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![Nitin Gupta](/assets/img/avatar_default.png)
Creates RAM based block devices (/dev/ramzswapX) which can be used (only) as swap disks. Pages swapped to these are compressed and stored in memory itself. The module is called ramzswap.ko. It depends on: - xvmalloc memory allocator (compiled with this driver) - lzo_compress.ko - lzo_decompress.ko See ramzswap.txt for usage details. Signed-off-by: Nitin Gupta <ngupta@vflare.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
1435 lines
34 KiB
C
1435 lines
34 KiB
C
/*
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* Compressed RAM based swap device
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*
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* Copyright (C) 2008, 2009 Nitin Gupta
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*
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* This code is released using a dual license strategy: BSD/GPL
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* You can choose the licence that better fits your requirements.
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*
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* Released under the terms of 3-clause BSD License
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* Released under the terms of GNU General Public License Version 2.0
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*
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* Project home: http://compcache.googlecode.com
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*/
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#define KMSG_COMPONENT "ramzswap"
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#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/bitops.h>
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#include <linux/blkdev.h>
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#include <linux/buffer_head.h>
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#include <linux/device.h>
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#include <linux/genhd.h>
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#include <linux/highmem.h>
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#include <linux/lzo.h>
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#include <linux/mutex.h>
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#include <linux/string.h>
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#include <linux/swap.h>
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#include <linux/swapops.h>
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#include <linux/vmalloc.h>
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#include <linux/version.h>
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#include "ramzswap_drv.h"
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/* Globals */
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static int ramzswap_major;
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static struct ramzswap *devices;
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/*
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* Pages that compress to larger than this size are
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* forwarded to backing swap, if present or stored
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* uncompressed in memory otherwise.
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*/
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static unsigned int max_zpage_size;
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/* Module params (documentation at end) */
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static unsigned int num_devices;
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static int rzs_test_flag(struct ramzswap *rzs, u32 index,
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enum rzs_pageflags flag)
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{
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return rzs->table[index].flags & BIT(flag);
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}
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static void rzs_set_flag(struct ramzswap *rzs, u32 index,
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enum rzs_pageflags flag)
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{
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rzs->table[index].flags |= BIT(flag);
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}
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static void rzs_clear_flag(struct ramzswap *rzs, u32 index,
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enum rzs_pageflags flag)
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{
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rzs->table[index].flags &= ~BIT(flag);
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}
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static int page_zero_filled(void *ptr)
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{
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unsigned int pos;
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unsigned long *page;
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page = (unsigned long *)ptr;
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for (pos = 0; pos != PAGE_SIZE / sizeof(*page); pos++) {
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if (page[pos])
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return 0;
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}
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return 1;
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}
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/*
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* memlimit cannot be greater than backing disk size.
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*/
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static void ramzswap_set_memlimit(struct ramzswap *rzs, size_t totalram_bytes)
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{
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int memlimit_valid = 1;
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if (!rzs->memlimit) {
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pr_info("Memory limit not set.\n");
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memlimit_valid = 0;
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}
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if (rzs->memlimit > rzs->disksize) {
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pr_info("Memory limit cannot be greater than "
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"disksize: limit=%zu, disksize=%zu\n",
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rzs->memlimit, rzs->disksize);
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memlimit_valid = 0;
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}
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if (!memlimit_valid) {
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size_t mempart, disksize;
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pr_info("Using default: smaller of (%u%% of RAM) and "
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"(backing disk size).\n",
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default_memlimit_perc_ram);
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mempart = default_memlimit_perc_ram * (totalram_bytes / 100);
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disksize = rzs->disksize;
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rzs->memlimit = mempart > disksize ? disksize : mempart;
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}
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if (rzs->memlimit > totalram_bytes / 2) {
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pr_info(
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"Its not advisable setting limit more than half of "
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"size of memory since we expect a 2:1 compression ratio. "
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"Limit represents amount of *compressed* data we can keep "
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"in memory!\n"
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"\tMemory Size: %zu kB\n"
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"\tLimit you selected: %zu kB\n"
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"Continuing anyway ...\n",
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totalram_bytes >> 10, rzs->memlimit >> 10
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);
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}
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rzs->memlimit &= PAGE_MASK;
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BUG_ON(!rzs->memlimit);
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}
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static void ramzswap_set_disksize(struct ramzswap *rzs, size_t totalram_bytes)
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{
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if (!rzs->disksize) {
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pr_info(
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"disk size not provided. You can use disksize_kb module "
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"param to specify size.\nUsing default: (%u%% of RAM).\n",
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default_disksize_perc_ram
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);
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rzs->disksize = default_disksize_perc_ram *
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(totalram_bytes / 100);
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}
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if (rzs->disksize > 2 * (totalram_bytes)) {
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pr_info(
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"There is little point creating a ramzswap of greater than "
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"twice the size of memory since we expect a 2:1 compression "
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"ratio. Note that ramzswap uses about 0.1%% of the size of "
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"the swap device when not in use so a huge ramzswap is "
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"wasteful.\n"
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"\tMemory Size: %zu kB\n"
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"\tSize you selected: %zu kB\n"
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"Continuing anyway ...\n",
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totalram_bytes >> 10, rzs->disksize
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);
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}
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rzs->disksize &= PAGE_MASK;
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}
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/*
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* Swap header (1st page of swap device) contains information
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* to indentify it as a swap partition. Prepare such a header
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* for ramzswap device (ramzswap0) so that swapon can identify
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* it as swap partition. In case backing swap device is provided,
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* copy its swap header.
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*/
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static int setup_swap_header(struct ramzswap *rzs, union swap_header *s)
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{
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int ret = 0;
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struct page *page;
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struct address_space *mapping;
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union swap_header *backing_swap_header;
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/*
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* There is no backing swap device. Create a swap header
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* that is acceptable by swapon.
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*/
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if (!rzs->backing_swap) {
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s->info.version = 1;
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s->info.last_page = (rzs->disksize >> PAGE_SHIFT) - 1;
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s->info.nr_badpages = 0;
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memcpy(s->magic.magic, "SWAPSPACE2", 10);
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return 0;
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}
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/*
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* We have a backing swap device. Copy its swap header
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* to ramzswap device header. If this header contains
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* invalid information (backing device not a swap
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* partition, etc.), swapon will fail for ramzswap
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* which is correct behavior - we don't want to swap
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* over filesystem partition!
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*/
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/* Read the backing swap header (code from sys_swapon) */
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mapping = rzs->swap_file->f_mapping;
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if (!mapping->a_ops->readpage) {
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ret = -EINVAL;
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goto out;
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}
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page = read_mapping_page(mapping, 0, rzs->swap_file);
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if (IS_ERR(page)) {
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ret = PTR_ERR(page);
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goto out;
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}
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backing_swap_header = kmap(page);
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memcpy(s, backing_swap_header, sizeof(*s));
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if (s->info.nr_badpages) {
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pr_info("Cannot use backing swap with bad pages (%u)\n",
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s->info.nr_badpages);
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ret = -EINVAL;
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}
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/*
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* ramzswap disksize equals number of usable pages in backing
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* swap. Set last_page in swap header to match this disksize
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* ('last_page' means 0-based index of last usable swap page).
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*/
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s->info.last_page = (rzs->disksize >> PAGE_SHIFT) - 1;
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kunmap(page);
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out:
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return ret;
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}
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static void ramzswap_flush_dcache_page(struct page *page)
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{
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#ifdef CONFIG_ARM
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int flag = 0;
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/*
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* Ugly hack to get flush_dcache_page() work on ARM.
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* page_mapping(page) == NULL after clearing this swap cache flag.
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* Without clearing this flag, flush_dcache_page() will simply set
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* "PG_dcache_dirty" bit and return.
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*/
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if (PageSwapCache(page)) {
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flag = 1;
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ClearPageSwapCache(page);
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}
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#endif
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flush_dcache_page(page);
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#ifdef CONFIG_ARM
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if (flag)
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SetPageSwapCache(page);
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#endif
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}
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void ramzswap_ioctl_get_stats(struct ramzswap *rzs,
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struct ramzswap_ioctl_stats *s)
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{
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strncpy(s->backing_swap_name, rzs->backing_swap_name,
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MAX_SWAP_NAME_LEN - 1);
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s->backing_swap_name[MAX_SWAP_NAME_LEN - 1] = '\0';
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s->disksize = rzs->disksize;
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s->memlimit = rzs->memlimit;
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#if defined(CONFIG_RAMZSWAP_STATS)
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{
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struct ramzswap_stats *rs = &rzs->stats;
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size_t succ_writes, mem_used;
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unsigned int good_compress_perc = 0, no_compress_perc = 0;
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mem_used = xv_get_total_size_bytes(rzs->mem_pool)
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+ (rs->pages_expand << PAGE_SHIFT);
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succ_writes = rs->num_writes - rs->failed_writes;
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if (succ_writes && rs->pages_stored) {
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good_compress_perc = rs->good_compress * 100
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/ rs->pages_stored;
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no_compress_perc = rs->pages_expand * 100
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/ rs->pages_stored;
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}
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s->num_reads = rs->num_reads;
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s->num_writes = rs->num_writes;
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s->failed_reads = rs->failed_reads;
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s->failed_writes = rs->failed_writes;
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s->invalid_io = rs->invalid_io;
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s->pages_zero = rs->pages_zero;
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s->good_compress_pct = good_compress_perc;
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s->pages_expand_pct = no_compress_perc;
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s->pages_stored = rs->pages_stored;
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s->pages_used = mem_used >> PAGE_SHIFT;
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s->orig_data_size = rs->pages_stored << PAGE_SHIFT;
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s->compr_data_size = rs->compr_size;
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s->mem_used_total = mem_used;
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s->bdev_num_reads = rs->bdev_num_reads;
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s->bdev_num_writes = rs->bdev_num_writes;
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}
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#endif /* CONFIG_RAMZSWAP_STATS */
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}
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static int add_backing_swap_extent(struct ramzswap *rzs,
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pgoff_t phy_pagenum,
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pgoff_t num_pages)
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{
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unsigned int idx;
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struct list_head *head;
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struct page *curr_page, *new_page;
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unsigned int extents_per_page = PAGE_SIZE /
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sizeof(struct ramzswap_backing_extent);
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idx = rzs->num_extents % extents_per_page;
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if (!idx) {
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new_page = alloc_page(__GFP_ZERO);
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if (!new_page)
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return -ENOMEM;
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if (rzs->num_extents) {
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curr_page = virt_to_page(rzs->curr_extent);
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head = &curr_page->lru;
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} else {
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head = &rzs->backing_swap_extent_list;
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}
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list_add(&new_page->lru, head);
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rzs->curr_extent = page_address(new_page);
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}
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rzs->curr_extent->phy_pagenum = phy_pagenum;
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rzs->curr_extent->num_pages = num_pages;
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pr_debug("add_extent: idx=%u, phy_pgnum=%lu, num_pgs=%lu, "
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"pg_last=%lu, curr_ext=%p\n", idx, phy_pagenum, num_pages,
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phy_pagenum + num_pages - 1, rzs->curr_extent);
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if (idx != extents_per_page - 1)
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rzs->curr_extent++;
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return 0;
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}
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static int setup_backing_swap_extents(struct ramzswap *rzs,
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struct inode *inode, unsigned long *num_pages)
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{
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int ret = 0;
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unsigned blkbits;
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unsigned blocks_per_page;
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pgoff_t contig_pages = 0, total_pages = 0;
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pgoff_t pagenum = 0, prev_pagenum = 0;
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sector_t probe_block = 0;
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sector_t last_block;
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blkbits = inode->i_blkbits;
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blocks_per_page = PAGE_SIZE >> blkbits;
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last_block = i_size_read(inode) >> blkbits;
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while (probe_block + blocks_per_page <= last_block) {
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unsigned block_in_page;
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sector_t first_block;
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first_block = bmap(inode, probe_block);
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if (first_block == 0)
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goto bad_bmap;
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/* It must be PAGE_SIZE aligned on-disk */
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if (first_block & (blocks_per_page - 1)) {
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probe_block++;
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goto probe_next;
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}
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/* All blocks within this page must be contiguous on disk */
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for (block_in_page = 1; block_in_page < blocks_per_page;
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block_in_page++) {
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sector_t block;
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block = bmap(inode, probe_block + block_in_page);
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if (block == 0)
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goto bad_bmap;
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if (block != first_block + block_in_page) {
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/* Discontiguity */
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probe_block++;
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goto probe_next;
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}
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}
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/*
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* We found a PAGE_SIZE length, PAGE_SIZE aligned
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* run of blocks.
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*/
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pagenum = first_block >> (PAGE_SHIFT - blkbits);
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if (total_pages && (pagenum != prev_pagenum + 1)) {
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ret = add_backing_swap_extent(rzs, prev_pagenum -
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(contig_pages - 1), contig_pages);
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if (ret < 0)
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goto out;
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rzs->num_extents++;
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contig_pages = 0;
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}
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total_pages++;
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contig_pages++;
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prev_pagenum = pagenum;
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probe_block += blocks_per_page;
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probe_next:
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continue;
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}
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if (contig_pages) {
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pr_debug("adding last extent: pagenum=%lu, "
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"contig_pages=%lu\n", pagenum, contig_pages);
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ret = add_backing_swap_extent(rzs,
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prev_pagenum - (contig_pages - 1), contig_pages);
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if (ret < 0)
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goto out;
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rzs->num_extents++;
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}
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if (!rzs->num_extents) {
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pr_err("No swap extents found!\n");
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ret = -EINVAL;
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}
|
|
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if (!ret) {
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*num_pages = total_pages;
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pr_info("Found %lu extents containing %luk\n",
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rzs->num_extents, *num_pages << (PAGE_SHIFT - 10));
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}
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goto out;
|
|
|
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bad_bmap:
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pr_err("Backing swapfile has holes\n");
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ret = -EINVAL;
|
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out:
|
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while (ret && !list_empty(&rzs->backing_swap_extent_list)) {
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struct page *page;
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struct list_head *entry = rzs->backing_swap_extent_list.next;
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page = list_entry(entry, struct page, lru);
|
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list_del(entry);
|
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__free_page(page);
|
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}
|
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return ret;
|
|
}
|
|
|
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static void map_backing_swap_extents(struct ramzswap *rzs)
|
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{
|
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struct ramzswap_backing_extent *se;
|
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struct page *table_page, *se_page;
|
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unsigned long num_pages, num_table_pages, entry;
|
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unsigned long se_idx, span;
|
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unsigned entries_per_page = PAGE_SIZE / sizeof(*rzs->table);
|
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unsigned extents_per_page = PAGE_SIZE / sizeof(*se);
|
|
|
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/* True for block device */
|
|
if (!rzs->num_extents)
|
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return;
|
|
|
|
se_page = list_entry(rzs->backing_swap_extent_list.next,
|
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struct page, lru);
|
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se = page_address(se_page);
|
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span = se->num_pages;
|
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num_pages = rzs->disksize >> PAGE_SHIFT;
|
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num_table_pages = DIV_ROUND_UP(num_pages * sizeof(*rzs->table),
|
|
PAGE_SIZE);
|
|
|
|
entry = 0;
|
|
se_idx = 0;
|
|
while (num_table_pages--) {
|
|
table_page = vmalloc_to_page(&rzs->table[entry]);
|
|
while (span <= entry) {
|
|
se_idx++;
|
|
if (se_idx == rzs->num_extents)
|
|
BUG();
|
|
|
|
if (!(se_idx % extents_per_page)) {
|
|
se_page = list_entry(se_page->lru.next,
|
|
struct page, lru);
|
|
se = page_address(se_page);
|
|
} else
|
|
se++;
|
|
|
|
span += se->num_pages;
|
|
}
|
|
table_page->mapping = (struct address_space *)se;
|
|
table_page->private = se->num_pages - (span - entry);
|
|
pr_debug("map_table: entry=%lu, span=%lu, map=%p, priv=%lu\n",
|
|
entry, span, table_page->mapping, table_page->private);
|
|
entry += entries_per_page;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Check if value of backing_swap module param is sane.
|
|
* Claim this device and set ramzswap size equal to
|
|
* size of this block device.
|
|
*/
|
|
static int setup_backing_swap(struct ramzswap *rzs)
|
|
{
|
|
int ret = 0;
|
|
size_t disksize;
|
|
unsigned long num_pages = 0;
|
|
struct inode *inode;
|
|
struct file *swap_file;
|
|
struct address_space *mapping;
|
|
struct block_device *bdev = NULL;
|
|
|
|
if (!rzs->backing_swap_name[0]) {
|
|
pr_debug("backing_swap param not given\n");
|
|
goto out;
|
|
}
|
|
|
|
pr_info("Using backing swap device: %s\n", rzs->backing_swap_name);
|
|
|
|
swap_file = filp_open(rzs->backing_swap_name,
|
|
O_RDWR | O_LARGEFILE, 0);
|
|
if (IS_ERR(swap_file)) {
|
|
pr_err("Error opening backing device: %s\n",
|
|
rzs->backing_swap_name);
|
|
ret = -EINVAL;
|
|
goto out;
|
|
}
|
|
|
|
mapping = swap_file->f_mapping;
|
|
inode = mapping->host;
|
|
|
|
if (S_ISBLK(inode->i_mode)) {
|
|
bdev = I_BDEV(inode);
|
|
ret = bd_claim(bdev, setup_backing_swap);
|
|
if (ret < 0) {
|
|
bdev = NULL;
|
|
goto bad_param;
|
|
}
|
|
disksize = i_size_read(inode);
|
|
} else if (S_ISREG(inode->i_mode)) {
|
|
bdev = inode->i_sb->s_bdev;
|
|
if (IS_SWAPFILE(inode)) {
|
|
ret = -EBUSY;
|
|
goto bad_param;
|
|
}
|
|
ret = setup_backing_swap_extents(rzs, inode, &num_pages);
|
|
if (ret < 0)
|
|
goto bad_param;
|
|
disksize = num_pages << PAGE_SHIFT;
|
|
} else {
|
|
goto bad_param;
|
|
}
|
|
|
|
rzs->swap_file = swap_file;
|
|
rzs->backing_swap = bdev;
|
|
rzs->disksize = disksize;
|
|
BUG_ON(!rzs->disksize);
|
|
|
|
return 0;
|
|
|
|
bad_param:
|
|
if (bdev)
|
|
bd_release(bdev);
|
|
filp_close(swap_file, NULL);
|
|
|
|
out:
|
|
rzs->backing_swap = NULL;
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Map logical page number 'pagenum' to physical page number
|
|
* on backing swap device. For block device, this is a nop.
|
|
*/
|
|
u32 map_backing_swap_page(struct ramzswap *rzs, u32 pagenum)
|
|
{
|
|
u32 skip_pages, entries_per_page;
|
|
size_t delta, se_offset, skipped;
|
|
struct page *table_page, *se_page;
|
|
struct ramzswap_backing_extent *se;
|
|
|
|
if (!rzs->num_extents)
|
|
return pagenum;
|
|
|
|
entries_per_page = PAGE_SIZE / sizeof(*rzs->table);
|
|
|
|
table_page = vmalloc_to_page(&rzs->table[pagenum]);
|
|
se = (struct ramzswap_backing_extent *)table_page->mapping;
|
|
se_page = virt_to_page(se);
|
|
|
|
skip_pages = pagenum - (pagenum / entries_per_page * entries_per_page);
|
|
se_offset = table_page->private + skip_pages;
|
|
|
|
if (se_offset < se->num_pages)
|
|
return se->phy_pagenum + se_offset;
|
|
|
|
skipped = se->num_pages - table_page->private;
|
|
do {
|
|
struct ramzswap_backing_extent *se_base;
|
|
u32 se_entries_per_page = PAGE_SIZE / sizeof(*se);
|
|
|
|
/* Get next swap extent */
|
|
se_base = (struct ramzswap_backing_extent *)
|
|
page_address(se_page);
|
|
if (se - se_base == se_entries_per_page - 1) {
|
|
se_page = list_entry(se_page->lru.next,
|
|
struct page, lru);
|
|
se = page_address(se_page);
|
|
} else {
|
|
se++;
|
|
}
|
|
|
|
skipped += se->num_pages;
|
|
} while (skipped < skip_pages);
|
|
|
|
delta = skipped - skip_pages;
|
|
se_offset = se->num_pages - delta;
|
|
|
|
return se->phy_pagenum + se_offset;
|
|
}
|
|
|
|
static void ramzswap_free_page(struct ramzswap *rzs, size_t index)
|
|
{
|
|
u32 clen;
|
|
void *obj;
|
|
|
|
struct page *page = rzs->table[index].page;
|
|
u32 offset = rzs->table[index].offset;
|
|
|
|
if (unlikely(!page)) {
|
|
if (rzs_test_flag(rzs, index, RZS_ZERO)) {
|
|
rzs_clear_flag(rzs, index, RZS_ZERO);
|
|
stat_dec(rzs->stats.pages_zero);
|
|
}
|
|
return;
|
|
}
|
|
|
|
if (unlikely(rzs_test_flag(rzs, index, RZS_UNCOMPRESSED))) {
|
|
clen = PAGE_SIZE;
|
|
__free_page(page);
|
|
rzs_clear_flag(rzs, index, RZS_UNCOMPRESSED);
|
|
stat_dec(rzs->stats.pages_expand);
|
|
goto out;
|
|
}
|
|
|
|
obj = kmap_atomic(page, KM_USER0) + offset;
|
|
clen = xv_get_object_size(obj) - sizeof(struct zobj_header);
|
|
kunmap_atomic(obj, KM_USER0);
|
|
|
|
xv_free(rzs->mem_pool, page, offset);
|
|
if (clen <= PAGE_SIZE / 2)
|
|
stat_dec(rzs->stats.good_compress);
|
|
|
|
out:
|
|
rzs->stats.compr_size -= clen;
|
|
stat_dec(rzs->stats.pages_stored);
|
|
|
|
rzs->table[index].page = NULL;
|
|
rzs->table[index].offset = 0;
|
|
}
|
|
|
|
static int handle_zero_page(struct bio *bio)
|
|
{
|
|
void *user_mem;
|
|
struct page *page = bio->bi_io_vec[0].bv_page;
|
|
|
|
user_mem = kmap_atomic(page, KM_USER0);
|
|
memset(user_mem, 0, PAGE_SIZE);
|
|
kunmap_atomic(user_mem, KM_USER0);
|
|
|
|
ramzswap_flush_dcache_page(page);
|
|
|
|
set_bit(BIO_UPTODATE, &bio->bi_flags);
|
|
bio_endio(bio, 0);
|
|
return 0;
|
|
}
|
|
|
|
static int handle_uncompressed_page(struct ramzswap *rzs, struct bio *bio)
|
|
{
|
|
u32 index;
|
|
struct page *page;
|
|
unsigned char *user_mem, *cmem;
|
|
|
|
page = bio->bi_io_vec[0].bv_page;
|
|
index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT;
|
|
|
|
user_mem = kmap_atomic(page, KM_USER0);
|
|
cmem = kmap_atomic(rzs->table[index].page, KM_USER1) +
|
|
rzs->table[index].offset;
|
|
|
|
memcpy(user_mem, cmem, PAGE_SIZE);
|
|
kunmap_atomic(user_mem, KM_USER0);
|
|
kunmap_atomic(cmem, KM_USER1);
|
|
|
|
ramzswap_flush_dcache_page(page);
|
|
|
|
set_bit(BIO_UPTODATE, &bio->bi_flags);
|
|
bio_endio(bio, 0);
|
|
return 0;
|
|
}
|
|
|
|
|
|
/*
|
|
* Called when request page is not present in ramzswap.
|
|
* Its either in backing swap device (if present) or
|
|
* this is an attempt to read before any previous write
|
|
* to this location - this happens due to readahead when
|
|
* swap device is read from user-space (e.g. during swapon)
|
|
*/
|
|
static int handle_ramzswap_fault(struct ramzswap *rzs, struct bio *bio)
|
|
{
|
|
/*
|
|
* Always forward such requests to backing swap
|
|
* device (if present)
|
|
*/
|
|
if (rzs->backing_swap) {
|
|
u32 pagenum;
|
|
stat_dec(rzs->stats.num_reads);
|
|
stat_inc(rzs->stats.bdev_num_reads);
|
|
bio->bi_bdev = rzs->backing_swap;
|
|
|
|
/*
|
|
* In case backing swap is a file, find the right offset within
|
|
* the file corresponding to logical position 'index'. For block
|
|
* device, this is a nop.
|
|
*/
|
|
pagenum = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT;
|
|
bio->bi_sector = map_backing_swap_page(rzs, pagenum)
|
|
<< SECTORS_PER_PAGE_SHIFT;
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Its unlikely event in case backing dev is
|
|
* not present
|
|
*/
|
|
pr_debug("Read before write on swap device: "
|
|
"sector=%lu, size=%u, offset=%u\n",
|
|
(ulong)(bio->bi_sector), bio->bi_size,
|
|
bio->bi_io_vec[0].bv_offset);
|
|
|
|
/* Do nothing. Just return success */
|
|
set_bit(BIO_UPTODATE, &bio->bi_flags);
|
|
bio_endio(bio, 0);
|
|
return 0;
|
|
}
|
|
|
|
static int ramzswap_read(struct ramzswap *rzs, struct bio *bio)
|
|
{
|
|
int ret;
|
|
u32 index;
|
|
size_t clen;
|
|
struct page *page;
|
|
struct zobj_header *zheader;
|
|
unsigned char *user_mem, *cmem;
|
|
|
|
stat_inc(rzs->stats.num_reads);
|
|
|
|
page = bio->bi_io_vec[0].bv_page;
|
|
index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT;
|
|
|
|
if (rzs_test_flag(rzs, index, RZS_ZERO))
|
|
return handle_zero_page(bio);
|
|
|
|
/* Requested page is not present in compressed area */
|
|
if (!rzs->table[index].page)
|
|
return handle_ramzswap_fault(rzs, bio);
|
|
|
|
/* Page is stored uncompressed since its incompressible */
|
|
if (unlikely(rzs_test_flag(rzs, index, RZS_UNCOMPRESSED)))
|
|
return handle_uncompressed_page(rzs, bio);
|
|
|
|
user_mem = kmap_atomic(page, KM_USER0);
|
|
clen = PAGE_SIZE;
|
|
|
|
cmem = kmap_atomic(rzs->table[index].page, KM_USER1) +
|
|
rzs->table[index].offset;
|
|
|
|
ret = lzo1x_decompress_safe(
|
|
cmem + sizeof(*zheader),
|
|
xv_get_object_size(cmem) - sizeof(*zheader),
|
|
user_mem, &clen);
|
|
|
|
kunmap_atomic(user_mem, KM_USER0);
|
|
kunmap_atomic(cmem, KM_USER1);
|
|
|
|
/* should NEVER happen */
|
|
if (unlikely(ret != LZO_E_OK)) {
|
|
pr_err("Decompression failed! err=%d, page=%u\n",
|
|
ret, index);
|
|
stat_inc(rzs->stats.failed_reads);
|
|
goto out;
|
|
}
|
|
|
|
ramzswap_flush_dcache_page(page);
|
|
|
|
set_bit(BIO_UPTODATE, &bio->bi_flags);
|
|
bio_endio(bio, 0);
|
|
return 0;
|
|
|
|
out:
|
|
bio_io_error(bio);
|
|
return 0;
|
|
}
|
|
|
|
static int ramzswap_write(struct ramzswap *rzs, struct bio *bio)
|
|
{
|
|
int ret, fwd_write_request = 0;
|
|
u32 offset, index;
|
|
size_t clen;
|
|
struct zobj_header *zheader;
|
|
struct page *page, *page_store;
|
|
unsigned char *user_mem, *cmem, *src;
|
|
|
|
stat_inc(rzs->stats.num_writes);
|
|
|
|
page = bio->bi_io_vec[0].bv_page;
|
|
index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT;
|
|
|
|
src = rzs->compress_buffer;
|
|
|
|
/*
|
|
* System swaps to same sector again when the stored page
|
|
* is no longer referenced by any process. So, its now safe
|
|
* to free the memory that was allocated for this page.
|
|
*/
|
|
if (rzs->table[index].page)
|
|
ramzswap_free_page(rzs, index);
|
|
|
|
/*
|
|
* No memory ia allocated for zero filled pages.
|
|
* Simply clear zero page flag.
|
|
*/
|
|
if (rzs_test_flag(rzs, index, RZS_ZERO)) {
|
|
stat_dec(rzs->stats.pages_zero);
|
|
rzs_clear_flag(rzs, index, RZS_ZERO);
|
|
}
|
|
|
|
mutex_lock(&rzs->lock);
|
|
|
|
user_mem = kmap_atomic(page, KM_USER0);
|
|
if (page_zero_filled(user_mem)) {
|
|
kunmap_atomic(user_mem, KM_USER0);
|
|
mutex_unlock(&rzs->lock);
|
|
stat_inc(rzs->stats.pages_zero);
|
|
rzs_set_flag(rzs, index, RZS_ZERO);
|
|
|
|
set_bit(BIO_UPTODATE, &bio->bi_flags);
|
|
bio_endio(bio, 0);
|
|
return 0;
|
|
}
|
|
|
|
if (rzs->backing_swap &&
|
|
(rzs->stats.compr_size > rzs->memlimit - PAGE_SIZE)) {
|
|
kunmap_atomic(user_mem, KM_USER0);
|
|
mutex_unlock(&rzs->lock);
|
|
fwd_write_request = 1;
|
|
goto out;
|
|
}
|
|
|
|
ret = lzo1x_1_compress(user_mem, PAGE_SIZE, src, &clen,
|
|
rzs->compress_workmem);
|
|
|
|
kunmap_atomic(user_mem, KM_USER0);
|
|
|
|
if (unlikely(ret != LZO_E_OK)) {
|
|
mutex_unlock(&rzs->lock);
|
|
pr_err("Compression failed! err=%d\n", ret);
|
|
stat_inc(rzs->stats.failed_writes);
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* Page is incompressible. Forward it to backing swap
|
|
* if present. Otherwise, store it as-is (uncompressed)
|
|
* since we do not want to return too many swap write
|
|
* errors which has side effect of hanging the system.
|
|
*/
|
|
if (unlikely(clen > max_zpage_size)) {
|
|
if (rzs->backing_swap) {
|
|
mutex_unlock(&rzs->lock);
|
|
fwd_write_request = 1;
|
|
goto out;
|
|
}
|
|
|
|
clen = PAGE_SIZE;
|
|
page_store = alloc_page(GFP_NOIO | __GFP_HIGHMEM);
|
|
if (unlikely(!page_store)) {
|
|
mutex_unlock(&rzs->lock);
|
|
pr_info("Error allocating memory for incompressible "
|
|
"page: %u\n", index);
|
|
stat_inc(rzs->stats.failed_writes);
|
|
goto out;
|
|
}
|
|
|
|
offset = 0;
|
|
rzs_set_flag(rzs, index, RZS_UNCOMPRESSED);
|
|
stat_inc(rzs->stats.pages_expand);
|
|
rzs->table[index].page = page_store;
|
|
src = kmap_atomic(page, KM_USER0);
|
|
goto memstore;
|
|
}
|
|
|
|
if (xv_malloc(rzs->mem_pool, clen + sizeof(*zheader),
|
|
&rzs->table[index].page, &offset,
|
|
GFP_NOIO | __GFP_HIGHMEM)) {
|
|
mutex_unlock(&rzs->lock);
|
|
pr_info("Error allocating memory for compressed "
|
|
"page: %u, size=%zu\n", index, clen);
|
|
stat_inc(rzs->stats.failed_writes);
|
|
if (rzs->backing_swap)
|
|
fwd_write_request = 1;
|
|
goto out;
|
|
}
|
|
|
|
memstore:
|
|
rzs->table[index].offset = offset;
|
|
|
|
cmem = kmap_atomic(rzs->table[index].page, KM_USER1) +
|
|
rzs->table[index].offset;
|
|
|
|
#if 0
|
|
/* Back-reference needed for memory defragmentation */
|
|
if (!rzs_test_flag(rzs, index, RZS_UNCOMPRESSED)) {
|
|
zheader = (struct zobj_header *)cmem;
|
|
zheader->table_idx = index;
|
|
cmem += sizeof(*zheader);
|
|
}
|
|
#endif
|
|
|
|
memcpy(cmem, src, clen);
|
|
|
|
kunmap_atomic(cmem, KM_USER1);
|
|
if (unlikely(rzs_test_flag(rzs, index, RZS_UNCOMPRESSED)))
|
|
kunmap_atomic(src, KM_USER0);
|
|
|
|
/* Update stats */
|
|
rzs->stats.compr_size += clen;
|
|
stat_inc(rzs->stats.pages_stored);
|
|
if (clen <= PAGE_SIZE / 2)
|
|
stat_inc(rzs->stats.good_compress);
|
|
|
|
mutex_unlock(&rzs->lock);
|
|
|
|
set_bit(BIO_UPTODATE, &bio->bi_flags);
|
|
bio_endio(bio, 0);
|
|
return 0;
|
|
|
|
out:
|
|
if (fwd_write_request) {
|
|
stat_inc(rzs->stats.bdev_num_writes);
|
|
bio->bi_bdev = rzs->backing_swap;
|
|
#if 0
|
|
/*
|
|
* TODO: We currently have linear mapping of ramzswap and
|
|
* backing swap sectors. This is not desired since we want
|
|
* to optimize writes to backing swap to minimize disk seeks
|
|
* or have effective wear leveling (for SSDs). Also, a
|
|
* non-linear mapping is required to implement compressed
|
|
* on-disk swapping.
|
|
*/
|
|
bio->bi_sector = get_backing_swap_page()
|
|
<< SECTORS_PER_PAGE_SHIFT;
|
|
#endif
|
|
/*
|
|
* In case backing swap is a file, find the right offset within
|
|
* the file corresponding to logical position 'index'. For block
|
|
* device, this is a nop.
|
|
*/
|
|
bio->bi_sector = map_backing_swap_page(rzs, index)
|
|
<< SECTORS_PER_PAGE_SHIFT;
|
|
return 1;
|
|
}
|
|
|
|
bio_io_error(bio);
|
|
return 0;
|
|
}
|
|
|
|
|
|
/*
|
|
* Check if request is within bounds and page aligned.
|
|
*/
|
|
static inline int valid_swap_request(struct ramzswap *rzs, struct bio *bio)
|
|
{
|
|
if (unlikely(
|
|
(bio->bi_sector >= (rzs->disksize >> SECTOR_SHIFT)) ||
|
|
(bio->bi_sector & (SECTORS_PER_PAGE - 1)) ||
|
|
(bio->bi_vcnt != 1) ||
|
|
(bio->bi_size != PAGE_SIZE) ||
|
|
(bio->bi_io_vec[0].bv_offset != 0))) {
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* swap request is valid */
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Handler function for all ramzswap I/O requests.
|
|
*/
|
|
static int ramzswap_make_request(struct request_queue *queue, struct bio *bio)
|
|
{
|
|
int ret = 0;
|
|
struct ramzswap *rzs = queue->queuedata;
|
|
|
|
if (unlikely(!rzs->init_done)) {
|
|
bio_io_error(bio);
|
|
return 0;
|
|
}
|
|
|
|
if (!valid_swap_request(rzs, bio)) {
|
|
stat_inc(rzs->stats.invalid_io);
|
|
bio_io_error(bio);
|
|
return 0;
|
|
}
|
|
|
|
switch (bio_data_dir(bio)) {
|
|
case READ:
|
|
ret = ramzswap_read(rzs, bio);
|
|
break;
|
|
|
|
case WRITE:
|
|
ret = ramzswap_write(rzs, bio);
|
|
break;
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
static void reset_device(struct ramzswap *rzs)
|
|
{
|
|
int is_backing_blkdev = 0;
|
|
size_t index, num_pages;
|
|
unsigned entries_per_page;
|
|
unsigned long num_table_pages, entry = 0;
|
|
|
|
if (rzs->backing_swap && !rzs->num_extents)
|
|
is_backing_blkdev = 1;
|
|
|
|
num_pages = rzs->disksize >> PAGE_SHIFT;
|
|
|
|
/* Free various per-device buffers */
|
|
kfree(rzs->compress_workmem);
|
|
free_pages((unsigned long)rzs->compress_buffer, 1);
|
|
|
|
rzs->compress_workmem = NULL;
|
|
rzs->compress_buffer = NULL;
|
|
|
|
/* Free all pages that are still in this ramzswap device */
|
|
for (index = 0; index < num_pages; index++) {
|
|
struct page *page;
|
|
u16 offset;
|
|
|
|
page = rzs->table[index].page;
|
|
offset = rzs->table[index].offset;
|
|
|
|
if (!page)
|
|
continue;
|
|
|
|
if (unlikely(rzs_test_flag(rzs, index, RZS_UNCOMPRESSED)))
|
|
__free_page(page);
|
|
else
|
|
xv_free(rzs->mem_pool, page, offset);
|
|
}
|
|
|
|
entries_per_page = PAGE_SIZE / sizeof(*rzs->table);
|
|
num_table_pages = DIV_ROUND_UP(num_pages * sizeof(*rzs->table),
|
|
PAGE_SIZE);
|
|
/*
|
|
* Set page->mapping to NULL for every table page.
|
|
* Otherwise, we will hit bad_page() during free.
|
|
*/
|
|
while (rzs->num_extents && num_table_pages--) {
|
|
struct page *page;
|
|
page = vmalloc_to_page(&rzs->table[entry]);
|
|
page->mapping = NULL;
|
|
entry += entries_per_page;
|
|
}
|
|
vfree(rzs->table);
|
|
rzs->table = NULL;
|
|
|
|
xv_destroy_pool(rzs->mem_pool);
|
|
rzs->mem_pool = NULL;
|
|
|
|
/* Free all swap extent pages */
|
|
while (!list_empty(&rzs->backing_swap_extent_list)) {
|
|
struct page *page;
|
|
struct list_head *entry;
|
|
entry = rzs->backing_swap_extent_list.next;
|
|
page = list_entry(entry, struct page, lru);
|
|
list_del(entry);
|
|
__free_page(page);
|
|
}
|
|
INIT_LIST_HEAD(&rzs->backing_swap_extent_list);
|
|
rzs->num_extents = 0;
|
|
|
|
/* Close backing swap device, if present */
|
|
if (rzs->backing_swap) {
|
|
if (is_backing_blkdev)
|
|
bd_release(rzs->backing_swap);
|
|
filp_close(rzs->swap_file, NULL);
|
|
rzs->backing_swap = NULL;
|
|
}
|
|
|
|
/* Reset stats */
|
|
memset(&rzs->stats, 0, sizeof(rzs->stats));
|
|
|
|
rzs->disksize = 0;
|
|
rzs->memlimit = 0;
|
|
|
|
/* Back to uninitialized state */
|
|
rzs->init_done = 0;
|
|
}
|
|
|
|
static int ramzswap_ioctl_init_device(struct ramzswap *rzs)
|
|
{
|
|
int ret;
|
|
size_t num_pages;
|
|
struct page *page;
|
|
union swap_header *swap_header;
|
|
|
|
if (rzs->init_done) {
|
|
pr_info("Device already initialized!\n");
|
|
return -EBUSY;
|
|
}
|
|
|
|
ret = setup_backing_swap(rzs);
|
|
if (ret)
|
|
goto fail;
|
|
|
|
if (rzs->backing_swap)
|
|
ramzswap_set_memlimit(rzs, totalram_pages << PAGE_SHIFT);
|
|
else
|
|
ramzswap_set_disksize(rzs, totalram_pages << PAGE_SHIFT);
|
|
|
|
rzs->compress_workmem = kzalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
|
|
if (!rzs->compress_workmem) {
|
|
pr_err("Error allocating compressor working memory!\n");
|
|
ret = -ENOMEM;
|
|
goto fail;
|
|
}
|
|
|
|
rzs->compress_buffer = (void *)__get_free_pages(__GFP_ZERO, 1);
|
|
if (!rzs->compress_buffer) {
|
|
pr_err("Error allocating compressor buffer space\n");
|
|
ret = -ENOMEM;
|
|
goto fail;
|
|
}
|
|
|
|
num_pages = rzs->disksize >> PAGE_SHIFT;
|
|
rzs->table = vmalloc(num_pages * sizeof(*rzs->table));
|
|
if (!rzs->table) {
|
|
pr_err("Error allocating ramzswap address table\n");
|
|
/* To prevent accessing table entries during cleanup */
|
|
rzs->disksize = 0;
|
|
ret = -ENOMEM;
|
|
goto fail;
|
|
}
|
|
memset(rzs->table, 0, num_pages * sizeof(*rzs->table));
|
|
|
|
map_backing_swap_extents(rzs);
|
|
|
|
page = alloc_page(__GFP_ZERO);
|
|
if (!page) {
|
|
pr_err("Error allocating swap header page\n");
|
|
ret = -ENOMEM;
|
|
goto fail;
|
|
}
|
|
rzs->table[0].page = page;
|
|
rzs_set_flag(rzs, 0, RZS_UNCOMPRESSED);
|
|
|
|
swap_header = kmap(page);
|
|
ret = setup_swap_header(rzs, swap_header);
|
|
kunmap(page);
|
|
if (ret) {
|
|
pr_err("Error setting swap header\n");
|
|
goto fail;
|
|
}
|
|
|
|
set_capacity(rzs->disk, rzs->disksize >> SECTOR_SHIFT);
|
|
|
|
/*
|
|
* We have ident mapping of sectors for ramzswap and
|
|
* and the backing swap device. So, this queue flag
|
|
* should be according to backing dev.
|
|
*/
|
|
if (!rzs->backing_swap ||
|
|
blk_queue_nonrot(rzs->backing_swap->bd_disk->queue))
|
|
queue_flag_set_unlocked(QUEUE_FLAG_NONROT, rzs->disk->queue);
|
|
|
|
rzs->mem_pool = xv_create_pool();
|
|
if (!rzs->mem_pool) {
|
|
pr_err("Error creating memory pool\n");
|
|
ret = -ENOMEM;
|
|
goto fail;
|
|
}
|
|
|
|
/*
|
|
* Pages that compress to size greater than this are forwarded
|
|
* to physical swap disk (if backing dev is provided)
|
|
* TODO: make this configurable
|
|
*/
|
|
if (rzs->backing_swap)
|
|
max_zpage_size = max_zpage_size_bdev;
|
|
else
|
|
max_zpage_size = max_zpage_size_nobdev;
|
|
pr_debug("Max compressed page size: %u bytes\n", max_zpage_size);
|
|
|
|
rzs->init_done = 1;
|
|
|
|
pr_debug("Initialization done!\n");
|
|
return 0;
|
|
|
|
fail:
|
|
reset_device(rzs);
|
|
|
|
pr_err("Initialization failed: err=%d\n", ret);
|
|
return ret;
|
|
}
|
|
|
|
static int ramzswap_ioctl_reset_device(struct ramzswap *rzs)
|
|
{
|
|
if (rzs->init_done)
|
|
reset_device(rzs);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int ramzswap_ioctl(struct block_device *bdev, fmode_t mode,
|
|
unsigned int cmd, unsigned long arg)
|
|
{
|
|
int ret = 0;
|
|
size_t disksize_kb, memlimit_kb;
|
|
|
|
struct ramzswap *rzs = bdev->bd_disk->private_data;
|
|
|
|
switch (cmd) {
|
|
case RZSIO_SET_DISKSIZE_KB:
|
|
if (rzs->init_done) {
|
|
ret = -EBUSY;
|
|
goto out;
|
|
}
|
|
if (copy_from_user(&disksize_kb, (void *)arg,
|
|
_IOC_SIZE(cmd))) {
|
|
ret = -EFAULT;
|
|
goto out;
|
|
}
|
|
rzs->disksize = disksize_kb << 10;
|
|
pr_info("Disk size set to %zu kB\n", disksize_kb);
|
|
break;
|
|
|
|
case RZSIO_SET_MEMLIMIT_KB:
|
|
if (rzs->init_done) {
|
|
/* TODO: allow changing memlimit */
|
|
ret = -EBUSY;
|
|
goto out;
|
|
}
|
|
if (copy_from_user(&memlimit_kb, (void *)arg,
|
|
_IOC_SIZE(cmd))) {
|
|
ret = -EFAULT;
|
|
goto out;
|
|
}
|
|
rzs->memlimit = memlimit_kb << 10;
|
|
pr_info("Memory limit set to %zu kB\n", memlimit_kb);
|
|
break;
|
|
|
|
case RZSIO_SET_BACKING_SWAP:
|
|
if (rzs->init_done) {
|
|
ret = -EBUSY;
|
|
goto out;
|
|
}
|
|
|
|
if (copy_from_user(&rzs->backing_swap_name, (void *)arg,
|
|
_IOC_SIZE(cmd))) {
|
|
ret = -EFAULT;
|
|
goto out;
|
|
}
|
|
rzs->backing_swap_name[MAX_SWAP_NAME_LEN - 1] = '\0';
|
|
pr_info("Backing swap set to %s\n", rzs->backing_swap_name);
|
|
break;
|
|
|
|
case RZSIO_GET_STATS:
|
|
{
|
|
struct ramzswap_ioctl_stats *stats;
|
|
if (!rzs->init_done) {
|
|
ret = -ENOTTY;
|
|
goto out;
|
|
}
|
|
stats = kzalloc(sizeof(*stats), GFP_KERNEL);
|
|
if (!stats) {
|
|
ret = -ENOMEM;
|
|
goto out;
|
|
}
|
|
ramzswap_ioctl_get_stats(rzs, stats);
|
|
if (copy_to_user((void *)arg, stats, sizeof(*stats))) {
|
|
kfree(stats);
|
|
ret = -EFAULT;
|
|
goto out;
|
|
}
|
|
kfree(stats);
|
|
break;
|
|
}
|
|
case RZSIO_INIT:
|
|
ret = ramzswap_ioctl_init_device(rzs);
|
|
break;
|
|
|
|
case RZSIO_RESET:
|
|
/* Do not reset an active device! */
|
|
if (bdev->bd_holders) {
|
|
ret = -EBUSY;
|
|
goto out;
|
|
}
|
|
ret = ramzswap_ioctl_reset_device(rzs);
|
|
break;
|
|
|
|
default:
|
|
pr_info("Invalid ioctl %u\n", cmd);
|
|
ret = -ENOTTY;
|
|
}
|
|
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
static struct block_device_operations ramzswap_devops = {
|
|
.ioctl = ramzswap_ioctl,
|
|
.owner = THIS_MODULE,
|
|
};
|
|
|
|
static void create_device(struct ramzswap *rzs, int device_id)
|
|
{
|
|
mutex_init(&rzs->lock);
|
|
INIT_LIST_HEAD(&rzs->backing_swap_extent_list);
|
|
|
|
rzs->queue = blk_alloc_queue(GFP_KERNEL);
|
|
if (!rzs->queue) {
|
|
pr_err("Error allocating disk queue for device %d\n",
|
|
device_id);
|
|
return;
|
|
}
|
|
|
|
blk_queue_make_request(rzs->queue, ramzswap_make_request);
|
|
rzs->queue->queuedata = rzs;
|
|
|
|
/* gendisk structure */
|
|
rzs->disk = alloc_disk(1);
|
|
if (!rzs->disk) {
|
|
blk_cleanup_queue(rzs->queue);
|
|
pr_warning("Error allocating disk structure for device %d\n",
|
|
device_id);
|
|
return;
|
|
}
|
|
|
|
rzs->disk->major = ramzswap_major;
|
|
rzs->disk->first_minor = device_id;
|
|
rzs->disk->fops = &ramzswap_devops;
|
|
rzs->disk->queue = rzs->queue;
|
|
rzs->disk->private_data = rzs;
|
|
snprintf(rzs->disk->disk_name, 16, "ramzswap%d", device_id);
|
|
|
|
/*
|
|
* Actual capacity set using RZSIO_SET_DISKSIZE_KB ioctl
|
|
* or set equal to backing swap device (if provided)
|
|
*/
|
|
set_capacity(rzs->disk, 0);
|
|
add_disk(rzs->disk);
|
|
|
|
rzs->init_done = 0;
|
|
}
|
|
|
|
static void destroy_device(struct ramzswap *rzs)
|
|
{
|
|
if (rzs->disk) {
|
|
del_gendisk(rzs->disk);
|
|
put_disk(rzs->disk);
|
|
}
|
|
|
|
if (rzs->queue)
|
|
blk_cleanup_queue(rzs->queue);
|
|
}
|
|
|
|
static int __init ramzswap_init(void)
|
|
{
|
|
int i, ret;
|
|
|
|
if (num_devices > max_num_devices) {
|
|
pr_warning("Invalid value for num_devices: %u\n",
|
|
num_devices);
|
|
return -EINVAL;
|
|
}
|
|
|
|
ramzswap_major = register_blkdev(0, "ramzswap");
|
|
if (ramzswap_major <= 0) {
|
|
pr_warning("Unable to get major number\n");
|
|
return -EBUSY;
|
|
}
|
|
|
|
if (!num_devices) {
|
|
pr_info("num_devices not specified. Using default: 1\n");
|
|
num_devices = 1;
|
|
}
|
|
|
|
/* Allocate the device array and initialize each one */
|
|
pr_info("Creating %u devices ...\n", num_devices);
|
|
devices = kzalloc(num_devices * sizeof(struct ramzswap), GFP_KERNEL);
|
|
if (!devices) {
|
|
ret = -ENOMEM;
|
|
goto out;
|
|
}
|
|
|
|
for (i = 0; i < num_devices; i++)
|
|
create_device(&devices[i], i);
|
|
|
|
return 0;
|
|
out:
|
|
unregister_blkdev(ramzswap_major, "ramzswap");
|
|
return ret;
|
|
}
|
|
|
|
static void __exit ramzswap_exit(void)
|
|
{
|
|
int i;
|
|
struct ramzswap *rzs;
|
|
|
|
for (i = 0; i < num_devices; i++) {
|
|
rzs = &devices[i];
|
|
|
|
destroy_device(rzs);
|
|
if (rzs->init_done)
|
|
reset_device(rzs);
|
|
}
|
|
|
|
unregister_blkdev(ramzswap_major, "ramzswap");
|
|
|
|
kfree(devices);
|
|
pr_debug("Cleanup done!\n");
|
|
}
|
|
|
|
module_param(num_devices, uint, 0);
|
|
MODULE_PARM_DESC(num_devices, "Number of ramzswap devices");
|
|
|
|
module_init(ramzswap_init);
|
|
module_exit(ramzswap_exit);
|
|
|
|
MODULE_LICENSE("Dual BSD/GPL");
|
|
MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
|
|
MODULE_DESCRIPTION("Compressed RAM Based Swap Device");
|