[PATCH][UBI]:Remove the prot tree from the WL unit
xiaochuan-xu
xiaochuan-xu at cqu.edu.cn
Wed Jul 16 06:49:07 EDT 2008
Hi Artem,
This is the patch you asked for.
Only the prot tree and a few comments were modified.
Please check it. and I'll test it a bit later.
>From 3df5422ade6d77cfa763ca0e1e8374b984982fee Mon Sep 17 00:00:00 2001
From: XiaoChuan-Xu <xiaochuan-xu at cqu.edu.cn>
Date: Wed, 16 Jul 2008 18:12:13 +0800
Subject: [PATCH] Remove the prot tree from the WL unit
Signed-off-by: XiaoChuan-Xu <xiaochuan-xu at cqu.edu.cn>
---
drivers/mtd/ubi/ubi.h | 9 +--
drivers/mtd/ubi/wl.c | 295 ++-----------------------------------------------
2 files changed, 13 insertions(+), 291 deletions(-)
diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
index 940f6b7..8d61247 100644
--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -286,10 +286,7 @@ struct ubi_wl_entry;
* @used: RB-tree of used physical eraseblocks
* @free: RB-tree of free physical eraseblocks
* @scrub: RB-tree of physical eraseblocks which need scrubbing
- * @prot: protection trees
- * @prot.pnum: protection tree indexed by physical eraseblock numbers
- * @prot.aec: protection tree indexed by absolute erase counter value
- * @wl_lock: protects the @used, @free, @prot, @lookuptbl, @abs_ec, @move_from,
+ * @wl_lock: protects the @used, @free, @lookuptbl, @abs_ec, @move_from,
* @move_to, @move_to_put @erase_pending, @wl_scheduled, and @works
* fields
* @move_mutex: serializes eraseblock moves
@@ -369,10 +366,6 @@ struct ubi_device {
struct rb_root used;
struct rb_root free;
struct rb_root scrub;
- struct {
- struct rb_root pnum;
- struct rb_root aec;
- } prot;
spinlock_t wl_lock;
struct mutex move_mutex;
struct rw_semaphore work_sem;
diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
index cc8fe29..bdac635 100644
--- a/drivers/mtd/ubi/wl.c
+++ b/drivers/mtd/ubi/wl.c
@@ -54,8 +54,7 @@
*
* As it was said, for the UBI unit all physical eraseblocks are either "free"
* or "used". Free eraseblock are kept in the @wl->free RB-tree, while used
- * eraseblocks are kept in a set of different RB-trees: @wl->used,
- * @wl->prot.pnum, @wl->prot.aec, and @wl->scrub.
+ * eraseblocks are kept in the @wl->used.
*
* 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
@@ -83,14 +82,6 @@
#define WL_RESERVED_PEBS 1
/*
- * How many erase cycles are short term, unknown, and long term physical
- * eraseblocks protected.
- */
-#define ST_PROTECTION 16
-#define U_PROTECTION 10
-#define LT_PROTECTION 4
-
-/*
* Maximum difference between two erase counters. If this threshold is
* exceeded, the WL unit starts moving data from used physical eraseblocks with
* low erase counter to free physical eraseblocks with high erase counter.
@@ -117,60 +108,6 @@
#define WL_MAX_FAILURES 32
/**
- * struct ubi_wl_prot_entry - PEB protection entry.
- * @rb_pnum: link in the @wl->prot.pnum RB-tree
- * @rb_aec: link in the @wl->prot.aec RB-tree
- * @abs_ec: the absolute erase counter value when the protection ends
- * @e: the wear-leveling entry of the physical eraseblock under protection
- *
- * When the WL unit 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 one more tree in between where this physical eraseblock is
- * temporarily stored (@wl->prot).
- *
- * 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; this is
- * especially important in case of "short term" physical eraseblocks.
- *
- * 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
- * absolute erase counter (@wl->abs_ec). When it reaches certain value, the
- * physical eraseblocks are moved from the protection trees (@wl->prot.*) to
- * the @wl->used tree.
- *
- * Protected physical eraseblocks are searched by physical eraseblock number
- * (when they are put) and by the absolute erase counter (to check if it is
- * time to move them to the @wl->used tree). So there are actually 2 RB-trees
- * storing the protected physical eraseblocks: @wl->prot.pnum and
- * @wl->prot.aec. They are referred to as the "protection" trees. The
- * first one is indexed by the physical eraseblock number. The second one is
- * indexed by the absolute erase counter. Both trees store
- * &struct ubi_wl_prot_entry objects.
- *
- * 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 temporarily prohibited (@wl->prot.pnum and
- * @wl->prot.aec trees);
- * 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 trees.
- */
-struct ubi_wl_prot_entry {
- struct rb_node rb_pnum;
- struct rb_node rb_aec;
- unsigned long long abs_ec;
- struct ubi_wl_entry *e;
-};
-
-/**
* struct ubi_work - UBI work description data structure.
* @list: a link in the list of pending works
* @func: worker function
@@ -353,53 +290,6 @@ static int in_wl_tree(struct ubi_wl_entry *e, struct rb_root *root)
}
/**
- * prot_tree_add - add physical eraseblock to protection trees.
- * @ubi: UBI device description object
- * @e: the physical eraseblock to add
- * @pe: protection entry object to use
- * @abs_ec: absolute erase counter value when this physical eraseblock has
- * to be removed from the protection trees.
- *
- * @wl->lock has to be locked.
- */
-static void prot_tree_add(struct ubi_device *ubi, struct ubi_wl_entry *e,
- struct ubi_wl_prot_entry *pe, int abs_ec)
-{
- struct rb_node **p, *parent = NULL;
- struct ubi_wl_prot_entry *pe1;
-
- pe->e = e;
- pe->abs_ec = ubi->abs_ec + abs_ec;
-
- p = &ubi->prot.pnum.rb_node;
- while (*p) {
- parent = *p;
- pe1 = rb_entry(parent, struct ubi_wl_prot_entry, rb_pnum);
-
- if (e->pnum < pe1->e->pnum)
- p = &(*p)->rb_left;
- else
- p = &(*p)->rb_right;
- }
- rb_link_node(&pe->rb_pnum, parent, p);
- rb_insert_color(&pe->rb_pnum, &ubi->prot.pnum);
-
- p = &ubi->prot.aec.rb_node;
- parent = NULL;
- while (*p) {
- parent = *p;
- pe1 = rb_entry(parent, struct ubi_wl_prot_entry, rb_aec);
-
- if (pe->abs_ec < pe1->abs_ec)
- p = &(*p)->rb_left;
- else
- p = &(*p)->rb_right;
- }
- rb_link_node(&pe->rb_aec, parent, p);
- rb_insert_color(&pe->rb_aec, &ubi->prot.aec);
-}
-
-/**
* find_wl_entry - find wear-leveling entry closest to certain erase counter.
* @root: the RB-tree where to look for
* @max: highest possible erase counter
@@ -441,17 +331,12 @@ static struct ubi_wl_entry *find_wl_entry(struct rb_root *root, int max)
*/
int ubi_wl_get_peb(struct ubi_device *ubi, int dtype)
{
- int err, protect, medium_ec;
+ int err, medium_ec;
struct ubi_wl_entry *e, *first, *last;
- struct ubi_wl_prot_entry *pe;
ubi_assert(dtype == UBI_LONGTERM || dtype == UBI_SHORTTERM ||
dtype == UBI_UNKNOWN);
- pe = kmalloc(sizeof(struct ubi_wl_prot_entry), GFP_NOFS);
- if (!pe)
- return -ENOMEM;
-
retry:
spin_lock(&ubi->wl_lock);
if (!ubi->free.rb_node) {
@@ -481,7 +366,6 @@ retry:
* erase counter plus %WL_FREE_MAX_DIFF.
*/
e = find_wl_entry(&ubi->free, WL_FREE_MAX_DIFF);
- protect = LT_PROTECTION;
break;
case UBI_UNKNOWN:
/*
@@ -503,7 +387,6 @@ retry:
medium_ec = (first->ec + WL_FREE_MAX_DIFF)/2;
e = find_wl_entry(&ubi->free, medium_ec);
}
- protect = U_PROTECTION;
break;
case UBI_SHORTTERM:
/*
@@ -513,67 +396,26 @@ retry:
*/
e = rb_entry(rb_first(&ubi->free),
struct ubi_wl_entry, rb);
- protect = ST_PROTECTION;
break;
default:
- protect = 0;
e = NULL;
BUG();
}
/*
- * Move the physical eraseblock to the protection trees where it will
- * be protected from being moved for some time.
+ * Move the physical eraseblock to the used tree.
*/
paranoid_check_in_wl_tree(e, &ubi->free);
rb_erase(&e->rb, &ubi->free);
- prot_tree_add(ubi, e, pe, protect);
+ wl_tree_add(e, &ubi->used);
- dbg_wl("PEB %d EC %d, protection %d", e->pnum, e->ec, protect);
+ dbg_wl("get PEB %d EC %d", e->pnum, e->ec);
spin_unlock(&ubi->wl_lock);
return e->pnum;
}
/**
- * prot_tree_del - remove a physical eraseblock from the protection trees
- * @ubi: UBI device description object
- * @pnum: the physical eraseblock to remove
- *
- * This function returns PEB @pnum from the protection trees and returns zero
- * in case of success and %-ENODEV if the PEB was not found in the protection
- * trees.
- */
-static int prot_tree_del(struct ubi_device *ubi, int pnum)
-{
- struct rb_node *p;
- struct ubi_wl_prot_entry *pe = NULL;
-
- p = ubi->prot.pnum.rb_node;
- while (p) {
-
- pe = rb_entry(p, struct ubi_wl_prot_entry, rb_pnum);
-
- if (pnum == pe->e->pnum)
- goto found;
-
- if (pnum < pe->e->pnum)
- p = p->rb_left;
- else
- p = p->rb_right;
- }
-
- return -ENODEV;
-
-found:
- ubi_assert(pe->e->pnum == pnum);
- rb_erase(&pe->rb_aec, &ubi->prot.aec);
- rb_erase(&pe->rb_pnum, &ubi->prot.pnum);
- kfree(pe);
- return 0;
-}
-
-/**
* sync_erase - synchronously erase a physical eraseblock.
* @ubi: UBI device description object
* @e: the the physical eraseblock to erase
@@ -634,51 +476,6 @@ out_free:
}
/**
- * check_protection_over - check if it is time to stop protecting some
- * physical eraseblocks.
- * @ubi: UBI device description object
- *
- * This function is called after each erase operation, when the absolute erase
- * counter is incremented, to check if some physical eraseblock have not to be
- * protected any longer. These physical eraseblocks are moved from the
- * protection trees to the used tree.
- */
-static void check_protection_over(struct ubi_device *ubi)
-{
- struct ubi_wl_prot_entry *pe;
-
- /*
- * There may be several protected physical eraseblock to remove,
- * process them all.
- */
- while (1) {
- spin_lock(&ubi->wl_lock);
- if (!ubi->prot.aec.rb_node) {
- spin_unlock(&ubi->wl_lock);
- break;
- }
-
- pe = rb_entry(rb_first(&ubi->prot.aec),
- struct ubi_wl_prot_entry, rb_aec);
-
- if (pe->abs_ec > ubi->abs_ec) {
- spin_unlock(&ubi->wl_lock);
- break;
- }
-
- dbg_wl("PEB %d protection over, abs_ec %llu, PEB abs_ec %llu",
- pe->e->pnum, ubi->abs_ec, pe->abs_ec);
- rb_erase(&pe->rb_aec, &ubi->prot.aec);
- rb_erase(&pe->rb_pnum, &ubi->prot.pnum);
- wl_tree_add(pe->e, &ubi->used);
- spin_unlock(&ubi->wl_lock);
-
- kfree(pe);
- cond_resched();
- }
-}
-
-/**
* schedule_ubi_work - schedule a work.
* @ubi: UBI device description object
* @wrk: the work to schedule
@@ -743,7 +540,6 @@ static int wear_leveling_worker(struct ubi_device *ubi, struct ubi_work *wrk,
int cancel)
{
int err, put = 0, scrubbing = 0, protect = 0;
- struct ubi_wl_prot_entry *uninitialized_var(pe);
struct ubi_wl_entry *e1, *e2;
struct ubi_vid_hdr *vid_hdr;
@@ -768,10 +564,7 @@ static int wear_leveling_worker(struct ubi_device *ubi, struct ubi_work *wrk,
* 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.
+ * No used physical eraseblocks?. cancel this wl worker.
*/
dbg_wl("cancel WL, a list is empty: free %d, used %d",
!ubi->free.rb_node, !ubi->used.rb_node);
@@ -855,25 +648,17 @@ static int wear_leveling_worker(struct ubi_device *ubi, struct ubi_work *wrk,
/*
* For some reason the LEB was not moved - it might be because
- * the volume is being deleted. We should prevent this PEB from
- * being selected for wear-levelling movement for some "time",
- * so put it to the protection tree.
+ * the volume is being deleted. Nothing we can do but insert
+ * this PEB back to used tree.
*/
dbg_wl("cancelled moving PEB %d", e1->pnum);
- pe = kmalloc(sizeof(struct ubi_wl_prot_entry), GFP_NOFS);
- if (!pe) {
- err = -ENOMEM;
- goto out_error;
- }
protect = 1;
}
ubi_free_vid_hdr(ubi, vid_hdr);
spin_lock(&ubi->wl_lock);
- if (protect)
- prot_tree_add(ubi, e1, pe, protect);
if (!ubi->move_to_put)
wl_tree_add(e2, &ubi->used);
else
@@ -897,8 +682,8 @@ static int wear_leveling_worker(struct ubi_device *ubi, struct ubi_work *wrk,
err = schedule_erase(ubi, e1, 0);
if (err)
goto out_error;
- }
-
+ } else
+ wl_tree_add(e1, &ubi->used);
dbg_wl("done");
mutex_unlock(&ubi->move_mutex);
@@ -1053,13 +838,9 @@ static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk,
wl_tree_add(e, &ubi->free);
spin_unlock(&ubi->wl_lock);
- /*
- * One more erase operation has happened, take care about protected
- * physical eraseblocks.
+ /* One more erase operation has happened,
+ * take care about wear-leveling
*/
- check_protection_over(ubi);
-
- /* And take care about wear-leveling */
err = ensure_wear_leveling(ubi);
return err;
}
@@ -1193,14 +974,6 @@ retry:
} else if (in_wl_tree(e, &ubi->scrub)) {
paranoid_check_in_wl_tree(e, &ubi->scrub);
rb_erase(&e->rb, &ubi->scrub);
- } else {
- err = prot_tree_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);
@@ -1255,16 +1028,6 @@ retry:
if (in_wl_tree(e, &ubi->used)) {
paranoid_check_in_wl_tree(e, &ubi->used);
rb_erase(&e->rb, &ubi->used);
- } else {
- int err;
-
- err = prot_tree_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);
@@ -1443,7 +1206,6 @@ int ubi_wl_init_scan(struct ubi_device *ubi, struct ubi_scan_info *si)
ubi->used = ubi->free = ubi->scrub = RB_ROOT;
- ubi->prot.pnum = ubi->prot.aec = RB_ROOT;
spin_lock_init(&ubi->wl_lock);
mutex_init(&ubi->move_mutex);
init_rwsem(&ubi->work_sem);
@@ -1551,38 +1313,6 @@ out_free:
}
/**
- * protection_trees_destroy - destroy the protection RB-trees.
- * @ubi: UBI device description object
- */
-static void protection_trees_destroy(struct ubi_device *ubi)
-{
- struct rb_node *rb;
- struct ubi_wl_prot_entry *pe;
-
- rb = ubi->prot.aec.rb_node;
- while (rb) {
- if (rb->rb_left)
- rb = rb->rb_left;
- else if (rb->rb_right)
- rb = rb->rb_right;
- else {
- pe = rb_entry(rb, struct ubi_wl_prot_entry, rb_aec);
-
- rb = rb_parent(rb);
- if (rb) {
- if (rb->rb_left == &pe->rb_aec)
- rb->rb_left = NULL;
- else
- rb->rb_right = NULL;
- }
-
- kmem_cache_free(ubi_wl_entry_slab, pe->e);
- kfree(pe);
- }
- }
-}
-
-/**
* ubi_wl_close - close the wear-leveling unit.
* @ubi: UBI device description object
*/
@@ -1591,7 +1321,6 @@ void ubi_wl_close(struct ubi_device *ubi)
dbg_wl("close the UBI wear-leveling unit");
cancel_pending(ubi);
- protection_trees_destroy(ubi);
tree_destroy(&ubi->used);
tree_destroy(&ubi->free);
tree_destroy(&ubi->scrub);
--
1.5.3.2
--
yours Sincerely,
xiaochuan-xu (许小川)
More information about the linux-mtd
mailing list