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Diffstat (limited to '')
| -rw-r--r-- | drivers/mtd/ubi/wl.c | 2159 |
1 files changed, 2159 insertions, 0 deletions
diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c new file mode 100644 index 000000000..6049ab9e4 --- /dev/null +++ b/drivers/mtd/ubi/wl.c @@ -0,0 +1,2159 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (c) International Business Machines Corp., 2006 + * + * 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" +#include "wl.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); + +/** + * 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); +} + +/** + * wl_tree_destroy - destroy a wear-leveling entry. + * @ubi: UBI device description object + * @e: the wear-leveling entry to add + * + * This function destroys a wear leveling entry and removes + * the reference from the lookup table. + */ +static void wl_entry_destroy(struct ubi_device *ubi, struct ubi_wl_entry *e) +{ + ubi->lookuptbl[e->pnum] = NULL; + kmem_cache_free(ubi_wl_entry_slab, e); +} + +/** + * 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(ubi, "work failed with error code %d", err); + up_read(&ubi->work_sem); + + return err; +} + +/** + * 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; +} + +/** + * in_pq - check if a wear-leveling entry is present in the protection queue. + * @ubi: UBI device description object + * @e: the wear-leveling entry to check + * + * This function returns non-zero if @e is in the protection queue and zero + * if it is not. + */ +static inline int in_pq(const struct ubi_device *ubi, struct ubi_wl_entry *e) +{ + struct ubi_wl_entry *p; + int i; + + for (i = 0; i < UBI_PROT_QUEUE_LEN; ++i) + list_for_each_entry(p, &ubi->pq[i], u.list) + if (p == e) + return 1; + + 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; + 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; + e = e1; + } + } + + 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); + + /* 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. */ + e = may_reserve_for_fm(ubi, e, root); + } else + e = find_wl_entry(ubi, root, WL_FREE_MAX_DIFF/2); + + return e; +} + +/** + * wl_get_wle - get a mean wl entry to be used by ubi_wl_get_peb() or + * refill_wl_user_pool(). + * @ubi: UBI device description object + * + * This function returns a wear leveling entry in case of success and + * NULL in case of failure. + */ +static struct ubi_wl_entry *wl_get_wle(struct ubi_device *ubi) +{ + struct ubi_wl_entry *e; + + e = find_mean_wl_entry(ubi, &ubi->free); + if (!e) { + ubi_err(ubi, "no free eraseblocks"); + return NULL; + } + + 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); + + return e; +} + +/** + * 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 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(ubi, "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 if 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 shutdown); + +/** + * 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 + * @nested: denotes whether the work_sem is already held + * + * 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, bool nested) +{ + struct ubi_work *wl_wrk; + + ubi_assert(e); + + 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; + + if (nested) + __schedule_ubi_work(ubi, wl_wrk); + else + schedule_ubi_work(ubi, wl_wrk); + return 0; +} + +static int __erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk); +/** + * 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.e = e; + wl_wrk.vol_id = vol_id; + wl_wrk.lnum = lnum; + wl_wrk.torture = torture; + + return __erase_worker(ubi, &wl_wrk); +} + +static int ensure_wear_leveling(struct ubi_device *ubi, int nested); +/** + * wear_leveling_worker - wear-leveling worker function. + * @ubi: UBI device description object + * @wrk: the work object + * @shutdown: non-zero if the worker has to free memory and exit + * because the WL-subsystem is shutting down + * + * 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 shutdown) +{ + int err, scrubbing = 0, torture = 0, protect = 0, erroneous = 0; + int erase = 0, keep = 0, vol_id = -1, lnum = -1; + struct ubi_wl_entry *e1, *e2; + struct ubi_vid_io_buf *vidb; + struct ubi_vid_hdr *vid_hdr; + int dst_leb_clean = 0; + + kfree(wrk); + if (shutdown) + return 0; + + vidb = ubi_alloc_vid_buf(ubi, GFP_NOFS); + if (!vidb) + return -ENOMEM; + + vid_hdr = ubi_get_vid_hdr(vidb); + + down_read(&ubi->fm_eba_sem); + mutex_lock(&ubi->move_mutex); + spin_lock(&ubi->wl_lock); + ubi_assert(!ubi->move_from && !ubi->move_to); + ubi_assert(!ubi->move_to_put); + +#ifdef CONFIG_MTD_UBI_FASTMAP + if (!next_peb_for_wl(ubi) || +#else + if (!ubi->free.rb_node || +#endif + (!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 + e1 = find_anchor_wl_entry(&ubi->used); + if (e1 && ubi->fm_anchor && + (ubi->fm_anchor->ec - e1->ec >= UBI_WL_THRESHOLD)) { + ubi->fm_do_produce_anchor = 1; + /* + * fm_anchor is no longer considered a good anchor. + * NULL assignment also prevents multiple wear level checks + * of this PEB. + */ + wl_tree_add(ubi->fm_anchor, &ubi->free); + ubi->fm_anchor = NULL; + ubi->free_count++; + } + + if (ubi->fm_do_produce_anchor) { + 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); + ubi->fm_do_produce_anchor = 0; + } 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); + + /* Give the unused PEB back */ + wl_tree_add(e2, &ubi->free); + ubi->free_count++; + 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, vidb, 0); + if (err && err != UBI_IO_BITFLIPS) { + dst_leb_clean = 1; + 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; + } else if (ubi->fast_attach && err == UBI_IO_BAD_HDR_EBADMSG) { + /* + * While a full scan would detect interrupted erasures + * at attach time we can face them here when attached from + * Fastmap. + */ + dbg_wl("PEB %d has ECC errors, maybe from an interrupted erasure", + e1->pnum); + erase = 1; + goto out_not_moved; + } + + ubi_err(ubi, "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, vidb); + 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; + dst_leb_clean = 1; + goto out_not_moved; + } + if (err == MOVE_RETRY) { + scrubbing = 1; + dst_leb_clean = 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; + keep = 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(ubi, "too many erroneous eraseblocks (%d)", + ubi->erroneous_peb_count); + goto out_error; + } + dst_leb_clean = 1; + 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(ubi, "scrubbed PEB %d (LEB %d:%d), data moved to PEB %d", + e1->pnum, vol_id, lnum, e2->pnum); + ubi_free_vid_buf(vidb); + + 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) { + if (e2) { + spin_lock(&ubi->wl_lock); + wl_entry_destroy(ubi, e2); + spin_unlock(&ubi->wl_lock); + } + 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) + goto out_ro; + } + + dbg_wl("done"); + mutex_unlock(&ubi->move_mutex); + up_read(&ubi->fm_eba_sem); + 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 if (keep) + wl_tree_add(e1, &ubi->used); + if (dst_leb_clean) { + wl_tree_add(e2, &ubi->free); + ubi->free_count++; + } + + 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_buf(vidb); + if (dst_leb_clean) { + ensure_wear_leveling(ubi, 1); + } else { + err = do_sync_erase(ubi, e2, vol_id, lnum, torture); + if (err) + goto out_ro; + } + + if (erase) { + err = do_sync_erase(ubi, e1, vol_id, lnum, 1); + if (err) + goto out_ro; + } + + mutex_unlock(&ubi->move_mutex); + up_read(&ubi->fm_eba_sem); + return 0; + +out_error: + if (vol_id != -1) + ubi_err(ubi, "error %d while moving PEB %d to PEB %d", + err, e1->pnum, e2->pnum); + else + ubi_err(ubi, "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; + wl_entry_destroy(ubi, e1); + wl_entry_destroy(ubi, e2); + spin_unlock(&ubi->wl_lock); + + ubi_free_vid_buf(vidb); + +out_ro: + ubi_ro_mode(ubi); + mutex_unlock(&ubi->move_mutex); + up_read(&ubi->fm_eba_sem); + 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); + up_read(&ubi->fm_eba_sem); + ubi_free_vid_buf(vidb); + 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_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 + * WL worker has to be scheduled anyway. + */ + if (!ubi->scrub.rb_node) { +#ifdef CONFIG_MTD_UBI_FASTMAP + if (!need_wear_leveling(ubi)) + goto out_unlock; +#else + struct ubi_wl_entry *e1; + struct ubi_wl_entry *e2; + + 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; +#endif + 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->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; +} + +/** + * __erase_worker - physical eraseblock erase worker function. + * @ubi: UBI device description object + * @wl_wrk: the work object + * + * 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) +{ + 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; + + dbg_wl("erase PEB %d EC %d LEB %d:%d", + pnum, e->ec, wl_wrk->vol_id, wl_wrk->lnum); + + err = sync_erase(ubi, e, wl_wrk->torture); + if (!err) { + spin_lock(&ubi->wl_lock); + + if (!ubi->fm_disabled && !ubi->fm_anchor && + e->pnum < UBI_FM_MAX_START) { + /* + * Abort anchor production, if needed it will be + * enabled again in the wear leveling started below. + */ + ubi->fm_anchor = e; + ubi->fm_do_produce_anchor = 0; + } else { + 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(ubi, "failed to erase PEB %d, error %d", pnum, err); + + 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, true); + if (err1) { + spin_lock(&ubi->wl_lock); + wl_entry_destroy(ubi, e); + spin_unlock(&ubi->wl_lock); + err = err1; + goto out_ro; + } + return err; + } + + spin_lock(&ubi->wl_lock); + wl_entry_destroy(ubi, e); + spin_unlock(&ubi->wl_lock); + 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(ubi, "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(ubi, "no reserved/available physical eraseblocks"); + goto out_ro; + } + ubi->avail_pebs -= 1; + available_consumed = 1; + } + spin_unlock(&ubi->volumes_lock); + + ubi_msg(ubi, "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(ubi, "no PEBs in the reserved pool, used an available PEB"); + else if (ubi->beb_rsvd_pebs) + ubi_msg(ubi, "%d PEBs left in the reserve", + ubi->beb_rsvd_pebs); + else + ubi_warn(ubi, "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; +} + +static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk, + int shutdown) +{ + int ret; + + if (shutdown) { + struct ubi_wl_entry *e = wl_wrk->e; + + dbg_wl("cancel erasure of PEB %d EC %d", e->pnum, e->ec); + kfree(wl_wrk); + wl_entry_destroy(ubi, e); + return 0; + } + + ret = __erase_worker(ubi, wl_wrk); + kfree(wl_wrk); + return ret; +} + +/** + * 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); + + down_read(&ubi->fm_protect); + +retry: + spin_lock(&ubi->wl_lock); + e = ubi->lookuptbl[pnum]; + if (!e) { + /* + * This wl entry has been removed for some errors by other + * process (eg. wear leveling worker), corresponding process + * (except __erase_worker, which cannot concurrent with + * ubi_wl_put_peb) will set ubi ro_mode at the same time, + * just ignore this wl entry. + */ + spin_unlock(&ubi->wl_lock); + up_read(&ubi->fm_protect); + return 0; + } + 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); + up_read(&ubi->fm_protect); + 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(ubi, "PEB %d not found", pnum); + ubi_ro_mode(ubi); + spin_unlock(&ubi->wl_lock); + up_read(&ubi->fm_protect); + return err; + } + } + } + spin_unlock(&ubi->wl_lock); + + err = schedule_erase(ubi, e, vol_id, lnum, torture, false); + if (err) { + spin_lock(&ubi->wl_lock); + wl_tree_add(e, &ubi->used); + spin_unlock(&ubi->wl_lock); + } + + up_read(&ubi->fm_protect); + 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(ubi, "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(ubi, "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, *tmp; + found = 0; + + down_read(&ubi->work_sem); + spin_lock(&ubi->wl_lock); + list_for_each_entry_safe(wrk, tmp, &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; +} + +static bool scrub_possible(struct ubi_device *ubi, struct ubi_wl_entry *e) +{ + if (in_wl_tree(e, &ubi->scrub)) + return false; + else if (in_wl_tree(e, &ubi->erroneous)) + return false; + else if (ubi->move_from == e) + return false; + else if (ubi->move_to == e) + return false; + + return true; +} + +/** + * ubi_bitflip_check - Check an eraseblock for bitflips and scrub it if needed. + * @ubi: UBI device description object + * @pnum: the physical eraseblock to schedule + * @force: don't read the block, assume bitflips happened and take action. + * + * This function reads the given eraseblock and checks if bitflips occured. + * In case of bitflips, the eraseblock is scheduled for scrubbing. + * If scrubbing is forced with @force, the eraseblock is not read, + * but scheduled for scrubbing right away. + * + * Returns: + * %EINVAL, PEB is out of range + * %ENOENT, PEB is no longer used by UBI + * %EBUSY, PEB cannot be checked now or a check is currently running on it + * %EAGAIN, bit flips happened but scrubbing is currently not possible + * %EUCLEAN, bit flips happened and PEB is scheduled for scrubbing + * %0, no bit flips detected + */ +int ubi_bitflip_check(struct ubi_device *ubi, int pnum, int force) +{ + int err = 0; + struct ubi_wl_entry *e; + + if (pnum < 0 || pnum >= ubi->peb_count) { + err = -EINVAL; + goto out; + } + + /* + * Pause all parallel work, otherwise it can happen that the + * erase worker frees a wl entry under us. + */ + down_write(&ubi->work_sem); + + /* + * Make sure that the wl entry does not change state while + * inspecting it. + */ + spin_lock(&ubi->wl_lock); + e = ubi->lookuptbl[pnum]; + if (!e) { + spin_unlock(&ubi->wl_lock); + err = -ENOENT; + goto out_resume; + } + + /* + * Does it make sense to check this PEB? + */ + if (!scrub_possible(ubi, e)) { + spin_unlock(&ubi->wl_lock); + err = -EBUSY; + goto out_resume; + } + spin_unlock(&ubi->wl_lock); + + if (!force) { + mutex_lock(&ubi->buf_mutex); + err = ubi_io_read(ubi, ubi->peb_buf, pnum, 0, ubi->peb_size); + mutex_unlock(&ubi->buf_mutex); + } + + if (force || err == UBI_IO_BITFLIPS) { + /* + * Okay, bit flip happened, let's figure out what we can do. + */ + spin_lock(&ubi->wl_lock); + + /* + * Recheck. We released wl_lock, UBI might have killed the + * wl entry under us. + */ + e = ubi->lookuptbl[pnum]; + if (!e) { + spin_unlock(&ubi->wl_lock); + err = -ENOENT; + goto out_resume; + } + + /* + * Need to re-check state + */ + if (!scrub_possible(ubi, e)) { + spin_unlock(&ubi->wl_lock); + err = -EBUSY; + goto out_resume; + } + + if (in_pq(ubi, e)) { + prot_queue_del(ubi, e->pnum); + wl_tree_add(e, &ubi->scrub); + spin_unlock(&ubi->wl_lock); + + err = ensure_wear_leveling(ubi, 1); + } else if (in_wl_tree(e, &ubi->used)) { + rb_erase(&e->u.rb, &ubi->used); + wl_tree_add(e, &ubi->scrub); + spin_unlock(&ubi->wl_lock); + + err = ensure_wear_leveling(ubi, 1); + } else if (in_wl_tree(e, &ubi->free)) { + rb_erase(&e->u.rb, &ubi->free); + ubi->free_count--; + spin_unlock(&ubi->wl_lock); + + /* + * This PEB is empty we can schedule it for + * erasure right away. No wear leveling needed. + */ + err = schedule_erase(ubi, e, UBI_UNKNOWN, UBI_UNKNOWN, + force ? 0 : 1, true); + } else { + spin_unlock(&ubi->wl_lock); + err = -EAGAIN; + } + + if (!err && !force) + err = -EUCLEAN; + } else { + err = 0; + } + +out_resume: + up_write(&ubi->work_sem); +out: + + return err; +} + +/** + * tree_destroy - destroy an RB-tree. + * @ubi: UBI device description object + * @root: the root of the tree to destroy + */ +static void tree_destroy(struct ubi_device *ubi, 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; + } + + wl_entry_destroy(ubi, 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(ubi, "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); + + /* + * Check kthread_should_stop() after we set the task + * state to guarantee that we either see the stop bit + * and exit or the task state is reset to runnable such + * that it's not scheduled out indefinitely and detects + * the stop bit at kthread_should_stop(). + */ + if (kthread_should_stop()) { + set_current_state(TASK_RUNNING); + break; + } + + schedule(); + continue; + } + spin_unlock(&ubi->wl_lock); + + err = do_work(ubi); + if (err) { + ubi_err(ubi, "%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(ubi, "%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); + ubi->thread_enabled = 0; + return 0; +} + +/** + * shutdown_work - shutdown all pending works. + * @ubi: UBI device description object + */ +static void shutdown_work(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); + } +} + +/** + * erase_aeb - erase a PEB given in UBI attach info PEB + * @ubi: UBI device description object + * @aeb: UBI attach info PEB + * @sync: If true, erase synchronously. Otherwise schedule for erasure + */ +static int erase_aeb(struct ubi_device *ubi, struct ubi_ainf_peb *aeb, bool sync) +{ + struct ubi_wl_entry *e; + int err; + + e = kmem_cache_alloc(ubi_wl_entry_slab, GFP_KERNEL); + if (!e) + return -ENOMEM; + + e->pnum = aeb->pnum; + e->ec = aeb->ec; + ubi->lookuptbl[e->pnum] = e; + + if (sync) { + err = sync_erase(ubi, e, false); + if (err) + goto out_free; + + wl_tree_add(e, &ubi->free); + ubi->free_count++; + } else { + err = schedule_erase(ubi, e, aeb->vol_id, aeb->lnum, 0, false); + if (err) + goto out_free; + } + + return 0; + +out_free: + wl_entry_destroy(ubi, e); + + return err; +} + +/** + * 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); + + sprintf(ubi->bgt_name, UBI_BGT_NAME_PATTERN, ubi->ubi_num); + + err = -ENOMEM; + ubi->lookuptbl = kcalloc(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; + + ubi->free_count = 0; + list_for_each_entry_safe(aeb, tmp, &ai->erase, u.list) { + cond_resched(); + + err = erase_aeb(ubi, aeb, false); + if (err) + goto out_free; + + found_pebs++; + } + + list_for_each_entry(aeb, &ai->free, u.list) { + cond_resched(); + + e = kmem_cache_alloc(ubi_wl_entry_slab, GFP_KERNEL); + if (!e) { + err = -ENOMEM; + goto out_free; + } + + e->pnum = aeb->pnum; + e->ec = aeb->ec; + ubi_assert(e->ec >= 0); + + 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) { + err = -ENOMEM; + 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++; + } + } + + list_for_each_entry(aeb, &ai->fastmap, u.list) { + cond_resched(); + + e = ubi_find_fm_block(ubi, aeb->pnum); + + if (e) { + ubi_assert(!ubi->lookuptbl[e->pnum]); + ubi->lookuptbl[e->pnum] = e; + } else { + bool sync = false; + + /* + * Usually old Fastmap PEBs are scheduled for erasure + * and we don't have to care about them but if we face + * an power cut before scheduling them we need to + * take care of them here. + */ + if (ubi->lookuptbl[aeb->pnum]) + continue; + + /* + * The fastmap update code might not find a free PEB for + * writing the fastmap anchor to and then reuses the + * current fastmap anchor PEB. When this PEB gets erased + * and a power cut happens before it is written again we + * must make sure that the fastmap attach code doesn't + * find any outdated fastmap anchors, hence we erase the + * outdated fastmap anchor PEBs synchronously here. + */ + if (aeb->vol_id == UBI_FM_SB_VOLUME_ID) + sync = true; + + err = erase_aeb(ubi, aeb, sync); + if (err) + goto out_free; + } + + found_pebs++; + } + + dbg_wl("found %i PEBs", found_pebs); + + ubi_assert(ubi->good_peb_count == found_pebs); + + reserved_pebs = WL_RESERVED_PEBS; + ubi_fastmap_init(ubi, &reserved_pebs); + + if (ubi->avail_pebs < reserved_pebs) { + ubi_err(ubi, "no enough physical eraseblocks (%d, need %d)", + ubi->avail_pebs, reserved_pebs); + if (ubi->corr_peb_count) + ubi_err(ubi, "%d PEBs are corrupted and not used", + ubi->corr_peb_count); + err = -ENOSPC; + 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; + +#ifdef CONFIG_MTD_UBI_FASTMAP + if (!ubi->ro_mode && !ubi->fm_disabled) + ubi_ensure_anchor_pebs(ubi); +#endif + return 0; + +out_free: + shutdown_work(ubi); + tree_destroy(ubi, &ubi->used); + tree_destroy(ubi, &ubi->free); + tree_destroy(ubi, &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); + wl_entry_destroy(ubi, 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"); + ubi_fastmap_close(ubi); + shutdown_work(ubi); + protection_queue_destroy(ubi); + tree_destroy(ubi, &ubi->used); + tree_destroy(ubi, &ubi->erroneous); + tree_destroy(ubi, &ubi->free); + tree_destroy(ubi, &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(ubi, "self-check failed for PEB %d", pnum); + ubi_err(ubi, "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(ubi, "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) +{ + if (!ubi_dbg_chk_gen(ubi)) + return 0; + + if (in_pq(ubi, e)) + return 0; + + ubi_err(ubi, "self-check failed for PEB %d, EC %d, Protect queue", + e->pnum, e->ec); + dump_stack(); + return -EINVAL; +} +#ifndef CONFIG_MTD_UBI_FASTMAP +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); + ubi->free_count--; + ubi_assert(ubi->free_count >= 0); + rb_erase(&e->u.rb, &ubi->free); + + return e; +} + +/** + * 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 && ubi->works_count) { + 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; +} + +/** + * ubi_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. + * Returns with ubi->fm_eba_sem held in read mode! + */ +int ubi_wl_get_peb(struct ubi_device *ubi) +{ + int err; + struct ubi_wl_entry *e; + +retry: + down_read(&ubi->fm_eba_sem); + spin_lock(&ubi->wl_lock); + if (!ubi->free.rb_node) { + if (ubi->works_count == 0) { + ubi_err(ubi, "no free eraseblocks"); + ubi_assert(list_empty(&ubi->works)); + spin_unlock(&ubi->wl_lock); + return -ENOSPC; + } + + err = produce_free_peb(ubi); + if (err < 0) { + spin_unlock(&ubi->wl_lock); + return err; + } + spin_unlock(&ubi->wl_lock); + up_read(&ubi->fm_eba_sem); + goto retry; + + } + e = wl_get_wle(ubi); + prot_queue_add(ubi, e); + spin_unlock(&ubi->wl_lock); + + err = ubi_self_check_all_ff(ubi, e->pnum, ubi->vid_hdr_aloffset, + ubi->peb_size - ubi->vid_hdr_aloffset); + if (err) { + ubi_err(ubi, "new PEB %d does not contain all 0xFF bytes", e->pnum); + return err; + } + + return e->pnum; +} +#else +#include "fastmap-wl.c" +#endif |