Moved, renamed, and deleted files

The original directory structure was scattered and unorganized.
Changes are basically to make it look like kernel structure.

6 files changed, 1206 insertions, 0 deletions

diff --git a/drivers/staging/zram/Kconfig b/drivers/staging/zram/Kconfig
new file mode 100644
index 00000000..983314c4
--- /dev/null
+++ b/drivers/staging/zram/Kconfig
@@ -0,0 +1,25 @@
+config ZRAM
+	tristate "Compressed RAM block device support"
+	depends on BLOCK && SYSFS && ZSMALLOC
+	select LZO_COMPRESS
+	select LZO_DECOMPRESS
+	default n
+	help
+	  Creates virtual block devices called /dev/zramX (X = 0, 1, ...).
+	  Pages written to these disks are compressed and stored in memory
+	  itself. These disks allow very fast I/O and compression provides
+	  good amounts of memory savings.
+
+	  It has several use cases, for example: /tmp storage, use as swap
+	  disks and maybe many more.
+
+	  See zram.txt for more information.
+	  Project home: <https://compcache.googlecode.com/>
+
+config ZRAM_DEBUG
+	bool "Compressed RAM block device debug support"
+	depends on ZRAM
+	default n
+	help
+	  This option adds additional debugging code to the compressed
+	  RAM block device driver.
diff --git a/drivers/staging/zram/Makefile b/drivers/staging/zram/Makefile
new file mode 100644
index 00000000..7f4a3019
--- /dev/null
+++ b/drivers/staging/zram/Makefile
@@ -0,0 +1,3 @@
+zram-y	:=	zram_drv.o zram_sysfs.o
+
+obj-$(CONFIG_ZRAM)	+=	zram.o
diff --git a/drivers/staging/zram/zram.txt b/drivers/staging/zram/zram.txt
new file mode 100644
index 00000000..765d790a
--- /dev/null
+++ b/drivers/staging/zram/zram.txt
@@ -0,0 +1,77 @@
+zram: Compressed RAM based block devices
+----------------------------------------
+
+Project home: http://compcache.googlecode.com/
+
+* Introduction
+
+The zram module creates RAM based block devices named /dev/zram<id>
+(<id> = 0, 1, ...). Pages written to these disks are compressed and stored
+in memory itself. These disks allow very fast I/O and compression provides
+good amounts of memory savings. Some of the usecases include /tmp storage,
+use as swap disks, various caches under /var and maybe many more :)
+
+Statistics for individual zram devices are exported through sysfs nodes at
+/sys/block/zram<id>/
+
+* Usage
+
+Following shows a typical sequence of steps for using zram.
+
+1) Load Module:
+	modprobe zram num_devices=4
+	This creates 4 devices: /dev/zram{0,1,2,3}
+	(num_devices parameter is optional. Default: 1)
+
+2) Set Disksize
+        Set disk size by writing the value to sysfs node 'disksize'.
+        The value can be either in bytes or you can use mem suffixes.
+        Examples:
+            # Initialize /dev/zram0 with 50MB disksize
+            echo $((50*1024*1024)) > /sys/block/zram0/disksize
+
+            # Using mem suffixes
+            echo 256K > /sys/block/zram0/disksize
+            echo 512M > /sys/block/zram0/disksize
+            echo 1G > /sys/block/zram0/disksize
+
+3) Activate:
+	mkswap /dev/zram0
+	swapon /dev/zram0
+
+	mkfs.ext4 /dev/zram1
+	mount /dev/zram1 /tmp
+
+4) Stats:
+	Per-device statistics are exported as various nodes under
+	/sys/block/zram<id>/
+		disksize
+		num_reads
+		num_writes
+		invalid_io
+		notify_free
+		discard
+		zero_pages
+		orig_data_size
+		compr_data_size
+		mem_used_total
+
+5) Deactivate:
+	swapoff /dev/zram0
+	umount /dev/zram1
+
+6) Reset:
+	Write any positive value to 'reset' sysfs node
+	echo 1 > /sys/block/zram0/reset
+	echo 1 > /sys/block/zram1/reset
+
+	This frees all the memory allocated for the given device and
+	resets the disksize to zero. You must set the disksize again
+	before reusing the device.
+
+Please report any problems at:
+ - Mailing list: linux-mm-cc at laptop dot org
+ - Issue tracker: http://code.google.com/p/compcache/issues/list
+
+Nitin Gupta
+ngupta@vflare.org
diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
new file mode 100644
index 00000000..5918fd7d
--- /dev/null
+++ b/drivers/staging/zram/zram_drv.c
@@ -0,0 +1,751 @@
+/*
+ * Compressed RAM block device
+ *
+ * Copyright (C) 2008, 2009, 2010  Nitin Gupta
+ *
+ * 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
+ *
+ * Project home: http://compcache.googlecode.com
+ */
+
+#define KMSG_COMPONENT "zram"
+#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
+
+#ifdef CONFIG_ZRAM_DEBUG
+#define DEBUG
+#endif
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/bio.h>
+#include <linux/bitops.h>
+#include <linux/blkdev.h>
+#include <linux/buffer_head.h>
+#include <linux/device.h>
+#include <linux/genhd.h>
+#include <linux/highmem.h>
+#include <linux/slab.h>
+#include <linux/lzo.h>
+#include <linux/string.h>
+#include <linux/vmalloc.h>
+
+#include "zram_drv.h"
+
+/* Globals */
+static int zram_major;
+struct zram *zram_devices;
+
+/* Module params (documentation at end) */
+static unsigned int num_devices = 1;
+
+static void zram_stat64_add(struct zram *zram, u64 *v, u64 inc)
+{
+	spin_lock(&zram->stat64_lock);
+	*v = *v + inc;
+	spin_unlock(&zram->stat64_lock);
+}
+
+static void zram_stat64_sub(struct zram *zram, u64 *v, u64 dec)
+{
+	spin_lock(&zram->stat64_lock);
+	*v = *v - dec;
+	spin_unlock(&zram->stat64_lock);
+}
+
+static void zram_stat64_inc(struct zram *zram, u64 *v)
+{
+	zram_stat64_add(zram, v, 1);
+}
+
+static int zram_test_flag(struct zram_meta *meta, u32 index,
+			enum zram_pageflags flag)
+{
+	return meta->table[index].flags & BIT(flag);
+}
+
+static void zram_set_flag(struct zram_meta *meta, u32 index,
+			enum zram_pageflags flag)
+{
+	meta->table[index].flags |= BIT(flag);
+}
+
+static void zram_clear_flag(struct zram_meta *meta, u32 index,
+			enum zram_pageflags flag)
+{
+	meta->table[index].flags &= ~BIT(flag);
+}
+
+static int page_zero_filled(void *ptr)
+{
+	unsigned int pos;
+	unsigned long *page;
+
+	page = (unsigned long *)ptr;
+
+	for (pos = 0; pos != PAGE_SIZE / sizeof(*page); pos++) {
+		if (page[pos])
+			return 0;
+	}
+
+	return 1;
+}
+
+static void zram_free_page(struct zram *zram, size_t index)
+{
+	struct zram_meta *meta = zram->meta;
+	unsigned long handle = meta->table[index].handle;
+	u16 size = meta->table[index].size;
+
+	if (unlikely(!handle)) {
+		/*
+		 * No memory is allocated for zero filled pages.
+		 * Simply clear zero page flag.
+		 */
+		if (zram_test_flag(meta, index, ZRAM_ZERO)) {
+			zram_clear_flag(meta, index, ZRAM_ZERO);
+			zram->stats.pages_zero--;
+		}
+		return;
+	}
+
+	if (unlikely(size > max_zpage_size))
+		zram->stats.bad_compress--;
+
+	zs_free(meta->mem_pool, handle);
+
+	if (size <= PAGE_SIZE / 2)
+		zram->stats.good_compress--;
+
+	zram_stat64_sub(zram, &zram->stats.compr_size,
+			meta->table[index].size);
+	zram->stats.pages_stored--;
+
+	meta->table[index].handle = 0;
+	meta->table[index].size = 0;
+}
+
+static void handle_zero_page(struct bio_vec *bvec)
+{
+	struct page *page = bvec->bv_page;
+	void *user_mem;
+
+	user_mem = kmap_atomic(page);
+	memset(user_mem + bvec->bv_offset, 0, bvec->bv_len);
+	kunmap_atomic(user_mem);
+
+	flush_dcache_page(page);
+}
+
+static inline int is_partial_io(struct bio_vec *bvec)
+{
+	return bvec->bv_len != PAGE_SIZE;
+}
+
+static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
+{
+	int ret = LZO_E_OK;
+	size_t clen = PAGE_SIZE;
+	unsigned char *cmem;
+	struct zram_meta *meta = zram->meta;
+	unsigned long handle = meta->table[index].handle;
+
+	if (!handle || zram_test_flag(meta, index, ZRAM_ZERO)) {
+		memset(mem, 0, PAGE_SIZE);
+		return 0;
+	}
+
+	cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_RO);
+	if (meta->table[index].size == PAGE_SIZE)
+		memcpy(mem, cmem, PAGE_SIZE);
+	else
+		ret = lzo1x_decompress_safe(cmem, meta->table[index].size,
+						mem, &clen);
+	zs_unmap_object(meta->mem_pool, handle);
+
+	/* Should NEVER happen. Return bio error if it does. */
+	if (unlikely(ret != LZO_E_OK)) {
+		pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
+		zram_stat64_inc(zram, &zram->stats.failed_reads);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
+			  u32 index, int offset, struct bio *bio)
+{
+	int ret;
+	struct page *page;
+	unsigned char *user_mem, *uncmem = NULL;
+	struct zram_meta *meta = zram->meta;
+	page = bvec->bv_page;
+
+	if (unlikely(!meta->table[index].handle) ||
+			zram_test_flag(meta, index, ZRAM_ZERO)) {
+		handle_zero_page(bvec);
+		return 0;
+	}
+
+	if (is_partial_io(bvec))
+		/* Use  a temporary buffer to decompress the page */
+		uncmem = kmalloc(PAGE_SIZE, GFP_NOIO);
+
+	user_mem = kmap_atomic(page);
+	if (!is_partial_io(bvec))
+		uncmem = user_mem;
+
+	if (!uncmem) {
+		pr_info("Unable to allocate temp memory\n");
+		ret = -ENOMEM;
+		goto out_cleanup;
+	}
+
+	ret = zram_decompress_page(zram, uncmem, index);
+	/* Should NEVER happen. Return bio error if it does. */
+	if (unlikely(ret != LZO_E_OK)) {
+		pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
+		zram_stat64_inc(zram, &zram->stats.failed_reads);
+		goto out_cleanup;
+	}
+
+	if (is_partial_io(bvec))
+		memcpy(user_mem + bvec->bv_offset, uncmem + offset,
+				bvec->bv_len);
+
+	flush_dcache_page(page);
+	ret = 0;
+out_cleanup:
+	kunmap_atomic(user_mem);
+	if (is_partial_io(bvec))
+		kfree(uncmem);
+	return ret;
+}
+
+static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
+			   int offset)
+{
+	int ret = 0;
+	size_t clen;
+	unsigned long handle;
+	struct page *page;
+	unsigned char *user_mem, *cmem, *src, *uncmem = NULL;
+	struct zram_meta *meta = zram->meta;
+
+	page = bvec->bv_page;
+	src = meta->compress_buffer;
+
+	if (is_partial_io(bvec)) {
+		/*
+		 * This is a partial IO. We need to read the full page
+		 * before to write the changes.
+		 */
+		uncmem = kmalloc(PAGE_SIZE, GFP_NOIO);
+		if (!uncmem) {
+			ret = -ENOMEM;
+			goto out;
+		}
+		ret = zram_decompress_page(zram, uncmem, index);
+		if (ret)
+			goto out;
+	}
+
+	/*
+	 * System overwrites unused sectors. Free memory associated
+	 * with this sector now.
+	 */
+	if (meta->table[index].handle ||
+	    zram_test_flag(meta, index, ZRAM_ZERO))
+		zram_free_page(zram, index);
+
+	user_mem = kmap_atomic(page);
+
+	if (is_partial_io(bvec)) {
+		memcpy(uncmem + offset, user_mem + bvec->bv_offset,
+		       bvec->bv_len);
+		kunmap_atomic(user_mem);
+		user_mem = NULL;
+	} else {
+		uncmem = user_mem;
+	}
+
+	if (page_zero_filled(uncmem)) {
+		kunmap_atomic(user_mem);
+		if (is_partial_io(bvec))
+			kfree(uncmem);
+		zram->stats.pages_zero++;
+		zram_set_flag(meta, index, ZRAM_ZERO);
+		ret = 0;
+		goto out;
+	}
+
+	ret = lzo1x_1_compress(uncmem, PAGE_SIZE, src, &clen,
+			       meta->compress_workmem);
+
+	if (!is_partial_io(bvec)) {
+		kunmap_atomic(user_mem);
+		user_mem = NULL;
+		uncmem = NULL;
+	}
+
+	if (unlikely(ret != LZO_E_OK)) {
+		pr_err("Compression failed! err=%d\n", ret);
+		goto out;
+	}
+
+	if (unlikely(clen > max_zpage_size)) {
+		zram->stats.bad_compress++;
+		clen = PAGE_SIZE;
+		src = NULL;
+		if (is_partial_io(bvec))
+			src = uncmem;
+	}
+
+	handle = zs_malloc(meta->mem_pool, clen);
+	if (!handle) {
+		pr_info("Error allocating memory for compressed "
+			"page: %u, size=%zu\n", index, clen);
+		ret = -ENOMEM;
+		goto out;
+	}
+	cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_WO);
+
+	if ((clen == PAGE_SIZE) && !is_partial_io(bvec))
+		src = kmap_atomic(page);
+	memcpy(cmem, src, clen);
+	if ((clen == PAGE_SIZE) && !is_partial_io(bvec))
+		kunmap_atomic(src);
+
+	zs_unmap_object(meta->mem_pool, handle);
+
+	meta->table[index].handle = handle;
+	meta->table[index].size = clen;
+
+	/* Update stats */
+	zram_stat64_add(zram, &zram->stats.compr_size, clen);
+	zram->stats.pages_stored++;
+	if (clen <= PAGE_SIZE / 2)
+		zram->stats.good_compress++;
+
+out:
+	if (is_partial_io(bvec))
+		kfree(uncmem);
+
+	if (ret)
+		zram_stat64_inc(zram, &zram->stats.failed_writes);
+	return ret;
+}
+
+static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
+			int offset, struct bio *bio, int rw)
+{
+	int ret;
+
+	if (rw == READ) {
+		down_read(&zram->lock);
+		ret = zram_bvec_read(zram, bvec, index, offset, bio);
+		up_read(&zram->lock);
+	} else {
+		down_write(&zram->lock);
+		ret = zram_bvec_write(zram, bvec, index, offset);
+		up_write(&zram->lock);
+	}
+
+	return ret;
+}
+
+static void update_position(u32 *index, int *offset, struct bio_vec *bvec)
+{
+	if (*offset + bvec->bv_len >= PAGE_SIZE)
+		(*index)++;
+	*offset = (*offset + bvec->bv_len) % PAGE_SIZE;
+}
+
+static void __zram_make_request(struct zram *zram, struct bio *bio, int rw)
+{
+	int i, offset;
+	u32 index;
+	struct bio_vec *bvec;
+
+	switch (rw) {
+	case READ:
+		zram_stat64_inc(zram, &zram->stats.num_reads);
+		break;
+	case WRITE:
+		zram_stat64_inc(zram, &zram->stats.num_writes);
+		break;
+	}
+
+	index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT;
+	offset = (bio->bi_sector & (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;
+
+	bio_for_each_segment(bvec, bio, i) {
+		int max_transfer_size = PAGE_SIZE - offset;
+
+		if (bvec->bv_len > max_transfer_size) {
+			/*
+			 * zram_bvec_rw() can only make operation on a single
+			 * zram page. Split the bio vector.
+			 */
+			struct bio_vec bv;
+
+			bv.bv_page = bvec->bv_page;
+			bv.bv_len = max_transfer_size;
+			bv.bv_offset = bvec->bv_offset;
+
+			if (zram_bvec_rw(zram, &bv, index, offset, bio, rw) < 0)
+				goto out;
+
+			bv.bv_len = bvec->bv_len - max_transfer_size;
+			bv.bv_offset += max_transfer_size;
+			if (zram_bvec_rw(zram, &bv, index+1, 0, bio, rw) < 0)
+				goto out;
+		} else
+			if (zram_bvec_rw(zram, bvec, index, offset, bio, rw)
+			    < 0)
+				goto out;
+
+		update_position(&index, &offset, bvec);
+	}
+
+	set_bit(BIO_UPTODATE, &bio->bi_flags);
+	bio_endio(bio, 0);
+	return;
+
+out:
+	bio_io_error(bio);
+}
+
+/*
+ * Check if request is within bounds and aligned on zram logical blocks.
+ */
+static inline int valid_io_request(struct zram *zram, struct bio *bio)
+{
+	if (unlikely(
+		(bio->bi_sector >= (zram->disksize >> SECTOR_SHIFT)) ||
+		(bio->bi_sector & (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1)) ||
+		(bio->bi_size & (ZRAM_LOGICAL_BLOCK_SIZE - 1)))) {
+
+		return 0;
+	}
+
+	/* I/O request is valid */
+	return 1;
+}
+
+/*
+ * Handler function for all zram I/O requests.
+ */
+static void zram_make_request(struct request_queue *queue, struct bio *bio)
+{
+	struct zram *zram = queue->queuedata;
+
+	down_read(&zram->init_lock);
+	if (unlikely(!zram->init_done))
+		goto error;
+
+	if (!valid_io_request(zram, bio)) {
+		zram_stat64_inc(zram, &zram->stats.invalid_io);
+		goto error;
+	}
+
+	__zram_make_request(zram, bio, bio_data_dir(bio));
+	up_read(&zram->init_lock);
+
+	return;
+
+error:
+	up_read(&zram->init_lock);
+	bio_io_error(bio);
+}
+
+static void __zram_reset_device(struct zram *zram)
+{
+	size_t index;
+	struct zram_meta *meta;
+
+	if (!zram->init_done)
+		return;
+
+	meta = zram->meta;
+	zram->init_done = 0;
+
+	/* Free all pages that are still in this zram device */
+	for (index = 0; index < zram->disksize >> PAGE_SHIFT; index++) {
+		unsigned long handle = meta->table[index].handle;
+		if (!handle)
+			continue;
+
+		zs_free(meta->mem_pool, handle);
+	}
+
+	zram_meta_free(zram->meta);
+	zram->meta = NULL;
+	/* Reset stats */
+	memset(&zram->stats, 0, sizeof(zram->stats));
+
+	zram->disksize = 0;
+	set_capacity(zram->disk, 0);
+}
+
+void zram_reset_device(struct zram *zram)
+{
+	down_write(&zram->init_lock);
+	__zram_reset_device(zram);
+	up_write(&zram->init_lock);
+}
+
+void zram_meta_free(struct zram_meta *meta)
+{
+	zs_destroy_pool(meta->mem_pool);
+	kfree(meta->compress_workmem);
+	free_pages((unsigned long)meta->compress_buffer, 1);
+	vfree(meta->table);
+	kfree(meta);
+}
+
+struct zram_meta *zram_meta_alloc(u64 disksize)
+{
+	size_t num_pages;
+	struct zram_meta *meta = kmalloc(sizeof(*meta), GFP_KERNEL);
+	if (!meta)
+		goto out;
+
+	meta->compress_workmem = kzalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
+	if (!meta->compress_workmem)
+		goto free_meta;
+
+	meta->compress_buffer =
+		(void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
+	if (!meta->compress_buffer) {
+		pr_err("Error allocating compressor buffer space\n");
+		goto free_workmem;
+	}
+
+	num_pages = disksize >> PAGE_SHIFT;
+	meta->table = vzalloc(num_pages * sizeof(*meta->table));
+	if (!meta->table) {
+		pr_err("Error allocating zram address table\n");
+		goto free_buffer;
+	}
+
+	meta->mem_pool = zs_create_pool(GFP_NOIO | __GFP_HIGHMEM);
+	if (!meta->mem_pool) {
+		pr_err("Error creating memory pool\n");
+		goto free_table;
+	}
+
+	return meta;
+
+free_table:
+	vfree(meta->table);
+free_buffer:
+	free_pages((unsigned long)meta->compress_buffer, 1);
+free_workmem:
+	kfree(meta->compress_workmem);
+free_meta:
+	kfree(meta);
+	meta = NULL;
+out:
+	return meta;
+}
+
+void zram_init_device(struct zram *zram, struct zram_meta *meta)
+{
+	if (zram->disksize > 2 * (totalram_pages << PAGE_SHIFT)) {
+		pr_info(
+		"There is little point creating a zram of greater than "
+		"twice the size of memory since we expect a 2:1 compression "
+		"ratio. Note that zram uses about 0.1%% of the size of "
+		"the disk when not in use so a huge zram is "
+		"wasteful.\n"
+		"\tMemory Size: %lu kB\n"
+		"\tSize you selected: %llu kB\n"
+		"Continuing anyway ...\n",
+		(totalram_pages << PAGE_SHIFT) >> 10, zram->disksize >> 10
+		);
+	}
+
+	/* zram devices sort of resembles non-rotational disks */
+	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
+
+	zram->meta = meta;
+	zram->init_done = 1;
+
+	pr_debug("Initialization done!\n");
+}
+
+static void zram_slot_free_notify(struct block_device *bdev,
+				unsigned long index)
+{
+	struct zram *zram;
+
+	zram = bdev->bd_disk->private_data;
+	zram_free_page(zram, index);
+	zram_stat64_inc(zram, &zram->stats.notify_free);
+}
+
+static const struct block_device_operations zram_devops = {
+	.swap_slot_free_notify = zram_slot_free_notify,
+	.owner = THIS_MODULE
+};
+
+static int create_device(struct zram *zram, int device_id)
+{
+	int ret = 0;
+
+	init_rwsem(&zram->lock);
+	init_rwsem(&zram->init_lock);
+	spin_lock_init(&zram->stat64_lock);
+
+	zram->queue = blk_alloc_queue(GFP_KERNEL);
+	if (!zram->queue) {
+		pr_err("Error allocating disk queue for device %d\n",
+			device_id);
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	blk_queue_make_request(zram->queue, zram_make_request);
+	zram->queue->queuedata = zram;
+
+	 /* gendisk structure */
+	zram->disk = alloc_disk(1);
+	if (!zram->disk) {
+		blk_cleanup_queue(zram->queue);
+		pr_warn("Error allocating disk structure for device %d\n",
+			device_id);
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	zram->disk->major = zram_major;
+	zram->disk->first_minor = device_id;
+	zram->disk->fops = &zram_devops;
+	zram->disk->queue = zram->queue;
+	zram->disk->private_data = zram;
+	snprintf(zram->disk->disk_name, 16, "zram%d", device_id);
+
+	/* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
+	set_capacity(zram->disk, 0);
+
+	/*
+	 * To ensure that we always get PAGE_SIZE aligned
+	 * and n*PAGE_SIZED sized I/O requests.
+	 */
+	blk_queue_physical_block_size(zram->disk->queue, PAGE_SIZE);
+	blk_queue_logical_block_size(zram->disk->queue,
+					ZRAM_LOGICAL_BLOCK_SIZE);
+	blk_queue_io_min(zram->disk->queue, PAGE_SIZE);
+	blk_queue_io_opt(zram->disk->queue, PAGE_SIZE);
+
+	add_disk(zram->disk);
+
+	ret = sysfs_create_group(&disk_to_dev(zram->disk)->kobj,
+				&zram_disk_attr_group);
+	if (ret < 0) {
+		pr_warn("Error creating sysfs group");
+		goto out;
+	}
+
+	zram->init_done = 0;
+
+out:
+	return ret;
+}
+
+static void destroy_device(struct zram *zram)
+{
+	sysfs_remove_group(&disk_to_dev(zram->disk)->kobj,
+			&zram_disk_attr_group);
+
+	if (zram->disk) {
+		del_gendisk(zram->disk);
+		put_disk(zram->disk);
+	}
+
+	if (zram->queue)
+		blk_cleanup_queue(zram->queue);
+}
+
+unsigned int zram_get_num_devices(void)
+{
+	return num_devices;
+}
+
+static int __init zram_init(void)
+{
+	int ret, dev_id;
+
+	if (num_devices > max_num_devices) {
+		pr_warn("Invalid value for num_devices: %u\n",
+				num_devices);
+		ret = -EINVAL;
+		goto out;
+	}
+
+	zram_major = register_blkdev(0, "zram");
+	if (zram_major <= 0) {
+		pr_warn("Unable to get major number\n");
+		ret = -EBUSY;
+		goto out;
+	}
+
+	/* Allocate the device array and initialize each one */
+	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(&zram_devices[dev_id], dev_id);
+		if (ret)
+			goto free_devices;
+	}
+
+	pr_info("Created %u device(s) ...\n", num_devices);
+
+	return 0;
+
+free_devices:
+	while (dev_id)
+		destroy_device(&zram_devices[--dev_id]);
+	kfree(zram_devices);
+unregister:
+	unregister_blkdev(zram_major, "zram");
+out:
+	return ret;
+}
+
+static void __exit zram_exit(void)
+{
+	int i;
+	struct zram *zram;
+
+	for (i = 0; i < num_devices; i++) {
+		zram = &zram_devices[i];
+
+		destroy_device(zram);
+		zram_reset_device(zram);
+	}
+
+	unregister_blkdev(zram_major, "zram");
+
+	kfree(zram_devices);
+	pr_debug("Cleanup done!\n");
+}
+
+module_param(num_devices, uint, 0);
+MODULE_PARM_DESC(num_devices, "Number of zram devices");
+
+module_init(zram_init);
+module_exit(zram_exit);
+
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
+MODULE_DESCRIPTION("Compressed RAM Block Device");
diff --git a/drivers/staging/zram/zram_drv.h b/drivers/staging/zram/zram_drv.h
new file mode 100644
index 00000000..2d1a3f1e
--- /dev/null
+++ b/drivers/staging/zram/zram_drv.h
@@ -0,0 +1,123 @@
+/*
+ * Compressed RAM block device
+ *
+ * Copyright (C) 2008, 2009, 2010  Nitin Gupta
+ *
+ * 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
+ *
+ * Project home: http://compcache.googlecode.com
+ */
+
+#ifndef _ZRAM_DRV_H_
+#define _ZRAM_DRV_H_
+
+#include <linux/spinlock.h>
+#include <linux/mutex.h>
+
+#include "../zsmalloc/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 {
+	u64 compr_size;		/* compressed size of pages stored */
+	u64 num_reads;		/* failed + successful */
+	u64 num_writes;		/* --do-- */
+	u64 failed_reads;	/* should NEVER! happen */
+	u64 failed_writes;	/* can happen when memory is too low */
+	u64 invalid_io;		/* non-page-aligned I/O requests */
+	u64 notify_free;	/* no. of swap slot free notifications */
+	u32 pages_zero;		/* no. of zero filled pages */
+	u32 pages_stored;	/* no. of pages currently stored */
+	u32 good_compress;	/* % of pages with compression ratio<=50% */
+	u32 bad_compress;	/* % of pages with compression ratio>=75% */
+};
+
+struct zram_meta {
+	void *compress_workmem;
+	void *compress_buffer;
+	struct table *table;
+	struct zs_pool *mem_pool;
+};
+
+struct zram {
+	struct zram_meta *meta;
+	spinlock_t stat64_lock;	/* protect 64-bit stats */
+	struct rw_semaphore lock; /* protect compression buffers and table
+				   * against concurrent read and writes */
+	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;
+};
+
+extern struct zram *zram_devices;
+unsigned int zram_get_num_devices(void);
+#ifdef CONFIG_SYSFS
+extern struct attribute_group zram_disk_attr_group;
+#endif
+
+extern void zram_reset_device(struct zram *zram);
+extern struct zram_meta *zram_meta_alloc(u64 disksize);
+extern void zram_meta_free(struct zram_meta *meta);
+extern void zram_init_device(struct zram *zram, struct zram_meta *meta);
+
+#endif
diff --git a/drivers/staging/zram/zram_sysfs.c b/drivers/staging/zram/zram_sysfs.c
new file mode 100644
index 00000000..e6a929d4
--- /dev/null
+++ b/drivers/staging/zram/zram_sysfs.c
@@ -0,0 +1,227 @@
+/*
+ * Compressed RAM block device
+ *
+ * Copyright (C) 2008, 2009, 2010  Nitin Gupta
+ *
+ * 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
+ *
+ * Project home: http://compcache.googlecode.com/
+ */
+
+#include <linux/device.h>
+#include <linux/genhd.h>
+#include <linux/mm.h>
+#include <linux/kernel.h>
+
+#include "zram_drv.h"
+
+static u64 zram_stat64_read(struct zram *zram, u64 *v)
+{
+	u64 val;
+
+	spin_lock(&zram->stat64_lock);
+	val = *v;
+	spin_unlock(&zram->stat64_lock);
+
+	return val;
+}
+
+static struct zram *dev_to_zram(struct device *dev)
+{
+	int i;
+	struct zram *zram = NULL;
+
+	for (i = 0; i < zram_get_num_devices(); i++) {
+		zram = &zram_devices[i];
+		if (disk_to_dev(zram->disk) == dev)
+			break;
+	}
+
+	return zram;
+}
+
+static ssize_t disksize_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct zram *zram = dev_to_zram(dev);
+
+	return sprintf(buf, "%llu\n", zram->disksize);
+}
+
+static ssize_t disksize_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t len)
+{
+	u64 disksize;
+	struct zram_meta *meta;
+	struct zram *zram = dev_to_zram(dev);
+
+	disksize = memparse(buf, NULL);
+	if (!disksize)
+		return -EINVAL;
+
+	disksize = PAGE_ALIGN(disksize);
+	meta = zram_meta_alloc(disksize);
+	down_write(&zram->init_lock);
+	if (zram->init_done) {
+		up_write(&zram->init_lock);
+		zram_meta_free(meta);
+		pr_info("Cannot change disksize for initialized device\n");
+		return -EBUSY;
+	}
+
+	zram->disksize = disksize;
+	set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
+	zram_init_device(zram, meta);
+	up_write(&zram->init_lock);
+
+	return len;
+}
+
+static ssize_t initstate_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct zram *zram = dev_to_zram(dev);
+
+	return sprintf(buf, "%u\n", zram->init_done);
+}
+
+static ssize_t reset_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t len)
+{
+	int ret;
+	unsigned short do_reset;
+	struct zram *zram;
+	struct block_device *bdev;
+
+	zram = dev_to_zram(dev);
+	bdev = bdget_disk(zram->disk, 0);
+
+	/* Do not reset an active device! */
+	if (bdev->bd_holders)
+		return -EBUSY;
+
+	ret = kstrtou16(buf, 10, &do_reset);
+	if (ret)
+		return ret;
+
+	if (!do_reset)
+		return -EINVAL;
+
+	/* Make sure all pending I/O is finished */
+	if (bdev)
+		fsync_bdev(bdev);
+
+	zram_reset_device(zram);
+	return len;
+}
+
+static ssize_t num_reads_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct zram *zram = dev_to_zram(dev);
+
+	return sprintf(buf, "%llu\n",
+		zram_stat64_read(zram, &zram->stats.num_reads));
+}
+
+static ssize_t num_writes_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct zram *zram = dev_to_zram(dev);
+
+	return sprintf(buf, "%llu\n",
+		zram_stat64_read(zram, &zram->stats.num_writes));
+}
+
+static ssize_t invalid_io_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct zram *zram = dev_to_zram(dev);
+
+	return sprintf(buf, "%llu\n",
+		zram_stat64_read(zram, &zram->stats.invalid_io));
+}
+
+static ssize_t notify_free_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct zram *zram = dev_to_zram(dev);
+
+	return sprintf(buf, "%llu\n",
+		zram_stat64_read(zram, &zram->stats.notify_free));
+}
+
+static ssize_t zero_pages_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct zram *zram = dev_to_zram(dev);
+
+	return sprintf(buf, "%u\n", zram->stats.pages_zero);
+}
+
+static ssize_t orig_data_size_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct zram *zram = dev_to_zram(dev);
+
+	return sprintf(buf, "%llu\n",
+		(u64)(zram->stats.pages_stored) << PAGE_SHIFT);
+}
+
+static ssize_t compr_data_size_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct zram *zram = dev_to_zram(dev);
+
+	return sprintf(buf, "%llu\n",
+		zram_stat64_read(zram, &zram->stats.compr_size));
+}
+
+static ssize_t mem_used_total_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	u64 val = 0;
+	struct zram *zram = dev_to_zram(dev);
+	struct zram_meta *meta = zram->meta;
+
+	if (zram->init_done)
+		val = zs_get_total_size_bytes(meta->mem_pool);
+
+	return sprintf(buf, "%llu\n", val);
+}
+
+static DEVICE_ATTR(disksize, S_IRUGO | S_IWUSR,
+		disksize_show, disksize_store);
+static DEVICE_ATTR(initstate, S_IRUGO, initstate_show, NULL);
+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);
+static DEVICE_ATTR(invalid_io, S_IRUGO, invalid_io_show, NULL);
+static DEVICE_ATTR(notify_free, S_IRUGO, notify_free_show, NULL);
+static DEVICE_ATTR(zero_pages, S_IRUGO, zero_pages_show, NULL);
+static DEVICE_ATTR(orig_data_size, S_IRUGO, orig_data_size_show, NULL);
+static DEVICE_ATTR(compr_data_size, S_IRUGO, compr_data_size_show, NULL);
+static DEVICE_ATTR(mem_used_total, S_IRUGO, mem_used_total_show, NULL);
+
+static struct attribute *zram_disk_attrs[] = {
+	&dev_attr_disksize.attr,
+	&dev_attr_initstate.attr,
+	&dev_attr_reset.attr,
+	&dev_attr_num_reads.attr,
+	&dev_attr_num_writes.attr,
+	&dev_attr_invalid_io.attr,
+	&dev_attr_notify_free.attr,
+	&dev_attr_zero_pages.attr,
+	&dev_attr_orig_data_size.attr,
+	&dev_attr_compr_data_size.attr,
+	&dev_attr_mem_used_total.attr,
+	NULL,
+};
+
+struct attribute_group zram_disk_attr_group = {
+	.attrs = zram_disk_attrs,
+};