From: Timofey Titovets <[email protected]>
This add supporting of autochange count of zram devices on demand, like
loop devices;
This working by following rules:
- Always save minimum devices count specified by num_device (can be
specified while kernel module loading)
- if last device already using add new device;
- if last and prelast devices is free - delete last zram device;
Signed-off-by: Timofey Titovets <[email protected]>
From v1 -> v2:
Delete useless variable 'ret', added documentation for explain new zram
behaviour
Please pull from:
https://github.com/Nefelim4ag/linux.git
---
Tested on 3.15.5-2-ARCH, can be applied on any kernel version
after this patch 'zram: add LZ4 compression support' -
https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/?id=6e76668e415adf799839f0ab205142ad7002d260
---
diff --git a/Documentation/blockdev/zram.txt
b/Documentation/blockdev/zram.txt
index 0595c3f..7f5c921 100644
--- a/Documentation/blockdev/zram.txt
+++ b/Documentation/blockdev/zram.txt
@@ -18,9 +18,19 @@ 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}
+ This pre creates 4 devices: /dev/zram{0,1,2,3}
(num_devices parameter is optional. Default: 1)
+ Kernel dynamically changes number of zram devices by demand
+ (between num_devices and 31)
+ If set disk size(4) for last device
+ kernel automatically adds new zram device
+ If last two devices have zero disk size after reset(8),
+ kernel will destroy last device
+
+ Summing up all features, comes one simple rule:
+ "The last zram device is always free for use"
+
2) Set max number of compression streams
Compression backend may use up to max_comp_streams compression streams,
thus allowing up to max_comp_streams concurrent compression operations.
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 089e72c..9b2fc89 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -42,6 +42,10 @@ static const char *default_compressor = "lzo";
/* Module params (documentation at end) */
static unsigned int num_devices = 1;
+static unsigned int last_created_dev = 1;
+
+static void zram_add_dev(void);
+static void zram_del_dev(void);
#define ZRAM_ATTR_RO(name) \
static ssize_t zram_attr_##name##_show(struct device *d, \
@@ -168,6 +172,7 @@ static ssize_t comp_algorithm_store(struct device *dev,
struct device_attribute *attr, const char *buf, size_t len)
{
struct zram *zram = dev_to_zram(dev);
+
down_write(&zram->init_lock);
if (init_done(zram)) {
up_write(&zram->init_lock);
@@ -239,6 +244,7 @@ static 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;
@@ -374,6 +380,7 @@ static int zram_bvec_read(struct zram *zram, struct
bio_vec *bvec,
struct page *page;
unsigned char *user_mem, *uncmem = NULL;
struct zram_meta *meta = zram->meta;
+
page = bvec->bv_page;
read_lock(&meta->tb_lock);
@@ -607,6 +614,7 @@ static void zram_reset_device(struct zram *zram,
bool reset_capacity)
/* 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;
@@ -668,6 +676,7 @@ static ssize_t disksize_store(struct device *dev,
set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
revalidate_disk(zram->disk);
up_write(&zram->init_lock);
+ zram_add_dev();
return len;
out_destroy_comp:
@@ -712,6 +721,7 @@ static ssize_t reset_store(struct device *dev,
bdput(bdev);
zram_reset_device(zram, true);
+ zram_del_dev();
return len;
out:
@@ -954,6 +964,41 @@ static void destroy_device(struct zram *zram)
blk_cleanup_queue(zram->queue);
}
+/* remove last free device, if last and prelast dev a free */
+static void zram_del_dev(void)
+{
+ if (last_created_dev < num_devices)
+ return;
+
+ if (zram_devices[last_created_dev].disksize == 0 &&
+ zram_devices[last_created_dev-1].disksize == 0
+ ) {
+ destroy_device(&zram_devices[last_created_dev]);
+ last_created_dev--;
+ pr_info("Deleted zram%u device\n", last_created_dev);
+ }
+}
+
+/* Auto add empty zram device, if last device in use */
+static void zram_add_dev(void)
+{
+ if (last_created_dev+1 > max_num_devices) {
+ pr_warn("Can't add zram%u, max device number reached\n",
+ num_devices);
+ return;
+ }
+
+ if (&zram_devices[last_created_dev].disksize > 0) {
+ last_created_dev++;
+ if (create_device(&zram_devices[last_created_dev], last_created_dev)) {
+ destroy_device(&zram_devices[last_created_dev]);
+ last_created_dev--;
+ return;
+ }
+ pr_info("Created zram%u device\n", last_created_dev);
+ }
+}
+
static int __init zram_init(void)
{
int ret, dev_id;
@@ -972,18 +1017,20 @@ static int __init zram_init(void)
goto out;
}
- /* Allocate the device array and initialize each one */
- zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
+ /* Allocate the device array */
+ zram_devices = kcalloc(max_num_devices, sizeof(struct zram), GFP_KERNEL);
if (!zram_devices) {
ret = -ENOMEM;
goto unregister;
}
+ /* Initialise zram{0..num_devices} */
for (dev_id = 0; dev_id < num_devices; dev_id++) {
ret = create_device(&zram_devices[dev_id], dev_id);
if (ret)
goto free_devices;
}
+ last_created_dev = num_devices-1;
pr_info("Created %u device(s) ...\n", num_devices);
@@ -1004,7 +1051,7 @@ static void __exit zram_exit(void)
int i;
struct zram *zram;
- for (i = 0; i < num_devices; i++) {
+ for (i = 0; i < last_created_dev+1; i++) {
zram = &zram_devices[i];
destroy_device(zram);
@@ -1025,7 +1072,7 @@ module_init(zram_init);
module_exit(zram_exit);
module_param(num_devices, uint, 0);
-MODULE_PARM_DESC(num_devices, "Number of zram devices");
+MODULE_PARM_DESC(num_devices, "Number of pre created zram devices");
MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("Nitin Gupta <[email protected]>");
On (07/17/14 15:27), Timofey Titovets wrote:
> This add supporting of autochange count of zram devices on demand, like loop
> devices;
> This working by following rules:
> - Always save minimum devices count specified by num_device (can be
> specified while kernel module loading)
> - if last device already using add new device;
> - if last and prelast devices is free - delete last zram device;
>
> Signed-off-by: Timofey Titovets <[email protected]>
>
> From v1 -> v2:
> Delete useless variable 'ret', added documentation for explain new zram
> behaviour
>
> Please pull from:
> https://github.com/Nefelim4ag/linux.git
> ---
> Tested on 3.15.5-2-ARCH, can be applied on any kernel version
> after this patch 'zram: add LZ4 compression support' - https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/?id=6e76668e415adf799839f0ab205142ad7002d260
> ---
> diff --git a/Documentation/blockdev/zram.txt
> b/Documentation/blockdev/zram.txt
> index 0595c3f..7f5c921 100644
> --- a/Documentation/blockdev/zram.txt
> +++ b/Documentation/blockdev/zram.txt
> @@ -18,9 +18,19 @@ 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}
> + This pre creates 4 devices: /dev/zram{0,1,2,3}
> (num_devices parameter is optional. Default: 1)
>
> + Kernel dynamically changes number of zram devices by demand
> + (between num_devices and 31)
> + If set disk size(4) for last device
> + kernel automatically adds new zram device
> + If last two devices have zero disk size after reset(8),
> + kernel will destroy last device
> +
> + Summing up all features, comes one simple rule:
> + "The last zram device is always free for use"
I can't understand what is the real benefit?
> 2) Set max number of compression streams
> Compression backend may use up to max_comp_streams compression streams,
> thus allowing up to max_comp_streams concurrent compression operations.
> diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> index 089e72c..9b2fc89 100644
> --- a/drivers/block/zram/zram_drv.c
> +++ b/drivers/block/zram/zram_drv.c
> @@ -42,6 +42,10 @@ static const char *default_compressor = "lzo";
>
> /* Module params (documentation at end) */
> static unsigned int num_devices = 1;
> +static unsigned int last_created_dev = 1;
> +
> +static void zram_add_dev(void);
> +static void zram_del_dev(void);
> #define ZRAM_ATTR_RO(name) \
> static ssize_t zram_attr_##name##_show(struct device *d, \
> @@ -168,6 +172,7 @@ static ssize_t comp_algorithm_store(struct device *dev,
> struct device_attribute *attr, const char *buf, size_t len)
> {
> struct zram *zram = dev_to_zram(dev);
> +
> down_write(&zram->init_lock);
> if (init_done(zram)) {
> up_write(&zram->init_lock);
> @@ -239,6 +244,7 @@ static 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;
>
> @@ -374,6 +380,7 @@ static int zram_bvec_read(struct zram *zram, struct
> bio_vec *bvec,
> struct page *page;
> unsigned char *user_mem, *uncmem = NULL;
> struct zram_meta *meta = zram->meta;
> +
> page = bvec->bv_page;
>
> read_lock(&meta->tb_lock);
> @@ -607,6 +614,7 @@ static void zram_reset_device(struct zram *zram, bool
> reset_capacity)
> /* 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;
>
> @@ -668,6 +676,7 @@ static ssize_t disksize_store(struct device *dev,
> set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
> revalidate_disk(zram->disk);
> up_write(&zram->init_lock);
> + zram_add_dev();
> return len;
>
> out_destroy_comp:
> @@ -712,6 +721,7 @@ static ssize_t reset_store(struct device *dev,
> bdput(bdev);
>
> zram_reset_device(zram, true);
> + zram_del_dev();
> return len;
>
> out:
> @@ -954,6 +964,41 @@ static void destroy_device(struct zram *zram)
> blk_cleanup_queue(zram->queue);
> }
>
> +/* remove last free device, if last and prelast dev a free */
> +static void zram_del_dev(void)
> +{
> + if (last_created_dev < num_devices)
> + return;
> +
> + if (zram_devices[last_created_dev].disksize == 0 &&
> + zram_devices[last_created_dev-1].disksize == 0
> + ) {
racy?
> + destroy_device(&zram_devices[last_created_dev]);
> + last_created_dev--;
> + pr_info("Deleted zram%u device\n", last_created_dev);
> + }
> +}
> +
> +/* Auto add empty zram device, if last device in use */
> +static void zram_add_dev(void)
> +{
> + if (last_created_dev+1 > max_num_devices) {
> + pr_warn("Can't add zram%u, max device number reached\n",
> + num_devices);
> + return;
> + }
racy?
> + if (&zram_devices[last_created_dev].disksize > 0) {
> + last_created_dev++;
> + if (create_device(&zram_devices[last_created_dev], last_created_dev)) {
> + destroy_device(&zram_devices[last_created_dev]);
> + last_created_dev--;
racy?
-ss
> + return;
> + }
> + pr_info("Created zram%u device\n", last_created_dev);
> + }
> +}
> +
> static int __init zram_init(void)
> {
> int ret, dev_id;
> @@ -972,18 +1017,20 @@ static int __init zram_init(void)
> goto out;
> }
>
> - /* Allocate the device array and initialize each one */
> - zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
> + /* Allocate the device array */
> + zram_devices = kcalloc(max_num_devices, sizeof(struct zram), GFP_KERNEL);
> if (!zram_devices) {
> ret = -ENOMEM;
> goto unregister;
> }
>
> + /* Initialise zram{0..num_devices} */
> for (dev_id = 0; dev_id < num_devices; dev_id++) {
> ret = create_device(&zram_devices[dev_id], dev_id);
> if (ret)
> goto free_devices;
> }
> + last_created_dev = num_devices-1;
>
> pr_info("Created %u device(s) ...\n", num_devices);
>
> @@ -1004,7 +1051,7 @@ static void __exit zram_exit(void)
> int i;
> struct zram *zram;
>
> - for (i = 0; i < num_devices; i++) {
> + for (i = 0; i < last_created_dev+1; i++) {
> zram = &zram_devices[i];
>
> destroy_device(zram);
> @@ -1025,7 +1072,7 @@ module_init(zram_init);
> module_exit(zram_exit);
>
> module_param(num_devices, uint, 0);
> -MODULE_PARM_DESC(num_devices, "Number of zram devices");
> +MODULE_PARM_DESC(num_devices, "Number of pre created zram devices");
>
> MODULE_LICENSE("Dual BSD/GPL");
> MODULE_AUTHOR("Nitin Gupta <[email protected]>");
>
On 07/17/2014 05:04 PM, Sergey Senozhatsky wrote:
> On (07/17/14 15:27), Timofey Titovets wrote:
>> This add supporting of autochange count of zram devices on demand, like loop
>> devices;
>> This working by following rules:
>> - Always save minimum devices count specified by num_device (can be
>> specified while kernel module loading)
>> - if last device already using add new device;
>> - if last and prelast devices is free - delete last zram device;
>>
>> Signed-off-by: Timofey Titovets <[email protected]>
>>
>> From v1 -> v2:
>> Delete useless variable 'ret', added documentation for explain new zram
>> behaviour
>>
>> Please pull from:
>> https://github.com/Nefelim4ag/linux.git
>> ---
>> Tested on 3.15.5-2-ARCH, can be applied on any kernel version
>> after this patch 'zram: add LZ4 compression support' - https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/?id=6e76668e415adf799839f0ab205142ad7002d260
>> ---
>> diff --git a/Documentation/blockdev/zram.txt
>> b/Documentation/blockdev/zram.txt
>> index 0595c3f..7f5c921 100644
>> --- a/Documentation/blockdev/zram.txt
>> +++ b/Documentation/blockdev/zram.txt
>> @@ -18,9 +18,19 @@ 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}
>> + This pre creates 4 devices: /dev/zram{0,1,2,3}
>> (num_devices parameter is optional. Default: 1)
>>
>> + Kernel dynamically changes number of zram devices by demand
>> + (between num_devices and 31)
>> + If set disk size(4) for last device
>> + kernel automatically adds new zram device
>> + If last two devices have zero disk size after reset(8),
>> + kernel will destroy last device
>> +
>> + Summing up all features, comes one simple rule:
>> + "The last zram device is always free for use"
>
> I can't understand what is the real benefit?
>
>
>> 2) Set max number of compression streams
>> Compression backend may use up to max_comp_streams compression streams,
>> thus allowing up to max_comp_streams concurrent compression operations.
>> diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
>> index 089e72c..9b2fc89 100644
>> --- a/drivers/block/zram/zram_drv.c
>> +++ b/drivers/block/zram/zram_drv.c
>> @@ -42,6 +42,10 @@ static const char *default_compressor = "lzo";
>>
>> /* Module params (documentation at end) */
>> static unsigned int num_devices = 1;
>> +static unsigned int last_created_dev = 1;
>> +
>> +static void zram_add_dev(void);
>> +static void zram_del_dev(void);
>> #define ZRAM_ATTR_RO(name) \
>> static ssize_t zram_attr_##name##_show(struct device *d, \
>> @@ -168,6 +172,7 @@ static ssize_t comp_algorithm_store(struct device *dev,
>> struct device_attribute *attr, const char *buf, size_t len)
>> {
>> struct zram *zram = dev_to_zram(dev);
>> +
>> down_write(&zram->init_lock);
>> if (init_done(zram)) {
>> up_write(&zram->init_lock);
>> @@ -239,6 +244,7 @@ static 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;
>>
>> @@ -374,6 +380,7 @@ static int zram_bvec_read(struct zram *zram, struct
>> bio_vec *bvec,
>> struct page *page;
>> unsigned char *user_mem, *uncmem = NULL;
>> struct zram_meta *meta = zram->meta;
>> +
>> page = bvec->bv_page;
>>
>> read_lock(&meta->tb_lock);
>> @@ -607,6 +614,7 @@ static void zram_reset_device(struct zram *zram, bool
>> reset_capacity)
>> /* 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;
>>
>> @@ -668,6 +676,7 @@ static ssize_t disksize_store(struct device *dev,
>> set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
>> revalidate_disk(zram->disk);
>> up_write(&zram->init_lock);
>> + zram_add_dev();
>> return len;
>>
>> out_destroy_comp:
>> @@ -712,6 +721,7 @@ static ssize_t reset_store(struct device *dev,
>> bdput(bdev);
>>
>> zram_reset_device(zram, true);
>> + zram_del_dev();
>> return len;
>>
>> out:
>> @@ -954,6 +964,41 @@ static void destroy_device(struct zram *zram)
>> blk_cleanup_queue(zram->queue);
>> }
>>
>> +/* remove last free device, if last and prelast dev a free */
>> +static void zram_del_dev(void)
>> +{
>> + if (last_created_dev < num_devices)
>> + return;
>> +
>> + if (zram_devices[last_created_dev].disksize == 0 &&
>> + zram_devices[last_created_dev-1].disksize == 0
>> + ) {
>
> racy?
>
>> + destroy_device(&zram_devices[last_created_dev]);
>> + last_created_dev--;
>> + pr_info("Deleted zram%u device\n", last_created_dev);
>> + }
>> +}
>> +
>> +/* Auto add empty zram device, if last device in use */
>> +static void zram_add_dev(void)
>> +{
>> + if (last_created_dev+1 > max_num_devices) {
>> + pr_warn("Can't add zram%u, max device number reached\n",
>> + num_devices);
>> + return;
>> + }
>
> racy?
>
>> + if (&zram_devices[last_created_dev].disksize > 0) {
>> + last_created_dev++;
>> + if (create_device(&zram_devices[last_created_dev], last_created_dev)) {
>> + destroy_device(&zram_devices[last_created_dev]);
>> + last_created_dev--;
>
> racy?
>
>
> -ss
>
>
>> + return;
>> + }
>> + pr_info("Created zram%u device\n", last_created_dev);
>> + }
>> +}
>> +
>> static int __init zram_init(void)
>> {
>> int ret, dev_id;
>> @@ -972,18 +1017,20 @@ static int __init zram_init(void)
>> goto out;
>> }
>>
>> - /* Allocate the device array and initialize each one */
>> - zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
>> + /* Allocate the device array */
>> + zram_devices = kcalloc(max_num_devices, sizeof(struct zram), GFP_KERNEL);
>> if (!zram_devices) {
>> ret = -ENOMEM;
>> goto unregister;
>> }
>>
>> + /* Initialise zram{0..num_devices} */
>> for (dev_id = 0; dev_id < num_devices; dev_id++) {
>> ret = create_device(&zram_devices[dev_id], dev_id);
>> if (ret)
>> goto free_devices;
>> }
>> + last_created_dev = num_devices-1;
>>
>> pr_info("Created %u device(s) ...\n", num_devices);
>>
>> @@ -1004,7 +1051,7 @@ static void __exit zram_exit(void)
>> int i;
>> struct zram *zram;
>>
>> - for (i = 0; i < num_devices; i++) {
>> + for (i = 0; i < last_created_dev+1; i++) {
>> zram = &zram_devices[i];
>>
>> destroy_device(zram);
>> @@ -1025,7 +1072,7 @@ module_init(zram_init);
>> module_exit(zram_exit);
>>
>> module_param(num_devices, uint, 0);
>> -MODULE_PARM_DESC(num_devices, "Number of zram devices");
>> +MODULE_PARM_DESC(num_devices, "Number of pre created zram devices");
>>
>> MODULE_LICENSE("Dual BSD/GPL");
>> MODULE_AUTHOR("Nitin Gupta <[email protected]>");
>>
I can't understand what do you mean on "racy?"
if you mind random empty lines in code, I've just checked code by
checkpatch.pl and fixed warnings.
I'll try to explain, why I wrote a patch:
zram, as a loop device, is a virtual device, not physical, and i think
that adding new free devices automatically (like loop) is useful and
expected behavior (for virtual device).
By default, zram creates only one device, and if I need to use two
devices (for example), my actions lead to module?s reloading:
1. umount busy device
2. lose my data. Yes, I can backup it, and restore, but this is also
useless, if I can do it more beautiful
3. unload module
4. load module again with new num devices parameter or make it parametre
"permanent" by creating file in modprobe.d
This is handwork and such behavior is uncomfortable.
if number of devices is dynamically changeable, I can skip this actions
and save my time and energy instead of wasting on these activities.
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
On 07/17/2014 04:04 PM, Sergey Senozhatsky wrote:
> On (07/17/14 15:27), Timofey Titovets wrote:
>> This add supporting of autochange count of zram devices on
>> demand, like loop devices; This working by following rules: -
>> Always save minimum devices count specified by num_device (can
>> be specified while kernel module loading) - if last device
>> already using add new device; - if last and prelast devices is
>> free - delete last zram device;
>>
>> Signed-off-by: Timofey Titovets <[email protected]>
>>
>> From v1 -> v2: Delete useless variable 'ret', added documentation
>> for explain new zram behaviour
>>
>> Please pull from: https://github.com/Nefelim4ag/linux.git ---
>> Tested on 3.15.5-2-ARCH, can be applied on any kernel version
>> after this patch 'zram: add LZ4 compression support' -
>> https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/?id=6e76668e415adf799839f0ab205142ad7002d260
>>
>>
- ---
>> diff --git a/Documentation/blockdev/zram.txt
>> b/Documentation/blockdev/zram.txt index 0595c3f..7f5c921 100644
>> --- a/Documentation/blockdev/zram.txt +++
>> b/Documentation/blockdev/zram.txt @@ -18,9 +18,19 @@ 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} + This pre creates 4 devices:
>> /dev/zram{0,1,2,3} (num_devices parameter is optional. Default:
>> 1)
>>
>> + Kernel dynamically changes number of zram devices by demand +
>> (between num_devices and 31) + If set disk size(4) for last
>> device + kernel automatically adds new zram device + If last two
>> devices have zero disk size after reset(8), + kernel will destroy
>> last device + + Summing up all features, comes one simple rule: +
>> "The last zram device is always free for use"
>
> I can't understand what is the real benefit?
>
>
>> 2) Set max number of compression streams Compression backend may
>> use up to max_comp_streams compression streams, thus allowing up
>> to max_comp_streams concurrent compression operations. diff --git
>> a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
>> index 089e72c..9b2fc89 100644 ---
>> a/drivers/block/zram/zram_drv.c +++
>> b/drivers/block/zram/zram_drv.c @@ -42,6 +42,10 @@ static const
>> char *default_compressor = "lzo";
>>
>> /* Module params (documentation at end) */ static unsigned int
>> num_devices = 1; +static unsigned int last_created_dev = 1; +
>> +static void zram_add_dev(void); +static void
>> zram_del_dev(void); #define ZRAM_ATTR_RO(name) \ static
>> ssize_t zram_attr_##name##_show(struct device *d, \ @@ -168,6
>> +172,7 @@ static ssize_t comp_algorithm_store(struct device
>> *dev, struct device_attribute *attr, const char *buf, size_t
>> len) { struct zram *zram = dev_to_zram(dev); +
>> down_write(&zram->init_lock); if (init_done(zram)) {
>> up_write(&zram->init_lock); @@ -239,6 +244,7 @@ static 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;
>>
>> @@ -374,6 +380,7 @@ static int zram_bvec_read(struct zram *zram,
>> struct bio_vec *bvec, struct page *page; unsigned char *user_mem,
>> *uncmem = NULL; struct zram_meta *meta = zram->meta; + page =
>> bvec->bv_page;
>>
>> read_lock(&meta->tb_lock); @@ -607,6 +614,7 @@ static void
>> zram_reset_device(struct zram *zram, bool reset_capacity) /* 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;
>>
>> @@ -668,6 +676,7 @@ static ssize_t disksize_store(struct device
>> *dev, set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
>> revalidate_disk(zram->disk); up_write(&zram->init_lock); +
>> zram_add_dev(); return len;
>>
>> out_destroy_comp: @@ -712,6 +721,7 @@ static ssize_t
>> reset_store(struct device *dev, bdput(bdev);
>>
>> zram_reset_device(zram, true); + zram_del_dev(); return len;
>>
>> out: @@ -954,6 +964,41 @@ static void destroy_device(struct zram
>> *zram) blk_cleanup_queue(zram->queue); }
>>
>> +/* remove last free device, if last and prelast dev a free */
>> +static void zram_del_dev(void) +{ + if (last_created_dev <
>> num_devices) + return; + + if
>> (zram_devices[last_created_dev].disksize == 0 && +
>> zram_devices[last_created_dev-1].disksize == 0 + ) {
>
> racy?
>
>> + destroy_device(&zram_devices[last_created_dev]); +
>> last_created_dev--; + pr_info("Deleted zram%u device\n",
>> last_created_dev); + } +} + +/* Auto add empty zram device, if
>> last device in use */ +static void zram_add_dev(void) +{ + if
>> (last_created_dev+1 > max_num_devices) { + pr_warn("Can't add
>> zram%u, max device number reached\n", + num_devices); +
>> return; + }
>
> racy?
>
>> + if (&zram_devices[last_created_dev].disksize > 0) { +
>> last_created_dev++; + if
>> (create_device(&zram_devices[last_created_dev],
>> last_created_dev)) { +
>> destroy_device(&zram_devices[last_created_dev]); +
>> last_created_dev--;
>
> racy?
Looks like it:
$ cat conctest.sh
#! /bin/sh
modprobe zram
while true; do
for i in `seq 1 10`; do
echo 10485760 > /sys/block/zram0/disksize&
echo 1 > /sys/block/zram0/reset&
done
done
$ sudo ./conctest.sh
[ 51.535387] ------------[ cut here ]------------
[ 51.536305] WARNING: CPU: 0 PID: 840 at fs/kernfs/dir.c:1209
kernfs_remove_by_name_ns+0x95/0xa0()
[ 51.537908] kernfs: can not remove 'max_comp_streams', no directory
[ 51.539089] Modules linked in: zram lz4_compress xt_conntrack
cfg80211 rfkill ebtable_nat ebtable_broute bridge stp llc
ebtable_filter ebtables ip6_tables iptable_nat nf_conntrack_ipv4
nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack iptable_mangle
iptable_security iptable_raw ppdev crct10dif_pclmul crc32_pclmul
crc32c_intel joydev ghash_clmulni_intel microcode serio_raw pcspkr
virtio_balloon virtio_console parport_pc pvpanic virtio_net parport
floppy i2c_piix4 nfsd auth_rpcgss nfs_acl lockd sunrpc qxl
drm_kms_helper ttm virtio_blk drm virtio_pci virtio_ring virtio
ata_generic pata_acpi
[ 51.550844] CPU: 0 PID: 840 Comm: conc_init.sh Tainted: G D W
3.16.0-rc5-memacct-next-20140715+ #146
[ 51.552606] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[ 51.553691] 0000000000000009 ffff880078343d20 ffffffff8172d344
ffff880078343d68
[ 51.555412] ffff880078343d58 ffffffff8108ad1d 0000000000000000
ffffffffa0320242
[ 51.557811] ffffffffa0321058 0000000000000002 ffff880078343f50
ffff880078343db8
[ 51.559580] Call Trace:
[ 51.560139] [<ffffffff8172d344>] dump_stack+0x45/0x56
[ 51.561161] [<ffffffff8108ad1d>] warn_slowpath_common+0x7d/0xa0
[ 51.562333] [<ffffffff8108ad8c>] warn_slowpath_fmt+0x4c/0x50
[ 51.563445] [<ffffffff81218196>] ? evict+0x106/0x170
[ 51.564432] [<ffffffff81275695>] kernfs_remove_by_name_ns+0x95/0xa0
[ 51.565627] [<ffffffff81277ee9>] remove_files.isra.1+0x39/0x70
[ 51.566753] [<ffffffff812781f4>] sysfs_remove_group+0x44/0xa0
[ 51.567870] [<ffffffffa031e058>] destroy_device.isra.17+0x28/0x50
[zram]
[ 51.569089] [<ffffffffa031e5d0>] reset_store+0x100/0x140 [zram]
[ 51.570197] [<ffffffff8146c3e8>] dev_attr_store+0x18/0x30
[ 51.571247] [<ffffffff81276fd4>] sysfs_kf_write+0x44/0x60
[ 51.572201] [<ffffffff812768d7>] kernfs_fop_write+0xe7/0x170
[ 51.573283] [<ffffffff811fbcf7>] vfs_write+0xb7/0x1f0
[ 51.574143] [<ffffffff811fc8a9>] SyS_write+0x49/0xb0
[ 51.574976] [<ffffffff8112e724>] ? __audit_syscall_entry+0xb4/0x110
[ 51.576213] [<ffffffff817362a9>] system_call_fastpath+0x16/0x1b
[ 51.577422] ---[ end trace cdb79035dad379f3 ]---
[ 51.578401] ------------[ cut here ]------------
[ 51.579354] WARNING: CPU: 0 PID: 840 at fs/kernfs/dir.c:1209
kernfs_remove_by_name_ns+0x95/0xa0()
[ 51.580966] kernfs: can not remove 'comp_algorithm', no directory
[ 51.582108] Modules linked in: zram lz4_compress xt_conntrack
cfg80211 rfkill ebtable_nat ebtable_broute bridge stp llc
ebtable_filter ebtables ip6_tables iptable_nat nf_conntrack_ipv4
nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack iptable_mangle
iptable_security iptable_raw ppdev crct10dif_pclmul crc32_pclmul
crc32c_intel joydev ghash_clmulni_intel microcode serio_raw pcspkr
virtio_balloon virtio_console parport_pc pvpanic virtio_net parport
floppy i2c_piix4 nfsd auth_rpcgss nfs_acl lockd sunrpc qxl
drm_kms_helper ttm virtio_blk drm virtio_pci virtio_ring virtio
ata_generic pata_acpi
[ 51.597177] CPU: 0 PID: 840 Comm: conc_init.sh Tainted: G D W
3.16.0-rc5-memacct-next-20140715+ #146
[ 51.598549] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[ 51.599661] 0000000000000009 ffff880078343d20 ffffffff8172d344
ffff880078343d68
[ 51.601519] ffff880078343d58 ffffffff8108ad1d 0000000000000000
ffffffffa0320233
[ 51.603362] ffffffffa0321058 0000000000000002 ffff880078343f50
ffff880078343db8
[ 51.604913] Call Trace:
[ 51.605444] [<ffffffff8172d344>] dump_stack+0x45/0x56
[ 51.606537] [<ffffffff8108ad1d>] warn_slowpath_common+0x7d/0xa0
[ 51.607507] [<ffffffff8108ad8c>] warn_slowpath_fmt+0x4c/0x50
[ 51.608582] [<ffffffff81218196>] ? evict+0x106/0x170
[ 51.609423] [<ffffffff81275695>] kernfs_remove_by_name_ns+0x95/0xa0
[ 51.610436] [<ffffffff81277ee9>] remove_files.isra.1+0x39/0x70
[ 51.611408] [<ffffffff812781f4>] sysfs_remove_group+0x44/0xa0
[ 51.612431] [<ffffffffa031e058>] destroy_device.isra.17+0x28/0x50
[zram]
[ 51.613214] [<ffffffffa031e5d0>] reset_store+0x100/0x140 [zram]
[ 51.613928] [<ffffffff8146c3e8>] dev_attr_store+0x18/0x30
[ 51.614634] [<ffffffff81276fd4>] sysfs_kf_write+0x44/0x60
[ 51.615387] [<ffffffff812768d7>] kernfs_fop_write+0xe7/0x170
[ 51.616246] [<ffffffff811fbcf7>] vfs_write+0xb7/0x1f0
[ 51.619107] [<ffffffff811fc8a9>] SyS_write+0x49/0xb0
[ 51.620063] [<ffffffff8112e724>] ? __audit_syscall_entry+0xb4/0x110
[ 51.622071] [<ffffffff817362a9>] system_call_fastpath+0x16/0x1b
[ 51.623256] ---[ end trace cdb79035dad379f4 ]---
And lots more of similar messages.
Jerome
>
>
> -ss
>
>
>> + return; + } + pr_info("Created zram%u device\n",
>> last_created_dev); + } +} + static int __init zram_init(void) {
>> int ret, dev_id; @@ -972,18 +1017,20 @@ static int __init
>> zram_init(void) goto out; }
>>
>> - /* Allocate the device array and initialize each one */ -
>> zram_devices = kzalloc(num_devices * sizeof(struct zram),
>> GFP_KERNEL); + /* Allocate the device array */ + zram_devices =
>> kcalloc(max_num_devices, sizeof(struct zram), GFP_KERNEL); if
>> (!zram_devices) { ret = -ENOMEM; goto unregister; }
>>
>> + /* Initialise zram{0..num_devices} */ for (dev_id = 0; dev_id <
>> num_devices; dev_id++) { ret =
>> create_device(&zram_devices[dev_id], dev_id); if (ret) goto
>> free_devices; } + last_created_dev = num_devices-1;
>>
>> pr_info("Created %u device(s) ...\n", num_devices);
>>
>> @@ -1004,7 +1051,7 @@ static void __exit zram_exit(void) int i;
>> struct zram *zram;
>>
>> - for (i = 0; i < num_devices; i++) { + for (i = 0; i <
>> last_created_dev+1; i++) { zram = &zram_devices[i];
>>
>> destroy_device(zram); @@ -1025,7 +1072,7 @@
>> module_init(zram_init); module_exit(zram_exit);
>>
>> module_param(num_devices, uint, 0);
>> -MODULE_PARM_DESC(num_devices, "Number of zram devices");
>> +MODULE_PARM_DESC(num_devices, "Number of pre created zram
>> devices");
>>
>> MODULE_LICENSE("Dual BSD/GPL"); MODULE_AUTHOR("Nitin Gupta
>> <[email protected]>");
>>
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On 07/17/2014 05:17 PM, Jerome Marchand wrote:
> Looks like it:
>
> $ cat conctest.sh
> #! /bin/sh
>
> modprobe zram
>
> while true; do
> for i in `seq 1 10`; do
> echo 10485760 > /sys/block/zram0/disksize&
> echo 1 > /sys/block/zram0/reset&
> done
> done
> $ sudo ./conctest.sh
>
> [ 51.535387] ------------[ cut here ]------------
> [ 51.536305] WARNING: CPU: 0 PID: 840 at fs/kernfs/dir.c:1209
> kernfs_remove_by_name_ns+0x95/0xa0()
> [ 51.537908] kernfs: can not remove 'max_comp_streams', no directory
> [ 51.539089] Modules linked in: zram lz4_compress xt_conntrack
> cfg80211 rfkill ebtable_nat ebtable_broute bridge stp llc
> ebtable_filter ebtables ip6_tables iptable_nat nf_conntrack_ipv4
> nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack iptable_mangle
> iptable_security iptable_raw ppdev crct10dif_pclmul crc32_pclmul
> crc32c_intel joydev ghash_clmulni_intel microcode serio_raw pcspkr
> virtio_balloon virtio_console parport_pc pvpanic virtio_net parport
> floppy i2c_piix4 nfsd auth_rpcgss nfs_acl lockd sunrpc qxl
> drm_kms_helper ttm virtio_blk drm virtio_pci virtio_ring virtio
> ata_generic pata_acpi
> [ 51.550844] CPU: 0 PID: 840 Comm: conc_init.sh Tainted: G D W
> 3.16.0-rc5-memacct-next-20140715+ #146
> [ 51.552606] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
> [ 51.553691] 0000000000000009 ffff880078343d20 ffffffff8172d344
> ffff880078343d68
> [ 51.555412] ffff880078343d58 ffffffff8108ad1d 0000000000000000
> ffffffffa0320242
> [ 51.557811] ffffffffa0321058 0000000000000002 ffff880078343f50
> ffff880078343db8
> [ 51.559580] Call Trace:
> [ 51.560139] [<ffffffff8172d344>] dump_stack+0x45/0x56
> [ 51.561161] [<ffffffff8108ad1d>] warn_slowpath_common+0x7d/0xa0
> [ 51.562333] [<ffffffff8108ad8c>] warn_slowpath_fmt+0x4c/0x50
> [ 51.563445] [<ffffffff81218196>] ? evict+0x106/0x170
> [ 51.564432] [<ffffffff81275695>] kernfs_remove_by_name_ns+0x95/0xa0
> [ 51.565627] [<ffffffff81277ee9>] remove_files.isra.1+0x39/0x70
> [ 51.566753] [<ffffffff812781f4>] sysfs_remove_group+0x44/0xa0
> [ 51.567870] [<ffffffffa031e058>] destroy_device.isra.17+0x28/0x50
> [zram]
> [ 51.569089] [<ffffffffa031e5d0>] reset_store+0x100/0x140 [zram]
> [ 51.570197] [<ffffffff8146c3e8>] dev_attr_store+0x18/0x30
> [ 51.571247] [<ffffffff81276fd4>] sysfs_kf_write+0x44/0x60
> [ 51.572201] [<ffffffff812768d7>] kernfs_fop_write+0xe7/0x170
> [ 51.573283] [<ffffffff811fbcf7>] vfs_write+0xb7/0x1f0
> [ 51.574143] [<ffffffff811fc8a9>] SyS_write+0x49/0xb0
> [ 51.574976] [<ffffffff8112e724>] ? __audit_syscall_entry+0xb4/0x110
> [ 51.576213] [<ffffffff817362a9>] system_call_fastpath+0x16/0x1b
> [ 51.577422] ---[ end trace cdb79035dad379f3 ]---
> [ 51.578401] ------------[ cut here ]------------
> [ 51.579354] WARNING: CPU: 0 PID: 840 at fs/kernfs/dir.c:1209
> kernfs_remove_by_name_ns+0x95/0xa0()
> [ 51.580966] kernfs: can not remove 'comp_algorithm', no directory
> [ 51.582108] Modules linked in: zram lz4_compress xt_conntrack
> cfg80211 rfkill ebtable_nat ebtable_broute bridge stp llc
> ebtable_filter ebtables ip6_tables iptable_nat nf_conntrack_ipv4
> nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack iptable_mangle
> iptable_security iptable_raw ppdev crct10dif_pclmul crc32_pclmul
> crc32c_intel joydev ghash_clmulni_intel microcode serio_raw pcspkr
> virtio_balloon virtio_console parport_pc pvpanic virtio_net parport
> floppy i2c_piix4 nfsd auth_rpcgss nfs_acl lockd sunrpc qxl
> drm_kms_helper ttm virtio_blk drm virtio_pci virtio_ring virtio
> ata_generic pata_acpi
> [ 51.597177] CPU: 0 PID: 840 Comm: conc_init.sh Tainted: G D W
> 3.16.0-rc5-memacct-next-20140715+ #146
> [ 51.598549] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
> [ 51.599661] 0000000000000009 ffff880078343d20 ffffffff8172d344
> ffff880078343d68
> [ 51.601519] ffff880078343d58 ffffffff8108ad1d 0000000000000000
> ffffffffa0320233
> [ 51.603362] ffffffffa0321058 0000000000000002 ffff880078343f50
> ffff880078343db8
> [ 51.604913] Call Trace:
> [ 51.605444] [<ffffffff8172d344>] dump_stack+0x45/0x56
> [ 51.606537] [<ffffffff8108ad1d>] warn_slowpath_common+0x7d/0xa0
> [ 51.607507] [<ffffffff8108ad8c>] warn_slowpath_fmt+0x4c/0x50
> [ 51.608582] [<ffffffff81218196>] ? evict+0x106/0x170
> [ 51.609423] [<ffffffff81275695>] kernfs_remove_by_name_ns+0x95/0xa0
> [ 51.610436] [<ffffffff81277ee9>] remove_files.isra.1+0x39/0x70
> [ 51.611408] [<ffffffff812781f4>] sysfs_remove_group+0x44/0xa0
> [ 51.612431] [<ffffffffa031e058>] destroy_device.isra.17+0x28/0x50
> [zram]
> [ 51.613214] [<ffffffffa031e5d0>] reset_store+0x100/0x140 [zram]
> [ 51.613928] [<ffffffff8146c3e8>] dev_attr_store+0x18/0x30
> [ 51.614634] [<ffffffff81276fd4>] sysfs_kf_write+0x44/0x60
> [ 51.615387] [<ffffffff812768d7>] kernfs_fop_write+0xe7/0x170
> [ 51.616246] [<ffffffff811fbcf7>] vfs_write+0xb7/0x1f0
> [ 51.619107] [<ffffffff811fc8a9>] SyS_write+0x49/0xb0
> [ 51.620063] [<ffffffff8112e724>] ? __audit_syscall_entry+0xb4/0x110
> [ 51.622071] [<ffffffff817362a9>] system_call_fastpath+0x16/0x1b
> [ 51.623256] ---[ end trace cdb79035dad379f4 ]---
>
> And lots more of similar messages.
>
> Jerome
>
Thanks for catching, i try fix it and resend patch.
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
On 07/17/2014 05:01 PM, Timofey Titovets wrote:
>
>
> On 07/17/2014 05:04 PM, Sergey Senozhatsky wrote:
>> On (07/17/14 15:27), Timofey Titovets wrote:
>>> This add supporting of autochange count of zram devices on
>>> demand, like loop devices; This working by following rules: -
>>> Always save minimum devices count specified by num_device (can
>>> be specified while kernel module loading) - if last device
>>> already using add new device; - if last and prelast devices is
>>> free - delete last zram device;
>>>
>>> Signed-off-by: Timofey Titovets <[email protected]>
>>>
>>> From v1 -> v2: Delete useless variable 'ret', added
>>> documentation for explain new zram behaviour
>>>
>>> Please pull from: https://github.com/Nefelim4ag/linux.git ---
>>> Tested on 3.15.5-2-ARCH, can be applied on any kernel version
>>> after this patch 'zram: add LZ4 compression support' -
>>> https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/?id=6e76668e415adf799839f0ab205142ad7002d260
>>>
>>>
>>>
- ---
>>> diff --git a/Documentation/blockdev/zram.txt
>>> b/Documentation/blockdev/zram.txt index 0595c3f..7f5c921
>>> 100644 --- a/Documentation/blockdev/zram.txt +++
>>> b/Documentation/blockdev/zram.txt @@ -18,9 +18,19 @@ 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} + This pre creates 4 devices:
>>> /dev/zram{0,1,2,3} (num_devices parameter is optional. Default:
>>> 1)
>>>
>>> + Kernel dynamically changes number of zram devices by
>>> demand + (between num_devices and 31) + If set disk
>>> size(4) for last device + kernel automatically adds new zram
>>> device + If last two devices have zero disk size after
>>> reset(8), + kernel will destroy last device + + Summing
>>> up all features, comes one simple rule: + "The last zram
>>> device is always free for use"
>>
>> I can't understand what is the real benefit?
>>
>>
>>> 2) Set max number of compression streams Compression backend
>>> may use up to max_comp_streams compression streams, thus
>>> allowing up to max_comp_streams concurrent compression
>>> operations. diff --git a/drivers/block/zram/zram_drv.c
>>> b/drivers/block/zram/zram_drv.c index 089e72c..9b2fc89 100644
>>> --- a/drivers/block/zram/zram_drv.c +++
>>> b/drivers/block/zram/zram_drv.c @@ -42,6 +42,10 @@ static const
>>> char *default_compressor = "lzo";
>>>
>>> /* Module params (documentation at end) */ static unsigned int
>>> num_devices = 1; +static unsigned int last_created_dev = 1; +
>>> +static void zram_add_dev(void); +static void
>>> zram_del_dev(void); #define ZRAM_ATTR_RO(name)
>>> \ static ssize_t zram_attr_##name##_show(struct device *d,
>>> \ @@ -168,6 +172,7 @@ static ssize_t
>>> comp_algorithm_store(struct device *dev, struct
>>> device_attribute *attr, const char *buf, size_t len) { struct
>>> zram *zram = dev_to_zram(dev); + down_write(&zram->init_lock);
>>> if (init_done(zram)) { up_write(&zram->init_lock); @@ -239,6
>>> +244,7 @@ static 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;
>>>
>>> @@ -374,6 +380,7 @@ static int zram_bvec_read(struct zram
>>> *zram, struct bio_vec *bvec, struct page *page; unsigned char
>>> *user_mem, *uncmem = NULL; struct zram_meta *meta =
>>> zram->meta; + page = bvec->bv_page;
>>>
>>> read_lock(&meta->tb_lock); @@ -607,6 +614,7 @@ static void
>>> zram_reset_device(struct zram *zram, bool reset_capacity) /*
>>> 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;
>>>
>>> @@ -668,6 +676,7 @@ static ssize_t disksize_store(struct device
>>> *dev, set_capacity(zram->disk, zram->disksize >>
>>> SECTOR_SHIFT); revalidate_disk(zram->disk);
>>> up_write(&zram->init_lock); + zram_add_dev(); return len;
>>>
>>> out_destroy_comp: @@ -712,6 +721,7 @@ static ssize_t
>>> reset_store(struct device *dev, bdput(bdev);
>>>
>>> zram_reset_device(zram, true); + zram_del_dev(); return
>>> len;
>>>
>>> out: @@ -954,6 +964,41 @@ static void destroy_device(struct
>>> zram *zram) blk_cleanup_queue(zram->queue); }
>>>
>>> +/* remove last free device, if last and prelast dev a free */
>>> +static void zram_del_dev(void) +{ + if (last_created_dev <
>>> num_devices) + return; + + if
>>> (zram_devices[last_created_dev].disksize == 0 && +
>>> zram_devices[last_created_dev-1].disksize == 0 + ) {
>>
>> racy?
>>
>>> + destroy_device(&zram_devices[last_created_dev]); +
>>> last_created_dev--; + pr_info("Deleted zram%u device\n",
>>> last_created_dev); + } +} + +/* Auto add empty zram device,
>>> if last device in use */ +static void zram_add_dev(void) +{ +
>>> if (last_created_dev+1 > max_num_devices) { +
>>> pr_warn("Can't add zram%u, max device number reached\n", +
>>> num_devices); + return; + }
>>
>> racy?
>>
>>> + if (&zram_devices[last_created_dev].disksize > 0) { +
>>> last_created_dev++; + if
>>> (create_device(&zram_devices[last_created_dev],
>>> last_created_dev)) { +
>>> destroy_device(&zram_devices[last_created_dev]); +
>>> last_created_dev--;
>>
>> racy?
>>
>>
>> -ss
>>
>>
>>> + return; + } + pr_info("Created
>>> zram%u device\n", last_created_dev); + } +} + static int
>>> __init zram_init(void) { int ret, dev_id; @@ -972,18 +1017,20
>>> @@ static int __init zram_init(void) goto out; }
>>>
>>> - /* Allocate the device array and initialize each one */ -
>>> zram_devices = kzalloc(num_devices * sizeof(struct zram),
>>> GFP_KERNEL); + /* Allocate the device array */ +
>>> zram_devices = kcalloc(max_num_devices, sizeof(struct zram),
>>> GFP_KERNEL); if (!zram_devices) { ret = -ENOMEM; goto
>>> unregister; }
>>>
>>> + /* Initialise zram{0..num_devices} */ for (dev_id = 0;
>>> dev_id < num_devices; dev_id++) { ret =
>>> create_device(&zram_devices[dev_id], dev_id); if (ret) goto
>>> free_devices; } + last_created_dev = num_devices-1;
>>>
>>> pr_info("Created %u device(s) ...\n", num_devices);
>>>
>>> @@ -1004,7 +1051,7 @@ static void __exit zram_exit(void) int
>>> i; struct zram *zram;
>>>
>>> - for (i = 0; i < num_devices; i++) { + for (i = 0; i <
>>> last_created_dev+1; i++) { zram = &zram_devices[i];
>>>
>>> destroy_device(zram); @@ -1025,7 +1072,7 @@
>>> module_init(zram_init); module_exit(zram_exit);
>>>
>>> module_param(num_devices, uint, 0);
>>> -MODULE_PARM_DESC(num_devices, "Number of zram devices");
>>> +MODULE_PARM_DESC(num_devices, "Number of pre created zram
>>> devices");
>>>
>>> MODULE_LICENSE("Dual BSD/GPL"); MODULE_AUTHOR("Nitin Gupta
>>> <[email protected]>");
>>>
>
> I can't understand what do you mean on "racy?"
Racy as in "race condition".
> if you mind random empty lines in code, I've just checked code by
> checkpatch.pl and fixed warnings.
>
> I'll try to explain, why I wrote a patch: zram, as a loop device,
> is a virtual device, not physical, and i think that adding new free
> devices automatically (like loop) is useful and expected behavior
> (for virtual device).
I don't know much about loop devices. How are they dynamically
added/deleted? Is that the same mechanism as your patch implement?
That may be a matter of taste, but I personally find that behaviour
rather awkward.
Jerome
>
> By default, zram creates only one device, and if I need to use two
> devices (for example), my actions lead to module?s reloading: 1.
> umount busy device 2. lose my data. Yes, I can backup it, and
> restore, but this is also useless, if I can do it more beautiful 3.
> unload module 4. load module again with new num devices parameter
> or make it parametre "permanent" by creating file in modprobe.d
>
> This is handwork and such behavior is uncomfortable.
>
> if number of devices is dynamically changeable, I can skip this
> actions and save my time and energy instead of wasting on these
> activities. -- To unsubscribe from this list: send the line
> "unsubscribe linux-kernel" in the body of a message to
> [email protected] More majordomo info at
> http://vger.kernel.org/majordomo-info.html Please read the FAQ at
> http://www.tux.org/lkml/
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On 07/17/2014 06:26 PM, Jerome Marchand wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> On 07/17/2014 05:01 PM, Timofey Titovets wrote:
>>
>>
>> On 07/17/2014 05:04 PM, Sergey Senozhatsky wrote:
>>> On (07/17/14 15:27), Timofey Titovets wrote:
>>>> This add supporting of autochange count of zram devices on
>>>> demand, like loop devices; This working by following rules: -
>>>> Always save minimum devices count specified by num_device (can
>>>> be specified while kernel module loading) - if last device
>>>> already using add new device; - if last and prelast devices is
>>>> free - delete last zram device;
>>>>
>>>> Signed-off-by: Timofey Titovets <[email protected]>
>>>>
>>>> From v1 -> v2: Delete useless variable 'ret', added
>>>> documentation for explain new zram behaviour
>>>>
>>>> Please pull from: https://github.com/Nefelim4ag/linux.git ---
>>>> Tested on 3.15.5-2-ARCH, can be applied on any kernel version
>>>> after this patch 'zram: add LZ4 compression support' -
>>>> https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/?id=6e76668e415adf799839f0ab205142ad7002d260
>>>>
>>>>
>>>>
> - ---
>>>> diff --git a/Documentation/blockdev/zram.txt
>>>> b/Documentation/blockdev/zram.txt index 0595c3f..7f5c921
>>>> 100644 --- a/Documentation/blockdev/zram.txt +++
>>>> b/Documentation/blockdev/zram.txt @@ -18,9 +18,19 @@ 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} + This pre creates 4 devices:
>>>> /dev/zram{0,1,2,3} (num_devices parameter is optional. Default:
>>>> 1)
>>>>
>>>> + Kernel dynamically changes number of zram devices by
>>>> demand + (between num_devices and 31) + If set disk
>>>> size(4) for last device + kernel automatically adds new zram
>>>> device + If last two devices have zero disk size after
>>>> reset(8), + kernel will destroy last device + + Summing
>>>> up all features, comes one simple rule: + "The last zram
>>>> device is always free for use"
>>>
>>> I can't understand what is the real benefit?
>>>
>>>
>>>> 2) Set max number of compression streams Compression backend
>>>> may use up to max_comp_streams compression streams, thus
>>>> allowing up to max_comp_streams concurrent compression
>>>> operations. diff --git a/drivers/block/zram/zram_drv.c
>>>> b/drivers/block/zram/zram_drv.c index 089e72c..9b2fc89 100644
>>>> --- a/drivers/block/zram/zram_drv.c +++
>>>> b/drivers/block/zram/zram_drv.c @@ -42,6 +42,10 @@ static const
>>>> char *default_compressor = "lzo";
>>>>
>>>> /* Module params (documentation at end) */ static unsigned int
>>>> num_devices = 1; +static unsigned int last_created_dev = 1; +
>>>> +static void zram_add_dev(void); +static void
>>>> zram_del_dev(void); #define ZRAM_ATTR_RO(name)
>>>> \ static ssize_t zram_attr_##name##_show(struct device *d,
>>>> \ @@ -168,6 +172,7 @@ static ssize_t
>>>> comp_algorithm_store(struct device *dev, struct
>>>> device_attribute *attr, const char *buf, size_t len) { struct
>>>> zram *zram = dev_to_zram(dev); + down_write(&zram->init_lock);
>>>> if (init_done(zram)) { up_write(&zram->init_lock); @@ -239,6
>>>> +244,7 @@ static 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;
>>>>
>>>> @@ -374,6 +380,7 @@ static int zram_bvec_read(struct zram
>>>> *zram, struct bio_vec *bvec, struct page *page; unsigned char
>>>> *user_mem, *uncmem = NULL; struct zram_meta *meta =
>>>> zram->meta; + page = bvec->bv_page;
>>>>
>>>> read_lock(&meta->tb_lock); @@ -607,6 +614,7 @@ static void
>>>> zram_reset_device(struct zram *zram, bool reset_capacity) /*
>>>> 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;
>>>>
>>>> @@ -668,6 +676,7 @@ static ssize_t disksize_store(struct device
>>>> *dev, set_capacity(zram->disk, zram->disksize >>
>>>> SECTOR_SHIFT); revalidate_disk(zram->disk);
>>>> up_write(&zram->init_lock); + zram_add_dev(); return len;
>>>>
>>>> out_destroy_comp: @@ -712,6 +721,7 @@ static ssize_t
>>>> reset_store(struct device *dev, bdput(bdev);
>>>>
>>>> zram_reset_device(zram, true); + zram_del_dev(); return
>>>> len;
>>>>
>>>> out: @@ -954,6 +964,41 @@ static void destroy_device(struct
>>>> zram *zram) blk_cleanup_queue(zram->queue); }
>>>>
>>>> +/* remove last free device, if last and prelast dev a free */
>>>> +static void zram_del_dev(void) +{ + if (last_created_dev <
>>>> num_devices) + return; + + if
>>>> (zram_devices[last_created_dev].disksize == 0 && +
>>>> zram_devices[last_created_dev-1].disksize == 0 + ) {
>>>
>>> racy?
>>>
>>>> + destroy_device(&zram_devices[last_created_dev]); +
>>>> last_created_dev--; + pr_info("Deleted zram%u device\n",
>>>> last_created_dev); + } +} + +/* Auto add empty zram device,
>>>> if last device in use */ +static void zram_add_dev(void) +{ +
>>>> if (last_created_dev+1 > max_num_devices) { +
>>>> pr_warn("Can't add zram%u, max device number reached\n", +
>>>> num_devices); + return; + }
>>>
>>> racy?
>>>
>>>> + if (&zram_devices[last_created_dev].disksize > 0) { +
>>>> last_created_dev++; + if
>>>> (create_device(&zram_devices[last_created_dev],
>>>> last_created_dev)) { +
>>>> destroy_device(&zram_devices[last_created_dev]); +
>>>> last_created_dev--;
>>>
>>> racy?
>>>
>>>
>>> -ss
>>>
>>>
>>>> + return; + } + pr_info("Created
>>>> zram%u device\n", last_created_dev); + } +} + static int
>>>> __init zram_init(void) { int ret, dev_id; @@ -972,18 +1017,20
>>>> @@ static int __init zram_init(void) goto out; }
>>>>
>>>> - /* Allocate the device array and initialize each one */ -
>>>> zram_devices = kzalloc(num_devices * sizeof(struct zram),
>>>> GFP_KERNEL); + /* Allocate the device array */ +
>>>> zram_devices = kcalloc(max_num_devices, sizeof(struct zram),
>>>> GFP_KERNEL); if (!zram_devices) { ret = -ENOMEM; goto
>>>> unregister; }
>>>>
>>>> + /* Initialise zram{0..num_devices} */ for (dev_id = 0;
>>>> dev_id < num_devices; dev_id++) { ret =
>>>> create_device(&zram_devices[dev_id], dev_id); if (ret) goto
>>>> free_devices; } + last_created_dev = num_devices-1;
>>>>
>>>> pr_info("Created %u device(s) ...\n", num_devices);
>>>>
>>>> @@ -1004,7 +1051,7 @@ static void __exit zram_exit(void) int
>>>> i; struct zram *zram;
>>>>
>>>> - for (i = 0; i < num_devices; i++) { + for (i = 0; i <
>>>> last_created_dev+1; i++) { zram = &zram_devices[i];
>>>>
>>>> destroy_device(zram); @@ -1025,7 +1072,7 @@
>>>> module_init(zram_init); module_exit(zram_exit);
>>>>
>>>> module_param(num_devices, uint, 0);
>>>> -MODULE_PARM_DESC(num_devices, "Number of zram devices");
>>>> +MODULE_PARM_DESC(num_devices, "Number of pre created zram
>>>> devices");
>>>>
>>>> MODULE_LICENSE("Dual BSD/GPL"); MODULE_AUTHOR("Nitin Gupta
>>>> <[email protected]>");
>>>>
>>
>> I can't understand what do you mean on "racy?"
>
> Racy as in "race condition".
>
>> if you mind random empty lines in code, I've just checked code by
>> checkpatch.pl and fixed warnings.
>>
>> I'll try to explain, why I wrote a patch: zram, as a loop device,
>> is a virtual device, not physical, and i think that adding new free
>> devices automatically (like loop) is useful and expected behavior
>> (for virtual device).
>
> I don't know much about loop devices. How are they dynamically
> added/deleted? Is that the same mechanism as your patch implement?
> That may be a matter of taste, but I personally find that behaviour
> rather awkward.
>
> Jerome
>
loop device has self logic, as i understand it's working through
loop-control and losetup.
I will try to understand clearer how loop devices are working and
rewrite my patch.
I think if in final i'll write clear, not buggy patch, it can be applied
on kernel, but now my code is crap and i must rewrite it =).
Anyway thanks for reviewing.
Timofey
>>
>> By default, zram creates only one device, and if I need to use two
>> devices (for example), my actions lead to module?s reloading: 1.
>> umount busy device 2. lose my data. Yes, I can backup it, and
>> restore, but this is also useless, if I can do it more beautiful 3.
>> unload module 4. load module again with new num devices parameter
>> or make it parametre "permanent" by creating file in modprobe.d
>>
>> This is handwork and such behavior is uncomfortable.
>>
>> if number of devices is dynamically changeable, I can skip this
>> actions and save my time and energy instead of wasting on these
>> activities. -- To unsubscribe from this list: send the line
>> "unsubscribe linux-kernel" in the body of a message to
>> [email protected] More majordomo info at
>> http://vger.kernel.org/majordomo-info.html Please read the FAQ at
>> http://www.tux.org/lkml/
>
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>
On 07/17/2014 06:19 PM, Timofey Titovets wrote:
>
> On 07/17/2014 05:17 PM, Jerome Marchand wrote:
>> Looks like it:
>>
>> $ cat conctest.sh
>> #! /bin/sh
>>
>> modprobe zram
>>
>> while true; do
>> for i in `seq 1 10`; do
>> echo 10485760 > /sys/block/zram0/disksize&
>> echo 1 > /sys/block/zram0/reset&
>> done
>> done
>> $ sudo ./conctest.sh
>>
>> [ 51.535387] ------------[ cut here ]------------
>> [ 51.536305] WARNING: CPU: 0 PID: 840 at fs/kernfs/dir.c:1209
>> kernfs_remove_by_name_ns+0x95/0xa0()
>> [ 51.537908] kernfs: can not remove 'max_comp_streams', no directory
>> [ 51.539089] Modules linked in: zram lz4_compress xt_conntrack
>> cfg80211 rfkill ebtable_nat ebtable_broute bridge stp llc
>> ebtable_filter ebtables ip6_tables iptable_nat nf_conntrack_ipv4
>> nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack iptable_mangle
>> iptable_security iptable_raw ppdev crct10dif_pclmul crc32_pclmul
>> crc32c_intel joydev ghash_clmulni_intel microcode serio_raw pcspkr
>> virtio_balloon virtio_console parport_pc pvpanic virtio_net parport
>> floppy i2c_piix4 nfsd auth_rpcgss nfs_acl lockd sunrpc qxl
>> drm_kms_helper ttm virtio_blk drm virtio_pci virtio_ring virtio
>> ata_generic pata_acpi
>> [ 51.550844] CPU: 0 PID: 840 Comm: conc_init.sh Tainted: G D W
>> 3.16.0-rc5-memacct-next-20140715+ #146
>> [ 51.552606] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
>> [ 51.553691] 0000000000000009 ffff880078343d20 ffffffff8172d344
>> ffff880078343d68
>> [ 51.555412] ffff880078343d58 ffffffff8108ad1d 0000000000000000
>> ffffffffa0320242
>> [ 51.557811] ffffffffa0321058 0000000000000002 ffff880078343f50
>> ffff880078343db8
>> [ 51.559580] Call Trace:
>> [ 51.560139] [<ffffffff8172d344>] dump_stack+0x45/0x56
>> [ 51.561161] [<ffffffff8108ad1d>] warn_slowpath_common+0x7d/0xa0
>> [ 51.562333] [<ffffffff8108ad8c>] warn_slowpath_fmt+0x4c/0x50
>> [ 51.563445] [<ffffffff81218196>] ? evict+0x106/0x170
>> [ 51.564432] [<ffffffff81275695>] kernfs_remove_by_name_ns+0x95/0xa0
>> [ 51.565627] [<ffffffff81277ee9>] remove_files.isra.1+0x39/0x70
>> [ 51.566753] [<ffffffff812781f4>] sysfs_remove_group+0x44/0xa0
>> [ 51.567870] [<ffffffffa031e058>] destroy_device.isra.17+0x28/0x50
>> [zram]
>> [ 51.569089] [<ffffffffa031e5d0>] reset_store+0x100/0x140 [zram]
>> [ 51.570197] [<ffffffff8146c3e8>] dev_attr_store+0x18/0x30
>> [ 51.571247] [<ffffffff81276fd4>] sysfs_kf_write+0x44/0x60
>> [ 51.572201] [<ffffffff812768d7>] kernfs_fop_write+0xe7/0x170
>> [ 51.573283] [<ffffffff811fbcf7>] vfs_write+0xb7/0x1f0
>> [ 51.574143] [<ffffffff811fc8a9>] SyS_write+0x49/0xb0
>> [ 51.574976] [<ffffffff8112e724>] ? __audit_syscall_entry+0xb4/0x110
>> [ 51.576213] [<ffffffff817362a9>] system_call_fastpath+0x16/0x1b
>> [ 51.577422] ---[ end trace cdb79035dad379f3 ]---
>> [ 51.578401] ------------[ cut here ]------------
>> [ 51.579354] WARNING: CPU: 0 PID: 840 at fs/kernfs/dir.c:1209
>> kernfs_remove_by_name_ns+0x95/0xa0()
>> [ 51.580966] kernfs: can not remove 'comp_algorithm', no directory
>> [ 51.582108] Modules linked in: zram lz4_compress xt_conntrack
>> cfg80211 rfkill ebtable_nat ebtable_broute bridge stp llc
>> ebtable_filter ebtables ip6_tables iptable_nat nf_conntrack_ipv4
>> nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack iptable_mangle
>> iptable_security iptable_raw ppdev crct10dif_pclmul crc32_pclmul
>> crc32c_intel joydev ghash_clmulni_intel microcode serio_raw pcspkr
>> virtio_balloon virtio_console parport_pc pvpanic virtio_net parport
>> floppy i2c_piix4 nfsd auth_rpcgss nfs_acl lockd sunrpc qxl
>> drm_kms_helper ttm virtio_blk drm virtio_pci virtio_ring virtio
>> ata_generic pata_acpi
>> [ 51.597177] CPU: 0 PID: 840 Comm: conc_init.sh Tainted: G D W
>> 3.16.0-rc5-memacct-next-20140715+ #146
>> [ 51.598549] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
>> [ 51.599661] 0000000000000009 ffff880078343d20 ffffffff8172d344
>> ffff880078343d68
>> [ 51.601519] ffff880078343d58 ffffffff8108ad1d 0000000000000000
>> ffffffffa0320233
>> [ 51.603362] ffffffffa0321058 0000000000000002 ffff880078343f50
>> ffff880078343db8
>> [ 51.604913] Call Trace:
>> [ 51.605444] [<ffffffff8172d344>] dump_stack+0x45/0x56
>> [ 51.606537] [<ffffffff8108ad1d>] warn_slowpath_common+0x7d/0xa0
>> [ 51.607507] [<ffffffff8108ad8c>] warn_slowpath_fmt+0x4c/0x50
>> [ 51.608582] [<ffffffff81218196>] ? evict+0x106/0x170
>> [ 51.609423] [<ffffffff81275695>] kernfs_remove_by_name_ns+0x95/0xa0
>> [ 51.610436] [<ffffffff81277ee9>] remove_files.isra.1+0x39/0x70
>> [ 51.611408] [<ffffffff812781f4>] sysfs_remove_group+0x44/0xa0
>> [ 51.612431] [<ffffffffa031e058>] destroy_device.isra.17+0x28/0x50
>> [zram]
>> [ 51.613214] [<ffffffffa031e5d0>] reset_store+0x100/0x140 [zram]
>> [ 51.613928] [<ffffffff8146c3e8>] dev_attr_store+0x18/0x30
>> [ 51.614634] [<ffffffff81276fd4>] sysfs_kf_write+0x44/0x60
>> [ 51.615387] [<ffffffff812768d7>] kernfs_fop_write+0xe7/0x170
>> [ 51.616246] [<ffffffff811fbcf7>] vfs_write+0xb7/0x1f0
>> [ 51.619107] [<ffffffff811fc8a9>] SyS_write+0x49/0xb0
>> [ 51.620063] [<ffffffff8112e724>] ? __audit_syscall_entry+0xb4/0x110
>> [ 51.622071] [<ffffffff817362a9>] system_call_fastpath+0x16/0x1b
>> [ 51.623256] ---[ end trace cdb79035dad379f4 ]---
>>
>> And lots more of similar messages.
>>
>> Jerome
>>
>
> Thanks for catching, i try fix it and resend patch.
I check loop device logic, and loop device not destroy automatically,
only creating on demand.
If i delete automatically destroy logic function from my patch, for
working like loop
(also loop create new device only if all device in use) and without
destroy function my patch pass your concurrency test.
Because we can't catch case when device created and destroyed in same time.
It have meaning to rework patch, for save only auto add logic and make
it working like loop (if all device in use -> add new)?
I also have until to setup zram devices (written on C++), like losetup
for loop devices, and i think if patch for kernel will be adopted.
I can port my util from C++ to C and try add to util-linux, for having
generic solution to setup zram devices, instead of several tens of
utilities for all distros).
I just think what all in linux can have generic, simple, fast and useful
solution, and if i can make something more useful, i must do it.
Thanks,
Timofey.