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lru_cache: allow multiple changes per transaction

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Allow multiple changes to the active set of elements in lru_cache.
The only current user of lru_cache, drbd, is driving this generalisation.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
This commit is contained in:
Lars Ellenberg 2011-02-21 13:21:01 +01:00 committed by Philipp Reisner
parent 45dfffebd0
commit 46a15bc3ec
4 changed files with 226 additions and 141 deletions
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50
drivers/block/drbd/drbd_actlog.c
View file

@ -175,7 +175,6 @@ static struct lc_element *_al_get(struct drbd_conf *mdev, unsigned int enr)
{
struct lc_element *al_ext;
struct lc_element *tmp;
unsigned long al_flags = 0;
int wake;
spin_lock_irq(&mdev->al_lock);
@ -190,19 +189,8 @@ static struct lc_element *_al_get(struct drbd_conf *mdev, unsigned int enr)
return NULL;
}
}
al_ext = lc_get(mdev->act_log, enr);
al_flags = mdev->act_log->flags;
al_ext = lc_get(mdev->act_log, enr);
spin_unlock_irq(&mdev->al_lock);
/*
if (!al_ext) {
if (al_flags & LC_STARVING)
dev_warn(DEV, "Have to wait for LRU element (AL too small?)\n");
if (al_flags & LC_DIRTY)
dev_warn(DEV, "Ongoing AL update (AL device too slow?)\n");
}
*/
return al_ext;
}
@ -235,7 +223,7 @@ void drbd_al_begin_io(struct drbd_conf *mdev, sector_t sector)
mdev->al_writ_cnt++;
spin_lock_irq(&mdev->al_lock);
lc_changed(mdev->act_log, al_ext);
lc_committed(mdev->act_log);
spin_unlock_irq(&mdev->al_lock);
wake_up(&mdev->al_wait);
}
@ -601,7 +589,7 @@ void drbd_al_shrink(struct drbd_conf *mdev)
struct lc_element *al_ext;
int i;
D_ASSERT(test_bit(__LC_DIRTY, &mdev->act_log->flags));
D_ASSERT(test_bit(__LC_LOCKED, &mdev->act_log->flags));
for (i = 0; i < mdev->act_log->nr_elements; i++) {
al_ext = lc_element_by_index(mdev->act_log, i);
@ -708,7 +696,9 @@ static void drbd_try_clear_on_disk_bm(struct drbd_conf *mdev, sector_t sector,
}
ext->rs_left = rs_left;
ext->rs_failed = success ? 0 : count;
lc_changed(mdev->resync, &ext->lce);
/* we don't keep a persistent log of the resync lru,
* we can commit any change right away. */
lc_committed(mdev->resync);
}
lc_put(mdev->resync, &ext->lce);
/* no race, we are within the al_lock! */
@ -892,7 +882,7 @@ struct bm_extent *_bme_get(struct drbd_conf *mdev, unsigned int enr)
if (bm_ext->lce.lc_number != enr) {
bm_ext->rs_left = drbd_bm_e_weight(mdev, enr);
bm_ext->rs_failed = 0;
lc_changed(mdev->resync, &bm_ext->lce);
lc_committed(mdev->resync);
wakeup = 1;
}
if (bm_ext->lce.refcnt == 1)
@ -908,7 +898,7 @@ struct bm_extent *_bme_get(struct drbd_conf *mdev, unsigned int enr)
if (rs_flags & LC_STARVING)
dev_warn(DEV, "Have to wait for element"
" (resync LRU too small?)\n");
BUG_ON(rs_flags & LC_DIRTY);
BUG_ON(rs_flags & LC_LOCKED);
}
return bm_ext;
@ -916,26 +906,12 @@ struct bm_extent *_bme_get(struct drbd_conf *mdev, unsigned int enr)
static int _is_in_al(struct drbd_conf *mdev, unsigned int enr)
{
struct lc_element *al_ext;
int rv = 0;
int rv;
spin_lock_irq(&mdev->al_lock);
if (unlikely(enr == mdev->act_log->new_number))
rv = 1;
else {
al_ext = lc_find(mdev->act_log, enr);
if (al_ext) {
if (al_ext->refcnt)
rv = 1;
}
}
rv = lc_is_used(mdev->act_log, enr);
spin_unlock_irq(&mdev->al_lock);
/*
if (unlikely(rv)) {
dev_info(DEV, "Delaying sync read until app's write is done\n");
}
*/
return rv;
}
@ -1065,13 +1041,13 @@ int drbd_try_rs_begin_io(struct drbd_conf *mdev, sector_t sector)
if (rs_flags & LC_STARVING)
dev_warn(DEV, "Have to wait for element"
" (resync LRU too small?)\n");
BUG_ON(rs_flags & LC_DIRTY);
BUG_ON(rs_flags & LC_LOCKED);
goto try_again;
}
if (bm_ext->lce.lc_number != enr) {
bm_ext->rs_left = drbd_bm_e_weight(mdev, enr);
bm_ext->rs_failed = 0;
lc_changed(mdev->resync, &bm_ext->lce);
lc_committed(mdev->resync);
wake_up(&mdev->al_wait);
D_ASSERT(test_bit(BME_LOCKED, &bm_ext->flags) == 0);
}
@ -1082,8 +1058,6 @@ int drbd_try_rs_begin_io(struct drbd_conf *mdev, sector_t sector)
}
check_al:
for (i = 0; i < AL_EXT_PER_BM_SECT; i++) {
if (unlikely(al_enr+i == mdev->act_log->new_number))
goto try_again;
if (lc_is_used(mdev->act_log, al_enr+i))
goto try_again;
}

4
drivers/block/drbd/drbd_nl.c
View file

@ -760,7 +760,7 @@ static int drbd_check_al_size(struct drbd_conf *mdev)
in_use = 0;
t = mdev->act_log;
n = lc_create("act_log", drbd_al_ext_cache,
n = lc_create("act_log", drbd_al_ext_cache, 1,
mdev->sync_conf.al_extents, sizeof(struct lc_element), 0);
if (n == NULL) {
@ -1016,7 +1016,7 @@ static int drbd_nl_disk_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp
}
resync_lru = lc_create("resync", drbd_bm_ext_cache,
61, sizeof(struct bm_extent),
1, 61, sizeof(struct bm_extent),
offsetof(struct bm_extent, lce));
if (!resync_lru) {
retcode = ERR_NOMEM;

70
include/linux/lru_cache.h
View file

@ -166,9 +166,11 @@ struct lc_element {
/* if we want to track a larger set of objects,
* it needs to become arch independend u64 */
unsigned lc_number;
/* special label when on free list */
#define LC_FREE (~0U)
/* for pending changes */
unsigned lc_new_number;
};
struct lru_cache {
@ -176,6 +178,7 @@ struct lru_cache {
struct list_head lru;
struct list_head free;
struct list_head in_use;
struct list_head to_be_changed;
/* the pre-created kmem cache to allocate the objects from */
struct kmem_cache *lc_cache;
@ -186,7 +189,7 @@ struct lru_cache {
size_t element_off;
/* number of elements (indices) */
unsigned int nr_elements;
unsigned int nr_elements;
/* Arbitrary limit on maximum tracked objects. Practical limit is much
* lower due to allocation failures, probably. For typical use cases,
* nr_elements should be a few thousand at most.
@ -194,18 +197,19 @@ struct lru_cache {
* 8 high bits of .lc_index to be overloaded with flags in the future. */
#define LC_MAX_ACTIVE (1<<24)
/* allow to accumulate a few (index:label) changes,
* but no more than max_pending_changes */
unsigned int max_pending_changes;
/* number of elements currently on to_be_changed list */
unsigned int pending_changes;
/* statistics */
unsigned used; /* number of lelements currently on in_use list */
unsigned long hits, misses, starving, dirty, changed;
unsigned used; /* number of elements currently on in_use list */
unsigned long hits, misses, starving, locked, changed;
/* see below: flag-bits for lru_cache */
unsigned long flags;
/* when changing the label of an index element */
unsigned int new_number;
/* for paranoia when changing the label of an index element */
struct lc_element *changing_element;
void *lc_private;
const char *name;
@ -221,10 +225,15 @@ enum {
/* debugging aid, to catch concurrent access early.
* user needs to guarantee exclusive access by proper locking! */
__LC_PARANOIA,
/* if we need to change the set, but currently there is a changing
* transaction pending, we are "dirty", and must deferr further
* changing requests */
/* annotate that the set is "dirty", possibly accumulating further
* changes, until a transaction is finally triggered */
__LC_DIRTY,
/* Locked, no further changes allowed.
* Also used to serialize changing transactions. */
__LC_LOCKED,
/* if we need to change the set, but currently there is no free nor
* unused element available, we are "starving", and must not give out
* further references, to guarantee that eventually some refcnt will
@ -236,9 +245,11 @@ enum {
};
#define LC_PARANOIA (1<<__LC_PARANOIA)
#define LC_DIRTY (1<<__LC_DIRTY)
#define LC_LOCKED (1<<__LC_LOCKED)
#define LC_STARVING (1<<__LC_STARVING)
extern struct lru_cache *lc_create(const char *name, struct kmem_cache *cache,
unsigned max_pending_changes,
unsigned e_count, size_t e_size, size_t e_off);
extern void lc_reset(struct lru_cache *lc);
extern void lc_destroy(struct lru_cache *lc);
@ -249,7 +260,7 @@ extern struct lc_element *lc_try_get(struct lru_cache *lc, unsigned int enr);
extern struct lc_element *lc_find(struct lru_cache *lc, unsigned int enr);
extern struct lc_element *lc_get(struct lru_cache *lc, unsigned int enr);
extern unsigned int lc_put(struct lru_cache *lc, struct lc_element *e);
extern void lc_changed(struct lru_cache *lc, struct lc_element *e);
extern void lc_committed(struct lru_cache *lc);
struct seq_file;
extern size_t lc_seq_printf_stats(struct seq_file *seq, struct lru_cache *lc);
@ -258,16 +269,28 @@ extern void lc_seq_dump_details(struct seq_file *seq, struct lru_cache *lc, char
void (*detail) (struct seq_file *, struct lc_element *));
/**
* lc_try_lock - can be used to stop lc_get() from changing the tracked set
* lc_try_lock_for_transaction - can be used to stop lc_get() from changing the tracked set
* @lc: the lru cache to operate on
*
* Allows (expects) the set to be "dirty". Note that the reference counts and
* order on the active and lru lists may still change. Used to serialize
* changing transactions. Returns true if we aquired the lock.
*/
static inline int lc_try_lock_for_transaction(struct lru_cache *lc)
{
return !test_and_set_bit(__LC_LOCKED, &lc->flags);
}
/**
* lc_try_lock - variant to stop lc_get() from changing the tracked set
* @lc: the lru cache to operate on
*
* Note that the reference counts and order on the active and lru lists may
* still change. Returns true if we acquired the lock.
* still change. Only works on a "clean" set. Returns true if we aquired the
* lock, which means there are no pending changes, and any further attempt to
* change the set will not succeed until the next lc_unlock().
*/
static inline int lc_try_lock(struct lru_cache *lc)
{
return !test_and_set_bit(__LC_DIRTY, &lc->flags);
}
extern int lc_try_lock(struct lru_cache *lc);
/**
* lc_unlock - unlock @lc, allow lc_get() to change the set again
@ -275,14 +298,11 @@ static inline int lc_try_lock(struct lru_cache *lc)
*/
static inline void lc_unlock(struct lru_cache *lc)
{
clear_bit_unlock(__LC_DIRTY, &lc->flags);
clear_bit(__LC_DIRTY, &lc->flags);
clear_bit_unlock(__LC_LOCKED, &lc->flags);
}
static inline int lc_is_used(struct lru_cache *lc, unsigned int enr)
{
struct lc_element *e = lc_find(lc, enr);
return e && e->refcnt;
}
extern bool lc_is_used(struct lru_cache *lc, unsigned int enr);
#define lc_entry(ptr, type, member) \
container_of(ptr, type, member)

243
lib/lru_cache.c
View file

@ -55,9 +55,40 @@ MODULE_LICENSE("GPL");
BUG_ON(i >= lc_->nr_elements); \
BUG_ON(lc_->lc_element[i] != e_); } while (0)
/* We need to atomically
* - try to grab the lock (set LC_LOCKED)
* - only if there is no pending transaction
* (neither LC_DIRTY nor LC_STARVING is set)
* Because of PARANOIA_ENTRY() above abusing lc->flags as well,
* it is not sufficient to just say
* return 0 == cmpxchg(&lc->flags, 0, LC_LOCKED);
*/
int lc_try_lock(struct lru_cache *lc)
{
unsigned long val;
do {
val = cmpxchg(&lc->flags, 0, LC_LOCKED);
} while (unlikely (val == LC_PARANOIA));
/* Spin until no-one is inside a PARANOIA_ENTRY()/RETURN() section. */
return 0 == val;
#if 0
/* Alternative approach, spin in case someone enters or leaves a
* PARANOIA_ENTRY()/RETURN() section. */
unsigned long old, new, val;
do {
old = lc->flags & LC_PARANOIA;
new = old | LC_LOCKED;
val = cmpxchg(&lc->flags, old, new);
} while (unlikely (val == (old ^ LC_PARANOIA)));
return old == val;
#endif
}
/**
* lc_create - prepares to track objects in an active set
* @name: descriptive name only used in lc_seq_printf_stats and lc_seq_dump_details
* @max_pending_changes: maximum changes to accumulate until a transaction is required
* @e_count: number of elements allowed to be active simultaneously
* @e_size: size of the tracked objects
* @e_off: offset to the &struct lc_element member in a tracked object
@ -66,6 +97,7 @@ MODULE_LICENSE("GPL");
* or NULL on (allocation) failure.
*/
struct lru_cache *lc_create(const char *name, struct kmem_cache *cache,
unsigned max_pending_changes,
unsigned e_count, size_t e_size, size_t e_off)
{
struct hlist_head *slot = NULL;
@ -98,12 +130,13 @@ struct lru_cache *lc_create(const char *name, struct kmem_cache *cache,
INIT_LIST_HEAD(&lc->in_use);
INIT_LIST_HEAD(&lc->lru);
INIT_LIST_HEAD(&lc->free);
INIT_LIST_HEAD(&lc->to_be_changed);
lc->name = name;
lc->element_size = e_size;
lc->element_off = e_off;
lc->nr_elements = e_count;
lc->new_number = LC_FREE;
lc->max_pending_changes = max_pending_changes;
lc->lc_cache = cache;
lc->lc_element = element;
lc->lc_slot = slot;
@ -117,6 +150,7 @@ struct lru_cache *lc_create(const char *name, struct kmem_cache *cache,
e = p + e_off;
e->lc_index = i;
e->lc_number = LC_FREE;
e->lc_new_number = LC_FREE;
list_add(&e->list, &lc->free);
element[i] = e;
}
@ -175,15 +209,15 @@ void lc_reset(struct lru_cache *lc)
INIT_LIST_HEAD(&lc->in_use);
INIT_LIST_HEAD(&lc->lru);
INIT_LIST_HEAD(&lc->free);
INIT_LIST_HEAD(&lc->to_be_changed);
lc->used = 0;
lc->hits = 0;
lc->misses = 0;
lc->starving = 0;
lc->dirty = 0;
lc->locked = 0;
lc->changed = 0;
lc->pending_changes = 0;
lc->flags = 0;
lc->changing_element = NULL;
lc->new_number = LC_FREE;
memset(lc->lc_slot, 0, sizeof(struct hlist_head) * lc->nr_elements);
for (i = 0; i < lc->nr_elements; i++) {
@ -194,6 +228,7 @@ void lc_reset(struct lru_cache *lc)
/* re-init it */
e->lc_index = i;
e->lc_number = LC_FREE;
e->lc_new_number = LC_FREE;
list_add(&e->list, &lc->free);
}
}
@ -208,14 +243,14 @@ size_t lc_seq_printf_stats(struct seq_file *seq, struct lru_cache *lc)
/* NOTE:
* total calls to lc_get are
* (starving + hits + misses)
* misses include "dirty" count (update from an other thread in
* misses include "locked" count (update from an other thread in
* progress) and "changed", when this in fact lead to an successful
* update of the cache.
*/
return seq_printf(seq, "\t%s: used:%u/%u "
"hits:%lu misses:%lu starving:%lu dirty:%lu changed:%lu\n",
"hits:%lu misses:%lu starving:%lu locked:%lu changed:%lu\n",
lc->name, lc->used, lc->nr_elements,
lc->hits, lc->misses, lc->starving, lc->dirty, lc->changed);
lc->hits, lc->misses, lc->starving, lc->locked, lc->changed);
}
static struct hlist_head *lc_hash_slot(struct lru_cache *lc, unsigned int enr)
@ -224,6 +259,27 @@ static struct hlist_head *lc_hash_slot(struct lru_cache *lc, unsigned int enr)
}
static struct lc_element *__lc_find(struct lru_cache *lc, unsigned int enr,
bool include_changing)
{
struct hlist_node *n;
struct lc_element *e;
BUG_ON(!lc);
BUG_ON(!lc->nr_elements);
hlist_for_each_entry(e, n, lc_hash_slot(lc, enr), colision) {
/* "about to be changed" elements, pending transaction commit,
* are hashed by their "new number". "Normal" elements have
* lc_number == lc_new_number. */
if (e->lc_new_number != enr)
continue;
if (e->lc_new_number == e->lc_number || include_changing)
return e;
break;
}
return NULL;
}
/**
* lc_find - find element by label, if present in the hash table
* @lc: The lru_cache object
@ -232,38 +288,28 @@ static struct hlist_head *lc_hash_slot(struct lru_cache *lc, unsigned int enr)
* Returns the pointer to an element, if the element with the requested
* "label" or element number is present in the hash table,
* or NULL if not found. Does not change the refcnt.
* Ignores elements that are "about to be used", i.e. not yet in the active
* set, but still pending transaction commit.
*/
struct lc_element *lc_find(struct lru_cache *lc, unsigned int enr)
{
struct hlist_node *n;
struct lc_element *e;
BUG_ON(!lc);
BUG_ON(!lc->nr_elements);
hlist_for_each_entry(e, n, lc_hash_slot(lc, enr), colision) {
if (e->lc_number == enr)
return e;
}
return NULL;
return __lc_find(lc, enr, 0);
}
/* returned element will be "recycled" immediately */
static struct lc_element *lc_evict(struct lru_cache *lc)
/**
* lc_is_used - find element by label
* @lc: The lru_cache object
* @enr: element number
*
* Returns true, if the element with the requested "label" or element number is
* present in the hash table, and is used (refcnt > 0).
* Also finds elements that are not _currently_ used but only "about to be
* used", i.e. on the "to_be_changed" list, pending transaction commit.
*/
bool lc_is_used(struct lru_cache *lc, unsigned int enr)
{
struct list_head *n;
struct lc_element *e;
if (list_empty(&lc->lru))
return NULL;
n = lc->lru.prev;
e = list_entry(n, struct lc_element, list);
PARANOIA_LC_ELEMENT(lc, e);
list_del(&e->list);
hlist_del(&e->colision);
return e;
struct lc_element *e = __lc_find(lc, enr, 1);
return e && e->refcnt;
}
/**
@ -280,22 +326,34 @@ void lc_del(struct lru_cache *lc, struct lc_element *e)
PARANOIA_LC_ELEMENT(lc, e);
BUG_ON(e->refcnt);
e->lc_number = LC_FREE;
e->lc_number = e->lc_new_number = LC_FREE;
hlist_del_init(&e->colision);
list_move(&e->list, &lc->free);
RETURN();
}
static struct lc_element *lc_get_unused_element(struct lru_cache *lc)
static struct lc_element *lc_prepare_for_change(struct lru_cache *lc, unsigned new_number)
{
struct list_head *n;
struct lc_element *e;
if (list_empty(&lc->free))
return lc_evict(lc);
if (!list_empty(&lc->free))
n = lc->free.next;
else if (!list_empty(&lc->lru))
n = lc->lru.prev;
else
return NULL;
n = lc->free.next;
list_del(n);
return list_entry(n, struct lc_element, list);
e = list_entry(n, struct lc_element, list);
PARANOIA_LC_ELEMENT(lc, e);
e->lc_new_number = new_number;
if (!hlist_unhashed(&e->colision))
__hlist_del(&e->colision);
hlist_add_head(&e->colision, lc_hash_slot(lc, new_number));
list_move(&e->list, &lc->to_be_changed);
return e;
}
static int lc_unused_element_available(struct lru_cache *lc)
@ -318,8 +376,12 @@ static struct lc_element *__lc_get(struct lru_cache *lc, unsigned int enr, bool
RETURN(NULL);
}
e = lc_find(lc, enr);
if (e) {
e = __lc_find(lc, enr, 1);
/* if lc_new_number != lc_number,
* this enr is currently being pulled in already,
* and will be available once the pending transaction
* has been committed. */
if (e && e->lc_new_number == e->lc_number) {
++lc->hits;
if (e->refcnt++ == 0)
lc->used++;
@ -331,6 +393,24 @@ static struct lc_element *__lc_get(struct lru_cache *lc, unsigned int enr, bool
if (!may_change)
RETURN(NULL);
/* It has been found above, but on the "to_be_changed" list, not yet
* committed. Don't pull it in twice, wait for the transaction, then
* try again */
if (e)
RETURN(NULL);
/* To avoid races with lc_try_lock(), first, mark us dirty
* (using test_and_set_bit, as it implies memory barriers), ... */
test_and_set_bit(__LC_DIRTY, &lc->flags);
/* ... only then check if it is locked anyways. If lc_unlock clears
* the dirty bit again, that's not a problem, we will come here again.
*/
if (test_bit(__LC_LOCKED, &lc->flags)) {
++lc->locked;
RETURN(NULL);
}
/* In case there is nothing available and we can not kick out
* the LRU element, we have to wait ...
*/
@ -339,24 +419,19 @@ static struct lc_element *__lc_get(struct lru_cache *lc, unsigned int enr, bool
RETURN(NULL);
}
/* it was not present in the active set.
* we are going to recycle an unused (or even "free") element.
* user may need to commit a transaction to record that change.
* we serialize on flags & LC_DIRTY */
if (test_and_set_bit(__LC_DIRTY, &lc->flags)) {
++lc->dirty;
/* It was not present in the active set. We are going to recycle an
* unused (or even "free") element, but we won't accumulate more than
* max_pending_changes changes. */
if (lc->pending_changes >= lc->max_pending_changes)
RETURN(NULL);
}
e = lc_get_unused_element(lc);
e = lc_prepare_for_change(lc, enr);
BUG_ON(!e);
clear_bit(__LC_STARVING, &lc->flags);
BUG_ON(++e->refcnt != 1);
lc->used++;
lc->changing_element = e;
lc->new_number = enr;
lc->pending_changes++;
RETURN(e);
}
@ -388,12 +463,15 @@ static struct lc_element *__lc_get(struct lru_cache *lc, unsigned int enr, bool
* pointer to an UNUSED element with some different element number,
* where that different number may also be %LC_FREE.
*
* In this case, the cache is marked %LC_DIRTY (blocking further changes),
* and the returned element pointer is removed from the lru list and
* hash collision chains. The user now should do whatever housekeeping
* is necessary.
* Then he must call lc_changed(lc,element_pointer), to finish
* the change.
* In this case, the cache is marked %LC_DIRTY,
* so lc_try_lock() will no longer succeed.
* The returned element pointer is moved to the "to_be_changed" list,
* and registered with the new element number on the hash collision chains,
* so it is possible to pick it up from lc_is_used().
* Up to "max_pending_changes" (see lc_create()) can be accumulated.
* The user now should do whatever housekeeping is necessary,
* typically serialize on lc_try_lock_for_transaction(), then call
* lc_committed(lc) and lc_unlock(), to finish the change.
*
* NOTE: The user needs to check the lc_number on EACH use, so he recognizes
* any cache set change.
@ -425,22 +503,25 @@ struct lc_element *lc_try_get(struct lru_cache *lc, unsigned int enr)
}
/**
* lc_changed - tell @lc that the change has been recorded
* lc_committed - tell @lc that pending changes have been recorded
* @lc: the lru cache to operate on
* @e: the element pending label change
*
* User is expected to serialize on explicit lc_try_lock_for_transaction()
* before the transaction is started, and later needs to lc_unlock() explicitly
* as well.
*/
void lc_changed(struct lru_cache *lc, struct lc_element *e)
void lc_committed(struct lru_cache *lc)
{
struct lc_element *e, *tmp;
PARANOIA_ENTRY();
BUG_ON(e != lc->changing_element);
PARANOIA_LC_ELEMENT(lc, e);
++lc->changed;
e->lc_number = lc->new_number;
list_add(&e->list, &lc->in_use);
hlist_add_head(&e->colision, lc_hash_slot(lc, lc->new_number));
lc->changing_element = NULL;
lc->new_number = LC_FREE;
clear_bit_unlock(__LC_DIRTY, &lc->flags);
list_for_each_entry_safe(e, tmp, &lc->to_be_changed, list) {
/* count number of changes, not number of transactions */
++lc->changed;
e->lc_number = e->lc_new_number;
list_move(&e->list, &lc->in_use);
}
lc->pending_changes = 0;
RETURN();
}
@ -459,7 +540,7 @@ unsigned int lc_put(struct lru_cache *lc, struct lc_element *e)
PARANOIA_ENTRY();
PARANOIA_LC_ELEMENT(lc, e);
BUG_ON(e->refcnt == 0);
BUG_ON(e == lc->changing_element);
BUG_ON(e->lc_number != e->lc_new_number);
if (--e->refcnt == 0) {
/* move it to the front of LRU. */
list_move(&e->list, &lc->lru);
@ -504,16 +585,24 @@ unsigned int lc_index_of(struct lru_cache *lc, struct lc_element *e)
void lc_set(struct lru_cache *lc, unsigned int enr, int index)
{
struct lc_element *e;
struct list_head *lh;
if (index < 0 || index >= lc->nr_elements)
return;
e = lc_element_by_index(lc, index);
e->lc_number = enr;
BUG_ON(e->lc_number != e->lc_new_number);
BUG_ON(e->refcnt != 0);
e->lc_number = e->lc_new_number = enr;
hlist_del_init(&e->colision);
hlist_add_head(&e->colision, lc_hash_slot(lc, enr));
list_move(&e->list, e->refcnt ? &lc->in_use : &lc->lru);
if (enr == LC_FREE)
lh = &lc->free;
else {
hlist_add_head(&e->colision, lc_hash_slot(lc, enr));
lh = &lc->lru;
}
list_move(&e->list, lh);
}
/**
@ -553,8 +642,10 @@ EXPORT_SYMBOL(lc_try_get);
EXPORT_SYMBOL(lc_find);
EXPORT_SYMBOL(lc_get);
EXPORT_SYMBOL(lc_put);
EXPORT_SYMBOL(lc_changed);
EXPORT_SYMBOL(lc_committed);
EXPORT_SYMBOL(lc_element_by_index);
EXPORT_SYMBOL(lc_index_of);
EXPORT_SYMBOL(lc_seq_printf_stats);
EXPORT_SYMBOL(lc_seq_dump_details);
EXPORT_SYMBOL(lc_try_lock);
EXPORT_SYMBOL(lc_is_used);