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>

drivers/staging/zram/Kconfig

@@ -15,15 +15,3 @@ config ZRAM
 
 	  See zram.txt for more information.
 	  Project home: http://compcache.googlecode.com/
-
-config ZRAM_STATS
-	bool "Enable statistics for compressed RAM disks"
-	depends on ZRAM
-	default y
-	help
-	  Enable statistics collection for compressed RAM devices. Statistics
-	  are exported through ioctl interface, so you have to use zramconfig
-	  program to get them. This adds only a minimal overhead.
-
-	  If unsure, say Y.
-

drivers/staging/zram/Makefile

-zram-objs	:=	zram_drv.o xvmalloc.o
+zram-objs	:=	zram_drv.o zram_sysfs.o xvmalloc.o
 
 obj-$(CONFIG_ZRAM)	+=	zram.o

drivers/staging/zram/zram_drv.c

@@ -33,10 +33,39 @@
 
 /* Globals */
 static int zram_major;
-static struct zram *devices;
+struct zram *devices;
 
 /* Module params (documentation at end) */
-static unsigned int num_devices;
+unsigned int num_devices;
+
+static void zram_stat_inc(u32 *v)
+{
+	*v = *v + 1;
+}
+
+static void zram_stat_dec(u32 *v)
+{
+	*v = *v - 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 *zram, u32 index,
 			enum zram_pageflags flag)
@@ -91,7 +120,7 @@ static void zram_set_disksize(struct zram *zram, size_t totalram_bytes)
 		"the disk when not in use so a huge zram is "
 		"wasteful.\n"
 		"\tMemory Size: %zu kB\n"
-		"\tSize you selected: %zu kB\n"
+		"\tSize you selected: %llu kB\n"
 		"Continuing anyway ...\n",
 		totalram_bytes >> 10, zram->disksize
 		);
@@ -100,49 +129,6 @@ static void zram_set_disksize(struct zram *zram, size_t totalram_bytes)
 	zram->disksize &= PAGE_MASK;
 }
 
-static void zram_ioctl_get_stats(struct zram *zram,
-			struct zram_ioctl_stats *s)
-{
-	s->disksize = zram->disksize;
-
-#if defined(CONFIG_ZRAM_STATS)
-	{
-	struct zram_stats *rs = &zram->stats;
-	size_t succ_writes, mem_used;
-	unsigned int good_compress_perc = 0, no_compress_perc = 0;
-
-	mem_used = xv_get_total_size_bytes(zram->mem_pool)
-			+ (rs->pages_expand << PAGE_SHIFT);
-	succ_writes = zram_stat64_read(zram, &rs->num_writes) -
-			zram_stat64_read(zram, &rs->failed_writes);
-
-	if (succ_writes && rs->pages_stored) {
-		good_compress_perc = rs->good_compress * 100
-					/ rs->pages_stored;
-		no_compress_perc = rs->pages_expand * 100
-					/ rs->pages_stored;
-	}
-
-	s->num_reads = zram_stat64_read(zram, &rs->num_reads);
-	s->num_writes = zram_stat64_read(zram, &rs->num_writes);
-	s->failed_reads = zram_stat64_read(zram, &rs->failed_reads);
-	s->failed_writes = zram_stat64_read(zram, &rs->failed_writes);
-	s->invalid_io = zram_stat64_read(zram, &rs->invalid_io);
-	s->notify_free = zram_stat64_read(zram, &rs->notify_free);
-	s->pages_zero = rs->pages_zero;
-
-	s->good_compress_pct = good_compress_perc;
-	s->pages_expand_pct = no_compress_perc;
-
-	s->pages_stored = rs->pages_stored;
-	s->pages_used = mem_used >> PAGE_SHIFT;
-	s->orig_data_size = rs->pages_stored << PAGE_SHIFT;
-	s->compr_data_size = rs->compr_size;
-	s->mem_used_total = mem_used;
-	}
-#endif /* CONFIG_ZRAM_STATS */
-}
-
 static void zram_free_page(struct zram *zram, size_t index)
 {
 	u32 clen;
@@ -180,7 +166,7 @@ static void zram_free_page(struct zram *zram, size_t index)
 		zram_stat_dec(&zram->stats.good_compress);
 
 out:
-	zram->stats.compr_size -= clen;
+	zram_stat64_sub(zram, &zram->stats.compr_size, clen);
 	zram_stat_dec(&zram->stats.pages_stored);
 
 	zram->table[index].page = NULL;
@@ -396,7 +382,7 @@ static int zram_write(struct zram *zram, struct bio *bio)
 			kunmap_atomic(src, KM_USER0);
 
 		/* Update stats */
-		zram->stats.compr_size += clen;
+		zram_stat64_add(zram, &zram->stats.compr_size, clen);
 		zram_stat_inc(&zram->stats.pages_stored);
 		if (clen <= PAGE_SIZE / 2)
 			zram_stat_inc(&zram->stats.good_compress);
@@ -463,7 +449,7 @@ static int zram_make_request(struct request_queue *queue, struct bio *bio)
 	return ret;
 }
 
-static void reset_device(struct zram *zram)
+void zram_reset_device(struct zram *zram)
 {
 	size_t index;
 
@@ -506,7 +492,7 @@ static void reset_device(struct zram *zram)
 	zram->disksize = 0;
 }
 
-static int zram_ioctl_init_device(struct zram *zram)
+int zram_init_device(struct zram *zram)
 {
 	int ret;
 	size_t num_pages;
@@ -561,91 +547,12 @@ static int zram_ioctl_init_device(struct zram *zram)
 	return 0;
 
 fail:
-	reset_device(zram);
+	zram_reset_device(zram);
 
 	pr_err("Initialization failed: err=%d\n", ret);
 	return ret;
 }
 
-static int zram_ioctl_reset_device(struct zram *zram)
-{
-	if (zram->init_done)
-		reset_device(zram);
-
-	return 0;
-}
-
-static int zram_ioctl(struct block_device *bdev, fmode_t mode,
-			unsigned int cmd, unsigned long arg)
-{
-	int ret = 0;
-	size_t disksize_kb;
-
-	struct zram *zram = bdev->bd_disk->private_data;
-
-	switch (cmd) {
-	case ZRAMIO_SET_DISKSIZE_KB:
-		if (zram->init_done) {
-			ret = -EBUSY;
-			goto out;
-		}
-		if (copy_from_user(&disksize_kb, (void *)arg,
-						_IOC_SIZE(cmd))) {
-			ret = -EFAULT;
-			goto out;
-		}
-		zram->disksize = disksize_kb << 10;
-		pr_info("Disk size set to %zu kB\n", disksize_kb);
-		break;
-
-	case ZRAMIO_GET_STATS:
-	{
-		struct zram_ioctl_stats *stats;
-		if (!zram->init_done) {
-			ret = -ENOTTY;
-			goto out;
-		}
-		stats = kzalloc(sizeof(*stats), GFP_KERNEL);
-		if (!stats) {
-			ret = -ENOMEM;
-			goto out;
-		}
-		zram_ioctl_get_stats(zram, stats);
-		if (copy_to_user((void *)arg, stats, sizeof(*stats))) {
-			kfree(stats);
-			ret = -EFAULT;
-			goto out;
-		}
-		kfree(stats);
-		break;
-	}
-	case ZRAMIO_INIT:
-		ret = zram_ioctl_init_device(zram);
-		break;
-
-	case ZRAMIO_RESET:
-		/* Do not reset an active device! */
-		if (bdev->bd_holders) {
-			ret = -EBUSY;
-			goto out;
-		}
-
-		/* Make sure all pending I/O is finished */
-		if (bdev)
-			fsync_bdev(bdev);
-
-		ret = zram_ioctl_reset_device(zram);
-		break;
-
-	default:
-		pr_info("Invalid ioctl %u\n", cmd);
-		ret = -ENOTTY;
-	}
-
-out:
-	return ret;
-}
-
 void zram_slot_free_notify(struct block_device *bdev, unsigned long index)
 {
 	struct zram *zram;
@@ -656,7 +563,6 @@ void zram_slot_free_notify(struct block_device *bdev, unsigned long index)
 }
 
 static const struct block_device_operations zram_devops = {
-	.ioctl = zram_ioctl,
 	.swap_slot_free_notify = zram_slot_free_notify,
 	.owner = THIS_MODULE
 };
@@ -696,7 +602,7 @@ static int create_device(struct zram *zram, int device_id)
 	zram->disk->private_data = zram;
 	snprintf(zram->disk->disk_name, 16, "zram%d", device_id);
 
-	/* Actual capacity set using ZRAMIO_SET_DISKSIZE_KB ioctl */
+	/* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
 	set_capacity(zram->disk, 0);
 
 	/*
@@ -710,6 +616,15 @@ static int create_device(struct zram *zram, int device_id)
 
 	add_disk(zram->disk);
 
+#ifdef CONFIG_SYSFS
+	ret = sysfs_create_group(&disk_to_dev(zram->disk)->kobj,
+				&zram_disk_attr_group);
+	if (ret < 0) {
+		pr_warning("Error creating sysfs group");
+		goto out;
+	}
+#endif
+
 	zram->init_done = 0;
 
 out:
@@ -718,6 +633,11 @@ static int create_device(struct zram *zram, int device_id)
 
 static void destroy_device(struct zram *zram)
 {
+#ifdef CONFIG_SYSFS
+	sysfs_remove_group(&disk_to_dev(zram->disk)->kobj,
+			&zram_disk_attr_group);
+#endif
+
 	if (zram->disk) {
 		del_gendisk(zram->disk);
 		put_disk(zram->disk);
@@ -785,7 +705,7 @@ static void __exit zram_exit(void)
 
 		destroy_device(zram);
 		if (zram->init_done)
-			reset_device(zram);
+			zram_reset_device(zram);
 	}
 
 	unregister_blkdev(zram_major, "zram");

drivers/staging/zram/zram_drv.h

@@ -18,7 +18,6 @@
 #include <linux/spinlock.h>
 #include <linux/mutex.h>
 
-#include "zram_ioctl.h"
 #include "xvmalloc.h"
 
 /*
@@ -85,11 +84,7 @@ struct table {
 } __attribute__((aligned(4)));
 
 struct zram_stats {
-	/* basic stats */
-	size_t compr_size;	/* compressed size of pages stored -
-				 * needed to enforce memlimit */
-	/* more stats */
-#if defined(CONFIG_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 */
@@ -100,7 +95,6 @@ struct zram_stats {
 	u32 pages_stored;	/* no. of pages currently stored */
 	u32 good_compress;	/* % of pages with compression ratio<=50% */
 	u32 pages_expand;	/* % of incompressible pages */
-#endif
 };
 
 struct zram {
@@ -118,47 +112,18 @@ struct zram {
 	 * This is the limit on amount of *uncompressed* worth of data
 	 * we can store in a disk.
 	 */
-	size_t disksize;	/* bytes */
+	u64 disksize;	/* bytes */
 
 	struct zram_stats stats;
 };
 
-/*-- */
-
-/* Debugging and Stats */
-#if defined(CONFIG_ZRAM_STATS)
-static void zram_stat_inc(u32 *v)
-{
-	*v = *v + 1;
-}
-
-static void zram_stat_dec(u32 *v)
-{
-	*v = *v - 1;
-}
-
-static void zram_stat64_inc(struct zram *zram, u64 *v)
-{
-	spin_lock(&zram->stat64_lock);
-	*v = *v + 1;
-	spin_unlock(&zram->stat64_lock);
-}
-
-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;
-}
-#else
-#define zram_stat_inc(v)
-#define zram_stat_dec(v)
-#define zram_stat64_inc(r, v)
-#define zram_stat64_read(r, v)
-#endif /* CONFIG_ZRAM_STATS */
+extern struct zram *devices;
+extern unsigned int num_devices;
+#ifdef CONFIG_SYSFS
+extern struct attribute_group zram_disk_attr_group;
+#endif
+
+extern int zram_init_device(struct zram *zram);
+extern void zram_reset_device(struct zram *zram);
 
 #endif

drivers/staging/zram/zram_ioctl.h

-/*
- * 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_IOCTL_H_
-#define _ZRAM_IOCTL_H_
-
-struct zram_ioctl_stats {
-	u64 disksize;		/* disksize in bytes (user specifies in KB) */
-	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 good_compress_pct;	/* no. of pages with compression ratio<=50% */
-	u32 pages_expand_pct;	/* no. of incompressible pages */
-	u32 pages_stored;
-	u32 pages_used;
-	u64 orig_data_size;
-	u64 compr_data_size;
-	u64 mem_used_total;
-} __attribute__ ((packed, aligned(4)));
-
-#define ZRAMIO_SET_DISKSIZE_KB	_IOW('z', 0, size_t)
-#define ZRAMIO_GET_STATS	_IOR('z', 1, struct zram_ioctl_stats)
-#define ZRAMIO_INIT		_IO('z', 2)
-#define ZRAMIO_RESET		_IO('z', 3)
-
-#endif

drivers/staging/zram/zram_sysfs.c

+/*
+ * 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 */