786 lines
17 KiB
C
786 lines
17 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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#ifdef CONFIG_ZRAM_DEBUG
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#define DEBUG
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#endif
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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 *zram_devices;
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/* Module params (documentation at end) */
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static 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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unsigned long handle = zram->table[index].handle;
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u16 size = zram->table[index].size;
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if (unlikely(!handle)) {
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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(size > max_zpage_size))
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zram_stat_dec(&zram->stats.bad_compress);
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zs_free(zram->mem_pool, handle);
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if (size <= PAGE_SIZE / 2)
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zram_stat_dec(&zram->stats.good_compress);
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zram_stat64_sub(zram, &zram->stats.compr_size,
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zram->table[index].size);
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zram_stat_dec(&zram->stats.pages_stored);
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zram->table[index].handle = 0;
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zram->table[index].size = 0;
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}
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static void handle_zero_page(struct bio_vec *bvec)
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{
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struct page *page = bvec->bv_page;
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void *user_mem;
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user_mem = kmap_atomic(page);
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memset(user_mem + bvec->bv_offset, 0, bvec->bv_len);
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kunmap_atomic(user_mem);
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flush_dcache_page(page);
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}
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static inline int is_partial_io(struct bio_vec *bvec)
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{
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return bvec->bv_len != PAGE_SIZE;
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}
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static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
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{
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int ret = LZO_E_OK;
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size_t clen = PAGE_SIZE;
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unsigned char *cmem;
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unsigned long handle = zram->table[index].handle;
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if (!handle || zram_test_flag(zram, index, ZRAM_ZERO)) {
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memset(mem, 0, PAGE_SIZE);
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return 0;
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}
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cmem = zs_map_object(zram->mem_pool, handle, ZS_MM_RO);
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if (zram->table[index].size == PAGE_SIZE)
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memcpy(mem, cmem, PAGE_SIZE);
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else
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ret = lzo1x_decompress_safe(cmem, zram->table[index].size,
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mem, &clen);
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zs_unmap_object(zram->mem_pool, handle);
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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", ret, index);
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zram_stat64_inc(zram, &zram->stats.failed_reads);
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return ret;
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}
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return 0;
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}
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static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
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u32 index, int offset, struct bio *bio)
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{
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int ret;
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struct page *page;
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unsigned char *user_mem, *uncmem = NULL;
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page = bvec->bv_page;
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if (unlikely(!zram->table[index].handle) ||
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zram_test_flag(zram, index, ZRAM_ZERO)) {
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handle_zero_page(bvec);
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return 0;
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}
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user_mem = kmap_atomic(page);
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if (is_partial_io(bvec))
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/* Use a temporary buffer to decompress the page */
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uncmem = kmalloc(PAGE_SIZE, GFP_KERNEL);
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else
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uncmem = user_mem;
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if (!uncmem) {
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pr_info("Unable to allocate temp memory\n");
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ret = -ENOMEM;
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goto out_cleanup;
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}
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ret = zram_decompress_page(zram, uncmem, index);
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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", ret, index);
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zram_stat64_inc(zram, &zram->stats.failed_reads);
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goto out_cleanup;
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}
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if (is_partial_io(bvec))
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memcpy(user_mem + bvec->bv_offset, uncmem + offset,
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bvec->bv_len);
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flush_dcache_page(page);
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ret = 0;
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out_cleanup:
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kunmap_atomic(user_mem);
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if (is_partial_io(bvec))
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kfree(uncmem);
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return ret;
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}
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static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
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int offset)
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{
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int ret = 0;
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size_t clen;
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unsigned long handle;
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struct page *page;
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unsigned char *user_mem, *cmem, *src, *uncmem = NULL;
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page = bvec->bv_page;
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src = zram->compress_buffer;
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if (is_partial_io(bvec)) {
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/*
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* This is a partial IO. We need to read the full page
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* before to write the changes.
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*/
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uncmem = kmalloc(PAGE_SIZE, GFP_KERNEL);
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if (!uncmem) {
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pr_info("Error allocating temp memory!\n");
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ret = -ENOMEM;
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goto out;
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}
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ret = zram_decompress_page(zram, uncmem, index);
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if (ret)
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goto out;
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}
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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].handle ||
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zram_test_flag(zram, index, ZRAM_ZERO))
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zram_free_page(zram, index);
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user_mem = kmap_atomic(page);
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if (is_partial_io(bvec)) {
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memcpy(uncmem + offset, user_mem + bvec->bv_offset,
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bvec->bv_len);
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kunmap_atomic(user_mem);
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user_mem = NULL;
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} else {
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uncmem = user_mem;
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}
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if (page_zero_filled(uncmem)) {
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if (!is_partial_io(bvec))
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kunmap_atomic(user_mem);
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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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ret = 0;
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goto out;
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}
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ret = lzo1x_1_compress(uncmem, PAGE_SIZE, src, &clen,
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zram->compress_workmem);
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if (!is_partial_io(bvec)) {
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kunmap_atomic(user_mem);
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user_mem = NULL;
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uncmem = NULL;
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}
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if (unlikely(ret != LZO_E_OK)) {
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pr_err("Compression failed! err=%d\n", ret);
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goto out;
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}
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if (unlikely(clen > max_zpage_size)) {
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zram_stat_inc(&zram->stats.bad_compress);
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clen = PAGE_SIZE;
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src = NULL;
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if (is_partial_io(bvec))
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src = uncmem;
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}
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handle = zs_malloc(zram->mem_pool, clen);
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if (!handle) {
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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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ret = -ENOMEM;
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goto out;
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}
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cmem = zs_map_object(zram->mem_pool, handle, ZS_MM_WO);
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if ((clen == PAGE_SIZE) && !is_partial_io(bvec))
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src = kmap_atomic(page);
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memcpy(cmem, src, clen);
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if ((clen == PAGE_SIZE) && !is_partial_io(bvec))
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kunmap_atomic(src);
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zs_unmap_object(zram->mem_pool, handle);
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zram->table[index].handle = handle;
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zram->table[index].size = clen;
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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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out:
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if (is_partial_io(bvec))
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kfree(uncmem);
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if (ret)
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zram_stat64_inc(zram, &zram->stats.failed_writes);
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return ret;
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}
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static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
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int offset, struct bio *bio, int rw)
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{
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int ret;
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if (rw == READ) {
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down_read(&zram->lock);
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ret = zram_bvec_read(zram, bvec, index, offset, bio);
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up_read(&zram->lock);
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} else {
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down_write(&zram->lock);
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ret = zram_bvec_write(zram, bvec, index, offset);
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up_write(&zram->lock);
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}
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return ret;
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}
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static void update_position(u32 *index, int *offset, struct bio_vec *bvec)
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{
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if (*offset + bvec->bv_len >= PAGE_SIZE)
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(*index)++;
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*offset = (*offset + bvec->bv_len) % PAGE_SIZE;
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}
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|
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static void __zram_make_request(struct zram *zram, struct bio *bio, int rw)
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{
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int i, offset;
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u32 index;
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struct bio_vec *bvec;
|
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switch (rw) {
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case READ:
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zram_stat64_inc(zram, &zram->stats.num_reads);
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break;
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case WRITE:
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zram_stat64_inc(zram, &zram->stats.num_writes);
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break;
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}
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index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT;
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offset = (bio->bi_sector & (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;
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bio_for_each_segment(bvec, bio, i) {
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int max_transfer_size = PAGE_SIZE - offset;
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|
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if (bvec->bv_len > max_transfer_size) {
|
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/*
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* zram_bvec_rw() can only make operation on a single
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* zram page. Split the bio vector.
|
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*/
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struct bio_vec bv;
|
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|
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bv.bv_page = bvec->bv_page;
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bv.bv_len = max_transfer_size;
|
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bv.bv_offset = bvec->bv_offset;
|
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|
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if (zram_bvec_rw(zram, &bv, index, offset, bio, rw) < 0)
|
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goto out;
|
|
|
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bv.bv_len = bvec->bv_len - max_transfer_size;
|
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bv.bv_offset += max_transfer_size;
|
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if (zram_bvec_rw(zram, &bv, index+1, 0, bio, rw) < 0)
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goto out;
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} else
|
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if (zram_bvec_rw(zram, bvec, index, offset, bio, rw)
|
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< 0)
|
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goto out;
|
|
|
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update_position(&index, &offset, bvec);
|
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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;
|
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|
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out:
|
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bio_io_error(bio);
|
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}
|
|
|
|
/*
|
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* Check if request is within bounds and aligned on zram logical blocks.
|
|
*/
|
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static inline int valid_io_request(struct zram *zram, struct bio *bio)
|
|
{
|
|
if (unlikely(
|
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(bio->bi_sector >= (zram->disksize >> SECTOR_SHIFT)) ||
|
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(bio->bi_sector & (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1)) ||
|
|
(bio->bi_size & (ZRAM_LOGICAL_BLOCK_SIZE - 1)))) {
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* I/O request is valid */
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Handler function for all zram I/O requests.
|
|
*/
|
|
static void zram_make_request(struct request_queue *queue, struct bio *bio)
|
|
{
|
|
struct zram *zram = queue->queuedata;
|
|
|
|
if (unlikely(!zram->init_done) && zram_init_device(zram))
|
|
goto error;
|
|
|
|
down_read(&zram->init_lock);
|
|
if (unlikely(!zram->init_done))
|
|
goto error_unlock;
|
|
|
|
if (!valid_io_request(zram, bio)) {
|
|
zram_stat64_inc(zram, &zram->stats.invalid_io);
|
|
goto error_unlock;
|
|
}
|
|
|
|
__zram_make_request(zram, bio, bio_data_dir(bio));
|
|
up_read(&zram->init_lock);
|
|
|
|
return;
|
|
|
|
error_unlock:
|
|
up_read(&zram->init_lock);
|
|
error:
|
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bio_io_error(bio);
|
|
}
|
|
|
|
void __zram_reset_device(struct zram *zram)
|
|
{
|
|
size_t index;
|
|
|
|
zram->init_done = 0;
|
|
|
|
/* Free various per-device buffers */
|
|
kfree(zram->compress_workmem);
|
|
free_pages((unsigned long)zram->compress_buffer, 1);
|
|
|
|
zram->compress_workmem = NULL;
|
|
zram->compress_buffer = NULL;
|
|
|
|
/* Free all pages that are still in this zram device */
|
|
for (index = 0; index < zram->disksize >> PAGE_SHIFT; index++) {
|
|
unsigned long handle = zram->table[index].handle;
|
|
if (!handle)
|
|
continue;
|
|
|
|
zs_free(zram->mem_pool, handle);
|
|
}
|
|
|
|
vfree(zram->table);
|
|
zram->table = NULL;
|
|
|
|
zs_destroy_pool(zram->mem_pool);
|
|
zram->mem_pool = NULL;
|
|
|
|
/* Reset stats */
|
|
memset(&zram->stats, 0, sizeof(zram->stats));
|
|
|
|
zram->disksize = 0;
|
|
}
|
|
|
|
void zram_reset_device(struct zram *zram)
|
|
{
|
|
down_write(&zram->init_lock);
|
|
__zram_reset_device(zram);
|
|
up_write(&zram->init_lock);
|
|
}
|
|
|
|
int zram_init_device(struct zram *zram)
|
|
{
|
|
int ret;
|
|
size_t num_pages;
|
|
|
|
down_write(&zram->init_lock);
|
|
|
|
if (zram->init_done) {
|
|
up_write(&zram->init_lock);
|
|
return 0;
|
|
}
|
|
|
|
zram_set_disksize(zram, totalram_pages << PAGE_SHIFT);
|
|
|
|
zram->compress_workmem = kzalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
|
|
if (!zram->compress_workmem) {
|
|
pr_err("Error allocating compressor working memory!\n");
|
|
ret = -ENOMEM;
|
|
goto fail_no_table;
|
|
}
|
|
|
|
zram->compress_buffer =
|
|
(void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
|
|
if (!zram->compress_buffer) {
|
|
pr_err("Error allocating compressor buffer space\n");
|
|
ret = -ENOMEM;
|
|
goto fail_no_table;
|
|
}
|
|
|
|
num_pages = zram->disksize >> PAGE_SHIFT;
|
|
zram->table = vzalloc(num_pages * sizeof(*zram->table));
|
|
if (!zram->table) {
|
|
pr_err("Error allocating zram address table\n");
|
|
ret = -ENOMEM;
|
|
goto fail_no_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 = zs_create_pool("zram", GFP_NOIO | __GFP_HIGHMEM);
|
|
if (!zram->mem_pool) {
|
|
pr_err("Error creating memory pool\n");
|
|
ret = -ENOMEM;
|
|
goto fail;
|
|
}
|
|
|
|
zram->init_done = 1;
|
|
up_write(&zram->init_lock);
|
|
|
|
pr_debug("Initialization done!\n");
|
|
return 0;
|
|
|
|
fail_no_table:
|
|
/* To prevent accessing table entries during cleanup */
|
|
zram->disksize = 0;
|
|
fail:
|
|
__zram_reset_device(zram);
|
|
up_write(&zram->init_lock);
|
|
pr_err("Initialization failed: err=%d\n", ret);
|
|
return ret;
|
|
}
|
|
|
|
static 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;
|
|
|
|
init_rwsem(&zram->lock);
|
|
init_rwsem(&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_warn("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,
|
|
ZRAM_LOGICAL_BLOCK_SIZE);
|
|
blk_queue_io_min(zram->disk->queue, PAGE_SIZE);
|
|
blk_queue_io_opt(zram->disk->queue, PAGE_SIZE);
|
|
|
|
add_disk(zram->disk);
|
|
|
|
ret = sysfs_create_group(&disk_to_dev(zram->disk)->kobj,
|
|
&zram_disk_attr_group);
|
|
if (ret < 0) {
|
|
pr_warn("Error creating sysfs group");
|
|
goto out;
|
|
}
|
|
|
|
zram->init_done = 0;
|
|
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
static void destroy_device(struct zram *zram)
|
|
{
|
|
sysfs_remove_group(&disk_to_dev(zram->disk)->kobj,
|
|
&zram_disk_attr_group);
|
|
|
|
if (zram->disk) {
|
|
del_gendisk(zram->disk);
|
|
put_disk(zram->disk);
|
|
}
|
|
|
|
if (zram->queue)
|
|
blk_cleanup_queue(zram->queue);
|
|
}
|
|
|
|
unsigned int zram_get_num_devices(void)
|
|
{
|
|
return num_devices;
|
|
}
|
|
|
|
static int __init zram_init(void)
|
|
{
|
|
int ret, dev_id;
|
|
|
|
if (num_devices > max_num_devices) {
|
|
pr_warn("Invalid value for num_devices: %u\n",
|
|
num_devices);
|
|
ret = -EINVAL;
|
|
goto out;
|
|
}
|
|
|
|
zram_major = register_blkdev(0, "zram");
|
|
if (zram_major <= 0) {
|
|
pr_warn("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);
|
|
zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
|
|
if (!zram_devices) {
|
|
ret = -ENOMEM;
|
|
goto unregister;
|
|
}
|
|
|
|
for (dev_id = 0; dev_id < num_devices; dev_id++) {
|
|
ret = create_device(&zram_devices[dev_id], dev_id);
|
|
if (ret)
|
|
goto free_devices;
|
|
}
|
|
|
|
return 0;
|
|
|
|
free_devices:
|
|
while (dev_id)
|
|
destroy_device(&zram_devices[--dev_id]);
|
|
kfree(zram_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 = &zram_devices[i];
|
|
|
|
destroy_device(zram);
|
|
if (zram->init_done)
|
|
zram_reset_device(zram);
|
|
}
|
|
|
|
unregister_blkdev(zram_major, "zram");
|
|
|
|
kfree(zram_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");
|