Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932611AbaGQM1f (ORCPT ); Thu, 17 Jul 2014 08:27:35 -0400 Received: from mail-we0-f169.google.com ([74.125.82.169]:53220 "EHLO mail-we0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932075AbaGQM1e (ORCPT ); Thu, 17 Jul 2014 08:27:34 -0400 Message-ID: <53C7C131.1060306@gmail.com> Date: Thu, 17 Jul 2014 15:27:29 +0300 From: Timofey Titovets User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: minchan@kernel.org CC: Sergey Senozhatsky , linux-kernel@vger.kernel.org, Andrew Morton , Jerome Marchand , Nitin Gupta Subject: [PATCH v2] zram: auto add/del devices on demand Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Timofey Titovets 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 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 "); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/