modified zram behavior optimized for android
diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
index aab4ec4..5258c78 100644
--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -32,12 +32,16 @@
 #include <linux/lzo.h>
 #include <linux/string.h>
 #include <linux/vmalloc.h>
+#ifdef CONFIG_ZRAM_FOR_ANDROID
+#include <linux/swap.h>
+#endif /* CONFIG_ZRAM_FOR_ANDROID */
+
 
 #include "zram_drv.h"
 
 /* Globals */
 static int zram_major;
-struct zram *devices;
+struct zram *zram_devices;
 
 /* Module params (documentation at end) */
 unsigned int num_devices;
@@ -133,6 +137,22 @@ static void zram_set_disksize(struct zram *zram, size_t totalram_bytes)
 	zram->disksize &= PAGE_MASK;
 }
 
+#ifdef CONFIG_ZRAM_FOR_ANDROID
+/*
+ * Swap header (1st page of swap device) contains information
+ * about a swap file/partition. Prepare such a header for the
+ * given ramzswap device so that swapon can identify it as a
+ * swap partition.
+ */
+static void setup_swap_header(struct zram *zram, union swap_header *s)
+{
+	s->info.version = 1;
+	s->info.last_page = (zram->disksize >> PAGE_SHIFT) - 1;
+	s->info.nr_badpages = 0;
+	memcpy(s->magic.magic, "SWAPSPACE2", 10);
+}
+#endif /* CONFIG_ZRAM_FOR_ANDROID */
+
 static void zram_free_page(struct zram *zram, size_t index)
 {
 	u32 clen;
@@ -501,6 +521,10 @@ int zram_init_device(struct zram *zram)
 {
 	int ret;
 	size_t num_pages;
+#ifdef CONFIG_ZRAM_FOR_ANDROID
+	struct page *page;
+	union swap_header *swap_header;
+#endif /* CONFIG_ZRAM_FOR_ANDROID */
 
 	mutex_lock(&zram->init_lock);
 
@@ -535,6 +559,19 @@ int zram_init_device(struct zram *zram)
 		goto fail;
 	}
 
+#ifdef CONFIG_ZRAM_FOR_ANDROID
+	page = alloc_page(__GFP_ZERO);
+	if (!page) {
+		pr_err("Error allocating swap header page\n");
+		ret = -ENOMEM;
+		goto fail;
+	}
+	zram->table[0].page = page;
+	zram_set_flag(zram, 0, ZRAM_UNCOMPRESSED);
+	swap_header = kmap(page);
+	setup_swap_header(zram, swap_header);
+	kunmap(page);
+#endif /* CONFIG_ZRAM_FOR_ANDROID */
 	set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
 
 	/* zram devices sort of resembles non-rotational disks */
@@ -678,14 +715,14 @@ static int __init zram_init(void)
 
 	/* Allocate the device array and initialize each one */
 	pr_info("Creating %u devices ...\n", num_devices);
-	devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
-	if (!devices) {
+	zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
+	if (!zram_devices) {
 		ret = -ENOMEM;
 		goto unregister;
 	}
 
 	for (dev_id = 0; dev_id < num_devices; dev_id++) {
-		ret = create_device(&devices[dev_id], dev_id);
+		ret = create_device(&zram_devices[dev_id], dev_id);
 		if (ret)
 			goto free_devices;
 	}
@@ -694,8 +731,8 @@ static int __init zram_init(void)
 
 free_devices:
 	while (dev_id)
-		destroy_device(&devices[--dev_id]);
-	kfree(devices);
+		destroy_device(&zram_devices[--dev_id]);
+	kfree(zram_devices);
 unregister:
 	unregister_blkdev(zram_major, "zram");
 out:
@@ -708,7 +745,7 @@ static void __exit zram_exit(void)
 	struct zram *zram;
 
 	for (i = 0; i < num_devices; i++) {
-		zram = &devices[i];
+		zram = &zram_devices[i];
 
 		destroy_device(zram);
 		if (zram->init_done)
@@ -717,7 +754,7 @@ static void __exit zram_exit(void)
 
 	unregister_blkdev(zram_major, "zram");
 
-	kfree(devices);
+	kfree(zram_devices);
 	pr_debug("Cleanup done!\n");
 }
 
diff --git a/drivers/staging/zram/zram_drv.h b/drivers/staging/zram/zram_drv.h
index 408b2c0..3ad9486 100644
--- a/drivers/staging/zram/zram_drv.h
+++ b/drivers/staging/zram/zram_drv.h
@@ -120,7 +120,7 @@ struct zram {
 	struct zram_stats stats;
 };
 
-extern struct zram *devices;
+extern struct zram *zram_devices;
 extern unsigned int num_devices;
 #ifdef CONFIG_SYSFS
 extern struct attribute_group zram_disk_attr_group;
diff --git a/drivers/staging/zram/zram_sysfs.c b/drivers/staging/zram/zram_sysfs.c
index a70cc01..8a23554 100644
--- a/drivers/staging/zram/zram_sysfs.c
+++ b/drivers/staging/zram/zram_sysfs.c
@@ -35,7 +35,7 @@ static struct zram *dev_to_zram(struct device *dev)
 	struct zram *zram = NULL;
 
 	for (i = 0; i < num_devices; i++) {
-		zram = &devices[i];
+		zram = &zram_devices[i];
 		if (disk_to_dev(zram->disk) == dev)
 			break;
 	}
@@ -80,6 +80,42 @@ static ssize_t initstate_show(struct device *dev,
 	return sprintf(buf, "%u\n", zram->init_done);
 }
 
+#ifdef CONFIG_ZRAM_FOR_ANDROID
+extern int swapon(const char*specialfile, int swap_flags);
+
+static ssize_t initstate_store(struct device *dev,
+			       struct device_attribute *attr, const char *buf,
+			       size_t len)
+{
+	int ret;
+	unsigned long do_init;
+	struct zram *zram = dev_to_zram(dev);
+
+	if (zram->init_done) {
+		pr_info("the device is initialized device\n");
+		return -EBUSY;
+	}
+
+	ret = strict_strtoul(buf, 10, &do_init);
+	if (ret)
+		return ret;
+	if (!do_init)
+		return -EINVAL;
+
+	zram_init_device(zram);
+	swapon("/dev/block/zram0", 0);
+	return len;
+}
+#else
+static inline ssize_t initstate_store(struct device *dev,
+				      struct device_attribute *attr,
+				      const char *buf, size_t len)
+{
+	return 0;
+}
+#endif /* CONFIG_ZRAM_FOR_ANDROID */
+
+
 static ssize_t reset_store(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t len)
 {
@@ -190,7 +226,7 @@ static ssize_t mem_used_total_show(struct device *dev,
 
 static DEVICE_ATTR(disksize, S_IRUGO | S_IWUSR,
 		disksize_show, disksize_store);
-static DEVICE_ATTR(initstate, S_IRUGO, initstate_show, NULL);
+static DEVICE_ATTR(initstate, S_IRUGO | S_IWUSR, initstate_show, initstate_store);
 static DEVICE_ATTR(reset, S_IWUSR, NULL, reset_store);
 static DEVICE_ATTR(num_reads, S_IRUGO, num_reads_show, NULL);
 static DEVICE_ATTR(num_writes, S_IRUGO, num_writes_show, NULL);