[PATCHv2 0/7] introduce dynamic device creation/removal

[PATCHv2 0/7] introduce dynamic device creation/removal

[Sergey Senozhatsky]

Hello,

This patchset introduces zram-control sysfs class, which has two sysfs
attrs:
 - zram_add	-- add a new specific (device_id) zram device
 - zram_remove	-- remove a specific (device_id) zram device


    Usage example:
        # add a new specific zram device
        echo 4 > /sys/class/zram-control/zram_add

        # remove a specific zram device
        echo 4 > /sys/class/zram-control/zram_remove


Patch set also does some cleanups and huge code reorganization.

v2:
switch to sysfs class, rather than using /dev/zram-control node and
doing IOCTL on it. we lose some features, though. like automatic
device_id generation.

Sergey Senozhatsky (7):
  zram: cosmetic ZRAM_ATTR_RO code formatting tweak
  zram: use idr instead of `zram_devices' array
  zram: factor out device reset from reset_store()
  zram: reorganize code layout
  zram: add dynamic device add/remove functionality
  zram: remove max_num_devices limitation
  zram: report every added and removed device

 Documentation/ABI/testing/sysfs-class-zram |  23 +
 drivers/block/zram/zram_drv.c              | 780 +++++++++++++++++------------
 drivers/block/zram/zram_drv.h              |   6 -
 3 files changed, 474 insertions(+), 335 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-class-zram

-- 
2.3.1.167.g7f4ba4b

[PATCHv2 1/7] zram: cosmetic ZRAM_ATTR_RO code formatting tweak

[Sergey Senozhatsky]

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
---
 drivers/block/zram/zram_drv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 871bd35..8fc2566 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -44,7 +44,7 @@ static const char *default_compressor = "lzo";
 static unsigned int num_devices = 1;
 
 #define ZRAM_ATTR_RO(name)						\
-static ssize_t name##_show(struct device *d,		\
+static ssize_t name##_show(struct device *d,				\
 				struct device_attribute *attr, char *b)	\
 {									\
 	struct zram *zram = dev_to_zram(d);				\
-- 
2.3.1.167.g7f4ba4b

[PATCHv2 2/7] zram: use idr instead of `zram_devices' array

[Sergey Senozhatsky]

This patch makes some preparations for dynamic device ADD/REMOVE functionality
via /dev/zram-control interface.

Remove `zram_devices' array and switch to id-to-pointer translation (idr).
idr doesn't bloat zram struct with additional members, f.e. list_head, yet
still provides ability to match the device_id with the device pointer.
No user-space visible changes.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
---
 drivers/block/zram/zram_drv.c | 81 ++++++++++++++++++++++++-------------------
 1 file changed, 46 insertions(+), 35 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 8fc2566..6707b7b 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -32,12 +32,12 @@
 #include <linux/string.h>
 #include <linux/vmalloc.h>
 #include <linux/err.h>
+#include <linux/idr.h>
 
 #include "zram_drv.h"
 
-/* Globals */
+static DEFINE_IDR(zram_index_idr);
 static int zram_major;
-static struct zram *zram_devices;
 static const char *default_compressor = "lzo";
 
 /* Module params (documentation at end) */
@@ -1061,18 +1061,28 @@ static struct attribute_group zram_disk_attr_group = {
 	.attrs = zram_disk_attrs,
 };
 
-static int create_device(struct zram *zram, int device_id)
+static int zram_add(int device_id)
 {
+	struct zram *zram;
 	struct request_queue *queue;
 	int ret = -ENOMEM;
 
+	zram = kzalloc(sizeof(struct zram), GFP_KERNEL);
+	if (!zram)
+		return ret;
+
+	ret = idr_alloc(&zram_index_idr, zram, device_id,
+			device_id + 1, GFP_KERNEL);
+	if (ret < 0)
+		goto out_free_dev;
+
 	init_rwsem(&zram->init_lock);
 
 	queue = blk_alloc_queue(GFP_KERNEL);
 	if (!queue) {
 		pr_err("Error allocating disk queue for device %d\n",
 			device_id);
-		goto out;
+		goto out_free_idr;
 	}
 
 	blk_queue_make_request(queue, zram_make_request);
@@ -1141,34 +1151,42 @@ out_free_disk:
 	put_disk(zram->disk);
 out_free_queue:
 	blk_cleanup_queue(queue);
-out:
+out_free_idr:
+	idr_remove(&zram_index_idr, device_id);
+out_free_dev:
+	kfree(zram);
 	return ret;
 }
 
-static void destroy_devices(unsigned int nr)
+static void zram_remove(struct zram *zram)
 {
-	struct zram *zram;
-	unsigned int i;
-
-	for (i = 0; i < nr; i++) {
-		zram = &zram_devices[i];
-		/*
-		 * Remove sysfs first, so no one will perform a disksize
-		 * store while we destroy the devices
-		 */
-		sysfs_remove_group(&disk_to_dev(zram->disk)->kobj,
-				&zram_disk_attr_group);
+	/*
+	 * Remove sysfs first, so no one will perform a disksize
+	 * store while we destroy the devices
+	 */
+	sysfs_remove_group(&disk_to_dev(zram->disk)->kobj,
+			&zram_disk_attr_group);
 
-		zram_reset_device(zram);
+	zram_reset_device(zram);
+	idr_remove(&zram_index_idr, zram->disk->first_minor);
+	blk_cleanup_queue(zram->disk->queue);
+	del_gendisk(zram->disk);
+	put_disk(zram->disk);
+	kfree(zram);
+}
 
-		blk_cleanup_queue(zram->disk->queue);
-		del_gendisk(zram->disk);
-		put_disk(zram->disk);
-	}
+static int zram_exit_cb(int id, void *ptr, void *data)
+{
+	zram_remove(ptr);
+	return 0;
+}
 
-	kfree(zram_devices);
+static void destroy_devices(void)
+{
+	idr_for_each(&zram_index_idr, &zram_exit_cb, NULL);
+	idr_destroy(&zram_index_idr);
 	unregister_blkdev(zram_major, "zram");
-	pr_info("Destroyed %u device(s)\n", nr);
+	pr_info("Destroyed device(s)\n");
 }
 
 static int __init zram_init(void)
@@ -1187,16 +1205,9 @@ static int __init zram_init(void)
 		return -EBUSY;
 	}
 
-	/* Allocate the device array and initialize each one */
-	zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
-	if (!zram_devices) {
-		unregister_blkdev(zram_major, "zram");
-		return -ENOMEM;
-	}
-
 	for (dev_id = 0; dev_id < num_devices; dev_id++) {
-		ret = create_device(&zram_devices[dev_id], dev_id);
-		if (ret)
+		ret = zram_add(dev_id);
+		if (ret != 0)
 			goto out_error;
 	}
 
@@ -1204,13 +1215,13 @@ static int __init zram_init(void)
 	return 0;
 
 out_error:
-	destroy_devices(dev_id);
+	destroy_devices();
 	return ret;
 }
 
 static void __exit zram_exit(void)
 {
-	destroy_devices(num_devices);
+	destroy_devices();
 }
 
 module_init(zram_init);
-- 
2.3.1.167.g7f4ba4b

[PATCHv2 3/7] zram: factor out device reset from reset_store()

[Sergey Senozhatsky]

Device reset currently consists of two steps:
a) holding ->bd_mutex we ensure that there are no device users
(bdev->bd_openers)

b) and internal part (executed under bdev->bd_mutex and partially
under zram->init_lock) that resets the device - frees allocated
memory and returns the device back to its initial (un-init) state.

Dynamic device removal requires the same amount of work and checks.
We can reuse internal cleanup part (b) zram_reset_device(), but step (a)
is done in sysfs ATTR reset_store() handler.

Rename step (b) from zram_reset_device() to zram_reset_device_internal()
and factor out step (a) to zram_reset_device(). Both reset_store() and
dynamic device removal will use zram_reset_device().

For readability let's keep them separated.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
---
 drivers/block/zram/zram_drv.c | 135 +++++++++++++++++++++---------------------
 1 file changed, 67 insertions(+), 68 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 6707b7b..59662dc 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -729,48 +729,6 @@ static void zram_bio_discard(struct zram *zram, u32 index,
 	}
 }
 
-static void zram_reset_device(struct zram *zram)
-{
-	struct zram_meta *meta;
-	struct zcomp *comp;
-	u64 disksize;
-
-	down_write(&zram->init_lock);
-
-	zram->limit_pages = 0;
-
-	if (!init_done(zram)) {
-		up_write(&zram->init_lock);
-		return;
-	}
-
-	meta = zram->meta;
-	comp = zram->comp;
-	disksize = zram->disksize;
-	/*
-	 * Refcount will go down to 0 eventually and r/w handler
-	 * cannot handle further I/O so it will bail out by
-	 * check zram_meta_get.
-	 */
-	zram_meta_put(zram);
-	/*
-	 * We want to free zram_meta in process context to avoid
-	 * deadlock between reclaim path and any other locks.
-	 */
-	wait_event(zram->io_done, atomic_read(&zram->refcount) == 0);
-
-	/* Reset stats */
-	memset(&zram->stats, 0, sizeof(zram->stats));
-	zram->disksize = 0;
-	zram->max_comp_streams = 1;
-	set_capacity(zram->disk, 0);
-
-	up_write(&zram->init_lock);
-	/* I/O operation under all of CPU are done so let's free */
-	zram_meta_free(meta, disksize);
-	zcomp_destroy(comp);
-}
-
 static ssize_t disksize_store(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t len)
 {
@@ -829,16 +787,54 @@ out_free_meta:
 	return err;
 }
 
-static ssize_t reset_store(struct device *dev,
-		struct device_attribute *attr, const char *buf, size_t len)
+/* internal device reset part -- cleanup allocated memory and
+ * return back to initial state */
+static void zram_reset_device_internal(struct zram *zram)
 {
-	int ret;
-	unsigned short do_reset;
-	struct zram *zram;
-	struct block_device *bdev;
+	struct zram_meta *meta;
+	struct zcomp *comp;
+	u64 disksize;
 
-	zram = dev_to_zram(dev);
-	bdev = bdget_disk(zram->disk, 0);
+	down_write(&zram->init_lock);
+
+	zram->limit_pages = 0;
+
+	if (!init_done(zram)) {
+		up_write(&zram->init_lock);
+		return;
+	}
+
+	meta = zram->meta;
+	comp = zram->comp;
+	disksize = zram->disksize;
+	/*
+	 * Refcount will go down to 0 eventually and r/w handler
+	 * cannot handle further I/O so it will bail out by
+	 * check zram_meta_get.
+	 */
+	zram_meta_put(zram);
+	/*
+	 * We want to free zram_meta in process context to avoid
+	 * deadlock between reclaim path and any other locks.
+	 */
+	wait_event(zram->io_done, atomic_read(&zram->refcount) == 0);
+
+	/* Reset stats */
+	memset(&zram->stats, 0, sizeof(zram->stats));
+	zram->disksize = 0;
+	zram->max_comp_streams = 1;
+	set_capacity(zram->disk, 0);
+
+	up_write(&zram->init_lock);
+	/* I/O operation under all of CPU are done so let's free */
+	zram_meta_free(meta, disksize);
+	zcomp_destroy(comp);
+}
+
+static int zram_reset_device(struct zram *zram)
+{
+	int ret = 0;
+	struct block_device *bdev = bdget_disk(zram->disk, 0);
 
 	if (!bdev)
 		return -ENOMEM;
@@ -850,31 +846,34 @@ static ssize_t reset_store(struct device *dev,
 		goto out;
 	}
 
-	ret = kstrtou16(buf, 10, &do_reset);
-	if (ret)
-		goto out;
-
-	if (!do_reset) {
-		ret = -EINVAL;
-		goto out;
-	}
-
 	/* Make sure all pending I/O is finished */
 	fsync_bdev(bdev);
-	zram_reset_device(zram);
-
-	mutex_unlock(&bdev->bd_mutex);
-	revalidate_disk(zram->disk);
-	bdput(bdev);
-
-	return len;
-
+	zram_reset_device_internal(zram);
 out:
 	mutex_unlock(&bdev->bd_mutex);
 	bdput(bdev);
 	return ret;
 }
 
+static ssize_t reset_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t len)
+{
+	int ret;
+	unsigned short do_reset;
+	struct zram *zram;
+
+	zram = dev_to_zram(dev);
+	ret = kstrtou16(buf, 10, &do_reset);
+	if (ret)
+		return ret;
+
+	if (!do_reset)
+		return -EINVAL;
+
+	ret = zram_reset_device(zram);
+	return ret ? ret : len;
+}
+
 static void __zram_make_request(struct zram *zram, struct bio *bio)
 {
 	int offset, rw;
@@ -1167,7 +1166,7 @@ static void zram_remove(struct zram *zram)
 	sysfs_remove_group(&disk_to_dev(zram->disk)->kobj,
 			&zram_disk_attr_group);
 
-	zram_reset_device(zram);
+	zram_reset_device_internal(zram);
 	idr_remove(&zram_index_idr, zram->disk->first_minor);
 	blk_cleanup_queue(zram->disk->queue);
 	del_gendisk(zram->disk);
-- 
2.3.1.167.g7f4ba4b

[PATCHv2 4/7] zram: reorganize code layout

[Sergey Senozhatsky]

This patch looks big, but basically it just moves code blocks forward
and backward. No functional changes.

Our current code layout looks a bit like a sandwitch.

For example,
a) between read/write handlers, we have update_used_max() helper function:

static int zram_decompress_page
static int zram_bvec_read
static inline void update_used_max
static int zram_bvec_write
static int zram_bvec_rw

b) RW request handlers __zram_make_request/zram_bio_discard are divided by
sysfs attr reset_store() function and corresponding zram_reset_device()
handler:

static void zram_bio_discard
static void zram_reset_device
static ssize_t disksize_store
static ssize_t reset_store
static void __zram_make_request

c) we first a bunch of sysfs read/store functions. then a number of
one-liners, then helper functions, RW functions, sysfs functions, helper
functions again, and so on.

Reorganize layout to be more logically grouped (a brief description,
`cat zram_drv.c | grep static` gives a bigger picture):

-- one-liners: zram_test_flag/etc.

-- helpers: is_partial_io/update_position/etc

-- sysfs attr show/store functions + ZRAM_ATTR_RO() generated stats
show() functions
exception: reset and disksize store functions are required to be after meta()
functions. because we do device create/destroy actions in these sysfs
handlers.

-- "mm" functions: meta get/put, meta alloc/free, page free
static inline bool zram_meta_get
static inline void zram_meta_put
static void zram_meta_free
static struct zram_meta *zram_meta_alloc
static void zram_free_page

-- a block of I/O functions
static int zram_decompress_page
static int zram_bvec_read
static int zram_bvec_write
static void zram_bio_discard
static int zram_bvec_rw
static void __zram_make_request
static void zram_make_request
static void zram_slot_free_notify
static int zram_rw_page

-- device contol: add/remove/init/reset functions (+zram-control class
will sit here)
static void zram_reset_device_internal
static int zram_reset_device
static ssize_t reset_store
static ssize_t disksize_store
static int zram_add
static void zram_remove
static int __init zram_init
static void __exit zram_exit

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
---
 drivers/block/zram/zram_drv.c | 593 +++++++++++++++++++++---------------------
 1 file changed, 296 insertions(+), 297 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 59662dc..bab8b20 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -63,6 +63,119 @@ static inline struct zram *dev_to_zram(struct device *dev)
 	return (struct zram *)dev_to_disk(dev)->private_data;
 }
 
+/* flag operations needs meta->tb_lock */
+static int zram_test_flag(struct zram_meta *meta, u32 index,
+			enum zram_pageflags flag)
+{
+	return meta->table[index].value & BIT(flag);
+}
+
+static void zram_set_flag(struct zram_meta *meta, u32 index,
+			enum zram_pageflags flag)
+{
+	meta->table[index].value |= BIT(flag);
+}
+
+static void zram_clear_flag(struct zram_meta *meta, u32 index,
+			enum zram_pageflags flag)
+{
+	meta->table[index].value &= ~BIT(flag);
+}
+
+static size_t zram_get_obj_size(struct zram_meta *meta, u32 index)
+{
+	return meta->table[index].value & (BIT(ZRAM_FLAG_SHIFT) - 1);
+}
+
+static void zram_set_obj_size(struct zram_meta *meta,
+					u32 index, size_t size)
+{
+	unsigned long flags = meta->table[index].value >> ZRAM_FLAG_SHIFT;
+
+	meta->table[index].value = (flags << ZRAM_FLAG_SHIFT) | size;
+}
+
+static inline int is_partial_io(struct bio_vec *bvec)
+{
+	return bvec->bv_len != PAGE_SIZE;
+}
+
+/*
+ * Check if request is within bounds and aligned on zram logical blocks.
+ */
+static inline int valid_io_request(struct zram *zram,
+		sector_t start, unsigned int size)
+{
+	u64 end, bound;
+
+	/* unaligned request */
+	if (unlikely(start & (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1)))
+		return 0;
+	if (unlikely(size & (ZRAM_LOGICAL_BLOCK_SIZE - 1)))
+		return 0;
+
+	end = start + (size >> SECTOR_SHIFT);
+	bound = zram->disksize >> SECTOR_SHIFT;
+	/* out of range range */
+	if (unlikely(start >= bound || end > bound || start > end))
+		return 0;
+
+	/* I/O request is valid */
+	return 1;
+}
+
+static void update_position(u32 *index, int *offset, struct bio_vec *bvec)
+{
+	if (*offset + bvec->bv_len >= PAGE_SIZE)
+		(*index)++;
+	*offset = (*offset + bvec->bv_len) % PAGE_SIZE;
+}
+
+static inline void update_used_max(struct zram *zram,
+					const unsigned long pages)
+{
+	unsigned long old_max, cur_max;
+
+	old_max = atomic_long_read(&zram->stats.max_used_pages);
+
+	do {
+		cur_max = old_max;
+		if (pages > cur_max)
+			old_max = atomic_long_cmpxchg(
+				&zram->stats.max_used_pages, cur_max, pages);
+	} while (old_max != cur_max);
+}
+
+static int page_zero_filled(void *ptr)
+{
+	unsigned int pos;
+	unsigned long *page;
+
+	page = (unsigned long *)ptr;
+
+	for (pos = 0; pos != PAGE_SIZE / sizeof(*page); pos++) {
+		if (page[pos])
+			return 0;
+	}
+
+	return 1;
+}
+
+static void handle_zero_page(struct bio_vec *bvec)
+{
+	struct page *page = bvec->bv_page;
+	void *user_mem;
+
+	user_mem = kmap_atomic(page);
+	if (is_partial_io(bvec))
+		memset(user_mem + bvec->bv_offset, 0, bvec->bv_len);
+	else
+		clear_page(user_mem);
+	kunmap_atomic(user_mem);
+
+	flush_dcache_page(page);
+}
+
 static ssize_t disksize_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
@@ -246,65 +359,25 @@ static ssize_t comp_algorithm_store(struct device *dev,
 	return len;
 }
 
-/* flag operations needs meta->tb_lock */
-static int zram_test_flag(struct zram_meta *meta, u32 index,
-			enum zram_pageflags flag)
-{
-	return meta->table[index].value & BIT(flag);
-}
-
-static void zram_set_flag(struct zram_meta *meta, u32 index,
-			enum zram_pageflags flag)
-{
-	meta->table[index].value |= BIT(flag);
-}
-
-static void zram_clear_flag(struct zram_meta *meta, u32 index,
-			enum zram_pageflags flag)
-{
-	meta->table[index].value &= ~BIT(flag);
-}
-
-static size_t zram_get_obj_size(struct zram_meta *meta, u32 index)
-{
-	return meta->table[index].value & (BIT(ZRAM_FLAG_SHIFT) - 1);
-}
-
-static void zram_set_obj_size(struct zram_meta *meta,
-					u32 index, size_t size)
-{
-	unsigned long flags = meta->table[index].value >> ZRAM_FLAG_SHIFT;
-
-	meta->table[index].value = (flags << ZRAM_FLAG_SHIFT) | size;
-}
+ZRAM_ATTR_RO(num_reads);
+ZRAM_ATTR_RO(num_writes);
+ZRAM_ATTR_RO(failed_reads);
+ZRAM_ATTR_RO(failed_writes);
+ZRAM_ATTR_RO(invalid_io);
+ZRAM_ATTR_RO(notify_free);
+ZRAM_ATTR_RO(zero_pages);
+ZRAM_ATTR_RO(compr_data_size);
 
-static inline int is_partial_io(struct bio_vec *bvec)
+static inline bool zram_meta_get(struct zram *zram)
 {
-	return bvec->bv_len != PAGE_SIZE;
+	if (atomic_inc_not_zero(&zram->refcount))
+		return true;
+	return false;
 }
 
-/*
- * Check if request is within bounds and aligned on zram logical blocks.
- */
-static inline int valid_io_request(struct zram *zram,
-		sector_t start, unsigned int size)
+static inline void zram_meta_put(struct zram *zram)
 {
-	u64 end, bound;
-
-	/* unaligned request */
-	if (unlikely(start & (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1)))
-		return 0;
-	if (unlikely(size & (ZRAM_LOGICAL_BLOCK_SIZE - 1)))
-		return 0;
-
-	end = start + (size >> SECTOR_SHIFT);
-	bound = zram->disksize >> SECTOR_SHIFT;
-	/* out of range range */
-	if (unlikely(start >= bound || end > bound || start > end))
-		return 0;
-
-	/* I/O request is valid */
-	return 1;
+	atomic_dec(&zram->refcount);
 }
 
 static void zram_meta_free(struct zram_meta *meta, u64 disksize)
@@ -358,56 +431,6 @@ out_error:
 	return NULL;
 }
 
-static inline bool zram_meta_get(struct zram *zram)
-{
-	if (atomic_inc_not_zero(&zram->refcount))
-		return true;
-	return false;
-}
-
-static inline void zram_meta_put(struct zram *zram)
-{
-	atomic_dec(&zram->refcount);
-}
-
-static void update_position(u32 *index, int *offset, struct bio_vec *bvec)
-{
-	if (*offset + bvec->bv_len >= PAGE_SIZE)
-		(*index)++;
-	*offset = (*offset + bvec->bv_len) % PAGE_SIZE;
-}
-
-static int page_zero_filled(void *ptr)
-{
-	unsigned int pos;
-	unsigned long *page;
-
-	page = (unsigned long *)ptr;
-
-	for (pos = 0; pos != PAGE_SIZE / sizeof(*page); pos++) {
-		if (page[pos])
-			return 0;
-	}
-
-	return 1;
-}
-
-static void handle_zero_page(struct bio_vec *bvec)
-{
-	struct page *page = bvec->bv_page;
-	void *user_mem;
-
-	user_mem = kmap_atomic(page);
-	if (is_partial_io(bvec))
-		memset(user_mem + bvec->bv_offset, 0, bvec->bv_len);
-	else
-		clear_page(user_mem);
-	kunmap_atomic(user_mem);
-
-	flush_dcache_page(page);
-}
-
-
 /*
  * To protect concurrent access to the same index entry,
  * caller should hold this table index entry's bit_spinlock to
@@ -440,6 +463,7 @@ static void zram_free_page(struct zram *zram, size_t index)
 	zram_set_obj_size(meta, index, 0);
 }
 
+
 static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
 {
 	int ret = 0;
@@ -525,21 +549,6 @@ out_cleanup:
 	return ret;
 }
 
-static inline void update_used_max(struct zram *zram,
-					const unsigned long pages)
-{
-	unsigned long old_max, cur_max;
-
-	old_max = atomic_long_read(&zram->stats.max_used_pages);
-
-	do {
-		cur_max = old_max;
-		if (pages > cur_max)
-			old_max = atomic_long_cmpxchg(
-				&zram->stats.max_used_pages, cur_max, pages);
-	} while (old_max != cur_max);
-}
-
 static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
 			   int offset)
 {
@@ -667,36 +676,13 @@ out:
 	return ret;
 }
 
-static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
-			int offset, int rw)
-{
-	int ret;
-
-	if (rw == READ) {
-		atomic64_inc(&zram->stats.num_reads);
-		ret = zram_bvec_read(zram, bvec, index, offset);
-	} else {
-		atomic64_inc(&zram->stats.num_writes);
-		ret = zram_bvec_write(zram, bvec, index, offset);
-	}
-
-	if (unlikely(ret)) {
-		if (rw == READ)
-			atomic64_inc(&zram->stats.failed_reads);
-		else
-			atomic64_inc(&zram->stats.failed_writes);
-	}
-
-	return ret;
-}
-
-/*
- * zram_bio_discard - handler on discard request
- * @index: physical block index in PAGE_SIZE units
- * @offset: byte offset within physical block
- */
-static void zram_bio_discard(struct zram *zram, u32 index,
-			     int offset, struct bio *bio)
+/*
+ * zram_bio_discard - handler on discard request
+ * @index: physical block index in PAGE_SIZE units
+ * @offset: byte offset within physical block
+ */
+static void zram_bio_discard(struct zram *zram, u32 index,
+			     int offset, struct bio *bio)
 {
 	size_t n = bio->bi_iter.bi_size;
 	struct zram_meta *meta = zram->meta;
@@ -729,151 +715,29 @@ static void zram_bio_discard(struct zram *zram, u32 index,
 	}
 }
 
-static ssize_t disksize_store(struct device *dev,
-		struct device_attribute *attr, const char *buf, size_t len)
-{
-	u64 disksize;
-	struct zcomp *comp;
-	struct zram_meta *meta;
-	struct zram *zram = dev_to_zram(dev);
-	int err;
-
-	disksize = memparse(buf, NULL);
-	if (!disksize)
-		return -EINVAL;
-
-	disksize = PAGE_ALIGN(disksize);
-	meta = zram_meta_alloc(zram->disk->first_minor, disksize);
-	if (!meta)
-		return -ENOMEM;
-
-	comp = zcomp_create(zram->compressor, zram->max_comp_streams);
-	if (IS_ERR(comp)) {
-		pr_info("Cannot initialise %s compressing backend\n",
-				zram->compressor);
-		err = PTR_ERR(comp);
-		goto out_free_meta;
-	}
-
-	down_write(&zram->init_lock);
-	if (init_done(zram)) {
-		pr_info("Cannot change disksize for initialized device\n");
-		err = -EBUSY;
-		goto out_destroy_comp;
-	}
-
-	init_waitqueue_head(&zram->io_done);
-	atomic_set(&zram->refcount, 1);
-	zram->meta = meta;
-	zram->comp = comp;
-	zram->disksize = disksize;
-	set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
-	up_write(&zram->init_lock);
-
-	/*
-	 * Revalidate disk out of the init_lock to avoid lockdep splat.
-	 * It's okay because disk's capacity is protected by init_lock
-	 * so that revalidate_disk always sees up-to-date capacity.
-	 */
-	revalidate_disk(zram->disk);
-
-	return len;
-
-out_destroy_comp:
-	up_write(&zram->init_lock);
-	zcomp_destroy(comp);
-out_free_meta:
-	zram_meta_free(meta, disksize);
-	return err;
-}
-
-/* internal device reset part -- cleanup allocated memory and
- * return back to initial state */
-static void zram_reset_device_internal(struct zram *zram)
+static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
+			int offset, int rw)
 {
-	struct zram_meta *meta;
-	struct zcomp *comp;
-	u64 disksize;
-
-	down_write(&zram->init_lock);
-
-	zram->limit_pages = 0;
+	int ret;
 
-	if (!init_done(zram)) {
-		up_write(&zram->init_lock);
-		return;
+	if (rw == READ) {
+		atomic64_inc(&zram->stats.num_reads);
+		ret = zram_bvec_read(zram, bvec, index, offset);
+	} else {
+		atomic64_inc(&zram->stats.num_writes);
+		ret = zram_bvec_write(zram, bvec, index, offset);
 	}
 
-	meta = zram->meta;
-	comp = zram->comp;
-	disksize = zram->disksize;
-	/*
-	 * Refcount will go down to 0 eventually and r/w handler
-	 * cannot handle further I/O so it will bail out by
-	 * check zram_meta_get.
-	 */
-	zram_meta_put(zram);
-	/*
-	 * We want to free zram_meta in process context to avoid
-	 * deadlock between reclaim path and any other locks.
-	 */
-	wait_event(zram->io_done, atomic_read(&zram->refcount) == 0);
-
-	/* Reset stats */
-	memset(&zram->stats, 0, sizeof(zram->stats));
-	zram->disksize = 0;
-	zram->max_comp_streams = 1;
-	set_capacity(zram->disk, 0);
-
-	up_write(&zram->init_lock);
-	/* I/O operation under all of CPU are done so let's free */
-	zram_meta_free(meta, disksize);
-	zcomp_destroy(comp);
-}
-
-static int zram_reset_device(struct zram *zram)
-{
-	int ret = 0;
-	struct block_device *bdev = bdget_disk(zram->disk, 0);
-
-	if (!bdev)
-		return -ENOMEM;
-
-	mutex_lock(&bdev->bd_mutex);
-	/* Do not reset an active device! */
-	if (bdev->bd_openers) {
-		ret = -EBUSY;
-		goto out;
+	if (unlikely(ret)) {
+		if (rw == READ)
+			atomic64_inc(&zram->stats.failed_reads);
+		else
+			atomic64_inc(&zram->stats.failed_writes);
 	}
 
-	/* Make sure all pending I/O is finished */
-	fsync_bdev(bdev);
-	zram_reset_device_internal(zram);
-out:
-	mutex_unlock(&bdev->bd_mutex);
-	bdput(bdev);
 	return ret;
 }
 
-static ssize_t reset_store(struct device *dev,
-		struct device_attribute *attr, const char *buf, size_t len)
-{
-	int ret;
-	unsigned short do_reset;
-	struct zram *zram;
-
-	zram = dev_to_zram(dev);
-	ret = kstrtou16(buf, 10, &do_reset);
-	if (ret)
-		return ret;
-
-	if (!do_reset)
-		return -EINVAL;
-
-	ret = zram_reset_device(zram);
-	return ret ? ret : len;
-}
-
 static void __zram_make_request(struct zram *zram, struct bio *bio)
 {
 	int offset, rw;
@@ -928,9 +792,7 @@ out:
 	bio_io_error(bio);
 }
 
-/*
- * Handler function for all zram I/O requests.
- */
+/* Handler function for all zram I/O requests */
 static void zram_make_request(struct request_queue *queue, struct bio *bio)
 {
 	struct zram *zram = queue->queuedata;
@@ -1010,6 +872,152 @@ out:
 	return err;
 }
 
+/* internal device reset part -- cleanup allocated memory and
+ * return back to initial state */
+static void zram_reset_device_internal(struct zram *zram)
+{
+	struct zram_meta *meta;
+	struct zcomp *comp;
+	u64 disksize;
+
+	down_write(&zram->init_lock);
+
+	zram->limit_pages = 0;
+
+	if (!init_done(zram)) {
+		up_write(&zram->init_lock);
+		return;
+	}
+
+	meta = zram->meta;
+	comp = zram->comp;
+	disksize = zram->disksize;
+	/*
+	 * Refcount will go down to 0 eventually and r/w handler
+	 * cannot handle further I/O so it will bail out by
+	 * check zram_meta_get.
+	 */
+	zram_meta_put(zram);
+	/*
+	 * We want to free zram_meta in process context to avoid
+	 * deadlock between reclaim path and any other locks.
+	 */
+	wait_event(zram->io_done, atomic_read(&zram->refcount) == 0);
+
+	/* Reset stats */
+	memset(&zram->stats, 0, sizeof(zram->stats));
+	zram->disksize = 0;
+	zram->max_comp_streams = 1;
+	set_capacity(zram->disk, 0);
+
+	up_write(&zram->init_lock);
+	/* I/O operation under all of CPU are done so let's free */
+	zram_meta_free(meta, disksize);
+	zcomp_destroy(comp);
+}
+
+static int zram_reset_device(struct zram *zram)
+{
+	int ret = 0;
+	struct block_device *bdev = bdget_disk(zram->disk, 0);
+
+	if (!bdev)
+		return -ENOMEM;
+
+	mutex_lock(&bdev->bd_mutex);
+	/* Do not reset an active device! */
+	if (bdev->bd_openers) {
+		ret = -EBUSY;
+		goto out;
+	}
+
+	/* Make sure all pending I/O is finished */
+	fsync_bdev(bdev);
+	zram_reset_device_internal(zram);
+out:
+	mutex_unlock(&bdev->bd_mutex);
+	bdput(bdev);
+	return ret;
+}
+
+static ssize_t reset_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t len)
+{
+	int ret;
+	unsigned short do_reset;
+	struct zram *zram;
+
+	zram = dev_to_zram(dev);
+	ret = kstrtou16(buf, 10, &do_reset);
+	if (ret)
+		return ret;
+
+	if (!do_reset)
+		return -EINVAL;
+
+	ret = zram_reset_device(zram);
+	return ret ? ret : len;
+}
+
+static ssize_t disksize_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t len)
+{
+	u64 disksize;
+	struct zcomp *comp;
+	struct zram_meta *meta;
+	struct zram *zram = dev_to_zram(dev);
+	int err;
+
+	disksize = memparse(buf, NULL);
+	if (!disksize)
+		return -EINVAL;
+
+	disksize = PAGE_ALIGN(disksize);
+	meta = zram_meta_alloc(zram->disk->first_minor, disksize);
+	if (!meta)
+		return -ENOMEM;
+
+	comp = zcomp_create(zram->compressor, zram->max_comp_streams);
+	if (IS_ERR(comp)) {
+		pr_info("Cannot initialise %s compressing backend\n",
+				zram->compressor);
+		err = PTR_ERR(comp);
+		goto out_free_meta;
+	}
+
+	down_write(&zram->init_lock);
+	if (init_done(zram)) {
+		pr_info("Cannot change disksize for initialized device\n");
+		err = -EBUSY;
+		goto out_destroy_comp;
+	}
+
+	init_waitqueue_head(&zram->io_done);
+	atomic_set(&zram->refcount, 1);
+	zram->meta = meta;
+	zram->comp = comp;
+	zram->disksize = disksize;
+	set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
+	up_write(&zram->init_lock);
+
+	/*
+	 * Revalidate disk out of the init_lock to avoid lockdep splat.
+	 * It's okay because disk's capacity is protected by init_lock
+	 * so that revalidate_disk always sees up-to-date capacity.
+	 */
+	revalidate_disk(zram->disk);
+
+	return len;
+
+out_destroy_comp:
+	up_write(&zram->init_lock);
+	zcomp_destroy(comp);
+out_free_meta:
+	zram_meta_free(meta, disksize);
+	return err;
+}
+
+/* per-device block device operations and sysfs attrs */
 static const struct block_device_operations zram_devops = {
 	.swap_slot_free_notify = zram_slot_free_notify,
 	.rw_page = zram_rw_page,
@@ -1026,15 +1034,6 @@ static DEVICE_ATTR_RW(mem_used_max);
 static DEVICE_ATTR_RW(max_comp_streams);
 static DEVICE_ATTR_RW(comp_algorithm);
 
-ZRAM_ATTR_RO(num_reads);
-ZRAM_ATTR_RO(num_writes);
-ZRAM_ATTR_RO(failed_reads);
-ZRAM_ATTR_RO(failed_writes);
-ZRAM_ATTR_RO(invalid_io);
-ZRAM_ATTR_RO(notify_free);
-ZRAM_ATTR_RO(zero_pages);
-ZRAM_ATTR_RO(compr_data_size);
-
 static struct attribute *zram_disk_attrs[] = {
 	&dev_attr_disksize.attr,
 	&dev_attr_initstate.attr,
-- 
2.3.1.167.g7f4ba4b

[PATCHv2 5/7] zram: add dynamic device add/remove functionality

[Sergey Senozhatsky]

Introduce zram-control sysfs class, which has two sysfs attrs:
- zram_add	-- add a new specific (device_id) zram device
- zram_remove	-- remove a specific (device_id) zram device

Usage example:
	# add a new specific zram device
	echo 4 > /sys/class/zram-control/zram_add

	# remove a specific zram device
	echo 4 > /sys/class/zram-control/zram_remove

There is no automatic device_id generation, so user is expected to
provide one.

NOTE, there might be users who already depend on the fact that at
least zram0 device gets always created by zram_init(). Thus, due to
compatibility reasons, along with requested device_id (f.e. 5) zram0
will also be created.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
---
 Documentation/ABI/testing/sysfs-class-zram |  23 ++++++
 drivers/block/zram/zram_drv.c              | 117 +++++++++++++++++++++++++++++
 2 files changed, 140 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-class-zram

diff --git a/Documentation/ABI/testing/sysfs-class-zram b/Documentation/ABI/testing/sysfs-class-zram
new file mode 100644
index 0000000..4cbde8d
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-zram
@@ -0,0 +1,23 @@
+What:		/sys/class/zram-control/
+Date:		March 2015
+KernelVersion:	4.0
+Contact:	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
+Description:
+		The zram-control/ class sub-directory belongs to zram
+		device class
+
+What:		/sys/class/zram-control/zram_add
+Date:		March 2015
+KernelVersion:	4.0
+Contact:	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
+Description:
+		Add a specific /dev/zramX device, where X is a device_id
+		provided by user
+
+		What:		/sys/class/zram-control/zram_add
+Date:		March 2015
+KernelVersion:	4.0
+Contact:	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
+Description:
+		Remove a specific /dev/zramX device, where X is a device_id
+		provided by user
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index bab8b20..8609c92 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -33,16 +33,23 @@
 #include <linux/vmalloc.h>
 #include <linux/err.h>
 #include <linux/idr.h>
+#include <linux/sysfs.h>
 
 #include "zram_drv.h"
 
 static DEFINE_IDR(zram_index_idr);
+/* idr index must be protected */
+static DEFINE_MUTEX(zram_index_mutex);
+
 static int zram_major;
 static const char *default_compressor = "lzo";
 
 /* Module params (documentation at end) */
 static unsigned int num_devices = 1;
 
+#define ZRAM_CTL_ADD		1
+#define ZRAM_CTL_REMOVE		2
+
 #define ZRAM_ATTR_RO(name)						\
 static ssize_t name##_show(struct device *d,				\
 				struct device_attribute *attr, char *b)	\
@@ -1173,6 +1180,107 @@ static void zram_remove(struct zram *zram)
 	kfree(zram);
 }
 
+/* lookup if there is any device pointer that match the given device_id.
+ * return device pointer if so, or ERR_PTR() otherwise. */
+static struct zram *zram_lookup(int dev_id)
+{
+	struct zram *zram;
+
+	zram = idr_find(&zram_index_idr, dev_id);
+	if (zram)
+		return zram;
+	return ERR_PTR(-ENODEV);
+}
+
+/* common zram-control add/remove handler */
+static int zram_control(int cmd, const char *buf)
+{
+	struct zram *zram;
+	int ret = -ENOSYS, err, dev_id;
+
+	/* dev_id is gendisk->first_minor, which is `int' */
+	ret = kstrtoint(buf, 10, &dev_id);
+	if (ret || dev_id < 0)
+		return ret;
+
+	mutex_lock(&zram_index_mutex);
+	zram = zram_lookup(dev_id);
+
+	switch (cmd) {
+	case ZRAM_CTL_ADD:
+		if (!IS_ERR(zram)) {
+			ret = -EEXIST;
+			break;
+		}
+		ret = zram_add(dev_id);
+		break;
+	case ZRAM_CTL_REMOVE:
+		if (IS_ERR(zram)) {
+			ret = PTR_ERR(zram);
+			break;
+		}
+
+		/* First, make ->disksize device attr RO, closing
+		 * ZRAM_CTL_REMOVE vs disksize_store() race window */
+		ret = sysfs_chmod_file(&disk_to_dev(zram->disk)->kobj,
+				&dev_attr_disksize.attr, S_IRUGO);
+		if (ret)
+			break;
+
+		ret = zram_reset_device(zram);
+		if (ret == 0) {
+			/* ->disksize is RO and there are no ->bd_openers */
+			zram_remove(zram);
+			break;
+		}
+
+		/* If there are still device bd_openers, try to make ->disksize
+		 * RW again and return. even if we fail to make ->disksize RW,
+		 * user still has RW ->reset attr. so it's possible to destroy
+		 * that device */
+		err = sysfs_chmod_file(&disk_to_dev(zram->disk)->kobj,
+				&dev_attr_disksize.attr,
+				S_IWUSR | S_IRUGO);
+		if (err)
+			ret = err;
+		break;
+	}
+	mutex_unlock(&zram_index_mutex);
+
+	return ret;
+}
+
+/* zram module control sysfs attributes */
+static ssize_t zram_add_store(struct class *class,
+			struct class_attribute *attr,
+			const char *buf,
+			size_t count)
+{
+	int ret = zram_control(ZRAM_CTL_ADD, buf);
+	return ret ? ret : count;
+}
+
+static ssize_t zram_remove_store(struct class *class,
+			struct class_attribute *attr,
+			const char *buf,
+			size_t count)
+{
+	int ret = zram_control(ZRAM_CTL_REMOVE, buf);
+	return ret ? ret : count;
+}
+
+static struct class_attribute zram_control_class_attrs[] = {
+	__ATTR_WO(zram_add),
+	__ATTR_WO(zram_remove),
+	__ATTR_NULL,
+};
+
+static struct class zram_control_class = {
+	.name		= "zram-control",
+	.owner		= THIS_MODULE,
+	.class_attrs	= zram_control_class_attrs,
+};
+
 static int zram_exit_cb(int id, void *ptr, void *data)
 {
 	zram_remove(ptr);
@@ -1181,6 +1289,7 @@ static int zram_exit_cb(int id, void *ptr, void *data)
 
 static void destroy_devices(void)
 {
+	class_destroy(&zram_control_class);
 	idr_for_each(&zram_index_idr, &zram_exit_cb, NULL);
 	idr_destroy(&zram_index_idr);
 	unregister_blkdev(zram_major, "zram");
@@ -1197,6 +1306,12 @@ static int __init zram_init(void)
 		return -EINVAL;
 	}
 
+	ret = class_register(&zram_control_class);
+	if (ret) {
+		pr_warn("Unable to register zram-control class\n");
+		return ret;
+	}
+
 	zram_major = register_blkdev(0, "zram");
 	if (zram_major <= 0) {
 		pr_warn("Unable to get major number\n");
@@ -1204,7 +1319,9 @@ static int __init zram_init(void)
 	}
 
 	for (dev_id = 0; dev_id < num_devices; dev_id++) {
+		mutex_lock(&zram_index_mutex);
 		ret = zram_add(dev_id);
+		mutex_unlock(&zram_index_mutex);
 		if (ret != 0)
 			goto out_error;
 	}
-- 
2.3.1.167.g7f4ba4b

[PATCHv2 6/7] zram: remove max_num_devices limitation

[Sergey Senozhatsky]

Limiting the number of zram devices to 32 (default max_num_devices value)
is confusing, let's drop it. A user with 2TB or 4TB of RAM, for example,
can request as many devices as he can handle.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
---
 drivers/block/zram/zram_drv.c | 8 +-------
 drivers/block/zram/zram_drv.h | 6 ------
 2 files changed, 1 insertion(+), 13 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 8609c92..5664b75 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1300,12 +1300,6 @@ static int __init zram_init(void)
 {
 	int ret, dev_id;
 
-	if (num_devices > max_num_devices) {
-		pr_warn("Invalid value for num_devices: %u\n",
-				num_devices);
-		return -EINVAL;
-	}
-
 	ret = class_register(&zram_control_class);
 	if (ret) {
 		pr_warn("Unable to register zram-control class\n");
@@ -1343,7 +1337,7 @@ 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 <ngupta@vflare.org>");
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index 17056e5..60d14bc 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -20,12 +20,6 @@
 
 #include "zcomp.h"
 
-/*
- * Some arbitrary value. This is just to catch
- * invalid value for num_devices module parameter.
- */
-static const unsigned max_num_devices = 32;
-
 /*-- Configurable parameters */
 
 /*
-- 
2.3.1.167.g7f4ba4b

[PATCHv2 7/7] zram: report every added and removed device

[Sergey Senozhatsky]

With dynamic device creation/removal printing num_devices in zram_init()
doesn't make a lot of sense, as well as printing the number of destroyed
devices in destroy_devices(). Print per-device action (added/removed) in
zram_add() and zram_remove() instead.

Example:

[ 3645.259652] zram: Added device: zram5
[ 3646.152074] zram: Added device: zram6
[ 3650.585012] zram: Removed device: zram5
[ 3655.845584] zram: Added device: zram8
[ 3660.975223] zram: Removed device: zram6

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
---
 drivers/block/zram/zram_drv.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 5664b75..b870916 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1149,6 +1149,8 @@ static int zram_add(int device_id)
 	strlcpy(zram->compressor, default_compressor, sizeof(zram->compressor));
 	zram->meta = NULL;
 	zram->max_comp_streams = 1;
+
+	pr_info("Added device: %s\n", zram->disk->disk_name);
 	return 0;
 
 out_free_disk:
@@ -1175,6 +1177,8 @@ static void zram_remove(struct zram *zram)
 	zram_reset_device_internal(zram);
 	idr_remove(&zram_index_idr, zram->disk->first_minor);
 	blk_cleanup_queue(zram->disk->queue);
+
+	pr_info("Removed device: %s\n", zram->disk->disk_name);
 	del_gendisk(zram->disk);
 	put_disk(zram->disk);
 	kfree(zram);
@@ -1293,7 +1297,6 @@ static void destroy_devices(void)
 	idr_for_each(&zram_index_idr, &zram_exit_cb, NULL);
 	idr_destroy(&zram_index_idr);
 	unregister_blkdev(zram_major, "zram");
-	pr_info("Destroyed device(s)\n");
 }
 
 static int __init zram_init(void)
@@ -1320,7 +1323,6 @@ static int __init zram_init(void)
 			goto out_error;
 	}
 
-	pr_info("Created %u device(s)\n", num_devices);
 	return 0;
 
 out_error:
-- 
2.3.1.167.g7f4ba4b

Re: [PATCHv2 0/7] introduce dynamic device creation/removal

[Sergey Senozhatsky]

On (03/01/15 17:42), Sergey Senozhatsky wrote:
> v2:
> switch to sysfs class, rather than using /dev/zram-control node and
> doing IOCTL on it. we lose some features, though. like automatic
> device_id generation.
> 

Hello,

will submit v3 later today:
-- add missing add/remove documentation
-- fix kernel version typo in class documentation
-- add new trivial cleanup patch

	-ss