Messages in this thread Patch in this message | | | Date | Fri, 18 Jul 2014 01:27:55 +0300 | From | Timofey Titovets <> | Subject | [PATCH v3] zram: auto add new devices on demand |
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From: Timofey Titovets <nefelim4ag@gmail.com>
This add supporting of auto allocate new zram devices on demand, like loop devices
This working by following rules: - Pre create zram devices specified by num_device - if all device already in use -> add new free device
From v1 -> v2: Delete useless variable 'ret', added documentation for explain new zram behaviour
From v2 -> v3 Delete logic to destroy not used devices, for avoid concurrency issues Code refactoring for made patch small and clean as possible Patch can pass the test: #!/bin/sh modprobe zram while true; do echo 10485760 > /sys/block/zram0/disksize& echo 1 > /sys/block/zram0/reset& done
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
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diff --git a/Documentation/blockdev/zram.txt b/Documentation/blockdev/zram.txt index 0595c3f..a090ac7 100644 --- a/Documentation/blockdev/zram.txt +++ b/Documentation/blockdev/zram.txt @@ -21,6 +21,9 @@ Following shows a typical sequence of steps for using zram. This creates 4 devices: /dev/zram{0,1,2,3} (num_devices parameter is optional. Default: 1)
+ If all device in use kernel will create new zram device + (between num_devices and 31) + 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..cc78779 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -43,6 +43,8 @@ static const char *default_compressor = "lzo"; /* Module params (documentation at end) */ static unsigned int num_devices = 1;
+static inline int zram_add_dev(void); + #define ZRAM_ATTR_RO(name) \ static ssize_t zram_attr_##name##_show(struct device *d, \ struct device_attribute *attr, char *b) \ @@ -168,6 +170,7 @@ 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 +242,7 @@ 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 +378,7 @@ 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 +612,7 @@ 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;
@@ -667,6 +673,7 @@ static ssize_t disksize_store(struct device *dev, zram->disksize = disksize; set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT); revalidate_disk(zram->disk); + zram_add_dev(); up_write(&zram->init_lock); return len;
@@ -954,6 +961,34 @@ static void destroy_device(struct zram *zram) blk_cleanup_queue(zram->queue); }
+/* + * Automatically add empty zram device, + * if all created devices already initialized + */ +static inline int zram_add_dev(void) +{ + int dev_id; + + for (dev_id = 0; dev_id < num_devices; dev_id++) { + if (!zram_devices[dev_id].disksize) + return 0; + } + + if (max_num_devices <= num_devices) { + pr_warn("Can't add zram%u, max device number reached\n", num_devices); + return 1; + } + + if (create_device(&zram_devices[num_devices], num_devices)) { + destroy_device(&zram_devices[num_devices]); + return 1; + } + pr_info("Created zram%u device\n", num_devices); + num_devices++; + + return 0; +} + static int __init zram_init(void) { int ret, dev_id; @@ -972,13 +1007,14 @@ 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) @@ -1025,7 +1061,7 @@ 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>");
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