Staging: zram: Replace ioctls with sysfs interface

Creates per-device sysfs nodes in /sys/block/zram<id>/
Currently following stats are exported:
 - disksize
 - num_reads
 - num_writes
 - invalid_io
 - zero_pages
 - orig_data_size
 - compr_data_size
 - mem_used_total

By default, disksize is set to 0. So, to start using
a zram device, fist write a disksize value and then
initialize device by writing any positive value to
initstate. For example:

        # initialize /dev/zram0 with 50MB disksize
        echo 50*1024*1024 | bc > /sys/block/zram0/disksize
        echo 1 > /sys/block/zram0/initstate

When done using a disk, issue reset to free its memory
by writing any positive value to reset node:

        echo 1 > /sys/block/zram0/reset

This change also obviates the need for 'rzscontrol' utility.

Signed-off-by: Nitin Gupta <ngupta@vflare.org>
Acked-by: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 242 insertions, 0 deletions

diff --git a/drivers/staging/zram/zram_sysfs.c b/drivers/staging/zram/zram_sysfs.c
new file mode 100644
index 0000000..b8dbaee
--- /dev/null
+++ b/drivers/staging/zram/zram_sysfs.c
@@ -0,0 +1,242 @@
+/*
+ * 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 "zram_drv.h"
+
+#ifdef CONFIG_SYSFS
+
+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 < num_devices; i++) {
+		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)
+{
+	int ret;
+	struct zram *zram = dev_to_zram(dev);
+
+	if (zram->init_done)
+		return -EBUSY;
+
+	ret = strict_strtoull(buf, 10, &zram->disksize);
+	if (ret)
+		return ret;
+
+	zram->disksize &= PAGE_MASK;
+	set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
+
+	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 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);
+
+	ret = strict_strtoul(buf, 10, &do_init);
+	if (ret)
+		return ret;
+
+	if (!do_init)
+		return -EINVAL;
+
+	zram_init_device(zram);
+
+	return len;
+}
+
+static ssize_t reset_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t len)
+{
+	int ret;
+	unsigned long 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 = strict_strtoul(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);
+
+	if (zram->init_done)
+		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);
+
+	if (zram->init_done) {
+		val = xv_get_total_size_bytes(zram->mem_pool) +
+			((u64)(zram->stats.pages_expand) << PAGE_SHIFT);
+	}
+
+	return sprintf(buf, "%llu\n", val);
+}
+
+static DEVICE_ATTR(disksize, S_IRUGO | S_IWUGO,
+		disksize_show, disksize_store);
+static DEVICE_ATTR(initstate, S_IRUGO | S_IWUGO,
+		initstate_show, initstate_store);
+static DEVICE_ATTR(reset, S_IWUGO, 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,
+};
+
+#endif	/* CONFIG_SYSFS */