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authorJoe Thornber <ejt@redhat.com>2013-03-01 22:45:50 +0000
committerAlasdair G Kergon <agk@redhat.com>2013-03-01 22:45:50 +0000
commit6beca5eb6e801aea810da6cbc4990d96e6c1c0bc (patch)
tree37586c9ecdd7bbc89ce4db07abde3ca32d6a8e1c /drivers/md/dm-bio-prison.c
parent4e7f1f9089660aec3b5ab2645ce62777c6f4c6a2 (diff)
dm bio prison: pass cell memory in
Change the dm_bio_prison interface so that instead of allocating memory internally, dm_bio_detain is supplied with a pre-allocated cell each time it is called. This enables a subsequent patch to move the allocation of the struct dm_bio_prison_cell outside the thin target's mapping function so it can no longer block there. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers/md/dm-bio-prison.c')
-rw-r--r--drivers/md/dm-bio-prison.c139
1 files changed, 72 insertions, 67 deletions
diff --git a/drivers/md/dm-bio-prison.c b/drivers/md/dm-bio-prison.c
index d9d3f1c7b662..ca5771d3ffd7 100644
--- a/drivers/md/dm-bio-prison.c
+++ b/drivers/md/dm-bio-prison.c
@@ -16,7 +16,6 @@
struct dm_bio_prison_cell {
struct hlist_node list;
- struct dm_bio_prison *prison;
struct dm_cell_key key;
struct bio *holder;
struct bio_list bios;
@@ -87,6 +86,19 @@ void dm_bio_prison_destroy(struct dm_bio_prison *prison)
}
EXPORT_SYMBOL_GPL(dm_bio_prison_destroy);
+struct dm_bio_prison_cell *dm_bio_prison_alloc_cell(struct dm_bio_prison *prison, gfp_t gfp)
+{
+ return mempool_alloc(prison->cell_pool, gfp);
+}
+EXPORT_SYMBOL_GPL(dm_bio_prison_alloc_cell);
+
+void dm_bio_prison_free_cell(struct dm_bio_prison *prison,
+ struct dm_bio_prison_cell *cell)
+{
+ mempool_free(cell, prison->cell_pool);
+}
+EXPORT_SYMBOL_GPL(dm_bio_prison_free_cell);
+
static uint32_t hash_key(struct dm_bio_prison *prison, struct dm_cell_key *key)
{
const unsigned long BIG_PRIME = 4294967291UL;
@@ -114,91 +126,86 @@ static struct dm_bio_prison_cell *__search_bucket(struct hlist_head *bucket,
return NULL;
}
-/*
- * This may block if a new cell needs allocating. You must ensure that
- * cells will be unlocked even if the calling thread is blocked.
- *
- * Returns 1 if the cell was already held, 0 if @inmate is the new holder.
- */
-int dm_bio_detain(struct dm_bio_prison *prison, struct dm_cell_key *key,
- struct bio *inmate, struct dm_bio_prison_cell **ref)
+static void __setup_new_cell(struct dm_bio_prison *prison,
+ struct dm_cell_key *key,
+ struct bio *holder,
+ uint32_t hash,
+ struct dm_bio_prison_cell *cell)
{
- int r = 1;
- unsigned long flags;
- uint32_t hash = hash_key(prison, key);
- struct dm_bio_prison_cell *cell, *cell2;
-
- BUG_ON(hash > prison->nr_buckets);
-
- spin_lock_irqsave(&prison->lock, flags);
-
- cell = __search_bucket(prison->cells + hash, key);
- if (cell) {
- bio_list_add(&cell->bios, inmate);
- goto out;
- }
+ memcpy(&cell->key, key, sizeof(cell->key));
+ cell->holder = holder;
+ bio_list_init(&cell->bios);
+ hlist_add_head(&cell->list, prison->cells + hash);
+}
- /*
- * Allocate a new cell
- */
- spin_unlock_irqrestore(&prison->lock, flags);
- cell2 = mempool_alloc(prison->cell_pool, GFP_NOIO);
- spin_lock_irqsave(&prison->lock, flags);
+static int __bio_detain(struct dm_bio_prison *prison,
+ struct dm_cell_key *key,
+ struct bio *inmate,
+ struct dm_bio_prison_cell *cell_prealloc,
+ struct dm_bio_prison_cell **cell_result)
+{
+ uint32_t hash = hash_key(prison, key);
+ struct dm_bio_prison_cell *cell;
- /*
- * We've been unlocked, so we have to double check that
- * nobody else has inserted this cell in the meantime.
- */
cell = __search_bucket(prison->cells + hash, key);
if (cell) {
- mempool_free(cell2, prison->cell_pool);
- bio_list_add(&cell->bios, inmate);
- goto out;
+ if (inmate)
+ bio_list_add(&cell->bios, inmate);
+ *cell_result = cell;
+ return 1;
}
- /*
- * Use new cell.
- */
- cell = cell2;
-
- cell->prison = prison;
- memcpy(&cell->key, key, sizeof(cell->key));
- cell->holder = inmate;
- bio_list_init(&cell->bios);
- hlist_add_head(&cell->list, prison->cells + hash);
+ __setup_new_cell(prison, key, inmate, hash, cell_prealloc);
+ *cell_result = cell_prealloc;
+ return 0;
+}
- r = 0;
+static int bio_detain(struct dm_bio_prison *prison,
+ struct dm_cell_key *key,
+ struct bio *inmate,
+ struct dm_bio_prison_cell *cell_prealloc,
+ struct dm_bio_prison_cell **cell_result)
+{
+ int r;
+ unsigned long flags;
-out:
+ spin_lock_irqsave(&prison->lock, flags);
+ r = __bio_detain(prison, key, inmate, cell_prealloc, cell_result);
spin_unlock_irqrestore(&prison->lock, flags);
- *ref = cell;
-
return r;
}
+
+int dm_bio_detain(struct dm_bio_prison *prison,
+ struct dm_cell_key *key,
+ struct bio *inmate,
+ struct dm_bio_prison_cell *cell_prealloc,
+ struct dm_bio_prison_cell **cell_result)
+{
+ return bio_detain(prison, key, inmate, cell_prealloc, cell_result);
+}
EXPORT_SYMBOL_GPL(dm_bio_detain);
/*
* @inmates must have been initialised prior to this call
*/
-static void __cell_release(struct dm_bio_prison_cell *cell, struct bio_list *inmates)
+static void __cell_release(struct dm_bio_prison_cell *cell,
+ struct bio_list *inmates)
{
- struct dm_bio_prison *prison = cell->prison;
-
hlist_del(&cell->list);
if (inmates) {
- bio_list_add(inmates, cell->holder);
+ if (cell->holder)
+ bio_list_add(inmates, cell->holder);
bio_list_merge(inmates, &cell->bios);
}
-
- mempool_free(cell, prison->cell_pool);
}
-void dm_cell_release(struct dm_bio_prison_cell *cell, struct bio_list *bios)
+void dm_cell_release(struct dm_bio_prison *prison,
+ struct dm_bio_prison_cell *cell,
+ struct bio_list *bios)
{
unsigned long flags;
- struct dm_bio_prison *prison = cell->prison;
spin_lock_irqsave(&prison->lock, flags);
__cell_release(cell, bios);
@@ -209,20 +216,18 @@ EXPORT_SYMBOL_GPL(dm_cell_release);
/*
* Sometimes we don't want the holder, just the additional bios.
*/
-static void __cell_release_no_holder(struct dm_bio_prison_cell *cell, struct bio_list *inmates)
+static void __cell_release_no_holder(struct dm_bio_prison_cell *cell,
+ struct bio_list *inmates)
{
- struct dm_bio_prison *prison = cell->prison;
-
hlist_del(&cell->list);
bio_list_merge(inmates, &cell->bios);
-
- mempool_free(cell, prison->cell_pool);
}
-void dm_cell_release_no_holder(struct dm_bio_prison_cell *cell, struct bio_list *inmates)
+void dm_cell_release_no_holder(struct dm_bio_prison *prison,
+ struct dm_bio_prison_cell *cell,
+ struct bio_list *inmates)
{
unsigned long flags;
- struct dm_bio_prison *prison = cell->prison;
spin_lock_irqsave(&prison->lock, flags);
__cell_release_no_holder(cell, inmates);
@@ -230,9 +235,9 @@ void dm_cell_release_no_holder(struct dm_bio_prison_cell *cell, struct bio_list
}
EXPORT_SYMBOL_GPL(dm_cell_release_no_holder);
-void dm_cell_error(struct dm_bio_prison_cell *cell)
+void dm_cell_error(struct dm_bio_prison *prison,
+ struct dm_bio_prison_cell *cell)
{
- struct dm_bio_prison *prison = cell->prison;
struct bio_list bios;
struct bio *bio;
unsigned long flags;