[PATCH 01/10] Replace ioctls with sysfs interface

Nitin Gupta
2010-08-09T17:26:48Z

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>
---
drivers/staging/zram/Kconfig | 12 --
drivers/staging/zram/Makefile | 2 +-
drivers/staging/zram/zram_drv.c | 186 ++++++++--------------------
drivers/staging/zram/zram_drv.h | 55 ++-------
drivers/staging/zram/zram_ioctl.h | 41 ------
drivers/staging/zram/zram_sysfs.c | 242 +++++++++++++++++++++++++++++++++++++
6 files changed, 306 insertions(+), 232 deletions(-)
delete mode 100644 drivers/staging/zram/zram_ioctl.h
create mode 100644 drivers/staging/zram/zram_sysfs.c

diff --git a/drivers/staging/zram/Kconfig b/drivers/staging/zram/Kconfig
index 4654ae2..da079f8 100644
--- a/drivers/staging/zram/Kconfig
+++ b/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.
-
diff --git a/drivers/staging/zram/Makefile b/drivers/staging/zram/Makefile
index b2c087a..c01160a 100644
--- a/drivers/staging/zram/Makefile
+++ b/drivers/staging/zram/Makefile
@@ -1,3 +1,3 @@
-zram-objs := zram_drv.o xvmalloc.o
+zram-objs := zram_drv.o zram_sysfs.o xvmalloc.o

obj-$(CONFIG_ZRAM) += zram.o
diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
index 77d4d71..3f698a5 100644
--- a/drivers/staging/zram/zram_drv.c
+++ b/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 @@ memstore:
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 @@ out:

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");
diff --git a/drivers/staging/zram/zram_drv.h b/drivers/staging/zram/zram_drv.h
index 945f974..2ef93cc 100644
--- a/drivers/staging/zram/zram_drv.h
+++ b/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
diff --git a/drivers/staging/zram/zram_ioctl.h b/drivers/staging/zram/zram_ioctl.h
deleted file mode 100644
index 5c415fa..0000000
--- a/drivers/staging/zram/zram_ioctl.h
+++ /dev/null
@@ -1,41 +0,0 @@
-/*
- * 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
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 */
--
1.7.2.1