[dm-devel] [PATCH 2/3] dm thin: remove old bio prison code that now lives in dm-bio-prison.c
Mike Snitzer
snitzer at redhat.com
Tue Sep 25 22:35:28 UTC 2012
Signed-off-by: Mike Snitzer <snitzer at redhat.com>
---
drivers/md/dm-thin.c | 374 --------------------------------------------------
1 files changed, 0 insertions(+), 374 deletions(-)
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 39f4d40..1d4831f 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -98,380 +98,6 @@
/*----------------------------------------------------------------*/
-#if 0
-/*
- * Sometimes we can't deal with a bio straight away. We put them in prison
- * where they can't cause any mischief. Bios are put in a cell identified
- * by a key, multiple bios can be in the same cell. When the cell is
- * subsequently unlocked the bios become available.
- */
-struct bio_prison;
-
-struct cell_key {
- int virtual;
- dm_thin_id dev;
- dm_block_t block;
-};
-
-struct dm_bio_prison_cell {
- struct hlist_node list;
- struct bio_prison *prison;
- struct cell_key key;
- struct bio *holder;
- struct bio_list bios;
-};
-
-struct bio_prison {
- spinlock_t lock;
- mempool_t *cell_pool;
-
- unsigned nr_buckets;
- unsigned hash_mask;
- struct hlist_head *cells;
-};
-
-static uint32_t calc_nr_buckets(unsigned nr_cells)
-{
- uint32_t n = 128;
-
- nr_cells /= 4;
- nr_cells = min(nr_cells, 8192u);
-
- while (n < nr_cells)
- n <<= 1;
-
- return n;
-}
-
-static struct kmem_cache *_cell_cache;
-
-/*
- * @nr_cells should be the number of cells you want in use _concurrently_.
- * Don't confuse it with the number of distinct keys.
- */
-static struct bio_prison *prison_create(unsigned nr_cells)
-{
- unsigned i;
- uint32_t nr_buckets = calc_nr_buckets(nr_cells);
- size_t len = sizeof(struct bio_prison) +
- (sizeof(struct hlist_head) * nr_buckets);
- struct bio_prison *prison = kmalloc(len, GFP_KERNEL);
-
- if (!prison)
- return NULL;
-
- spin_lock_init(&prison->lock);
- prison->cell_pool = mempool_create_slab_pool(nr_cells, _cell_cache);
- if (!prison->cell_pool) {
- kfree(prison);
- return NULL;
- }
-
- prison->nr_buckets = nr_buckets;
- prison->hash_mask = nr_buckets - 1;
- prison->cells = (struct hlist_head *) (prison + 1);
- for (i = 0; i < nr_buckets; i++)
- INIT_HLIST_HEAD(prison->cells + i);
-
- return prison;
-}
-
-static void prison_destroy(struct bio_prison *prison)
-{
- mempool_destroy(prison->cell_pool);
- kfree(prison);
-}
-
-static uint32_t hash_key(struct bio_prison *prison, struct cell_key *key)
-{
- const unsigned long BIG_PRIME = 4294967291UL;
- uint64_t hash = key->block * BIG_PRIME;
-
- return (uint32_t) (hash & prison->hash_mask);
-}
-
-static int keys_equal(struct cell_key *lhs, struct cell_key *rhs)
-{
- return (lhs->virtual == rhs->virtual) &&
- (lhs->dev == rhs->dev) &&
- (lhs->block == rhs->block);
-}
-
-static struct dm_bio_prison_cell *__search_bucket(struct hlist_head *bucket,
- struct cell_key *key)
-{
- struct dm_bio_prison_cell *cell;
- struct hlist_node *tmp;
-
- hlist_for_each_entry(cell, tmp, bucket, list)
- if (keys_equal(&cell->key, key))
- return cell;
-
- 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.
- */
-static int bio_detain(struct bio_prison *prison, struct cell_key *key,
- struct bio *inmate, struct dm_bio_prison_cell **ref)
-{
- 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;
- }
-
- /*
- * 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);
- if (cell) {
- mempool_free(cell2, prison->cell_pool);
- bio_list_add(&cell->bios, inmate);
- goto out;
- }
-
- /*
- * 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);
-
- r = 0;
-
-out:
- spin_unlock_irqrestore(&prison->lock, flags);
-
- *ref = cell;
-
- return r;
-}
-
-/*
- * @inmates must have been initialised prior to this call
- */
-static void __cell_release(struct dm_bio_prison_cell *cell, struct bio_list *inmates)
-{
- struct bio_prison *prison = cell->prison;
-
- hlist_del(&cell->list);
-
- if (inmates) {
- bio_list_add(inmates, cell->holder);
- bio_list_merge(inmates, &cell->bios);
- }
-
- mempool_free(cell, prison->cell_pool);
-}
-
-static void cell_release(struct dm_bio_prison_cell *cell, struct bio_list *bios)
-{
- unsigned long flags;
- struct bio_prison *prison = cell->prison;
-
- spin_lock_irqsave(&prison->lock, flags);
- __cell_release(cell, bios);
- spin_unlock_irqrestore(&prison->lock, flags);
-}
-
-/*
- * There are a couple of places where we put a bio into a cell briefly
- * before taking it out again. In these situations we know that no other
- * bio may be in the cell. This function releases the cell, and also does
- * a sanity check.
- */
-static void __cell_release_singleton(struct dm_bio_prison_cell *cell, struct bio *bio)
-{
- BUG_ON(cell->holder != bio);
- BUG_ON(!bio_list_empty(&cell->bios));
-
- __cell_release(cell, NULL);
-}
-
-static void cell_release_singleton(struct dm_bio_prison_cell *cell, struct bio *bio)
-{
- unsigned long flags;
- struct bio_prison *prison = cell->prison;
-
- spin_lock_irqsave(&prison->lock, flags);
- __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 dm_bio_prison_cell *cell,
- struct bio_list *inmates)
-{
- struct bio_prison *prison = cell->prison;
-
- hlist_del(&cell->list);
- bio_list_merge(inmates, &cell->bios);
-
- mempool_free(cell, prison->cell_pool);
-}
-
-static void cell_release_no_holder(struct dm_bio_prison_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 dm_bio_prison_cell *cell)
-{
- struct bio_prison *prison = cell->prison;
- struct bio_list bios;
- struct bio *bio;
- unsigned long flags;
-
- bio_list_init(&bios);
-
- spin_lock_irqsave(&prison->lock, flags);
- __cell_release(cell, &bios);
- spin_unlock_irqrestore(&prison->lock, flags);
-
- while ((bio = bio_list_pop(&bios)))
- bio_io_error(bio);
-}
-
-/*----------------------------------------------------------------*/
-
-/*
- * We use the deferred set to keep track of pending reads to shared blocks.
- * We do this to ensure the new mapping caused by a write isn't performed
- * until these prior reads have completed. Otherwise the insertion of the
- * new mapping could free the old block that the read bios are mapped to.
- */
-
-struct deferred_set;
-struct deferred_entry {
- struct deferred_set *ds;
- unsigned count;
- struct list_head work_items;
-};
-
-struct deferred_set {
- spinlock_t lock;
- unsigned current_entry;
- unsigned sweeper;
- struct deferred_entry entries[DEFERRED_SET_SIZE];
-};
-
-static void ds_init(struct deferred_set *ds)
-{
- int i;
-
- spin_lock_init(&ds->lock);
- ds->current_entry = 0;
- ds->sweeper = 0;
- for (i = 0; i < DEFERRED_SET_SIZE; i++) {
- ds->entries[i].ds = ds;
- ds->entries[i].count = 0;
- INIT_LIST_HEAD(&ds->entries[i].work_items);
- }
-}
-
-static struct deferred_entry *ds_inc(struct deferred_set *ds)
-{
- unsigned long flags;
- struct deferred_entry *entry;
-
- spin_lock_irqsave(&ds->lock, flags);
- entry = ds->entries + ds->current_entry;
- entry->count++;
- spin_unlock_irqrestore(&ds->lock, flags);
-
- return entry;
-}
-
-static unsigned ds_next(unsigned index)
-{
- return (index + 1) % DEFERRED_SET_SIZE;
-}
-
-static void __sweep(struct deferred_set *ds, struct list_head *head)
-{
- while ((ds->sweeper != ds->current_entry) &&
- !ds->entries[ds->sweeper].count) {
- list_splice_init(&ds->entries[ds->sweeper].work_items, head);
- ds->sweeper = ds_next(ds->sweeper);
- }
-
- if ((ds->sweeper == ds->current_entry) && !ds->entries[ds->sweeper].count)
- list_splice_init(&ds->entries[ds->sweeper].work_items, head);
-}
-
-static void ds_dec(struct deferred_entry *entry, struct list_head *head)
-{
- unsigned long flags;
-
- spin_lock_irqsave(&entry->ds->lock, flags);
- BUG_ON(!entry->count);
- --entry->count;
- __sweep(entry->ds, head);
- spin_unlock_irqrestore(&entry->ds->lock, flags);
-}
-
-/*
- * Returns 1 if deferred or 0 if no pending items to delay job.
- */
-static int ds_add_work(struct deferred_set *ds, struct list_head *work)
-{
- int r = 1;
- unsigned long flags;
- unsigned next_entry;
-
- spin_lock_irqsave(&ds->lock, flags);
- if ((ds->sweeper == ds->current_entry) &&
- !ds->entries[ds->current_entry].count)
- r = 0;
- else {
- list_add(work, &ds->entries[ds->current_entry].work_items);
- next_entry = ds_next(ds->current_entry);
- if (!ds->entries[next_entry].count)
- ds->current_entry = next_entry;
- }
- spin_unlock_irqrestore(&ds->lock, flags);
-
- return r;
-}
-
-#endif
-
-/*----------------------------------------------------------------*/
-
/*
* Key building.
*/
--
1.7.1
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