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zram: auto add/del devices on demand

PATCH Superseded Timofey Titovets 2 participants 3 messages Jul 17, 2014

Subsystems (2)
Block layer zram

v1 of 3 Superseded Latest is v3 →

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Timofey Titovets

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#0 lore raw

PATCH 1/1 zram: auto add/del devices on demand

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]>

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
---
drivers/block/zram/zram_drv.c | 65 ++++++++++++++++++++++++++++++++++++++++---

1 file changed, 61 insertions(+), 4 deletions(-)
drivers/block/zram/zram_drv.c +61 -4
index 089e72c..d0a3055 100644
@@ -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 +964,51 @@ 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)
+{
+	int ret;
+
+	if (last_created_dev+1 > max_num_devices) {
+		pr_warn("Can't add zram%u, max device number reached\n",
+			num_devices);
+		last_created_dev--;
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (&zram_devices[last_created_dev].disksize > 0) {
+		last_created_dev++;
+		ret = create_device(&zram_devices[last_created_dev],
+							last_created_dev);
+		if (ret)
+			goto free;
+		pr_info("Created zram%u device\n", last_created_dev);
+	}
+
+	return;
+
+free:
+	destroy_device(&zram_devices[last_created_dev]);
+	last_created_dev--;
+out:;
+}
+
 static int __init zram_init(void)
 {
 	int ret, dev_id;

@@ -972,18 +1027,20 @@ 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 +1061,7 @@ 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 +1082,7 @@ 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]>");
#1 lore raw

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Quoted 9 lines · Timofey Titovets

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;

Hi Timofey,

Your patch change zram behaviour. Please describe what changes from the user point of view and update Documentation/blockdev/zram.txt accordingly.

Quoted 59 lines
Signed-off-by Timofey Titovets <[email protected]>

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

 --- drivers/block/zram/zram_drv.c | 65

++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 61 insertions(+), 4 deletions(-)

(quoted diff) +0 -0

b/drivers/block/zram/zram_drv.c index 089e72c..d0a3055 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;

(quoted diff) +0 -0
@@ -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;

(quoted diff) +0 -0
@@ -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 +964,51 @@ static void destroy_device(struct zram *zram) blk_cleanup_queue(zram->queue); }

(quoted diff) +2 -0
+/* 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 && +

Quoted 8 lines

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) +{ + int
ret; + + if (last_created_dev+1 > max_num_devices) { +
pr_warn("Can't add zram%u, max device number reached\n", +
num_devices); + last_created_dev--; + ret = -EINVAL;

Why do you set ret to EINVAL here? It's never used.

Quoted 1 line

+ goto out;

That label is useless. Just use return.

Quoted 4 lines

+ } + + if (&zram_devices[last_created_dev].disksize > 0) { +
last_created_dev++; + ret =
create_device(&zram_devices[last_created_dev], +
last_created_dev); + if (ret) + goto free;

If ret is only used to test that create_device() succeeded, then we can get rid of that variable altogether.

Thanks,
Jerome

Quoted 29 lines

+ pr_info("Created zram%u device\n", last_created_dev); +
} + + return; + +free: +
destroy_device(&zram_devices[last_created_dev]); + last_created_dev--; +out:; +} + static int __init zram_init(void) { int ret, dev_id; @@ -972,18 +1027,20 @@ 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);

drivers/block/zram/zram_drv.c +0 -1
@@ -1004,7 +1061,7 @@ 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 +1082,7 @@
module_init(zram_init); module_exit(zram_exit);

Quoted 6 lines

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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author
#2 lore raw

Thanks for comments, i will fix what you say and split patches one for code and one for Documentation. After, i will resend patch set

Quoted 154 lines · Jerome Marchand

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Hash: SHA1

Quoted 9 lines · Timofey Titovets

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;

Hi Timofey,

Your patch change zram behaviour. Please describe what changes from the user point of view and update Documentation/blockdev/zram.txt accordingly.

Quoted 59 lines
Signed-off-by Timofey Titovets <[email protected]>

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

  --- drivers/block/zram/zram_drv.c | 65

++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 61 insertions(+), 4 deletions(-)

(quoted diff) +0 -0

b/drivers/block/zram/zram_drv.c index 089e72c..d0a3055 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;

(quoted diff) +0 -0
@@ -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;

(quoted diff) +0 -0
@@ -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 +964,51 @@ static void destroy_device(struct zram *zram) blk_cleanup_queue(zram->queue); }

(quoted diff) +2 -0
+/* 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 && +

Quoted 8 lines

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) +{ + int
ret; + + if (last_created_dev+1 > max_num_devices) { +
pr_warn("Can't add zram%u, max device number reached\n", +
num_devices); + last_created_dev--; + ret = -EINVAL;

Why do you set ret to EINVAL here? It's never used.

Quoted 1 line

+ goto out;

That label is useless. Just use return.

Quoted 4 lines

+ } + + if (&zram_devices[last_created_dev].disksize > 0) { +
last_created_dev++; + ret =
create_device(&zram_devices[last_created_dev], +
last_created_dev); + if (ret) + goto free;

If ret is only used to test that create_device() succeeded, then we can get rid of that variable altogether.

Thanks,
Jerome

Quoted 29 lines

+ pr_info("Created zram%u device\n", last_created_dev); +
} + + return; + +free: +
destroy_device(&zram_devices[last_created_dev]); + last_created_dev--; +out:; +} + static int __init zram_init(void) { int ret, dev_id; @@ -972,18 +1027,20 @@ 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);

drivers/block/zram/zram_drv.c +0 -1
@@ -1004,7 +1061,7 @@ 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 +1082,7 @@
module_init(zram_init); module_exit(zram_exit);

Quoted 6 lines

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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