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-rw-r--r--drivers/md/dm-thin.c124
1 files changed, 73 insertions, 51 deletions
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index c308757..da2f021 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -124,7 +124,7 @@ struct cell {
struct hlist_node list;
struct bio_prison *prison;
struct cell_key key;
- unsigned count;
+ struct bio *holder;
struct bio_list bios;
};
@@ -220,55 +220,60 @@ static struct cell *__search_bucket(struct hlist_head *bucket,
* 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 the number of entries in the cell prior to the new addition
- * or < 0 on failure.
+ * Returns 1 if the cell was already held, 0 if @inmate is the new holder.
*/
static int bio_detain(struct bio_prison *prison, struct cell_key *key,
struct bio *inmate, struct cell **ref)
{
- int r;
+ int r = 1;
unsigned long flags;
uint32_t hash = hash_key(prison, key);
- struct cell *uninitialized_var(cell), *cell2 = NULL;
+ struct 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;
+ }
- if (!cell) {
- /*
- * Allocate a new cell
- */
- spin_unlock_irqrestore(&prison->lock, flags);
- cell2 = mempool_alloc(prison->cell_pool, GFP_NOIO);
- spin_lock_irqsave(&prison->lock, flags);
+ /*
+ * Allocate a new cell
+ */
+ spin_unlock_irqrestore(&prison->lock, flags);
+ cell2 = mempool_alloc(prison->cell_pool, GFP_NOIO);
+ spin_lock_irqsave(&prison->lock, flags);
- /*
- * 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);
+ /*
+ * 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;
+ }
+
+ /*
+ * Use new cell.
+ */
+ cell = cell2;
- if (!cell) {
- cell = cell2;
- cell2 = NULL;
+ 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);
- cell->prison = prison;
- memcpy(&cell->key, key, sizeof(cell->key));
- cell->count = 0;
- bio_list_init(&cell->bios);
- hlist_add_head(&cell->list, prison->cells + hash);
- }
- }
+ r = 0;
- r = cell->count++;
- bio_list_add(&cell->bios, inmate);
+out:
spin_unlock_irqrestore(&prison->lock, flags);
- if (cell2)
- mempool_free(cell2, prison->cell_pool);
-
*ref = cell;
return r;
@@ -283,8 +288,8 @@ static void __cell_release(struct cell *cell, struct bio_list *inmates)
hlist_del(&cell->list);
- if (inmates)
- bio_list_merge(inmates, &cell->bios);
+ bio_list_add(inmates, cell->holder);
+ bio_list_merge(inmates, &cell->bios);
mempool_free(cell, prison->cell_pool);
}
@@ -305,22 +310,44 @@ static void cell_release(struct cell *cell, struct bio_list *bios)
* bio may be in the cell. This function releases the cell, and also does
* a sanity check.
*/
+static void __cell_release_singleton(struct cell *cell, struct bio *bio)
+{
+ hlist_del(&cell->list);
+ BUG_ON(cell->holder != bio);
+ BUG_ON(!bio_list_empty(&cell->bios));
+}
+
static void cell_release_singleton(struct cell *cell, struct bio *bio)
{
- struct bio_prison *prison = cell->prison;
- struct bio_list bios;
- struct bio *b;
unsigned long flags;
-
- bio_list_init(&bios);
+ struct bio_prison *prison = cell->prison;
spin_lock_irqsave(&prison->lock, flags);
- __cell_release(cell, &bios);
+ __cell_release_singleton(cell, bio);
spin_unlock_irqrestore(&prison->lock, flags);
+}
+
+/*
+ * Sometimes we don't want the holder, just the additional bios.
+ */
+static void __cell_release_no_holder(struct cell *cell, struct bio_list *inmates)
+{
+ struct bio_prison *prison = cell->prison;
- b = bio_list_pop(&bios);
- BUG_ON(b != bio);
- BUG_ON(!bio_list_empty(&bios));
+ hlist_del(&cell->list);
+ bio_list_merge(inmates, &cell->bios);
+
+ mempool_free(cell, prison->cell_pool);
+}
+
+static void cell_release_no_holder(struct cell *cell, struct bio_list *inmates)
+{
+ unsigned long flags;
+ struct bio_prison *prison = cell->prison;
+
+ spin_lock_irqsave(&prison->lock, flags);
+ __cell_release_no_holder(cell, inmates);
+ spin_unlock_irqrestore(&prison->lock, flags);
}
static void cell_error(struct cell *cell)
@@ -800,21 +827,16 @@ static void cell_defer(struct thin_c *tc, struct cell *cell,
* Same as cell_defer above, except it omits one particular detainee,
* a write bio that covers the block and has already been processed.
*/
-static void cell_defer_except(struct thin_c *tc, struct cell *cell,
- struct bio *exception)
+static void cell_defer_except(struct thin_c *tc, struct cell *cell)
{
struct bio_list bios;
- struct bio *bio;
struct pool *pool = tc->pool;
unsigned long flags;
bio_list_init(&bios);
- cell_release(cell, &bios);
spin_lock_irqsave(&pool->lock, flags);
- while ((bio = bio_list_pop(&bios)))
- if (bio != exception)
- bio_list_add(&pool->deferred_bios, bio);
+ cell_release_no_holder(cell, &pool->deferred_bios);
spin_unlock_irqrestore(&pool->lock, flags);
wake_worker(pool);
@@ -854,7 +876,7 @@ static void process_prepared_mapping(struct new_mapping *m)
* the bios in the cell.
*/
if (bio) {
- cell_defer_except(tc, m->cell, bio);
+ cell_defer_except(tc, m->cell);
bio_endio(bio, 0);
} else
cell_defer(tc, m->cell, m->data_block);
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