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Staging: zram: Replace ioctls with sysfs interface
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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>
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Nitin Gupta authored and Greg Kroah-Hartman committed Aug 31, 2010
1 parent e1a164d commit 33863c2
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Showing 6 changed files with 306 additions and 232 deletions.
12 changes: 0 additions & 12 deletions drivers/staging/zram/Kconfig
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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.

2 changes: 1 addition & 1 deletion drivers/staging/zram/Makefile
View file
Original file line number Diff line number Diff line change
@@ -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
186 changes: 53 additions & 133 deletions drivers/staging/zram/zram_drv.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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)
Expand Down Expand Up @@ -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
);
Expand All @@ -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;
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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;

Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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;
Expand All @@ -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
};
Expand Down Expand Up @@ -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);

/*
Expand All @@ -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:
Expand All @@ -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);
Expand Down Expand Up @@ -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");
Expand Down
55 changes: 10 additions & 45 deletions drivers/staging/zram/zram_drv.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,6 @@
#include <linux/spinlock.h>
#include <linux/mutex.h>

#include "zram_ioctl.h"
#include "xvmalloc.h"

/*
Expand Down Expand Up @@ -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 */
Expand All @@ -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 {
Expand All @@ -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
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