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mtdswap.c
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/*
* Swap block device support for MTDs
* Turns an MTD device into a swap device with block wear leveling
*
* Copyright © 2007,2011 Nokia Corporation. All rights reserved.
*
* Authors: Jarkko Lavinen <[email protected]>
*
* Based on Richard Purdie's earlier implementation in 2007. Background
* support and lock-less operation written by Adrian Hunter.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* version 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/blktrans.h>
#include <linux/rbtree.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/genhd.h>
#include <linux/swap.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/device.h>
#include <linux/math64.h>
#define MTDSWAP_PREFIX "mtdswap"
/*
* The number of free eraseblocks when GC should stop
*/
#define CLEAN_BLOCK_THRESHOLD 20
/*
* Number of free eraseblocks below which GC can also collect low frag
* blocks.
*/
#define LOW_FRAG_GC_THRESHOLD 5
/*
* Wear level cost amortization. We want to do wear leveling on the background
* without disturbing gc too much. This is made by defining max GC frequency.
* Frequency value 6 means 1/6 of the GC passes will pick an erase block based
* on the biggest wear difference rather than the biggest dirtiness.
*
* The lower freq2 should be chosen so that it makes sure the maximum erase
* difference will decrease even if a malicious application is deliberately
* trying to make erase differences large.
*/
#define MAX_ERASE_DIFF 4000
#define COLLECT_NONDIRTY_BASE MAX_ERASE_DIFF
#define COLLECT_NONDIRTY_FREQ1 6
#define COLLECT_NONDIRTY_FREQ2 4
#define PAGE_UNDEF UINT_MAX
#define BLOCK_UNDEF UINT_MAX
#define BLOCK_ERROR (UINT_MAX - 1)
#define BLOCK_MAX (UINT_MAX - 2)
#define EBLOCK_BAD (1 << 0)
#define EBLOCK_NOMAGIC (1 << 1)
#define EBLOCK_BITFLIP (1 << 2)
#define EBLOCK_FAILED (1 << 3)
#define EBLOCK_READERR (1 << 4)
#define EBLOCK_IDX_SHIFT 5
struct swap_eb {
struct rb_node rb;
struct rb_root *root;
unsigned int flags;
unsigned int active_count;
unsigned int erase_count;
unsigned int pad; /* speeds up pointer decrement */
};
#define MTDSWAP_ECNT_MIN(rbroot) (rb_entry(rb_first(rbroot), struct swap_eb, \
rb)->erase_count)
#define MTDSWAP_ECNT_MAX(rbroot) (rb_entry(rb_last(rbroot), struct swap_eb, \
rb)->erase_count)
struct mtdswap_tree {
struct rb_root root;
unsigned int count;
};
enum {
MTDSWAP_CLEAN,
MTDSWAP_USED,
MTDSWAP_LOWFRAG,
MTDSWAP_HIFRAG,
MTDSWAP_DIRTY,
MTDSWAP_BITFLIP,
MTDSWAP_FAILING,
MTDSWAP_TREE_CNT,
};
struct mtdswap_dev {
struct mtd_blktrans_dev *mbd_dev;
struct mtd_info *mtd;
struct device *dev;
unsigned int *page_data;
unsigned int *revmap;
unsigned int eblks;
unsigned int spare_eblks;
unsigned int pages_per_eblk;
unsigned int max_erase_count;
struct swap_eb *eb_data;
struct mtdswap_tree trees[MTDSWAP_TREE_CNT];
unsigned long long sect_read_count;
unsigned long long sect_write_count;
unsigned long long mtd_write_count;
unsigned long long mtd_read_count;
unsigned long long discard_count;
unsigned long long discard_page_count;
unsigned int curr_write_pos;
struct swap_eb *curr_write;
char *page_buf;
char *oob_buf;
};
struct mtdswap_oobdata {
__le16 magic;
__le32 count;
} __packed;
#define MTDSWAP_MAGIC_CLEAN 0x2095
#define MTDSWAP_MAGIC_DIRTY (MTDSWAP_MAGIC_CLEAN + 1)
#define MTDSWAP_TYPE_CLEAN 0
#define MTDSWAP_TYPE_DIRTY 1
#define MTDSWAP_OOBSIZE sizeof(struct mtdswap_oobdata)
#define MTDSWAP_ERASE_RETRIES 3 /* Before marking erase block bad */
#define MTDSWAP_IO_RETRIES 3
enum {
MTDSWAP_SCANNED_CLEAN,
MTDSWAP_SCANNED_DIRTY,
MTDSWAP_SCANNED_BITFLIP,
MTDSWAP_SCANNED_BAD,
};
/*
* In the worst case mtdswap_writesect() has allocated the last clean
* page from the current block and is then pre-empted by the GC
* thread. The thread can consume a full erase block when moving a
* block.
*/
#define MIN_SPARE_EBLOCKS 2
#define MIN_ERASE_BLOCKS (MIN_SPARE_EBLOCKS + 1)
#define TREE_ROOT(d, name) (&d->trees[MTDSWAP_ ## name].root)
#define TREE_EMPTY(d, name) (TREE_ROOT(d, name)->rb_node == NULL)
#define TREE_NONEMPTY(d, name) (!TREE_EMPTY(d, name))
#define TREE_COUNT(d, name) (d->trees[MTDSWAP_ ## name].count)
#define MTDSWAP_MBD_TO_MTDSWAP(dev) ((struct mtdswap_dev *)dev->priv)
static char partitions[128] = "";
module_param_string(partitions, partitions, sizeof(partitions), 0444);
MODULE_PARM_DESC(partitions, "MTD partition numbers to use as swap "
"partitions=\"1,3,5\"");
static unsigned int spare_eblocks = 10;
module_param(spare_eblocks, uint, 0444);
MODULE_PARM_DESC(spare_eblocks, "Percentage of spare erase blocks for "
"garbage collection (default 10%)");
static bool header; /* false */
module_param(header, bool, 0444);
MODULE_PARM_DESC(header,
"Include builtin swap header (default 0, without header)");
static int mtdswap_gc(struct mtdswap_dev *d, unsigned int background);
static loff_t mtdswap_eb_offset(struct mtdswap_dev *d, struct swap_eb *eb)
{
return (loff_t)(eb - d->eb_data) * d->mtd->erasesize;
}
static void mtdswap_eb_detach(struct mtdswap_dev *d, struct swap_eb *eb)
{
unsigned int oldidx;
struct mtdswap_tree *tp;
if (eb->root) {
tp = container_of(eb->root, struct mtdswap_tree, root);
oldidx = tp - &d->trees[0];
d->trees[oldidx].count--;
rb_erase(&eb->rb, eb->root);
}
}
static void __mtdswap_rb_add(struct rb_root *root, struct swap_eb *eb)
{
struct rb_node **p, *parent = NULL;
struct swap_eb *cur;
p = &root->rb_node;
while (*p) {
parent = *p;
cur = rb_entry(parent, struct swap_eb, rb);
if (eb->erase_count > cur->erase_count)
p = &(*p)->rb_right;
else
p = &(*p)->rb_left;
}
rb_link_node(&eb->rb, parent, p);
rb_insert_color(&eb->rb, root);
}
static void mtdswap_rb_add(struct mtdswap_dev *d, struct swap_eb *eb, int idx)
{
struct rb_root *root;
if (eb->root == &d->trees[idx].root)
return;
mtdswap_eb_detach(d, eb);
root = &d->trees[idx].root;
__mtdswap_rb_add(root, eb);
eb->root = root;
d->trees[idx].count++;
}
static struct rb_node *mtdswap_rb_index(struct rb_root *root, unsigned int idx)
{
struct rb_node *p;
unsigned int i;
p = rb_first(root);
i = 0;
while (i < idx && p) {
p = rb_next(p);
i++;
}
return p;
}
static int mtdswap_handle_badblock(struct mtdswap_dev *d, struct swap_eb *eb)
{
int ret;
loff_t offset;
d->spare_eblks--;
eb->flags |= EBLOCK_BAD;
mtdswap_eb_detach(d, eb);
eb->root = NULL;
/* badblocks not supported */
if (!mtd_can_have_bb(d->mtd))
return 1;
offset = mtdswap_eb_offset(d, eb);
dev_warn(d->dev, "Marking bad block at %08llx\n", offset);
ret = mtd_block_markbad(d->mtd, offset);
if (ret) {
dev_warn(d->dev, "Mark block bad failed for block at %08llx "
"error %d\n", offset, ret);
return ret;
}
return 1;
}
static int mtdswap_handle_write_error(struct mtdswap_dev *d, struct swap_eb *eb)
{
unsigned int marked = eb->flags & EBLOCK_FAILED;
struct swap_eb *curr_write = d->curr_write;
eb->flags |= EBLOCK_FAILED;
if (curr_write == eb) {
d->curr_write = NULL;
if (!marked && d->curr_write_pos != 0) {
mtdswap_rb_add(d, eb, MTDSWAP_FAILING);
return 0;
}
}
return mtdswap_handle_badblock(d, eb);
}
static int mtdswap_read_oob(struct mtdswap_dev *d, loff_t from,
struct mtd_oob_ops *ops)
{
int ret = mtd_read_oob(d->mtd, from, ops);
if (mtd_is_bitflip(ret))
return ret;
if (ret) {
dev_warn(d->dev, "Read OOB failed %d for block at %08llx\n",
ret, from);
return ret;
}
if (ops->oobretlen < ops->ooblen) {
dev_warn(d->dev, "Read OOB return short read (%zd bytes not "
"%zd) for block at %08llx\n",
ops->oobretlen, ops->ooblen, from);
return -EIO;
}
return 0;
}
static int mtdswap_read_markers(struct mtdswap_dev *d, struct swap_eb *eb)
{
struct mtdswap_oobdata *data, *data2;
int ret;
loff_t offset;
struct mtd_oob_ops ops;
offset = mtdswap_eb_offset(d, eb);
/* Check first if the block is bad. */
if (mtd_can_have_bb(d->mtd) && mtd_block_isbad(d->mtd, offset))
return MTDSWAP_SCANNED_BAD;
ops.ooblen = 2 * d->mtd->oobavail;
ops.oobbuf = d->oob_buf;
ops.ooboffs = 0;
ops.datbuf = NULL;
ops.mode = MTD_OPS_AUTO_OOB;
ret = mtdswap_read_oob(d, offset, &ops);
if (ret && !mtd_is_bitflip(ret))
return ret;
data = (struct mtdswap_oobdata *)d->oob_buf;
data2 = (struct mtdswap_oobdata *)
(d->oob_buf + d->mtd->oobavail);
if (le16_to_cpu(data->magic) == MTDSWAP_MAGIC_CLEAN) {
eb->erase_count = le32_to_cpu(data->count);
if (mtd_is_bitflip(ret))
ret = MTDSWAP_SCANNED_BITFLIP;
else {
if (le16_to_cpu(data2->magic) == MTDSWAP_MAGIC_DIRTY)
ret = MTDSWAP_SCANNED_DIRTY;
else
ret = MTDSWAP_SCANNED_CLEAN;
}
} else {
eb->flags |= EBLOCK_NOMAGIC;
ret = MTDSWAP_SCANNED_DIRTY;
}
return ret;
}
static int mtdswap_write_marker(struct mtdswap_dev *d, struct swap_eb *eb,
u16 marker)
{
struct mtdswap_oobdata n;
int ret;
loff_t offset;
struct mtd_oob_ops ops;
ops.ooboffs = 0;
ops.oobbuf = (uint8_t *)&n;
ops.mode = MTD_OPS_AUTO_OOB;
ops.datbuf = NULL;
if (marker == MTDSWAP_TYPE_CLEAN) {
n.magic = cpu_to_le16(MTDSWAP_MAGIC_CLEAN);
n.count = cpu_to_le32(eb->erase_count);
ops.ooblen = MTDSWAP_OOBSIZE;
offset = mtdswap_eb_offset(d, eb);
} else {
n.magic = cpu_to_le16(MTDSWAP_MAGIC_DIRTY);
ops.ooblen = sizeof(n.magic);
offset = mtdswap_eb_offset(d, eb) + d->mtd->writesize;
}
ret = mtd_write_oob(d->mtd, offset, &ops);
if (ret) {
dev_warn(d->dev, "Write OOB failed for block at %08llx "
"error %d\n", offset, ret);
if (ret == -EIO || mtd_is_eccerr(ret))
mtdswap_handle_write_error(d, eb);
return ret;
}
if (ops.oobretlen != ops.ooblen) {
dev_warn(d->dev, "Short OOB write for block at %08llx: "
"%zd not %zd\n",
offset, ops.oobretlen, ops.ooblen);
return ret;
}
return 0;
}
/*
* Are there any erase blocks without MAGIC_CLEAN header, presumably
* because power was cut off after erase but before header write? We
* need to guestimate the erase count.
*/
static void mtdswap_check_counts(struct mtdswap_dev *d)
{
struct rb_root hist_root = RB_ROOT;
struct rb_node *medrb;
struct swap_eb *eb;
unsigned int i, cnt, median;
cnt = 0;
for (i = 0; i < d->eblks; i++) {
eb = d->eb_data + i;
if (eb->flags & (EBLOCK_NOMAGIC | EBLOCK_BAD | EBLOCK_READERR))
continue;
__mtdswap_rb_add(&hist_root, eb);
cnt++;
}
if (cnt == 0)
return;
medrb = mtdswap_rb_index(&hist_root, cnt / 2);
median = rb_entry(medrb, struct swap_eb, rb)->erase_count;
d->max_erase_count = MTDSWAP_ECNT_MAX(&hist_root);
for (i = 0; i < d->eblks; i++) {
eb = d->eb_data + i;
if (eb->flags & (EBLOCK_NOMAGIC | EBLOCK_READERR))
eb->erase_count = median;
if (eb->flags & (EBLOCK_NOMAGIC | EBLOCK_BAD | EBLOCK_READERR))
continue;
rb_erase(&eb->rb, &hist_root);
}
}
static void mtdswap_scan_eblks(struct mtdswap_dev *d)
{
int status;
unsigned int i, idx;
struct swap_eb *eb;
for (i = 0; i < d->eblks; i++) {
eb = d->eb_data + i;
status = mtdswap_read_markers(d, eb);
if (status < 0)
eb->flags |= EBLOCK_READERR;
else if (status == MTDSWAP_SCANNED_BAD) {
eb->flags |= EBLOCK_BAD;
continue;
}
switch (status) {
case MTDSWAP_SCANNED_CLEAN:
idx = MTDSWAP_CLEAN;
break;
case MTDSWAP_SCANNED_DIRTY:
case MTDSWAP_SCANNED_BITFLIP:
idx = MTDSWAP_DIRTY;
break;
default:
idx = MTDSWAP_FAILING;
}
eb->flags |= (idx << EBLOCK_IDX_SHIFT);
}
mtdswap_check_counts(d);
for (i = 0; i < d->eblks; i++) {
eb = d->eb_data + i;
if (eb->flags & EBLOCK_BAD)
continue;
idx = eb->flags >> EBLOCK_IDX_SHIFT;
mtdswap_rb_add(d, eb, idx);
}
}
/*
* Place eblk into a tree corresponding to its number of active blocks
* it contains.
*/
static void mtdswap_store_eb(struct mtdswap_dev *d, struct swap_eb *eb)
{
unsigned int weight = eb->active_count;
unsigned int maxweight = d->pages_per_eblk;
if (eb == d->curr_write)
return;
if (eb->flags & EBLOCK_BITFLIP)
mtdswap_rb_add(d, eb, MTDSWAP_BITFLIP);
else if (eb->flags & (EBLOCK_READERR | EBLOCK_FAILED))
mtdswap_rb_add(d, eb, MTDSWAP_FAILING);
if (weight == maxweight)
mtdswap_rb_add(d, eb, MTDSWAP_USED);
else if (weight == 0)
mtdswap_rb_add(d, eb, MTDSWAP_DIRTY);
else if (weight > (maxweight/2))
mtdswap_rb_add(d, eb, MTDSWAP_LOWFRAG);
else
mtdswap_rb_add(d, eb, MTDSWAP_HIFRAG);
}
static int mtdswap_erase_block(struct mtdswap_dev *d, struct swap_eb *eb)
{
struct mtd_info *mtd = d->mtd;
struct erase_info erase;
unsigned int retries = 0;
int ret;
eb->erase_count++;
if (eb->erase_count > d->max_erase_count)
d->max_erase_count = eb->erase_count;
retry:
memset(&erase, 0, sizeof(struct erase_info));
erase.addr = mtdswap_eb_offset(d, eb);
erase.len = mtd->erasesize;
ret = mtd_erase(mtd, &erase);
if (ret) {
if (retries++ < MTDSWAP_ERASE_RETRIES) {
dev_warn(d->dev,
"erase of erase block %#llx on %s failed",
erase.addr, mtd->name);
yield();
goto retry;
}
dev_err(d->dev, "Cannot erase erase block %#llx on %s\n",
erase.addr, mtd->name);
mtdswap_handle_badblock(d, eb);
return -EIO;
}
return 0;
}
static int mtdswap_map_free_block(struct mtdswap_dev *d, unsigned int page,
unsigned int *block)
{
int ret;
struct swap_eb *old_eb = d->curr_write;
struct rb_root *clean_root;
struct swap_eb *eb;
if (old_eb == NULL || d->curr_write_pos >= d->pages_per_eblk) {
do {
if (TREE_EMPTY(d, CLEAN))
return -ENOSPC;
clean_root = TREE_ROOT(d, CLEAN);
eb = rb_entry(rb_first(clean_root), struct swap_eb, rb);
rb_erase(&eb->rb, clean_root);
eb->root = NULL;
TREE_COUNT(d, CLEAN)--;
ret = mtdswap_write_marker(d, eb, MTDSWAP_TYPE_DIRTY);
} while (ret == -EIO || mtd_is_eccerr(ret));
if (ret)
return ret;
d->curr_write_pos = 0;
d->curr_write = eb;
if (old_eb)
mtdswap_store_eb(d, old_eb);
}
*block = (d->curr_write - d->eb_data) * d->pages_per_eblk +
d->curr_write_pos;
d->curr_write->active_count++;
d->revmap[*block] = page;
d->curr_write_pos++;
return 0;
}
static unsigned int mtdswap_free_page_cnt(struct mtdswap_dev *d)
{
return TREE_COUNT(d, CLEAN) * d->pages_per_eblk +
d->pages_per_eblk - d->curr_write_pos;
}
static unsigned int mtdswap_enough_free_pages(struct mtdswap_dev *d)
{
return mtdswap_free_page_cnt(d) > d->pages_per_eblk;
}
static int mtdswap_write_block(struct mtdswap_dev *d, char *buf,
unsigned int page, unsigned int *bp, int gc_context)
{
struct mtd_info *mtd = d->mtd;
struct swap_eb *eb;
size_t retlen;
loff_t writepos;
int ret;
retry:
if (!gc_context)
while (!mtdswap_enough_free_pages(d))
if (mtdswap_gc(d, 0) > 0)
return -ENOSPC;
ret = mtdswap_map_free_block(d, page, bp);
eb = d->eb_data + (*bp / d->pages_per_eblk);
if (ret == -EIO || mtd_is_eccerr(ret)) {
d->curr_write = NULL;
eb->active_count--;
d->revmap[*bp] = PAGE_UNDEF;
goto retry;
}
if (ret < 0)
return ret;
writepos = (loff_t)*bp << PAGE_SHIFT;
ret = mtd_write(mtd, writepos, PAGE_SIZE, &retlen, buf);
if (ret == -EIO || mtd_is_eccerr(ret)) {
d->curr_write_pos--;
eb->active_count--;
d->revmap[*bp] = PAGE_UNDEF;
mtdswap_handle_write_error(d, eb);
goto retry;
}
if (ret < 0) {
dev_err(d->dev, "Write to MTD device failed: %d (%zd written)",
ret, retlen);
goto err;
}
if (retlen != PAGE_SIZE) {
dev_err(d->dev, "Short write to MTD device: %zd written",
retlen);
ret = -EIO;
goto err;
}
return ret;
err:
d->curr_write_pos--;
eb->active_count--;
d->revmap[*bp] = PAGE_UNDEF;
return ret;
}
static int mtdswap_move_block(struct mtdswap_dev *d, unsigned int oldblock,
unsigned int *newblock)
{
struct mtd_info *mtd = d->mtd;
struct swap_eb *eb, *oldeb;
int ret;
size_t retlen;
unsigned int page, retries;
loff_t readpos;
page = d->revmap[oldblock];
readpos = (loff_t) oldblock << PAGE_SHIFT;
retries = 0;
retry:
ret = mtd_read(mtd, readpos, PAGE_SIZE, &retlen, d->page_buf);
if (ret < 0 && !mtd_is_bitflip(ret)) {
oldeb = d->eb_data + oldblock / d->pages_per_eblk;
oldeb->flags |= EBLOCK_READERR;
dev_err(d->dev, "Read Error: %d (block %u)\n", ret,
oldblock);
retries++;
if (retries < MTDSWAP_IO_RETRIES)
goto retry;
goto read_error;
}
if (retlen != PAGE_SIZE) {
dev_err(d->dev, "Short read: %zd (block %u)\n", retlen,
oldblock);
ret = -EIO;
goto read_error;
}
ret = mtdswap_write_block(d, d->page_buf, page, newblock, 1);
if (ret < 0) {
d->page_data[page] = BLOCK_ERROR;
dev_err(d->dev, "Write error: %d\n", ret);
return ret;
}
eb = d->eb_data + *newblock / d->pages_per_eblk;
d->page_data[page] = *newblock;
d->revmap[oldblock] = PAGE_UNDEF;
eb = d->eb_data + oldblock / d->pages_per_eblk;
eb->active_count--;
return 0;
read_error:
d->page_data[page] = BLOCK_ERROR;
d->revmap[oldblock] = PAGE_UNDEF;
return ret;
}
static int mtdswap_gc_eblock(struct mtdswap_dev *d, struct swap_eb *eb)
{
unsigned int i, block, eblk_base, newblock;
int ret, errcode;
errcode = 0;
eblk_base = (eb - d->eb_data) * d->pages_per_eblk;
for (i = 0; i < d->pages_per_eblk; i++) {
if (d->spare_eblks < MIN_SPARE_EBLOCKS)
return -ENOSPC;
block = eblk_base + i;
if (d->revmap[block] == PAGE_UNDEF)
continue;
ret = mtdswap_move_block(d, block, &newblock);
if (ret < 0 && !errcode)
errcode = ret;
}
return errcode;
}
static int __mtdswap_choose_gc_tree(struct mtdswap_dev *d)
{
int idx, stopat;
if (TREE_COUNT(d, CLEAN) < LOW_FRAG_GC_THRESHOLD)
stopat = MTDSWAP_LOWFRAG;
else
stopat = MTDSWAP_HIFRAG;
for (idx = MTDSWAP_BITFLIP; idx >= stopat; idx--)
if (d->trees[idx].root.rb_node != NULL)
return idx;
return -1;
}
static int mtdswap_wlfreq(unsigned int maxdiff)
{
unsigned int h, x, y, dist, base;
/*
* Calculate linear ramp down from f1 to f2 when maxdiff goes from
* MAX_ERASE_DIFF to MAX_ERASE_DIFF + COLLECT_NONDIRTY_BASE. Similar
* to triangle with height f1 - f1 and width COLLECT_NONDIRTY_BASE.
*/
dist = maxdiff - MAX_ERASE_DIFF;
if (dist > COLLECT_NONDIRTY_BASE)
dist = COLLECT_NONDIRTY_BASE;
/*
* Modelling the slop as right angular triangle with base
* COLLECT_NONDIRTY_BASE and height freq1 - freq2. The ratio y/x is
* equal to the ratio h/base.
*/
h = COLLECT_NONDIRTY_FREQ1 - COLLECT_NONDIRTY_FREQ2;
base = COLLECT_NONDIRTY_BASE;
x = dist - base;
y = (x * h + base / 2) / base;
return COLLECT_NONDIRTY_FREQ2 + y;
}
static int mtdswap_choose_wl_tree(struct mtdswap_dev *d)
{
static unsigned int pick_cnt;
unsigned int i, idx = -1, wear, max;
struct rb_root *root;
max = 0;
for (i = 0; i <= MTDSWAP_DIRTY; i++) {
root = &d->trees[i].root;
if (root->rb_node == NULL)
continue;
wear = d->max_erase_count - MTDSWAP_ECNT_MIN(root);
if (wear > max) {
max = wear;
idx = i;
}
}
if (max > MAX_ERASE_DIFF && pick_cnt >= mtdswap_wlfreq(max) - 1) {
pick_cnt = 0;
return idx;
}
pick_cnt++;
return -1;
}
static int mtdswap_choose_gc_tree(struct mtdswap_dev *d,
unsigned int background)
{
int idx;
if (TREE_NONEMPTY(d, FAILING) &&
(background || (TREE_EMPTY(d, CLEAN) && TREE_EMPTY(d, DIRTY))))
return MTDSWAP_FAILING;
idx = mtdswap_choose_wl_tree(d);
if (idx >= MTDSWAP_CLEAN)
return idx;
return __mtdswap_choose_gc_tree(d);
}
static struct swap_eb *mtdswap_pick_gc_eblk(struct mtdswap_dev *d,
unsigned int background)
{
struct rb_root *rp = NULL;
struct swap_eb *eb = NULL;
int idx;
if (background && TREE_COUNT(d, CLEAN) > CLEAN_BLOCK_THRESHOLD &&
TREE_EMPTY(d, DIRTY) && TREE_EMPTY(d, FAILING))
return NULL;
idx = mtdswap_choose_gc_tree(d, background);
if (idx < 0)
return NULL;
rp = &d->trees[idx].root;
eb = rb_entry(rb_first(rp), struct swap_eb, rb);
rb_erase(&eb->rb, rp);
eb->root = NULL;
d->trees[idx].count--;
return eb;
}
static unsigned int mtdswap_test_patt(unsigned int i)
{
return i % 2 ? 0x55555555 : 0xAAAAAAAA;
}
static unsigned int mtdswap_eblk_passes(struct mtdswap_dev *d,
struct swap_eb *eb)
{
struct mtd_info *mtd = d->mtd;
unsigned int test, i, j, patt, mtd_pages;
loff_t base, pos;
unsigned int *p1 = (unsigned int *)d->page_buf;
unsigned char *p2 = (unsigned char *)d->oob_buf;
struct mtd_oob_ops ops;
int ret;
ops.mode = MTD_OPS_AUTO_OOB;
ops.len = mtd->writesize;
ops.ooblen = mtd->oobavail;
ops.ooboffs = 0;
ops.datbuf = d->page_buf;
ops.oobbuf = d->oob_buf;
base = mtdswap_eb_offset(d, eb);
mtd_pages = d->pages_per_eblk * PAGE_SIZE / mtd->writesize;
for (test = 0; test < 2; test++) {
pos = base;
for (i = 0; i < mtd_pages; i++) {
patt = mtdswap_test_patt(test + i);
memset(d->page_buf, patt, mtd->writesize);
memset(d->oob_buf, patt, mtd->oobavail);
ret = mtd_write_oob(mtd, pos, &ops);
if (ret)
goto error;
pos += mtd->writesize;
}
pos = base;
for (i = 0; i < mtd_pages; i++) {
ret = mtd_read_oob(mtd, pos, &ops);
if (ret)
goto error;
patt = mtdswap_test_patt(test + i);
for (j = 0; j < mtd->writesize/sizeof(int); j++)
if (p1[j] != patt)
goto error;
for (j = 0; j < mtd->oobavail; j++)
if (p2[j] != (unsigned char)patt)
goto error;
pos += mtd->writesize;
}
ret = mtdswap_erase_block(d, eb);
if (ret)
goto error;
}
eb->flags &= ~EBLOCK_READERR;
return 1;
error:
mtdswap_handle_badblock(d, eb);
return 0;
}
static int mtdswap_gc(struct mtdswap_dev *d, unsigned int background)
{
struct swap_eb *eb;
int ret;
if (d->spare_eblks < MIN_SPARE_EBLOCKS)
return 1;
eb = mtdswap_pick_gc_eblk(d, background);
if (!eb)
return 1;
ret = mtdswap_gc_eblock(d, eb);
if (ret == -ENOSPC)
return 1;
if (eb->flags & EBLOCK_FAILED) {
mtdswap_handle_badblock(d, eb);
return 0;
}
eb->flags &= ~EBLOCK_BITFLIP;
ret = mtdswap_erase_block(d, eb);
if ((eb->flags & EBLOCK_READERR) &&
(ret || !mtdswap_eblk_passes(d, eb)))
return 0;
if (ret == 0)
ret = mtdswap_write_marker(d, eb, MTDSWAP_TYPE_CLEAN);
if (ret == 0)
mtdswap_rb_add(d, eb, MTDSWAP_CLEAN);
else if (ret != -EIO && !mtd_is_eccerr(ret))
mtdswap_rb_add(d, eb, MTDSWAP_DIRTY);
return 0;
}
static void mtdswap_background(struct mtd_blktrans_dev *dev)
{
struct mtdswap_dev *d = MTDSWAP_MBD_TO_MTDSWAP(dev);
int ret;
while (1) {
ret = mtdswap_gc(d, 1);
if (ret || mtd_blktrans_cease_background(dev))
return;
}
}