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T Makphaibulchoketytso
T Makphaibulchoke
authored and
tytso
committed
fs/mbcache.c: change block and index hash chain to hlist_bl_node
This patch changes each mb_cache's both block and index hash chains to use a hlist_bl_node, which contains a built-in lock. This is the first step in decoupling of locks serializing accesses to mb_cache global data and each mb_cache_entry local data. Signed-off-by: T. Makphaibulchoke <tmac@hp.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
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-44
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2 files changed

+85
-44
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‎fs/mbcache.c

Lines changed: 78 additions & 39 deletions
Original file line numberDiff line numberDiff line change
@@ -34,9 +34,9 @@
3434
#include <linux/mm.h>
3535
#include <linux/slab.h>
3636
#include <linux/sched.h>
37-
#include <linux/init.h>
37+
#include <linux/list_bl.h>
3838
#include <linux/mbcache.h>
39-
39+
#include <linux/init.h>
4040

4141
#ifdef MB_CACHE_DEBUG
4242
# define mb_debug(f...) do { \
@@ -87,21 +87,38 @@ static LIST_HEAD(mb_cache_lru_list);
8787
static DEFINE_SPINLOCK(mb_cache_spinlock);
8888

8989
static inline int
90-
__mb_cache_entry_is_hashed(struct mb_cache_entry *ce)
90+
__mb_cache_entry_is_block_hashed(struct mb_cache_entry *ce)
9191
{
92-
return !list_empty(&ce->e_block_list);
92+
return !hlist_bl_unhashed(&ce->e_block_list);
9393
}
9494

9595

96-
static void
97-
__mb_cache_entry_unhash(struct mb_cache_entry *ce)
96+
static inline void
97+
__mb_cache_entry_unhash_block(struct mb_cache_entry *ce)
9898
{
99-
if (__mb_cache_entry_is_hashed(ce)) {
100-
list_del_init(&ce->e_block_list);
101-
list_del(&ce->e_index.o_list);
102-
}
99+
if (__mb_cache_entry_is_block_hashed(ce))
100+
hlist_bl_del_init(&ce->e_block_list);
101+
}
102+
103+
static inline int
104+
__mb_cache_entry_is_index_hashed(struct mb_cache_entry *ce)
105+
{
106+
return !hlist_bl_unhashed(&ce->e_index.o_list);
103107
}
104108

109+
static inline void
110+
__mb_cache_entry_unhash_index(struct mb_cache_entry *ce)
111+
{
112+
if (__mb_cache_entry_is_index_hashed(ce))
113+
hlist_bl_del_init(&ce->e_index.o_list);
114+
}
115+
116+
static inline void
117+
__mb_cache_entry_unhash(struct mb_cache_entry *ce)
118+
{
119+
__mb_cache_entry_unhash_index(ce);
120+
__mb_cache_entry_unhash_block(ce);
121+
}
105122

106123
static void
107124
__mb_cache_entry_forget(struct mb_cache_entry *ce, gfp_t gfp_mask)
@@ -125,7 +142,7 @@ __mb_cache_entry_release_unlock(struct mb_cache_entry *ce)
125142
ce->e_used -= MB_CACHE_WRITER;
126143
ce->e_used--;
127144
if (!(ce->e_used || ce->e_queued)) {
128-
if (!__mb_cache_entry_is_hashed(ce))
145+
if (!__mb_cache_entry_is_block_hashed(ce))
129146
goto forget;
130147
mb_assert(list_empty(&ce->e_lru_list));
131148
list_add_tail(&ce->e_lru_list, &mb_cache_lru_list);
@@ -221,18 +238,18 @@ mb_cache_create(const char *name, int bucket_bits)
221238
cache->c_name = name;
222239
atomic_set(&cache->c_entry_count, 0);
223240
cache->c_bucket_bits = bucket_bits;
224-
cache->c_block_hash = kmalloc(bucket_count * sizeof(struct list_head),
225-
GFP_KERNEL);
241+
cache->c_block_hash = kmalloc(bucket_count *
242+
sizeof(struct hlist_bl_head), GFP_KERNEL);
226243
if (!cache->c_block_hash)
227244
goto fail;
228245
for (n=0; n<bucket_count; n++)
229-
INIT_LIST_HEAD(&cache->c_block_hash[n]);
230-
cache->c_index_hash = kmalloc(bucket_count * sizeof(struct list_head),
231-
GFP_KERNEL);
246+
INIT_HLIST_BL_HEAD(&cache->c_block_hash[n]);
247+
cache->c_index_hash = kmalloc(bucket_count *
248+
sizeof(struct hlist_bl_head), GFP_KERNEL);
232249
if (!cache->c_index_hash)
233250
goto fail;
234251
for (n=0; n<bucket_count; n++)
235-
INIT_LIST_HEAD(&cache->c_index_hash[n]);
252+
INIT_HLIST_BL_HEAD(&cache->c_index_hash[n]);
236253
cache->c_entry_cache = kmem_cache_create(name,
237254
sizeof(struct mb_cache_entry), 0,
238255
SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD, NULL);
@@ -364,10 +381,13 @@ mb_cache_entry_alloc(struct mb_cache *cache, gfp_t gfp_flags)
364381
return NULL;
365382
atomic_inc(&cache->c_entry_count);
366383
INIT_LIST_HEAD(&ce->e_lru_list);
367-
INIT_LIST_HEAD(&ce->e_block_list);
384+
INIT_HLIST_BL_NODE(&ce->e_block_list);
385+
INIT_HLIST_BL_NODE(&ce->e_index.o_list);
368386
ce->e_cache = cache;
369387
ce->e_queued = 0;
370388
}
389+
ce->e_block_hash_p = &cache->c_block_hash[0];
390+
ce->e_index_hash_p = &cache->c_index_hash[0];
371391
ce->e_used = 1 + MB_CACHE_WRITER;
372392
return ce;
373393
}
@@ -393,25 +413,32 @@ mb_cache_entry_insert(struct mb_cache_entry *ce, struct block_device *bdev,
393413
{
394414
struct mb_cache *cache = ce->e_cache;
395415
unsigned int bucket;
396-
struct list_head *l;
416+
struct hlist_bl_node *l;
397417
int error = -EBUSY;
418+
struct hlist_bl_head *block_hash_p;
419+
struct hlist_bl_head *index_hash_p;
420+
struct mb_cache_entry *lce;
398421

422+
mb_assert(ce);
399423
bucket = hash_long((unsigned long)bdev + (block & 0xffffffff),
400424
cache->c_bucket_bits);
425+
block_hash_p = &cache->c_block_hash[bucket];
401426
spin_lock(&mb_cache_spinlock);
402-
list_for_each_prev(l, &cache->c_block_hash[bucket]) {
403-
struct mb_cache_entry *ce =
404-
list_entry(l, struct mb_cache_entry, e_block_list);
405-
if (ce->e_bdev == bdev && ce->e_block == block)
427+
hlist_bl_for_each_entry(lce, l, block_hash_p, e_block_list) {
428+
if (lce->e_bdev == bdev && lce->e_block == block)
406429
goto out;
407430
}
431+
mb_assert(!__mb_cache_entry_is_block_hashed(ce));
408432
__mb_cache_entry_unhash(ce);
409433
ce->e_bdev = bdev;
410434
ce->e_block = block;
411-
list_add(&ce->e_block_list, &cache->c_block_hash[bucket]);
435+
ce->e_block_hash_p = block_hash_p;
412436
ce->e_index.o_key = key;
413437
bucket = hash_long(key, cache->c_bucket_bits);
414-
list_add(&ce->e_index.o_list, &cache->c_index_hash[bucket]);
438+
index_hash_p = &cache->c_index_hash[bucket];
439+
ce->e_index_hash_p = index_hash_p;
440+
hlist_bl_add_head(&ce->e_index.o_list, index_hash_p);
441+
hlist_bl_add_head(&ce->e_block_list, block_hash_p);
415442
error = 0;
416443
out:
417444
spin_unlock(&mb_cache_spinlock);
@@ -463,14 +490,16 @@ mb_cache_entry_get(struct mb_cache *cache, struct block_device *bdev,
463490
sector_t block)
464491
{
465492
unsigned int bucket;
466-
struct list_head *l;
493+
struct hlist_bl_node *l;
467494
struct mb_cache_entry *ce;
495+
struct hlist_bl_head *block_hash_p;
468496

469497
bucket = hash_long((unsigned long)bdev + (block & 0xffffffff),
470498
cache->c_bucket_bits);
499+
block_hash_p = &cache->c_block_hash[bucket];
471500
spin_lock(&mb_cache_spinlock);
472-
list_for_each(l, &cache->c_block_hash[bucket]) {
473-
ce = list_entry(l, struct mb_cache_entry, e_block_list);
501+
hlist_bl_for_each_entry(ce, l, block_hash_p, e_block_list) {
502+
mb_assert(ce->e_block_hash_p == block_hash_p);
474503
if (ce->e_bdev == bdev && ce->e_block == block) {
475504
DEFINE_WAIT(wait);
476505

@@ -489,7 +518,7 @@ mb_cache_entry_get(struct mb_cache *cache, struct block_device *bdev,
489518
finish_wait(&mb_cache_queue, &wait);
490519
ce->e_used += 1 + MB_CACHE_WRITER;
491520

492-
if (!__mb_cache_entry_is_hashed(ce)) {
521+
if (!__mb_cache_entry_is_block_hashed(ce)) {
493522
__mb_cache_entry_release_unlock(ce);
494523
return NULL;
495524
}
@@ -506,12 +535,14 @@ mb_cache_entry_get(struct mb_cache *cache, struct block_device *bdev,
506535
#if !defined(MB_CACHE_INDEXES_COUNT) || (MB_CACHE_INDEXES_COUNT > 0)
507536

508537
static struct mb_cache_entry *
509-
__mb_cache_entry_find(struct list_head *l, struct list_head *head,
538+
__mb_cache_entry_find(struct hlist_bl_node *l, struct hlist_bl_head *head,
510539
struct block_device *bdev, unsigned int key)
511540
{
512-
while (l != head) {
541+
while (l != NULL) {
513542
struct mb_cache_entry *ce =
514-
list_entry(l, struct mb_cache_entry, e_index.o_list);
543+
hlist_bl_entry(l, struct mb_cache_entry,
544+
e_index.o_list);
545+
mb_assert(ce->e_index_hash_p == head);
515546
if (ce->e_bdev == bdev && ce->e_index.o_key == key) {
516547
DEFINE_WAIT(wait);
517548

@@ -532,7 +563,7 @@ __mb_cache_entry_find(struct list_head *l, struct list_head *head,
532563
}
533564
finish_wait(&mb_cache_queue, &wait);
534565

535-
if (!__mb_cache_entry_is_hashed(ce)) {
566+
if (!__mb_cache_entry_is_block_hashed(ce)) {
536567
__mb_cache_entry_release_unlock(ce);
537568
spin_lock(&mb_cache_spinlock);
538569
return ERR_PTR(-EAGAIN);
@@ -562,12 +593,16 @@ mb_cache_entry_find_first(struct mb_cache *cache, struct block_device *bdev,
562593
unsigned int key)
563594
{
564595
unsigned int bucket = hash_long(key, cache->c_bucket_bits);
565-
struct list_head *l;
566-
struct mb_cache_entry *ce;
596+
struct hlist_bl_node *l;
597+
struct mb_cache_entry *ce = NULL;
598+
struct hlist_bl_head *index_hash_p;
567599

600+
index_hash_p = &cache->c_index_hash[bucket];
568601
spin_lock(&mb_cache_spinlock);
569-
l = cache->c_index_hash[bucket].next;
570-
ce = __mb_cache_entry_find(l, &cache->c_index_hash[bucket], bdev, key);
602+
if (!hlist_bl_empty(index_hash_p)) {
603+
l = hlist_bl_first(index_hash_p);
604+
ce = __mb_cache_entry_find(l, index_hash_p, bdev, key);
605+
}
571606
spin_unlock(&mb_cache_spinlock);
572607
return ce;
573608
}
@@ -597,12 +632,16 @@ mb_cache_entry_find_next(struct mb_cache_entry *prev,
597632
{
598633
struct mb_cache *cache = prev->e_cache;
599634
unsigned int bucket = hash_long(key, cache->c_bucket_bits);
600-
struct list_head *l;
635+
struct hlist_bl_node *l;
601636
struct mb_cache_entry *ce;
637+
struct hlist_bl_head *index_hash_p;
602638

639+
index_hash_p = &cache->c_index_hash[bucket];
640+
mb_assert(prev->e_index_hash_p == index_hash_p);
603641
spin_lock(&mb_cache_spinlock);
642+
mb_assert(!hlist_bl_empty(index_hash_p));
604643
l = prev->e_index.o_list.next;
605-
ce = __mb_cache_entry_find(l, &cache->c_index_hash[bucket], bdev, key);
644+
ce = __mb_cache_entry_find(l, index_hash_p, bdev, key);
606645
__mb_cache_entry_release_unlock(prev);
607646
return ce;
608647
}

‎include/linux/mbcache.h

Lines changed: 7 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -3,19 +3,21 @@
33
44
(C) 2001 by Andreas Gruenbacher, <a.gruenbacher@computer.org>
55
*/
6-
76
struct mb_cache_entry {
87
struct list_head e_lru_list;
98
struct mb_cache *e_cache;
109
unsigned short e_used;
1110
unsigned short e_queued;
11+
atomic_t e_refcnt;
1212
struct block_device *e_bdev;
1313
sector_t e_block;
14-
struct list_head e_block_list;
14+
struct hlist_bl_node e_block_list;
1515
struct {
16-
struct list_head o_list;
16+
struct hlist_bl_node o_list;
1717
unsigned int o_key;
1818
} e_index;
19+
struct hlist_bl_head *e_block_hash_p;
20+
struct hlist_bl_head *e_index_hash_p;
1921
};
2022

2123
struct mb_cache {
@@ -25,8 +27,8 @@ struct mb_cache {
2527
int c_max_entries;
2628
int c_bucket_bits;
2729
struct kmem_cache *c_entry_cache;
28-
struct list_head *c_block_hash;
29-
struct list_head *c_index_hash;
30+
struct hlist_bl_head *c_block_hash;
31+
struct hlist_bl_head *c_index_hash;
3032
};
3133

3234
/* Functions on caches */

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