forked from luck/tmp_suning_uos_patched
dm transaction manager: add support for prefetching blocks of metadata
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>
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@ -10,6 +10,8 @@
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#include "dm-persistent-data-internal.h"
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#include <linux/export.h>
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#include <linux/mutex.h>
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#include <linux/hash.h>
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#include <linux/slab.h>
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#include <linux/device-mapper.h>
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@ -17,6 +19,61 @@
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/*----------------------------------------------------------------*/
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#define PREFETCH_SIZE 128
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#define PREFETCH_BITS 7
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#define PREFETCH_SENTINEL ((dm_block_t) -1ULL)
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struct prefetch_set {
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struct mutex lock;
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dm_block_t blocks[PREFETCH_SIZE];
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};
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static unsigned prefetch_hash(dm_block_t b)
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{
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return hash_64(b, PREFETCH_BITS);
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}
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static void prefetch_wipe(struct prefetch_set *p)
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{
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unsigned i;
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for (i = 0; i < PREFETCH_SIZE; i++)
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p->blocks[i] = PREFETCH_SENTINEL;
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}
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static void prefetch_init(struct prefetch_set *p)
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{
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mutex_init(&p->lock);
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prefetch_wipe(p);
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}
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static void prefetch_add(struct prefetch_set *p, dm_block_t b)
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{
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unsigned h = prefetch_hash(b);
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mutex_lock(&p->lock);
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if (p->blocks[h] == PREFETCH_SENTINEL)
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p->blocks[h] = b;
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mutex_unlock(&p->lock);
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}
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static void prefetch_issue(struct prefetch_set *p, struct dm_block_manager *bm)
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{
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unsigned i;
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mutex_lock(&p->lock);
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for (i = 0; i < PREFETCH_SIZE; i++)
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if (p->blocks[i] != PREFETCH_SENTINEL) {
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dm_bm_prefetch(bm, p->blocks[i]);
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p->blocks[i] = PREFETCH_SENTINEL;
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}
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mutex_unlock(&p->lock);
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}
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/*----------------------------------------------------------------*/
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struct shadow_info {
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struct hlist_node hlist;
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dm_block_t where;
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@ -37,6 +94,8 @@ struct dm_transaction_manager {
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spinlock_t lock;
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struct hlist_head buckets[DM_HASH_SIZE];
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struct prefetch_set prefetches;
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};
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/*----------------------------------------------------------------*/
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@ -117,6 +176,8 @@ static struct dm_transaction_manager *dm_tm_create(struct dm_block_manager *bm,
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for (i = 0; i < DM_HASH_SIZE; i++)
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INIT_HLIST_HEAD(tm->buckets + i);
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prefetch_init(&tm->prefetches);
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return tm;
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}
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@ -268,8 +329,14 @@ int dm_tm_read_lock(struct dm_transaction_manager *tm, dm_block_t b,
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struct dm_block_validator *v,
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struct dm_block **blk)
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{
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if (tm->is_clone)
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return dm_bm_read_try_lock(tm->real->bm, b, v, blk);
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if (tm->is_clone) {
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int r = dm_bm_read_try_lock(tm->real->bm, b, v, blk);
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if (r == -EWOULDBLOCK)
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prefetch_add(&tm->real->prefetches, b);
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return r;
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}
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return dm_bm_read_lock(tm->bm, b, v, blk);
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}
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@ -317,6 +384,12 @@ struct dm_block_manager *dm_tm_get_bm(struct dm_transaction_manager *tm)
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return tm->bm;
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}
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void dm_tm_issue_prefetches(struct dm_transaction_manager *tm)
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{
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prefetch_issue(&tm->prefetches, tm->bm);
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}
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EXPORT_SYMBOL_GPL(dm_tm_issue_prefetches);
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/*----------------------------------------------------------------*/
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static int dm_tm_create_internal(struct dm_block_manager *bm,
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@ -108,6 +108,13 @@ int dm_tm_ref(struct dm_transaction_manager *tm, dm_block_t b,
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struct dm_block_manager *dm_tm_get_bm(struct dm_transaction_manager *tm);
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/*
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* If you're using a non-blocking clone the tm will build up a list of
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* requested blocks that weren't in core. This call will request those
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* blocks to be prefetched.
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*/
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void dm_tm_issue_prefetches(struct dm_transaction_manager *tm);
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/*
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* A little utility that ties the knot by producing a transaction manager
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* that has a space map managed by the transaction manager...
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