744 lines
16 KiB
C
744 lines
16 KiB
C
/*
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* Compressed RAM block device
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*
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* Copyright (C) 2008, 2009, 2010 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 "zram"
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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/bio.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/slab.h>
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#include <linux/lzo.h>
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#include <linux/string.h>
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#include <linux/vmalloc.h>
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#include "zram_drv.h"
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/* Globals */
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static int zram_major;
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struct zram *devices;
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/* Module params (documentation at end) */
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unsigned int num_devices;
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static void zram_stat_inc(u32 *v)
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{
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*v = *v + 1;
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}
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static void zram_stat_dec(u32 *v)
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{
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*v = *v - 1;
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}
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static void zram_stat64_add(struct zram *zram, u64 *v, u64 inc)
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{
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spin_lock(&zram->stat64_lock);
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*v = *v + inc;
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spin_unlock(&zram->stat64_lock);
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}
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static void zram_stat64_sub(struct zram *zram, u64 *v, u64 dec)
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{
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spin_lock(&zram->stat64_lock);
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*v = *v - dec;
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spin_unlock(&zram->stat64_lock);
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}
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static void zram_stat64_inc(struct zram *zram, u64 *v)
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{
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zram_stat64_add(zram, v, 1);
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}
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static int zram_test_flag(struct zram *zram, u32 index,
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enum zram_pageflags flag)
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{
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return zram->table[index].flags & BIT(flag);
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}
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static void zram_set_flag(struct zram *zram, u32 index,
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enum zram_pageflags flag)
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{
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zram->table[index].flags |= BIT(flag);
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}
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static void zram_clear_flag(struct zram *zram, u32 index,
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enum zram_pageflags flag)
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{
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zram->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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static void zram_set_disksize(struct zram *zram, size_t totalram_bytes)
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{
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if (!zram->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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zram->disksize = default_disksize_perc_ram *
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(totalram_bytes / 100);
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}
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if (zram->disksize > 2 * (totalram_bytes)) {
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pr_info(
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"There is little point creating a zram 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 zram uses about 0.1%% of the size of "
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"the disk when not in use so a huge zram is "
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"wasteful.\n"
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"\tMemory Size: %zu kB\n"
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"\tSize you selected: %llu kB\n"
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"Continuing anyway ...\n",
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totalram_bytes >> 10, zram->disksize
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);
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}
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zram->disksize &= PAGE_MASK;
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}
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static void zram_free_page(struct zram *zram, size_t index)
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{
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u32 clen;
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void *obj;
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struct page *page = zram->table[index].page;
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u32 offset = zram->table[index].offset;
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if (unlikely(!page)) {
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/*
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* No memory is allocated for zero filled pages.
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* Simply clear zero page flag.
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*/
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if (zram_test_flag(zram, index, ZRAM_ZERO)) {
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zram_clear_flag(zram, index, ZRAM_ZERO);
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zram_stat_dec(&zram->stats.pages_zero);
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}
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return;
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}
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if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED))) {
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clen = PAGE_SIZE;
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__free_page(page);
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zram_clear_flag(zram, index, ZRAM_UNCOMPRESSED);
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zram_stat_dec(&zram->stats.pages_expand);
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goto out;
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}
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obj = kmap_atomic(page, KM_USER0) + offset;
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clen = xv_get_object_size(obj) - sizeof(struct zobj_header);
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kunmap_atomic(obj, KM_USER0);
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xv_free(zram->mem_pool, page, offset);
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if (clen <= PAGE_SIZE / 2)
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zram_stat_dec(&zram->stats.good_compress);
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out:
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zram_stat64_sub(zram, &zram->stats.compr_size, clen);
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zram_stat_dec(&zram->stats.pages_stored);
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zram->table[index].page = NULL;
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zram->table[index].offset = 0;
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}
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static void handle_zero_page(struct page *page)
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{
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void *user_mem;
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user_mem = kmap_atomic(page, KM_USER0);
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memset(user_mem, 0, PAGE_SIZE);
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kunmap_atomic(user_mem, KM_USER0);
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flush_dcache_page(page);
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}
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static void handle_uncompressed_page(struct zram *zram,
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struct page *page, u32 index)
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{
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unsigned char *user_mem, *cmem;
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user_mem = kmap_atomic(page, KM_USER0);
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cmem = kmap_atomic(zram->table[index].page, KM_USER1) +
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zram->table[index].offset;
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memcpy(user_mem, cmem, PAGE_SIZE);
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kunmap_atomic(user_mem, KM_USER0);
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kunmap_atomic(cmem, KM_USER1);
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flush_dcache_page(page);
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}
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static int zram_read(struct zram *zram, struct bio *bio)
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{
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int i;
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u32 index;
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struct bio_vec *bvec;
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if (unlikely(!zram->init_done)) {
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set_bit(BIO_UPTODATE, &bio->bi_flags);
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bio_endio(bio, 0);
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return 0;
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}
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zram_stat64_inc(zram, &zram->stats.num_reads);
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index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT;
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bio_for_each_segment(bvec, bio, i) {
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int ret;
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size_t clen;
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struct page *page;
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struct zobj_header *zheader;
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unsigned char *user_mem, *cmem;
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page = bvec->bv_page;
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if (zram_test_flag(zram, index, ZRAM_ZERO)) {
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handle_zero_page(page);
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continue;
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}
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/* Requested page is not present in compressed area */
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if (unlikely(!zram->table[index].page)) {
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pr_debug("Read before write: sector=%lu, size=%u",
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(ulong)(bio->bi_sector), bio->bi_size);
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/* Do nothing */
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continue;
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}
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/* Page is stored uncompressed since it's incompressible */
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if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED))) {
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handle_uncompressed_page(zram, page, index);
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continue;
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}
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user_mem = kmap_atomic(page, KM_USER0);
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clen = PAGE_SIZE;
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cmem = kmap_atomic(zram->table[index].page, KM_USER1) +
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zram->table[index].offset;
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ret = lzo1x_decompress_safe(
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cmem + sizeof(*zheader),
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xv_get_object_size(cmem) - sizeof(*zheader),
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user_mem, &clen);
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kunmap_atomic(user_mem, KM_USER0);
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kunmap_atomic(cmem, KM_USER1);
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/* Should NEVER happen. Return bio error if it does. */
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if (unlikely(ret != LZO_E_OK)) {
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pr_err("Decompression failed! err=%d, page=%u\n",
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ret, index);
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zram_stat64_inc(zram, &zram->stats.failed_reads);
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goto out;
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}
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flush_dcache_page(page);
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index++;
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}
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set_bit(BIO_UPTODATE, &bio->bi_flags);
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bio_endio(bio, 0);
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return 0;
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out:
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bio_io_error(bio);
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return 0;
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}
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static int zram_write(struct zram *zram, struct bio *bio)
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{
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int i, ret;
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u32 index;
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struct bio_vec *bvec;
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if (unlikely(!zram->init_done)) {
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ret = zram_init_device(zram);
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if (ret)
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goto out;
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}
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zram_stat64_inc(zram, &zram->stats.num_writes);
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index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT;
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bio_for_each_segment(bvec, bio, i) {
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u32 offset;
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size_t clen;
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struct zobj_header *zheader;
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struct page *page, *page_store;
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unsigned char *user_mem, *cmem, *src;
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page = bvec->bv_page;
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src = zram->compress_buffer;
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/*
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* System overwrites unused sectors. Free memory associated
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* with this sector now.
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*/
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if (zram->table[index].page ||
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zram_test_flag(zram, index, ZRAM_ZERO))
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zram_free_page(zram, index);
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mutex_lock(&zram->lock);
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user_mem = kmap_atomic(page, KM_USER0);
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if (page_zero_filled(user_mem)) {
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kunmap_atomic(user_mem, KM_USER0);
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mutex_unlock(&zram->lock);
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zram_stat_inc(&zram->stats.pages_zero);
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zram_set_flag(zram, index, ZRAM_ZERO);
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continue;
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}
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ret = lzo1x_1_compress(user_mem, PAGE_SIZE, src, &clen,
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zram->compress_workmem);
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kunmap_atomic(user_mem, KM_USER0);
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if (unlikely(ret != LZO_E_OK)) {
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mutex_unlock(&zram->lock);
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pr_err("Compression failed! err=%d\n", ret);
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zram_stat64_inc(zram, &zram->stats.failed_writes);
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goto out;
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}
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/*
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* Page is incompressible. Store it as-is (uncompressed)
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* since we do not want to return too many disk write
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* errors which has side effect of hanging the system.
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*/
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if (unlikely(clen > max_zpage_size)) {
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clen = PAGE_SIZE;
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page_store = alloc_page(GFP_NOIO | __GFP_HIGHMEM);
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if (unlikely(!page_store)) {
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mutex_unlock(&zram->lock);
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pr_info("Error allocating memory for "
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"incompressible page: %u\n", index);
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zram_stat64_inc(zram,
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&zram->stats.failed_writes);
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goto out;
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}
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offset = 0;
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zram_set_flag(zram, index, ZRAM_UNCOMPRESSED);
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zram_stat_inc(&zram->stats.pages_expand);
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zram->table[index].page = page_store;
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src = kmap_atomic(page, KM_USER0);
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goto memstore;
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}
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if (xv_malloc(zram->mem_pool, clen + sizeof(*zheader),
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&zram->table[index].page, &offset,
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GFP_NOIO | __GFP_HIGHMEM)) {
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mutex_unlock(&zram->lock);
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pr_info("Error allocating memory for compressed "
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"page: %u, size=%zu\n", index, clen);
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zram_stat64_inc(zram, &zram->stats.failed_writes);
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goto out;
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}
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memstore:
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zram->table[index].offset = offset;
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cmem = kmap_atomic(zram->table[index].page, KM_USER1) +
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zram->table[index].offset;
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#if 0
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/* Back-reference needed for memory defragmentation */
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if (!zram_test_flag(zram, index, ZRAM_UNCOMPRESSED)) {
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zheader = (struct zobj_header *)cmem;
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zheader->table_idx = index;
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cmem += sizeof(*zheader);
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}
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#endif
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memcpy(cmem, src, clen);
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kunmap_atomic(cmem, KM_USER1);
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if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED)))
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kunmap_atomic(src, KM_USER0);
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/* Update stats */
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zram_stat64_add(zram, &zram->stats.compr_size, clen);
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zram_stat_inc(&zram->stats.pages_stored);
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if (clen <= PAGE_SIZE / 2)
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zram_stat_inc(&zram->stats.good_compress);
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mutex_unlock(&zram->lock);
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index++;
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}
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set_bit(BIO_UPTODATE, &bio->bi_flags);
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bio_endio(bio, 0);
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return 0;
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out:
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bio_io_error(bio);
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return 0;
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}
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/*
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* Check if request is within bounds and page aligned.
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*/
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static inline int valid_io_request(struct zram *zram, struct bio *bio)
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{
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if (unlikely(
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(bio->bi_sector >= (zram->disksize >> SECTOR_SHIFT)) ||
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(bio->bi_sector & (SECTORS_PER_PAGE - 1)) ||
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(bio->bi_size & (PAGE_SIZE - 1)))) {
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return 0;
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}
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/* I/O request is valid */
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return 1;
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}
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/*
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* Handler function for all zram I/O requests.
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*/
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static int zram_make_request(struct request_queue *queue, struct bio *bio)
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{
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int ret = 0;
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struct zram *zram = queue->queuedata;
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if (unlikely(!zram->init_done)) {
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set_bit(BIO_UPTODATE, &bio->bi_flags);
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bio_endio(bio, 0);
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return 0;
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}
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if (!valid_io_request(zram, bio)) {
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zram_stat64_inc(zram, &zram->stats.invalid_io);
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bio_io_error(bio);
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return 0;
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}
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switch (bio_data_dir(bio)) {
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case READ:
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ret = zram_read(zram, bio);
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break;
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case WRITE:
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ret = zram_write(zram, bio);
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break;
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}
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return ret;
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}
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void zram_reset_device(struct zram *zram)
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{
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size_t index;
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mutex_lock(&zram->init_lock);
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zram->init_done = 0;
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/* Free various per-device buffers */
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kfree(zram->compress_workmem);
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free_pages((unsigned long)zram->compress_buffer, 1);
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zram->compress_workmem = NULL;
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zram->compress_buffer = NULL;
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/* Free all pages that are still in this zram device */
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for (index = 0; index < zram->disksize >> PAGE_SHIFT; index++) {
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struct page *page;
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u16 offset;
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page = zram->table[index].page;
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offset = zram->table[index].offset;
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if (!page)
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continue;
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if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED)))
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__free_page(page);
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else
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xv_free(zram->mem_pool, page, offset);
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}
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vfree(zram->table);
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zram->table = NULL;
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xv_destroy_pool(zram->mem_pool);
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zram->mem_pool = NULL;
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/* Reset stats */
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memset(&zram->stats, 0, sizeof(zram->stats));
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zram->disksize = 0;
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mutex_unlock(&zram->init_lock);
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}
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int zram_init_device(struct zram *zram)
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{
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int ret;
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size_t num_pages;
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mutex_lock(&zram->init_lock);
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if (zram->init_done) {
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mutex_unlock(&zram->init_lock);
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return 0;
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}
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zram_set_disksize(zram, totalram_pages << PAGE_SHIFT);
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zram->compress_workmem = kzalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
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if (!zram->compress_workmem) {
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pr_err("Error allocating compressor working memory!\n");
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ret = -ENOMEM;
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goto fail;
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}
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zram->compress_buffer = (void *)__get_free_pages(__GFP_ZERO, 1);
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if (!zram->compress_buffer) {
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pr_err("Error allocating compressor buffer space\n");
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ret = -ENOMEM;
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goto fail;
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}
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num_pages = zram->disksize >> PAGE_SHIFT;
|
|
zram->table = vmalloc(num_pages * sizeof(*zram->table));
|
|
if (!zram->table) {
|
|
pr_err("Error allocating zram address table\n");
|
|
/* To prevent accessing table entries during cleanup */
|
|
zram->disksize = 0;
|
|
ret = -ENOMEM;
|
|
goto fail;
|
|
}
|
|
memset(zram->table, 0, num_pages * sizeof(*zram->table));
|
|
|
|
set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
|
|
|
|
/* zram devices sort of resembles non-rotational disks */
|
|
queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
|
|
|
|
zram->mem_pool = xv_create_pool();
|
|
if (!zram->mem_pool) {
|
|
pr_err("Error creating memory pool\n");
|
|
ret = -ENOMEM;
|
|
goto fail;
|
|
}
|
|
|
|
zram->init_done = 1;
|
|
mutex_unlock(&zram->init_lock);
|
|
|
|
pr_debug("Initialization done!\n");
|
|
return 0;
|
|
|
|
fail:
|
|
mutex_unlock(&zram->init_lock);
|
|
zram_reset_device(zram);
|
|
|
|
pr_err("Initialization failed: err=%d\n", ret);
|
|
return ret;
|
|
}
|
|
|
|
void zram_slot_free_notify(struct block_device *bdev, unsigned long index)
|
|
{
|
|
struct zram *zram;
|
|
|
|
zram = bdev->bd_disk->private_data;
|
|
zram_free_page(zram, index);
|
|
zram_stat64_inc(zram, &zram->stats.notify_free);
|
|
}
|
|
|
|
static const struct block_device_operations zram_devops = {
|
|
.swap_slot_free_notify = zram_slot_free_notify,
|
|
.owner = THIS_MODULE
|
|
};
|
|
|
|
static int create_device(struct zram *zram, int device_id)
|
|
{
|
|
int ret = 0;
|
|
|
|
mutex_init(&zram->lock);
|
|
mutex_init(&zram->init_lock);
|
|
spin_lock_init(&zram->stat64_lock);
|
|
|
|
zram->queue = blk_alloc_queue(GFP_KERNEL);
|
|
if (!zram->queue) {
|
|
pr_err("Error allocating disk queue for device %d\n",
|
|
device_id);
|
|
ret = -ENOMEM;
|
|
goto out;
|
|
}
|
|
|
|
blk_queue_make_request(zram->queue, zram_make_request);
|
|
zram->queue->queuedata = zram;
|
|
|
|
/* gendisk structure */
|
|
zram->disk = alloc_disk(1);
|
|
if (!zram->disk) {
|
|
blk_cleanup_queue(zram->queue);
|
|
pr_warning("Error allocating disk structure for device %d\n",
|
|
device_id);
|
|
ret = -ENOMEM;
|
|
goto out;
|
|
}
|
|
|
|
zram->disk->major = zram_major;
|
|
zram->disk->first_minor = device_id;
|
|
zram->disk->fops = &zram_devops;
|
|
zram->disk->queue = zram->queue;
|
|
zram->disk->private_data = zram;
|
|
snprintf(zram->disk->disk_name, 16, "zram%d", device_id);
|
|
|
|
/* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
|
|
set_capacity(zram->disk, 0);
|
|
|
|
/*
|
|
* To ensure that we always get PAGE_SIZE aligned
|
|
* and n*PAGE_SIZED sized I/O requests.
|
|
*/
|
|
blk_queue_physical_block_size(zram->disk->queue, PAGE_SIZE);
|
|
blk_queue_logical_block_size(zram->disk->queue, PAGE_SIZE);
|
|
blk_queue_io_min(zram->disk->queue, PAGE_SIZE);
|
|
blk_queue_io_opt(zram->disk->queue, PAGE_SIZE);
|
|
|
|
add_disk(zram->disk);
|
|
|
|
#ifdef CONFIG_SYSFS
|
|
ret = sysfs_create_group(&disk_to_dev(zram->disk)->kobj,
|
|
&zram_disk_attr_group);
|
|
if (ret < 0) {
|
|
pr_warning("Error creating sysfs group");
|
|
goto out;
|
|
}
|
|
#endif
|
|
|
|
zram->init_done = 0;
|
|
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
static void destroy_device(struct zram *zram)
|
|
{
|
|
#ifdef CONFIG_SYSFS
|
|
sysfs_remove_group(&disk_to_dev(zram->disk)->kobj,
|
|
&zram_disk_attr_group);
|
|
#endif
|
|
|
|
if (zram->disk) {
|
|
del_gendisk(zram->disk);
|
|
put_disk(zram->disk);
|
|
}
|
|
|
|
if (zram->queue)
|
|
blk_cleanup_queue(zram->queue);
|
|
}
|
|
|
|
static int __init zram_init(void)
|
|
{
|
|
int ret, dev_id;
|
|
|
|
if (num_devices > max_num_devices) {
|
|
pr_warning("Invalid value for num_devices: %u\n",
|
|
num_devices);
|
|
ret = -EINVAL;
|
|
goto out;
|
|
}
|
|
|
|
zram_major = register_blkdev(0, "zram");
|
|
if (zram_major <= 0) {
|
|
pr_warning("Unable to get major number\n");
|
|
ret = -EBUSY;
|
|
goto out;
|
|
}
|
|
|
|
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 zram), GFP_KERNEL);
|
|
if (!devices) {
|
|
ret = -ENOMEM;
|
|
goto unregister;
|
|
}
|
|
|
|
for (dev_id = 0; dev_id < num_devices; dev_id++) {
|
|
ret = create_device(&devices[dev_id], dev_id);
|
|
if (ret)
|
|
goto free_devices;
|
|
}
|
|
|
|
return 0;
|
|
|
|
free_devices:
|
|
while (dev_id)
|
|
destroy_device(&devices[--dev_id]);
|
|
kfree(devices);
|
|
unregister:
|
|
unregister_blkdev(zram_major, "zram");
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
static void __exit zram_exit(void)
|
|
{
|
|
int i;
|
|
struct zram *zram;
|
|
|
|
for (i = 0; i < num_devices; i++) {
|
|
zram = &devices[i];
|
|
|
|
destroy_device(zram);
|
|
if (zram->init_done)
|
|
zram_reset_device(zram);
|
|
}
|
|
|
|
unregister_blkdev(zram_major, "zram");
|
|
|
|
kfree(devices);
|
|
pr_debug("Cleanup done!\n");
|
|
}
|
|
|
|
module_param(num_devices, uint, 0);
|
|
MODULE_PARM_DESC(num_devices, "Number of zram devices");
|
|
|
|
module_init(zram_init);
|
|
module_exit(zram_exit);
|
|
|
|
MODULE_LICENSE("Dual BSD/GPL");
|
|
MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
|
|
MODULE_DESCRIPTION("Compressed RAM Block Device");
|