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dm transaction manager: add support for prefetching blocks of metadata

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Introduce the dm_tm_issue_prefetches interface.  If you're using a
non-blocking clone the tm will build up a list of requested blocks that
weren't in core.  dm_tm_issue_prefetches will request those blocks to be
prefetched.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Joe Thornber 2014-10-06 15:27:26 +01:00 committed by Mike Snitzer
parent e5cfc69a51
commit 4646015d7e
2 changed files with 82 additions and 2 deletions
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77
drivers/md/persistent-data/dm-transaction-manager.c
View file

@ -10,6 +10,8 @@
#include "dm-persistent-data-internal.h"
#include <linux/export.h>
#include <linux/mutex.h>
#include <linux/hash.h>
#include <linux/slab.h>
#include <linux/device-mapper.h>
@ -17,6 +19,61 @@
/*----------------------------------------------------------------*/
#define PREFETCH_SIZE 128
#define PREFETCH_BITS 7
#define PREFETCH_SENTINEL ((dm_block_t) -1ULL)
struct prefetch_set {
struct mutex lock;
dm_block_t blocks[PREFETCH_SIZE];
};
static unsigned prefetch_hash(dm_block_t b)
{
return hash_64(b, PREFETCH_BITS);
}
static void prefetch_wipe(struct prefetch_set *p)
{
unsigned i;
for (i = 0; i < PREFETCH_SIZE; i++)
p->blocks[i] = PREFETCH_SENTINEL;
}
static void prefetch_init(struct prefetch_set *p)
{
mutex_init(&p->lock);
prefetch_wipe(p);
}
static void prefetch_add(struct prefetch_set *p, dm_block_t b)
{
unsigned h = prefetch_hash(b);
mutex_lock(&p->lock);
if (p->blocks[h] == PREFETCH_SENTINEL)
p->blocks[h] = b;
mutex_unlock(&p->lock);
}
static void prefetch_issue(struct prefetch_set *p, struct dm_block_manager *bm)
{
unsigned i;
mutex_lock(&p->lock);
for (i = 0; i < PREFETCH_SIZE; i++)
if (p->blocks[i] != PREFETCH_SENTINEL) {
dm_bm_prefetch(bm, p->blocks[i]);
p->blocks[i] = PREFETCH_SENTINEL;
}
mutex_unlock(&p->lock);
}
/*----------------------------------------------------------------*/
struct shadow_info {
struct hlist_node hlist;
dm_block_t where;
@ -37,6 +94,8 @@ struct dm_transaction_manager {
spinlock_t lock;
struct hlist_head buckets[DM_HASH_SIZE];
struct prefetch_set prefetches;
};
/*----------------------------------------------------------------*/
@ -117,6 +176,8 @@ static struct dm_transaction_manager *dm_tm_create(struct dm_block_manager *bm,
for (i = 0; i < DM_HASH_SIZE; i++)
INIT_HLIST_HEAD(tm->buckets + i);
prefetch_init(&tm->prefetches);
return tm;
}
@ -268,8 +329,14 @@ int dm_tm_read_lock(struct dm_transaction_manager *tm, dm_block_t b,
struct dm_block_validator *v,
struct dm_block **blk)
{
if (tm->is_clone)
return dm_bm_read_try_lock(tm->real->bm, b, v, blk);
if (tm->is_clone) {
int r = dm_bm_read_try_lock(tm->real->bm, b, v, blk);
if (r == -EWOULDBLOCK)
prefetch_add(&tm->real->prefetches, b);
return r;
}
return dm_bm_read_lock(tm->bm, b, v, blk);
}
@ -317,6 +384,12 @@ struct dm_block_manager *dm_tm_get_bm(struct dm_transaction_manager *tm)
return tm->bm;
}
void dm_tm_issue_prefetches(struct dm_transaction_manager *tm)
{
prefetch_issue(&tm->prefetches, tm->bm);
}
EXPORT_SYMBOL_GPL(dm_tm_issue_prefetches);
/*----------------------------------------------------------------*/
static int dm_tm_create_internal(struct dm_block_manager *bm,

7
drivers/md/persistent-data/dm-transaction-manager.h
View file

@ -108,6 +108,13 @@ int dm_tm_ref(struct dm_transaction_manager *tm, dm_block_t b,
struct dm_block_manager *dm_tm_get_bm(struct dm_transaction_manager *tm);
/*
* If you're using a non-blocking clone the tm will build up a list of
* requested blocks that weren't in core. This call will request those
* blocks to be prefetched.
*/
void dm_tm_issue_prefetches(struct dm_transaction_manager *tm);
/*
* A little utility that ties the knot by producing a transaction manager
* that has a space map managed by the transaction manager...