/*
* Copyright (c) International Business Machines Corp., 2006
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Authors: Artem Bityutskiy (Битюцкий Артём), Thomas Gleixner
*/
/*
* UBI wear-leveling sub-system.
*
* This sub-system is responsible for wear-leveling. It works in terms of
* physical eraseblocks and erase counters and knows nothing about logical
* eraseblocks, volumes, etc. From this sub-system's perspective all physical
* eraseblocks are of two types - used and free. Used physical eraseblocks are
* those that were "get" by the 'ubi_wl_get_peb()' function, and free physical
* eraseblocks are those that were put by the 'ubi_wl_put_peb()' function.
*
* Physical eraseblocks returned by 'ubi_wl_get_peb()' have only erase counter
* header. The rest of the physical eraseblock contains only %0xFF bytes.
*
* When physical eraseblocks are returned to the WL sub-system by means of the
* 'ubi_wl_put_peb()' function, they are scheduled for erasure. The erasure is
* done asynchronously in context of the per-UBI device background thread,
* which is also managed by the WL sub-system.
*
* The wear-leveling is ensured by means of moving the contents of used
* physical eraseblocks with low erase counter to free physical eraseblocks
* with high erase counter.
*
* If the WL sub-system fails to erase a physical eraseblock, it marks it as
* bad.
*
* This sub-system is also responsible for scrubbing. If a bit-flip is detected
* in a physical eraseblock, it has to be moved. Technically this is the same
* as moving it for wear-leveling reasons.
*
* As it was said, for the UBI sub-system all physical eraseblocks are either
* "free" or "used". Free eraseblock are kept in the @wl->free RB-tree, while
* used eraseblocks are kept in @wl->used, @wl->erroneous, or @wl->scrub
* RB-trees, as well as (temporarily) in the @wl->pq queue.
*
* When the WL sub-system returns a physical eraseblock, the physical
* eraseblock is protected from being moved for some "time". For this reason,
* the physical eraseblock is not directly moved from the @wl->free tree to the
* @wl->used tree. There is a protection queue in between where this
* physical eraseblock is temporarily stored (@wl->pq).
*
* All this protection stuff is needed because:
* o we don't want to move physical eraseblocks just after we have given them
* to the user; instead, we first want to let users fill them up with data;
*
* o there is a chance that the user will put the physical eraseblock very
* soon, so it makes sense not to move it for some time, but wait.
*
* Physical eraseblocks stay protected only for limited time. But the "time" is
* measured in erase cycles in this case. This is implemented with help of the
* protection queue. Eraseblocks are put to the tail of this queue when they
* are returned by the 'ubi_wl_get_peb()', and eraseblocks are removed from the
* head of the queue on each erase operation (for any eraseblock). So the
* length of the queue defines how may (global) erase cycles PEBs are protected.
*
* To put it differently, each physical eraseblock has 2 main states: free and
* used. The former state corresponds to the @wl->free tree. The latter state
* is split up on several sub-states:
* o the WL movement is allowed (@wl->used tree);
* o the WL movement is disallowed (@wl->erroneous) because the PEB is
* erroneous - e.g., there was a read error;
* o the WL movement is temporarily prohibited (@wl->pq queue);
* o scrubbing is needed (@wl->scrub tree).
*
* Depending on the sub-state, wear-leveling entries of the used physical
* eraseblocks may be kept in one of those structures.
*
* Note, in this implementation, we keep a small in-RAM object for each physical
* eraseblock. This is surely not a scalable solution. But it appears to be good
* enough for moderately large flashes and it is simple. In future, one may
* re-work this sub-system and make it more scalable.
*
* At the moment this sub-system does not utilize the sequence number, which
* was introduced relatively recently. But it would be wise to do this because
* the sequence number of a logical eraseblock characterizes how old is it. For
* example, when we move a PEB with low erase counter, and we need to pick the
* target PEB, we pick a PEB with the highest EC if our PEB is "old" and we
* pick target PEB with an average EC if our PEB is not very "old". This is a
* room for future re-works of the WL sub-system.
*/
#include <linux/slab.h>
#include <linux/crc32.h>
#include <linux/freezer.h>
#include <linux/kthread.h>
#include "ubi.h"
/* Number of physical eraseblocks reserved for wear-leveling purposes */
#define WL_RESERVED_PEBS 1
/*
* Maximum difference between two erase counters. If this threshold is
* exceeded, the WL sub-system starts moving data from used physical
* eraseblocks with low erase counter to free physical eraseblocks with high
* erase counter.
*/
#define UBI_WL_THRESHOLD CONFIG_MTD_UBI_WL_THRESHOLD
/*
* When a physical eraseblock is moved, the WL sub-system has to pick the target
* physical eraseblock to move to. The simplest way would be just to pick the
* one with the highest erase counter. But in certain workloads this could lead
* to an unlimited wear of one or few physical eraseblock. Indeed, imagine a
* situation when the picked physical eraseblock is constantly erased after the
* data is written to it. So, we have a constant which limits the highest erase
* counter of the free physical eraseblock to pick. Namely, the WL sub-system
* does not pick eraseblocks with erase counter greater than the lowest erase
* counter plus %WL_FREE_MAX_DIFF.
*/
#define WL_FREE_MAX_DIFF (2*UBI_WL_THRESHOLD)
/*
* Maximum number of consecutive background thread failures which is enough to
* switch to read-only mode.
*/
#define WL_MAX_FAILURES 32
static int self_check_ec(struct ubi_device *ubi, int pnum, int ec);
static int self_check_in_wl_tree(const struct ubi_device *ubi,
struct ubi_wl_entry *e, struct rb_root *root);
static int self_check_in_pq(const struct ubi_device *ubi,
struct ubi_wl_entry *e);
#ifdef CONFIG_MTD_UBI_FASTMAP
/**
* update_fastmap_work_fn - calls ubi_update_fastmap from a work queue
* @wrk: the work description object
*/
static void update_fastmap_work_fn(struct work_struct *wrk)
{
struct ubi_device *ubi = container_of(wrk, struct ubi_device, fm_work);
ubi_update_fastmap(ubi);
}
/**
* ubi_ubi_is_fm_block - returns 1 if a PEB is currently used in a fastmap.
* @ubi: UBI device description object
* @pnum: the to be checked PEB
*/
static int ubi_is_fm_block(struct ubi_device *ubi, int pnum)
{
int i;
if (!ubi->fm)
return 0;
for (i = 0; i < ubi->fm->used_blocks; i++)
if (ubi->fm->e[i]->pnum == pnum)
return 1;
return 0;
}
#else
static int ubi_is_fm_block(struct ubi_device *ubi, int pnum)
{
return 0;
}
#endif
/**
* wl_tree_add - add a wear-leveling entry to a WL RB-tree.
* @e: the wear-leveling entry to add
* @root: the root of the tree
*
* Note, we use (erase counter, physical eraseblock number) pairs as keys in
* the @ubi->used and @ubi->free RB-trees.
*/
static void wl_tree_add(struct ubi_wl_entry *e, struct rb_root *root)
{
struct rb_node **p, *parent = NULL;
p = &root->rb_node;
while (*p) {
struct ubi_wl_entry *e1;
parent = *p;
e1 = rb_entry(parent, struct ubi_wl_entry, u.rb);
if (e->ec < e1->ec)
p = &(*p)->rb_left;
else if (e->ec > e1->ec)
p = &(*p)->rb_right;
else {
ubi_assert(e->pnum != e1->pnum);
if (e->pnum < e1->pnum)
p = &(*p)->rb_left;
else
p = &(*p)->rb_right;
}
}
rb_link_node(&e->u.rb, parent, p);
rb_insert_color(&e->u.rb, root);
}
/**
* do_work - do one pending work.
* @ubi: UBI device description object
*
* This function returns zero in case of success and a negative error code in
* case of failure.
*/
static int do_work(struct ubi_device *ubi)
{
int err;
struct ubi_work *wrk;
cond_resched();
/*
* @ubi->work_sem is used to synchronize with the workers. Workers take
* it in read mode, so many of them may be doing works at a time. But
* the queue flush code has to be sure the whole queue of works is
* done, and it takes the mutex in write mode.
*/
down_read(&ubi->work_sem);
spin_lock(&ubi->wl_lock);
if (list_empty(&ubi->works)) {
spin_unlock(&ubi->wl_lock);
up_read(&ubi->work_sem);
return 0;
}
wrk = list_entry(ubi->works.next, struct ubi_work, list);
list_del(&wrk->list);
ubi->works_count -= 1;
ubi_assert(ubi->works_count >= 0);
spin_unlock(&ubi->wl_lock);
/*
* Call the worker function. Do not touch the work structure
* after this call as it will have been freed or reused by that
* time by the worker function.
*/
err = wrk->func(ubi, wrk, 0);
if (err)
ubi_err("work failed with error code %d", err);
up_read(&ubi->work_sem);
return err;
}
/**
* produce_free_peb - produce a free physical eraseblock.
* @ubi: UBI device description object
*
* This function tries to make a free PEB by means of synchronous execution of
* pending works. This may be needed if, for example the background thread is
* disabled. Returns zero in case of success and a negative error code in case
* of failure.
*/
static int produce_free_peb(struct ubi_device *ubi)
{
int err;
while (!ubi->free.rb_node) {
spin_unlock(&ubi->wl_lock);
dbg_wl("do one work synchronously");
err = do_work(ubi);
spin_lock(&ubi->wl_lock);
if (err)
return err;
}
return 0;
}
/**
* in_wl_tree - check if wear-leveling entry is present in a WL RB-tree.
* @e: the wear-leveling entry to check
* @root: the root of the tree
*
* This function returns non-zero if @e is in the @root RB-tree and zero if it
* is not.
*/
static int in_wl_tree(struct ubi_wl_entry *e, struct rb_root *root)
{
struct rb_node *p;
p = root->rb_node;
while (p) {
struct ubi_wl_entry *e1;
e1 = rb_entry(p, struct ubi_wl_entry, u.rb);
if (e->pnum == e1->pnum) {
ubi_assert(e == e1);
return 1;
}
if (e->ec < e1->ec)
p = p->rb_left;
else if (e->ec > e1->ec)
p = p->rb_right;
else {
ubi_assert(e->pnum != e1->pnum);
if (e->pnum < e1->pnum)
p = p->rb_left;
else
p = p->rb_right;
}
}
return 0;
}
/**
* prot_queue_add - add physical eraseblock to the protection queue.
* @ubi: UBI device description object
* @e: the physical eraseblock to add
*
* This function adds @e to the tail of the protection queue @ubi->pq, where
* @e will stay for %UBI_PROT_QUEUE_LEN erase operations and will be
* temporarily protected from the wear-leveling worker. Note, @wl->lock has to
* be locked.
*/
static void prot_queue_add(struct ubi_device *ubi, struct ubi_wl_entry *e)
{
int pq_tail = ubi->pq_head - 1;
if (pq_tail < 0)
pq_tail = UBI_PROT_QUEUE_LEN - 1;
ubi_assert(pq_tail >= 0 && pq_tail < UBI_PROT_QUEUE_LEN);
list_add_tail(&e->u.list, &ubi->pq[pq_tail]);
dbg_wl("added PEB %d EC %d to the protection queue", e->pnum, e->ec);
}
/**
* find_wl_entry - find wear-leveling entry closest to certain erase counter.
* @ubi: UBI device description object
* @root: the RB-tree where to look for
* @diff: maximum possible difference from the smallest erase counter
*
* This function looks for a wear leveling entry with erase counter closest to
* min + @diff, where min is the smallest erase counter.
*/
static struct ubi_wl_entry *find_wl_entry(struct ubi_device *ubi,
struct rb_root *root, int diff)
{
struct rb_node *p;
struct ubi_wl_entry *e, *prev_e = NULL;
int max;
e = rb_entry(rb_first(root), struct ubi_wl_entry, u.rb);
max = e->ec + diff;
p = root->rb_node;
while (p) {
struct ubi_wl_entry *e1;
e1 = rb_entry(p, struct ubi_wl_entry, u.rb);
if (e1->ec >= max)
p = p->rb_left;
else {
p = p->rb_right;
prev_e = e;
e = e1;
}
}
/* If no fastmap has been written and this WL entry can be used
* as anchor PEB, hold it back and return the second best WL entry
* such that fastmap can use the anchor PEB later. */
if (prev_e && !ubi->fm_disabled &&
!ubi->fm && e->pnum < UBI_FM_MAX_START)
return prev_e;
return e;
}
/**
* find_mean_wl_entry - find wear-leveling entry with medium erase counter.
* @ubi: UBI device description object
* @root: the RB-tree where to look for
*
* This function looks for a wear leveling entry with medium erase counter,
* but not greater or equivalent than the lowest erase counter plus
* %WL_FREE_MAX_DIFF/2.
*/
static struct ubi_wl_entry *find_mean_wl_entry(struct ubi_device *ubi,
struct rb_root *root)
{
struct ubi_wl_entry *e, *first, *last;
first = rb_entry(rb_first(root), struct ubi_wl_entry, u.rb);
last = rb_entry(rb_last(root), struct ubi_wl_entry, u.rb);
if (last->ec - first->ec < WL_FREE_MAX_DIFF) {
e = rb_entry(root->rb_node, struct ubi_wl_entry, u.rb);
#ifdef CONFIG_MTD_UBI_FASTMAP
/* If no fastmap has been written and this WL entry can be used
* as anchor PEB, hold it back and return the second best
* WL entry such that fastmap can use the anchor PEB later. */
if (e && !ubi->fm_disabled && !ubi->fm &&
e->pnum < UBI_FM_MAX_START)
e = rb_entry(rb_next(root->rb_node),
struct ubi_wl_entry, u.rb);
#endif
} else
e = find_wl_entry(ubi, root, WL_FREE_MAX_DIFF/2);
return e;
}
#ifdef CONFIG_MTD_UBI_FASTMAP
/**
* find_anchor_wl_entry - find wear-leveling entry to used as anchor PEB.
* @root: the RB-tree where to look for
*/
static struct ubi_wl_entry *find_anchor_wl_entry(struct rb_root *root)
{
struct rb_node *p;
struct ubi_wl_entry *e, *victim = NULL;
int max_ec = UBI_MAX_ERASECOUNTER;
ubi_rb_for_each_entry(p, e, root, u.rb) {
if (e->pnum < UBI_FM_MAX_START && e->ec < max_ec) {
victim = e;
max_ec = e->ec;
}
}
return victim;
}
static int anchor_pebs_avalible(struct rb_root *root)
{
struct rb_node *p;
struct ubi_wl_entry *e;
ubi_rb_for_each_entry(p, e, root, u.rb)
if (e->pnum < UBI_FM_MAX_START)
return 1;
return 0;
}
/**
* ubi_wl_get_fm_peb - find a physical erase block with a given maximal number.
* @ubi: UBI device description object
* @anchor: This PEB will be used as anchor PEB by fastmap
*
* The function returns a physical erase block with a given maximal number
* and removes it from the wl subsystem.
* Must be called with wl_lock held!
*/
struct ubi_wl_entry *ubi_wl_get_fm_peb(struct ubi_device *ubi, int anchor)
{
struct ubi_wl_entry *e = NULL;
if (!ubi->free.rb_node || (ubi->free_count - ubi->beb_rsvd_pebs < 1))
goto out;
if (anchor)
e = find_anchor_wl_entry(&ubi->free);
else
e = find_mean_wl_entry(ubi, &ubi->free);
if (!e)
goto out;
self_check_in_wl_tree(ubi, e, &ubi->free);
/* remove it from the free list,
* the wl subsystem does no longer know this erase block */
rb_erase(&e->u.rb, &ubi->free);
ubi->free_count--;
out:
return e;
}
#endif
/**
* __wl_get_peb - get a physical eraseblock.
* @ubi: UBI device description object
*
* This function returns a physical eraseblock in case of success and a
* negative error code in case of failure.
*/
static int __wl_get_peb(struct ubi_device *ubi)
{
int err;
struct ubi_wl_entry *e;
retry:
if (!ubi->free.rb_node) {
if (ubi->works_count == 0) {
ubi_err("no free eraseblocks");
ubi_assert(list_empty(&ubi->works));
return -ENOSPC;
}
err = produce_free_peb(ubi);
if (err < 0)
return err;
goto retry;
}
e = find_mean_wl_entry(ubi, &ubi->free);
if (!e) {
ubi_err("no free eraseblocks");
return -ENOSPC;
}
self_check_in_wl_tree(ubi, e, &ubi->free);
/*
* Move the physical eraseblock to the protection queue where it will
* be protected from being moved for some time.
*/
rb_erase(&e->u.rb, &ubi->free);
ubi->free_count--;
dbg_wl("PEB %d EC %d", e->pnum, e->ec);
#ifndef CONFIG_MTD_UBI_FASTMAP
/* We have to enqueue e only if fastmap is disabled,
* is fastmap enabled prot_queue_add() will be called by
* ubi_wl_get_peb() after removing e from the pool. */
prot_queue_add(ubi, e);
#endif
return e->pnum;
}
#ifdef CONFIG_MTD_UBI_FASTMAP
/**
* return_unused_pool_pebs - returns unused PEB to the free tree.
* @ubi: UBI device description object
* @pool: fastmap pool description object
*/
static void return_unused_pool_pebs(struct ubi_device *ubi,
struct ubi_fm_pool *pool)
{
int i;
struct ubi_wl_entry *e;
for (i = pool->used; i < pool->size; i++) {
e = ubi->lookuptbl[pool->pebs[i]];
wl_tree_add(e, &ubi->free);
ubi->free_count++;
}
}
/**
* refill_wl_pool - refills all the fastmap pool used by the
* WL sub-system.
* @ubi: UBI device description object
*/
static void refill_wl_pool(struct ubi_device *ubi)
{
struct ubi_wl_entry *e;
struct ubi_fm_pool *pool = &ubi->fm_wl_pool;
return_unused_pool_pebs(ubi, pool);
for (pool->size = 0; pool->size < pool->max_size; pool->size++) {
if (!ubi->free.rb_node ||
(ubi->free_count - ubi->beb_rsvd_pebs < 5))
break;
e = find_wl_entry(ubi, &ubi->free, WL_FREE_MAX_DIFF);
self_check_in_wl_tree(ubi, e, &ubi->free);
rb_erase(&e->u.rb, &ubi->free);
ubi->free_count--;
pool->pebs[pool->size] = e->pnum;
}
pool->used = 0;
}
/**
* refill_wl_user_pool - refills all the fastmap pool used by ubi_wl_get_peb.
* @ubi: UBI device description object
*/
static void refill_wl_user_pool(struct ubi_device *ubi)
{
struct ubi_fm_pool *pool = &ubi->fm_pool;
return_unused_pool_pebs(ubi, pool);
for (pool->size = 0; pool->size < pool->max_size; pool->size++) {
if (!ubi->free.rb_node ||
(ubi->free_count - ubi->beb_rsvd_pebs < 1))
break;
pool->pebs[pool->size] = __wl_get_peb(ubi);
if (pool->pebs[pool->size] < 0)
break;
}
pool->used = 0;
}
/**
* ubi_refill_pools - refills all fastmap PEB pools.
* @ubi: UBI device description object
*/
void ubi_refill_pools(struct ubi_device *ubi)
{
spin_lock(&ubi->wl_lock);
refill_wl_pool(ubi);
refill_wl_user_pool(ubi);
spin_unlock(&ubi->wl_lock);
}
/* ubi_wl_get_peb - works exaclty like __wl_get_peb but keeps track of
* the fastmap pool.
*/
int ubi_wl_get_peb(struct ubi_device *ubi)
{
int ret;
struct ubi_fm_pool *pool = &ubi->fm_pool;
struct ubi_fm_pool *wl_pool = &ubi->fm_wl_pool;
if (!pool->size || !wl_pool->size || pool->used == pool->size ||
wl_pool->used == wl_pool->size)
ubi_update_fastmap(ubi);
/* we got not a single free PEB */
if (!pool->size)
ret = -ENOSPC;
else {
spin_lock(&ubi->wl_lock);
ret = pool->pebs[pool->used++];
prot_queue_add(ubi, ubi->lookuptbl[ret]);
spin_unlock(&ubi->wl_lock);
}
return ret;
}
/* get_peb_for_wl - returns a PEB to be used internally by the WL sub-system.
*
* @ubi: UBI device description object
*/
static struct ubi_wl_entry *get_peb_for_wl(struct ubi_device *ubi)
{
struct ubi_fm_pool *pool = &ubi->fm_wl_pool;
int pnum;
if (pool->used == pool->size || !pool->size) {
/* We cannot update the fastmap here because this
* function is called in atomic context.
* Let's fail here and refill/update it as soon as possible. */
schedule_work(&ubi->fm_work);
return NULL;
} else {
pnum = pool->pebs[pool->used++];
return ubi->lookuptbl[pnum];
}
}
#else
static struct ubi_wl_entry *get_peb_for_wl(struct ubi_device *ubi)
{
struct ubi_wl_entry *e;
e = find_wl_entry(ubi, &ubi->free, WL_FREE_MAX_DIFF);
self_check_in_wl_tree(ubi, e, &ubi->free);
rb_erase(&e->u.rb, &ubi->free);
return e;
}
int ubi_wl_get_peb(struct ubi_device *ubi)
{
int peb, err;
spin_lock(&ubi->wl_lock);
peb = __wl_get_peb(ubi);
spin_unlock(&ubi->wl_lock);
err = ubi_self_check_all_ff(ubi, peb, ubi->vid_hdr_aloffset,
ubi->peb_size - ubi->vid_hdr_aloffset);
if (err) {
ubi_err("new PEB %d does not contain all 0xFF bytes", peb);
return err;
}
return peb;
}
#endif
/**
* prot_queue_del - remove a physical eraseblock from the protection queue.
* @ubi: UBI device description object
* @pnum: the physical eraseblock to remove
*
* This function deletes PEB @pnum from the protection queue and returns zero
* in case of success and %-ENODEV if the PEB was not found.
*/
static int prot_queue_del(struct ubi_device *ubi, int pnum)
{
struct ubi_wl_entry *e;
e = ubi->lookuptbl[pnum];
if (!e)
return -ENODEV;
if (self_check_in_pq(ubi, e))
return -ENODEV;
list_del(&e->u.list);
dbg_wl("deleted PEB %d from the protection queue", e->pnum);
return 0;
}
/**
* sync_erase - synchronously erase a physical eraseblock.
* @ubi: UBI device description object
* @e: the the physical eraseblock to erase
* @torture: if the physical eraseblock has to be tortured
*
* This function returns zero in case of success and a negative error code in
* case of failure.
*/
static int sync_erase(struct ubi_device *ubi, struct ubi_wl_entry *e,
int torture)
{
int err;
struct ubi_ec_hdr *ec_hdr;
unsigned long long ec = e->ec;
dbg_wl("erase PEB %d, old EC %llu", e->pnum, ec);
err = self_check_ec(ubi, e->pnum, e->ec);
if (err)
return -EINVAL;
ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_NOFS);
if (!ec_hdr)
return -ENOMEM;
err = ubi_io_sync_erase(ubi, e->pnum, torture);
if (err < 0)
goto out_free;
ec += err;
if (ec > UBI_MAX_ERASECOUNTER) {
/*
* Erase counter overflow. Upgrade UBI and use 64-bit
* erase counters internally.
*/
ubi_err("erase counter overflow at PEB %d, EC %llu",
e->pnum, ec);
err = -EINVAL;
goto out_free;
}
dbg_wl("erased PEB %d, new EC %llu", e->pnum, ec);
ec_hdr->ec = cpu_to_be64(ec);
err = ubi_io_write_ec_hdr(ubi, e->pnum, ec_hdr);
if (err)
goto out_free;
e->ec = ec;
spin_lock(&ubi->wl_lock);
if (e->ec > ubi->max_ec)
ubi->max_ec = e->ec;
spin_unlock(&ubi->wl_lock);
out_free:
kfree(ec_hdr);
return err;
}
/**
* serve_prot_queue - check if it is time to stop protecting PEBs.
* @ubi: UBI device description object
*
* This function is called after each erase operation and removes PEBs from the
* tail of the protection queue. These PEBs have been protected for long enough
* and should be moved to the used tree.
*/
static void serve_prot_queue(struct ubi_device *ubi)
{
struct ubi_wl_entry *e, *tmp;
int count;
/*
* There may be several protected physical eraseblock to remove,
* process them all.
*/
repeat:
count = 0;
spin_lock(&ubi->wl_lock);
list_for_each_entry_safe(e, tmp, &ubi->pq[ubi->pq_head], u.list) {
dbg_wl("PEB %d EC %d protection over, move to used tree",
e->pnum, e->ec);
list_del(&e->u.list);
wl_tree_add(e, &ubi->used);
if (count++ > 32) {
/*
* Let's be nice and avoid holding the spinlock for
* too long.
*/
spin_unlock(&ubi->wl_lock);
cond_resched();
goto repeat;
}
}
ubi->pq_head += 1;
if (ubi->pq_head == UBI_PROT_QUEUE_LEN)
ubi->pq_head = 0;
ubi_assert(ubi->pq_head >= 0 && ubi->pq_head < UBI_PROT_QUEUE_LEN);
spin_unlock(&ubi->wl_lock);
}
/**
* __schedule_ubi_work - schedule a work.
* @ubi: UBI device description object
* @wrk: the work to schedule
*
* This function adds a work defined by @wrk to the tail of the pending works
* list. Can only be used of ubi->work_sem is already held in read mode!
*/
static void __schedule_ubi_work(struct ubi_device *ubi, struct ubi_work *wrk)
{
spin_lock(&ubi->wl_lock);
list_add_tail(&wrk->list, &ubi->works);
ubi_assert(ubi->works_count >= 0);
ubi->works_count += 1;
if (ubi->thread_enabled && !ubi_dbg_is_bgt_disabled(ubi))
wake_up_process(ubi->bgt_thread);
spin_unlock(&ubi->wl_lock);
}
/**
* schedule_ubi_work - schedule a work.
* @ubi: UBI device description object
* @wrk: the work to schedule
*
* This function adds a work defined by @wrk to the tail of the pending works
* list.
*/
static void schedule_ubi_work(struct ubi_device *ubi, struct ubi_work *wrk)
{
down_read(&ubi->work_sem);
__schedule_ubi_work(ubi, wrk);
up_read(&ubi->work_sem);
}
static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk,
int cancel);
#ifdef CONFIG_MTD_UBI_FASTMAP
/**
* ubi_is_erase_work - checks whether a work is erase work.
* @wrk: The work object to be checked
*/
int ubi_is_erase_work(struct ubi_work *wrk)
{
return wrk->func == erase_worker;
}
#endif
/**
* schedule_erase - schedule an erase work.
* @ubi: UBI device description object
* @e: the WL entry of the physical eraseblock to erase
* @vol_id: the volume ID that last used this PEB
* @lnum: the last used logical eraseblock number for the PEB
* @torture: if the physical eraseblock has to be tortured
*
* This function returns zero in case of success and a %-ENOMEM in case of
* failure.
*/
static int schedule_erase(struct ubi_device *ubi, struct ubi_wl_entry *e,
int vol_id, int lnum, int torture)
{
struct ubi_work *wl_wrk;
ubi_assert(e);
ubi_assert(!ubi_is_fm_block(ubi, e->pnum));
dbg_wl("schedule erasure of PEB %d, EC %d, torture %d",
e->pnum, e->ec, torture);
wl_wrk = kmalloc(sizeof(struct ubi_work), GFP_NOFS);
if (!wl_wrk)
return -ENOMEM;
wl_wrk->func = &erase_worker;
wl_wrk->e = e;
wl_wrk->vol_id = vol_id;
wl_wrk->lnum = lnum;
wl_wrk->torture = torture;
schedule_ubi_work(ubi, wl_wrk);
return 0;
}
/**
* do_sync_erase - run the erase worker synchronously.
* @ubi: UBI device description object
* @e: the WL entry of the physical eraseblock to erase
* @vol_id: the volume ID that last used this PEB
* @lnum: the last used logical eraseblock number for the PEB
* @torture: if the physical eraseblock has to be tortured
*
*/
static int do_sync_erase(struct ubi_device *ubi, struct ubi_wl_entry *e,
int vol_id, int lnum, int torture)
{
struct ubi_work *wl_wrk;
dbg_wl("sync erase of PEB %i", e->pnum);
wl_wrk = kmalloc(sizeof(struct ubi_work), GFP_NOFS);
if (!wl_wrk)
return -ENOMEM;
wl_wrk->e = e;
wl_wrk->vol_id = vol_id;
wl_wrk->lnum = lnum;
wl_wrk->torture = torture;
return erase_worker(ubi, wl_wrk, 0);
}
#ifdef CONFIG_MTD_UBI_FASTMAP
/**
* ubi_wl_put_fm_peb - returns a PEB used in a fastmap to the wear-leveling
* sub-system.
* see: ubi_wl_put_peb()
*
* @ubi: UBI device description object
* @fm_e: physical eraseblock to return
* @lnum: the last used logical eraseblock number for the PEB
* @torture: if this physical eraseblock has to be tortured
*/
int ubi_wl_put_fm_peb(struct ubi_device *ubi, struct ubi_wl_entry *fm_e,
int lnum, int torture)
{
struct ubi_wl_entry *e;
int vol_id, pnum = fm_e->pnum;
dbg_wl("PEB %d", pnum);
ubi_assert(pnum >= 0);
ubi_assert(pnum < ubi->peb_count);
spin_lock(&ubi->wl_lock);
e = ubi->lookuptbl[pnum];
/* This can happen if we recovered from a fastmap the very
* first time and writing now a new one. In this case the wl system
* has never seen any PEB used by the original fastmap.
*/
if (!e) {
e = fm_e;
ubi_assert(e->ec >= 0);
ubi->lookuptbl[pnum] = e;
} else {
e->ec = fm_e->ec;
kfree(fm_e);
}
spin_unlock(&ubi->wl_lock);
vol_id = lnum ? UBI_FM_DATA_VOLUME_ID : UBI_FM_SB_VOLUME_ID;
return schedule_erase(ubi, e, vol_id, lnum, torture);
}
#endif
/**
* wear_leveling_worker - wear-leveling worker function.
* @ubi: UBI device description object
* @wrk: the work object
* @cancel: non-zero if the worker has to free memory and exit
*
* This function copies a more worn out physical eraseblock to a less worn out
* one. Returns zero in case of success and a negative error code in case of
* failure.
*/
static int wear_leveling_worker(struct ubi_device *ubi, struct ubi_work *wrk,
int cancel)
{
int err, scrubbing = 0, torture = 0, protect = 0, erroneous = 0;
int vol_id = -1, uninitialized_var(lnum);
#ifdef CONFIG_MTD_UBI_FASTMAP
int anchor = wrk->anchor;
#endif
struct ubi_wl_entry *e1, *e2;
struct ubi_vid_hdr *vid_hdr;
kfree(wrk);
if (cancel)
return 0;
vid_hdr = ubi_zalloc_vid_hdr(ubi, GFP_NOFS);
if (!vid_hdr)
return -ENOMEM;
mutex_lock(&ubi->move_mutex);
spin_lock(&ubi->wl_lock);
ubi_assert(!ubi->move_from && !ubi->move_to);
ubi_assert(!ubi->move_to_put);
if (!ubi->free.rb_node ||
(!ubi->used.rb_node && !ubi->scrub.rb_node)) {
/*
* No free physical eraseblocks? Well, they must be waiting in
* the queue to be erased. Cancel movement - it will be
* triggered again when a free physical eraseblock appears.
*
* No used physical eraseblocks? They must be temporarily
* protected from being moved. They will be moved to the
* @ubi->used tree later and the wear-leveling will be
* triggered again.
*/
dbg_wl("cancel WL, a list is empty: free %d, used %d",
!ubi->free.rb_node, !ubi->used.rb_node);
goto out_cancel;
}
#ifdef CONFIG_MTD_UBI_FASTMAP
/* Check whether we need to produce an anchor PEB */
if (!anchor)
anchor = !anchor_pebs_avalible(&ubi->free);
if (anchor) {
e1 = find_anchor_wl_entry(&ubi->used);
if (!e1)
goto out_cancel;
e2 = get_peb_for_wl(ubi);
if (!e2)
goto out_cancel;
self_check_in_wl_tree(ubi, e1, &ubi->used);
rb_erase(&e1->u.rb, &ubi->used);
dbg_wl("anchor-move PEB %d to PEB %d", e1->pnum, e2->pnum);
} else if (!ubi->scrub.rb_node) {
#else
if (!ubi->scrub.rb_node) {
#endif
/*
* Now pick the least worn-out used physical eraseblock and a
* highly worn-out free physical eraseblock. If the erase
* counters differ much enough, start wear-leveling.
*/
e1 = rb_entry(rb_first(&ubi->used), struct ubi_wl_entry, u.rb);
e2 = get_peb_for_wl(ubi);
if (!e2)
goto out_cancel;
if (!(e2->ec - e1->ec >= UBI_WL_THRESHOLD)) {
dbg_wl("no WL needed: min used EC %d, max free EC %d",
e1->ec, e2->ec);
goto out_cancel;
}
self_check_in_wl_tree(ubi, e1, &ubi->used);
rb_erase(&e1->u.rb, &ubi->used);
dbg_wl("move PEB %d EC %d to PEB %d EC %d",
e1->pnum, e1->ec, e2->pnum, e2->ec);
} else {
/* Perform scrubbing */
scrubbing = 1;
e1 = rb_entry(rb_first(&ubi->scrub), struct ubi_wl_entry, u.rb);
e2 = get_peb_for_wl(ubi);
if (!e2)
goto out_cancel;
self_check_in_wl_tree(ubi, e1, &ubi->scrub);
rb_erase(&e1->u.rb, &ubi->scrub);
dbg_wl("scrub PEB %d to PEB %d", e1->pnum, e2->pnum);
}
ubi->move_from = e1;
ubi->move_to = e2;
spin_unlock(&ubi->wl_lock);
/*
* Now we are going to copy physical eraseblock @e1->pnum to @e2->pnum.
* We so far do not know which logical eraseblock our physical
* eraseblock (@e1) belongs to. We have to read the volume identifier
* header first.
*
* Note, we are protected from this PEB being unmapped and erased. The
* 'ubi_wl_put_peb()' would wait for moving to be finished if the PEB
* which is being moved was unmapped.
*/
err = ubi_io_read_vid_hdr(ubi, e1->pnum, vid_hdr, 0);
if (err && err != UBI_IO_BITFLIPS) {
if (err == UBI_IO_FF) {
/*
* We are trying to move PEB without a VID header. UBI
* always write VID headers shortly after the PEB was
* given, so we have a situation when it has not yet
* had a chance to write it, because it was preempted.
* So add this PEB to the protection queue so far,
* because presumably more data will be written there
* (including the missing VID header), and then we'll
* move it.
*/
dbg_wl("PEB %d has no VID header", e1->pnum);
protect = 1;
goto out_not_moved;
} else if (err == UBI_IO_FF_BITFLIPS) {
/*
* The same situation as %UBI_IO_FF, but bit-flips were
* detected. It is better to schedule this PEB for
* scrubbing.
*/
dbg_wl("PEB %d has no VID header but has bit-flips",
e1->pnum);
scrubbing = 1;
goto out_not_moved;
}
ubi_err("error %d while reading VID header from PEB %d",
err, e1->pnum);
goto out_error;
}
vol_id = be32_to_cpu(vid_hdr->vol_id);
lnum = be32_to_cpu(vid_hdr->lnum);
err = ubi_eba_copy_leb(ubi, e1->pnum, e2->pnum, vid_hdr);
if (err) {
if (err == MOVE_CANCEL_RACE) {
/*
* The LEB has not been moved because the volume is
* being deleted or the PEB has been put meanwhile. We
* should prevent this PEB from being selected for
* wear-leveling movement again, so put it to the
* protection queue.
*/
protect = 1;
goto out_not_moved;
}
if (err == MOVE_RETRY) {
scrubbing = 1;
goto out_not_moved;
}
if (err == MOVE_TARGET_BITFLIPS || err == MOVE_TARGET_WR_ERR ||
err == MOVE_TARGET_RD_ERR) {
/*
* Target PEB had bit-flips or write error - torture it.
*/
torture = 1;
goto out_not_moved;
}
if (err == MOVE_SOURCE_RD_ERR) {
/*
* An error happened while reading the source PEB. Do
* not switch to R/O mode in this case, and give the
* upper layers a possibility to recover from this,
* e.g. by unmapping corresponding LEB. Instead, just
* put this PEB to the @ubi->erroneous list to prevent
* UBI from trying to move it over and over again.
*/
if (ubi->erroneous_peb_count > ubi->max_erroneous) {
ubi_err("too many erroneous eraseblocks (%d)",
ubi->erroneous_peb_count);
goto out_error;
}
erroneous = 1;
goto out_not_moved;
}
if (err < 0)
goto out_error;
ubi_assert(0);
}
/* The PEB has been successfully moved */
if (scrubbing)
ubi_msg("scrubbed PEB %d (LEB %d:%d), data moved to PEB %d",
e1->pnum, vol_id, lnum, e2->pnum);
ubi_free_vid_hdr(ubi, vid_hdr);
spin_lock(&ubi->wl_lock);
if (!ubi->move_to_put) {
wl_tree_add(e2, &ubi->used);
e2 = NULL;
}
ubi->move_from = ubi->move_to = NULL;
ubi->move_to_put = ubi->wl_scheduled = 0;
spin_unlock(&ubi->wl_lock);
err = do_sync_erase(ubi, e1, vol_id, lnum, 0);
if (err) {
kmem_cache_free(ubi_wl_entry_slab, e1);
if (e2)
kmem_cache_free(ubi_wl_entry_slab, e2);
goto out_ro;
}
if (e2) {
/*
* Well, the target PEB was put meanwhile, schedule it for
* erasure.
*/
dbg_wl("PEB %d (LEB %d:%d) was put meanwhile, erase",
e2->pnum, vol_id, lnum);
err = do_sync_erase(ubi, e2, vol_id, lnum, 0);
if (err) {
kmem_cache_free(ubi_wl_entry_slab, e2);
goto out_ro;
}
}
dbg_wl("done");
mutex_unlock(&ubi->move_mutex);
return 0;
/*
* For some reasons the LEB was not moved, might be an error, might be
* something else. @e1 was not changed, so return it back. @e2 might
* have been changed, schedule it for erasure.
*/
out_not_moved:
if (vol_id != -1)
dbg_wl("cancel moving PEB %d (LEB %d:%d) to PEB %d (%d)",
e1->pnum, vol_id, lnum, e2->pnum, err);
else
dbg_wl("cancel moving PEB %d to PEB %d (%d)",
e1->pnum, e2->pnum, err);
spin_lock(&ubi->wl_lock);
if (protect)
prot_queue_add(ubi, e1);
else if (erroneous) {
wl_tree_add(e1, &ubi->erroneous);
ubi->erroneous_peb_count += 1;
} else if (scrubbing)
wl_tree_add(e1, &ubi->scrub);
else
wl_tree_add(e1, &ubi->used);
ubi_assert(!ubi->move_to_put);
ubi->move_from = ubi->move_to = NULL;
ubi->wl_scheduled = 0;
spin_unlock(&ubi->wl_lock);
ubi_free_vid_hdr(ubi, vid_hdr);
err = do_sync_erase(ubi, e2, vol_id, lnum, torture);
if (err) {
kmem_cache_free(ubi_wl_entry_slab, e2);
goto out_ro;
}
mutex_unlock(&ubi->move_mutex);
return 0;
out_error:
if (vol_id != -1)
ubi_err("error %d while moving PEB %d to PEB %d",
err, e1->pnum, e2->pnum);
else
ubi_err("error %d while moving PEB %d (LEB %d:%d) to PEB %d",
err, e1->pnum, vol_id, lnum, e2->pnum);
spin_lock(&ubi->wl_lock);
ubi->move_from = ubi->move_to = NULL;
ubi->move_to_put = ubi->wl_scheduled = 0;
spin_unlock(&ubi->wl_lock);
ubi_free_vid_hdr(ubi, vid_hdr);
kmem_cache_free(ubi_wl_entry_slab, e1);
kmem_cache_free(ubi_wl_entry_slab, e2);
out_ro:
ubi_ro_mode(ubi);
mutex_unlock(&ubi->move_mutex);
ubi_assert(err != 0);
return err < 0 ? err : -EIO;
out_cancel:
ubi->wl_scheduled = 0;
spin_unlock(&ubi->wl_lock);
mutex_unlock(&ubi->move_mutex);
ubi_free_vid_hdr(ubi, vid_hdr);
return 0;
}
/**
* ensure_wear_leveling - schedule wear-leveling if it is needed.
* @ubi: UBI device description object
* @nested: set to non-zero if this function is called from UBI worker
*
* This function checks if it is time to start wear-leveling and schedules it
* if yes. This function returns zero in case of success and a negative error
* code in case of failure.
*/
static int ensure_wear_leveling(struct ubi_device *ubi, int nested)
{
int err = 0;
struct ubi_wl_entry *e1;
struct ubi_wl_entry *e2;
struct ubi_work *wrk;
spin_lock(&ubi->wl_lock);
if (ubi->wl_scheduled)
/* Wear-leveling is already in the work queue */
goto out_unlock;
/*
* If the ubi->scrub tree is not empty, scrubbing is needed, and the
* the WL worker has to be scheduled anyway.
*/
if (!ubi->scrub.rb_node) {
if (!ubi->used.rb_node || !ubi->free.rb_node)
/* No physical eraseblocks - no deal */
goto out_unlock;
/*
* We schedule wear-leveling only if the difference between the
* lowest erase counter of used physical eraseblocks and a high
* erase counter of free physical eraseblocks is greater than
* %UBI_WL_THRESHOLD.
*/
e1 = rb_entry(rb_first(&ubi->used), struct ubi_wl_entry, u.rb);
e2 = find_wl_entry(ubi, &ubi->free, WL_FREE_MAX_DIFF);
if (!(e2->ec - e1->ec >= UBI_WL_THRESHOLD))
goto out_unlock;
dbg_wl("schedule wear-leveling");
} else
dbg_wl("schedule scrubbing");
ubi->wl_scheduled = 1;
spin_unlock(&ubi->wl_lock);
wrk = kmalloc(sizeof(struct ubi_work), GFP_NOFS);
if (!wrk) {
err = -ENOMEM;
goto out_cancel;
}
wrk->anchor = 0;
wrk->func = &wear_leveling_worker;
if (nested)
__schedule_ubi_work(ubi, wrk);
else
schedule_ubi_work(ubi, wrk);
return err;
out_cancel:
spin_lock(&ubi->wl_lock);
ubi->wl_scheduled = 0;
out_unlock:
spin_unlock(&ubi->wl_lock);
return err;
}
#ifdef CONFIG_MTD_UBI_FASTMAP
/**
* ubi_ensure_anchor_pebs - schedule wear-leveling to produce an anchor PEB.
* @ubi: UBI device description object
*/
int ubi_ensure_anchor_pebs(struct ubi_device *ubi)
{
struct ubi_work *wrk;
spin_lock(&ubi->wl_lock);
if (ubi->wl_scheduled) {
spin_unlock(&ubi->wl_lock);
return 0;
}
ubi->wl_scheduled = 1;
spin_unlock(&ubi->wl_lock);
wrk = kmalloc(sizeof(struct ubi_work), GFP_NOFS);
if (!wrk) {
spin_lock(&ubi->wl_lock);
ubi->wl_scheduled = 0;
spin_unlock(&ubi->wl_lock);
return -ENOMEM;
}
wrk->anchor = 1;
wrk->func = &wear_leveling_worker;
schedule_ubi_work(ubi, wrk);
return 0;
}
#endif
/**
* erase_worker - physical eraseblock erase worker function.
* @ubi: UBI device description object
* @wl_wrk: the work object
* @cancel: non-zero if the worker has to free memory and exit
*
* This function erases a physical eraseblock and perform torture testing if
* needed. It also takes care about marking the physical eraseblock bad if
* needed. Returns zero in case of success and a negative error code in case of
* failure.
*/
static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk,
int cancel)
{
struct ubi_wl_entry *e = wl_wrk->e;
int pnum = e->pnum;
int vol_id = wl_wrk->vol_id;
int lnum = wl_wrk->lnum;
int err, available_consumed = 0;
if (cancel) {
dbg_wl("cancel erasure of PEB %d EC %d", pnum, e->ec);
kfree(wl_wrk);
kmem_cache_free(ubi_wl_entry_slab, e);
return 0;
}
dbg_wl("erase PEB %d EC %d LEB %d:%d",
pnum, e->ec, wl_wrk->vol_id, wl_wrk->lnum);
ubi_assert(!ubi_is_fm_block(ubi, e->pnum));
err = sync_erase(ubi, e, wl_wrk->torture);
if (!err) {
/* Fine, we've erased it successfully */
kfree(wl_wrk);
spin_lock(&ubi->wl_lock);
wl_tree_add(e, &ubi->free);
ubi->free_count++;
spin_unlock(&ubi->wl_lock);
/*
* One more erase operation has happened, take care about
* protected physical eraseblocks.
*/
serve_prot_queue(ubi);
/* And take care about wear-leveling */
err = ensure_wear_leveling(ubi, 1);
return err;
}
ubi_err("failed to erase PEB %d, error %d", pnum, err);
kfree(wl_wrk);
if (err == -EINTR || err == -ENOMEM || err == -EAGAIN ||
err == -EBUSY) {
int err1;
/* Re-schedule the LEB for erasure */
err1 = schedule_erase(ubi, e, vol_id, lnum, 0);
if (err1) {
err = err1;
goto out_ro;
}
return err;
}
kmem_cache_free(ubi_wl_entry_slab, e);
if (err != -EIO)
/*
* If this is not %-EIO, we have no idea what to do. Scheduling
* this physical eraseblock for erasure again would cause
* errors again and again. Well, lets switch to R/O mode.
*/
goto out_ro;
/* It is %-EIO, the PEB went bad */
if (!ubi->bad_allowed) {
ubi_err("bad physical eraseblock %d detected", pnum);
goto out_ro;
}
spin_lock(&ubi->volumes_lock);
if (ubi->beb_rsvd_pebs == 0) {
if (ubi->avail_pebs == 0) {
spin_unlock(&ubi->volumes_lock);
ubi_err("no reserved/available physical eraseblocks");
goto out_ro;
}
ubi->avail_pebs -= 1;
available_consumed = 1;
}
spin_unlock(&ubi->volumes_lock);
ubi_msg("mark PEB %d as bad", pnum);
err = ubi_io_mark_bad(ubi, pnum);
if (err)
goto out_ro;
spin_lock(&ubi->volumes_lock);
if (ubi->beb_rsvd_pebs > 0) {
if (available_consumed) {
/*
* The amount of reserved PEBs increased since we last
* checked.
*/
ubi->avail_pebs += 1;
available_consumed = 0;
}
ubi->beb_rsvd_pebs -= 1;
}
ubi->bad_peb_count += 1;
ubi->good_peb_count -= 1;
ubi_calculate_reserved(ubi);
if (available_consumed)
ubi_warn("no PEBs in the reserved pool, used an available PEB");
else if (ubi->beb_rsvd_pebs)
ubi_msg("%d PEBs left in the reserve", ubi->beb_rsvd_pebs);
else
ubi_warn("last PEB from the reserve was used");
spin_unlock(&ubi->volumes_lock);
return err;
out_ro:
if (available_consumed) {
spin_lock(&ubi->volumes_lock);
ubi->avail_pebs += 1;
spin_unlock(&ubi->volumes_lock);
}
ubi_ro_mode(ubi);
return err;
}
/**
* ubi_wl_put_peb - return a PEB to the wear-leveling sub-system.
* @ubi: UBI device description object
* @vol_id: the volume ID that last used this PEB
* @lnum: the last used logical eraseblock number for the PEB
* @pnum: physical eraseblock to return
* @torture: if this physical eraseblock has to be tortured
*
* This function is called to return physical eraseblock @pnum to the pool of
* free physical eraseblocks. The @torture flag has to be set if an I/O error
* occurred to this @pnum and it has to be tested. This function returns zero
* in case of success, and a negative error code in case of failure.
*/
int ubi_wl_put_peb(struct ubi_device *ubi, int vol_id, int lnum,
int pnum, int torture)
{
int err;
struct ubi_wl_entry *e;
dbg_wl("PEB %d", pnum);
ubi_assert(pnum >= 0);
ubi_assert(pnum < ubi->peb_count);
retry:
spin_lock(&ubi->wl_lock);
e = ubi->lookuptbl[pnum];
if (e == ubi->move_from) {
/*
* User is putting the physical eraseblock which was selected to
* be moved. It will be scheduled for erasure in the
* wear-leveling worker.
*/
dbg_wl("PEB %d is being moved, wait", pnum);
spin_unlock(&ubi->wl_lock);
/* Wait for the WL worker by taking the @ubi->move_mutex */
mutex_lock(&ubi->move_mutex);
mutex_unlock(&ubi->move_mutex);
goto retry;
} else if (e == ubi->move_to) {
/*
* User is putting the physical eraseblock which was selected
* as the target the data is moved to. It may happen if the EBA
* sub-system already re-mapped the LEB in 'ubi_eba_copy_leb()'
* but the WL sub-system has not put the PEB to the "used" tree
* yet, but it is about to do this. So we just set a flag which
* will tell the WL worker that the PEB is not needed anymore
* and should be scheduled for erasure.
*/
dbg_wl("PEB %d is the target of data moving", pnum);
ubi_assert(!ubi->move_to_put);
ubi->move_to_put = 1;
spin_unlock(&ubi->wl_lock);
return 0;
} else {
if (in_wl_tree(e, &ubi->used)) {
self_check_in_wl_tree(ubi, e, &ubi->used);
rb_erase(&e->u.rb, &ubi->used);
} else if (in_wl_tree(e, &ubi->scrub)) {
self_check_in_wl_tree(ubi, e, &ubi->scrub);
rb_erase(&e->u.rb, &ubi->scrub);
} else if (in_wl_tree(e, &ubi->erroneous)) {
self_check_in_wl_tree(ubi, e, &ubi->erroneous);
rb_erase(&e->u.rb, &ubi->erroneous);
ubi->erroneous_peb_count -= 1;
ubi_assert(ubi->erroneous_peb_count >= 0);
/* Erroneous PEBs should be tortured */
torture = 1;
} else {
err = prot_queue_del(ubi, e->pnum);
if (err) {
ubi_err("PEB %d not found", pnum);
ubi_ro_mode(ubi);
spin_unlock(&ubi->wl_lock);
return err;
}
}
}
spin_unlock(&ubi->wl_lock);
err = schedule_erase(ubi, e, vol_id, lnum, torture);
if (err) {
spin_lock(&ubi->wl_lock);
wl_tree_add(e, &ubi->used);
spin_unlock(&ubi->wl_lock);
}
return err;
}
/**
* ubi_wl_scrub_peb - schedule a physical eraseblock for scrubbing.
* @ubi: UBI device description object
* @pnum: the physical eraseblock to schedule
*
* If a bit-flip in a physical eraseblock is detected, this physical eraseblock
* needs scrubbing. This function schedules a physical eraseblock for
* scrubbing which is done in background. This function returns zero in case of
* success and a negative error code in case of failure.
*/
int ubi_wl_scrub_peb(struct ubi_device *ubi, int pnum)
{
struct ubi_wl_entry *e;
ubi_msg("schedule PEB %d for scrubbing", pnum);
retry:
spin_lock(&ubi->wl_lock);
e = ubi->lookuptbl[pnum];
if (e == ubi->move_from || in_wl_tree(e, &ubi->scrub) ||
in_wl_tree(e, &ubi->erroneous)) {
spin_unlock(&ubi->wl_lock);
return 0;
}
if (e == ubi->move_to) {
/*
* This physical eraseblock was used to move data to. The data
* was moved but the PEB was not yet inserted to the proper
* tree. We should just wait a little and let the WL worker
* proceed.
*/
spin_unlock(&ubi->wl_lock);
dbg_wl("the PEB %d is not in proper tree, retry", pnum);
yield();
goto retry;
}
if (in_wl_tree(e, &ubi->used)) {
self_check_in_wl_tree(ubi, e, &ubi->used);
rb_erase(&e->u.rb, &ubi->used);
} else {
int err;
err = prot_queue_del(ubi, e->pnum);
if (err) {
ubi_err("PEB %d not found", pnum);
ubi_ro_mode(ubi);
spin_unlock(&ubi->wl_lock);
return err;
}
}
wl_tree_add(e, &ubi->scrub);
spin_unlock(&ubi->wl_lock);
/*
* Technically scrubbing is the same as wear-leveling, so it is done
* by the WL worker.
*/
return ensure_wear_leveling(ubi, 0);
}
/**
* ubi_wl_flush - flush all pending works.
* @ubi: UBI device description object
* @vol_id: the volume id to flush for
* @lnum: the logical eraseblock number to flush for
*
* This function executes all pending works for a particular volume id /
* logical eraseblock number pair. If either value is set to %UBI_ALL, then it
* acts as a wildcard for all of the corresponding volume numbers or logical
* eraseblock numbers. It returns zero in case of success and a negative error
* code in case of failure.
*/
int ubi_wl_flush(struct ubi_device *ubi, int vol_id, int lnum)
{
int err = 0;
int found = 1;
/*
* Erase while the pending works queue is not empty, but not more than
* the number of currently pending works.
*/
dbg_wl("flush pending work for LEB %d:%d (%d pending works)",
vol_id, lnum, ubi->works_count);
while (found) {
struct ubi_work *wrk;
found = 0;
down_read(&ubi->work_sem);
spin_lock(&ubi->wl_lock);
list_for_each_entry(wrk, &ubi->works, list) {
if ((vol_id == UBI_ALL || wrk->vol_id == vol_id) &&
(lnum == UBI_ALL || wrk->lnum == lnum)) {
list_del(&wrk->list);
ubi->works_count -= 1;
ubi_assert(ubi->works_count >= 0);
spin_unlock(&ubi->wl_lock);
err = wrk->func(ubi, wrk, 0);
if (err) {
up_read(&ubi->work_sem);
return err;
}
spin_lock(&ubi->wl_lock);
found = 1;
break;
}
}
spin_unlock(&ubi->wl_lock);
up_read(&ubi->work_sem);
}
/*
* Make sure all the works which have been done in parallel are
* finished.
*/
down_write(&ubi->work_sem);
up_write(&ubi->work_sem);
return err;
}
/**
* tree_destroy - destroy an RB-tree.
* @root: the root of the tree to destroy
*/
static void tree_destroy(struct rb_root *root)
{
struct rb_node *rb;
struct ubi_wl_entry *e;
rb = root->rb_node;
while (rb) {
if (rb->rb_left)
rb = rb->rb_left;
else if (rb->rb_right)
rb = rb->rb_right;
else {
e = rb_entry(rb, struct ubi_wl_entry, u.rb);
rb = rb_parent(rb);
if (rb) {
if (rb->rb_left == &e->u.rb)
rb->rb_left = NULL;
else
rb->rb_right = NULL;
}
kmem_cache_free(ubi_wl_entry_slab, e);
}
}
}
/**
* ubi_thread - UBI background thread.
* @u: the UBI device description object pointer
*/
int ubi_thread(void *u)
{
int failures = 0;
struct ubi_device *ubi = u;
ubi_msg("background thread \"%s\" started, PID %d",
ubi->bgt_name, task_pid_nr(current));
set_freezable();
for (;;) {
int err;
if (kthread_should_stop())
break;
if (try_to_freeze())
continue;
spin_lock(&ubi->wl_lock);
if (list_empty(&ubi->works) || ubi->ro_mode ||
!ubi->thread_enabled || ubi_dbg_is_bgt_disabled(ubi)) {
set_current_state(TASK_INTERRUPTIBLE);
spin_unlock(&ubi->wl_lock);
schedule();
continue;
}
spin_unlock(&ubi->wl_lock);
err = do_work(ubi);
if (err) {
ubi_err("%s: work failed with error code %d",
ubi->bgt_name, err);
if (failures++ > WL_MAX_FAILURES) {
/*
* Too many failures, disable the thread and
* switch to read-only mode.
*/
ubi_msg("%s: %d consecutive failures",
ubi->bgt_name, WL_MAX_FAILURES);
ubi_ro_mode(ubi);
ubi->thread_enabled = 0;
continue;
}
} else
failures = 0;
cond_resched();
}
dbg_wl("background thread \"%s\" is killed", ubi->bgt_name);
return 0;
}
/**
* cancel_pending - cancel all pending works.
* @ubi: UBI device description object
*/
static void cancel_pending(struct ubi_device *ubi)
{
while (!list_empty(&ubi->works)) {
struct ubi_work *wrk;
wrk = list_entry(ubi->works.next, struct ubi_work, list);
list_del(&wrk->list);
wrk->func(ubi, wrk, 1);
ubi->works_count -= 1;
ubi_assert(ubi->works_count >= 0);
}
}
/**
* ubi_wl_init - initialize the WL sub-system using attaching information.
* @ubi: UBI device description object
* @ai: attaching information
*
* This function returns zero in case of success, and a negative error code in
* case of failure.
*/
int ubi_wl_init(struct ubi_device *ubi, struct ubi_attach_info *ai)
{
int err, i, reserved_pebs, found_pebs = 0;
struct rb_node *rb1, *rb2;
struct ubi_ainf_volume *av;
struct ubi_ainf_peb *aeb, *tmp;
struct ubi_wl_entry *e;
ubi->used = ubi->erroneous = ubi->free = ubi->scrub = RB_ROOT;
spin_lock_init(&ubi->wl_lock);
mutex_init(&ubi->move_mutex);
init_rwsem(&ubi->work_sem);
ubi->max_ec = ai->max_ec;
INIT_LIST_HEAD(&ubi->works);
#ifdef CONFIG_MTD_UBI_FASTMAP
INIT_WORK(&ubi->fm_work, update_fastmap_work_fn);
#endif
sprintf(ubi->bgt_name, UBI_BGT_NAME_PATTERN, ubi->ubi_num);
err = -ENOMEM;
ubi->lookuptbl = kzalloc(ubi->peb_count * sizeof(void *), GFP_KERNEL);
if (!ubi->lookuptbl)
return err;
for (i = 0; i < UBI_PROT_QUEUE_LEN; i++)
INIT_LIST_HEAD(&ubi->pq[i]);
ubi->pq_head = 0;
list_for_each_entry_safe(aeb, tmp, &ai->erase, u.list) {
cond_resched();
e = kmem_cache_alloc(ubi_wl_entry_slab, GFP_KERNEL);
if (!e)
goto out_free;
e->pnum = aeb->pnum;
e->ec = aeb->ec;
ubi_assert(!ubi_is_fm_block(ubi, e->pnum));
ubi->lookuptbl[e->pnum] = e;
if (schedule_erase(ubi, e, aeb->vol_id, aeb->lnum, 0)) {
kmem_cache_free(ubi_wl_entry_slab, e);
goto out_free;
}
found_pebs++;
}
ubi->free_count = 0;
list_for_each_entry(aeb, &ai->free, u.list) {
cond_resched();
e = kmem_cache_alloc(ubi_wl_entry_slab, GFP_KERNEL);
if (!e)
goto out_free;
e->pnum = aeb->pnum;
e->ec = aeb->ec;
ubi_assert(e->ec >= 0);
ubi_assert(!ubi_is_fm_block(ubi, e->pnum));
wl_tree_add(e, &ubi->free);
ubi->free_count++;
ubi->lookuptbl[e->pnum] = e;
found_pebs++;
}
ubi_rb_for_each_entry(rb1, av, &ai->volumes, rb) {
ubi_rb_for_each_entry(rb2, aeb, &av->root, u.rb) {
cond_resched();
e = kmem_cache_alloc(ubi_wl_entry_slab, GFP_KERNEL);
if (!e)
goto out_free;
e->pnum = aeb->pnum;
e->ec = aeb->ec;
ubi->lookuptbl[e->pnum] = e;
if (!aeb->scrub) {
dbg_wl("add PEB %d EC %d to the used tree",
e->pnum, e->ec);
wl_tree_add(e, &ubi->used);
} else {
dbg_wl("add PEB %d EC %d to the scrub tree",
e->pnum, e->ec);
wl_tree_add(e, &ubi->scrub);
}
found_pebs++;
}
}
dbg_wl("found %i PEBs", found_pebs);
if (ubi->fm)
ubi_assert(ubi->good_peb_count == \
found_pebs + ubi->fm->used_blocks);
else
ubi_assert(ubi->good_peb_count == found_pebs);
reserved_pebs = WL_RESERVED_PEBS;
#ifdef CONFIG_MTD_UBI_FASTMAP
/* Reserve enough LEBs to store two fastmaps. */
reserved_pebs += (ubi->fm_size / ubi->leb_size) * 2;
#endif
if (ubi->avail_pebs < reserved_pebs) {
ubi_err("no enough physical eraseblocks (%d, need %d)",
ubi->avail_pebs, reserved_pebs);
if (ubi->corr_peb_count)
ubi_err("%d PEBs are corrupted and not used",
ubi->corr_peb_count);
goto out_free;
}
ubi->avail_pebs -= reserved_pebs;
ubi->rsvd_pebs += reserved_pebs;
/* Schedule wear-leveling if needed */
err = ensure_wear_leveling(ubi, 0);
if (err)
goto out_free;
return 0;
out_free:
cancel_pending(ubi);
tree_destroy(&ubi->used);
tree_destroy(&ubi->free);
tree_destroy(&ubi->scrub);
kfree(ubi->lookuptbl);
return err;
}
/**
* protection_queue_destroy - destroy the protection queue.
* @ubi: UBI device description object
*/
static void protection_queue_destroy(struct ubi_device *ubi)
{
int i;
struct ubi_wl_entry *e, *tmp;
for (i = 0; i < UBI_PROT_QUEUE_LEN; ++i) {
list_for_each_entry_safe(e, tmp, &ubi->pq[i], u.list) {
list_del(&e->u.list);
kmem_cache_free(ubi_wl_entry_slab, e);
}
}
}
/**
* ubi_wl_close - close the wear-leveling sub-system.
* @ubi: UBI device description object
*/
void ubi_wl_close(struct ubi_device *ubi)
{
dbg_wl("close the WL sub-system");
cancel_pending(ubi);
protection_queue_destroy(ubi);
tree_destroy(&ubi->used);
tree_destroy(&ubi->erroneous);
tree_destroy(&ubi->free);
tree_destroy(&ubi->scrub);
kfree(ubi->lookuptbl);
}
/**
* self_check_ec - make sure that the erase counter of a PEB is correct.
* @ubi: UBI device description object
* @pnum: the physical eraseblock number to check
* @ec: the erase counter to check
*
* This function returns zero if the erase counter of physical eraseblock @pnum
* is equivalent to @ec, and a negative error code if not or if an error
* occurred.
*/
static int self_check_ec(struct ubi_device *ubi, int pnum, int ec)
{
int err;
long long read_ec;
struct ubi_ec_hdr *ec_hdr;
if (!ubi_dbg_chk_gen(ubi))
return 0;
ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_NOFS);
if (!ec_hdr)
return -ENOMEM;
err = ubi_io_read_ec_hdr(ubi, pnum, ec_hdr, 0);
if (err && err != UBI_IO_BITFLIPS) {
/* The header does not have to exist */
err = 0;
goto out_free;
}
read_ec = be64_to_cpu(ec_hdr->ec);
if (ec != read_ec && read_ec - ec > 1) {
ubi_err("self-check failed for PEB %d", pnum);
ubi_err("read EC is %lld, should be %d", read_ec, ec);
dump_stack();
err = 1;
} else
err = 0;
out_free:
kfree(ec_hdr);
return err;
}
/**
* self_check_in_wl_tree - check that wear-leveling entry is in WL RB-tree.
* @ubi: UBI device description object
* @e: the wear-leveling entry to check
* @root: the root of the tree
*
* This function returns zero if @e is in the @root RB-tree and %-EINVAL if it
* is not.
*/
static int self_check_in_wl_tree(const struct ubi_device *ubi,
struct ubi_wl_entry *e, struct rb_root *root)
{
if (!ubi_dbg_chk_gen(ubi))
return 0;
if (in_wl_tree(e, root))
return 0;
ubi_err("self-check failed for PEB %d, EC %d, RB-tree %p ",
e->pnum, e->ec, root);
dump_stack();
return -EINVAL;
}
/**
* self_check_in_pq - check if wear-leveling entry is in the protection
* queue.
* @ubi: UBI device description object
* @e: the wear-leveling entry to check
*
* This function returns zero if @e is in @ubi->pq and %-EINVAL if it is not.
*/
static int self_check_in_pq(const struct ubi_device *ubi,
struct ubi_wl_entry *e)
{
struct ubi_wl_entry *p;
int i;
if (!ubi_dbg_chk_gen(ubi))
return 0;
for (i = 0; i < UBI_PROT_QUEUE_LEN; ++i)
list_for_each_entry(p, &ubi->pq[i], u.list)
if (p == e)
return 0;
ubi_err("self-check failed for PEB %d, EC %d, Protect queue",
e->pnum, e->ec);
dump_stack();
return -EINVAL;
}