dm thin: move bio_prison code to separate module
The bio prison code will be useful to other future DM targets so move it to a separate module. Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Este commit está contenido en:
Mike Snitzer
cometido por
Alasdair G Kergon
Alasdair G Kergon
padre
44feb387f6
commit
4f81a41762
@@ -5,6 +5,7 @@
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*/
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#include "dm-thin-metadata.h"
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#include "dm-bio-prison.h"
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#include "dm.h"
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#include <linux/device-mapper.h>
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@@ -21,7 +22,6 @@
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* Tunable constants
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*/
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#define ENDIO_HOOK_POOL_SIZE 1024
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#define DEFERRED_SET_SIZE 64
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#define MAPPING_POOL_SIZE 1024
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#define PRISON_CELLS 1024
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#define COMMIT_PERIOD HZ
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@@ -98,404 +98,6 @@
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/*----------------------------------------------------------------*/
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/*
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* Sometimes we can't deal with a bio straight away. We put them in prison
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* where they can't cause any mischief. Bios are put in a cell identified
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* by a key, multiple bios can be in the same cell. When the cell is
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* subsequently unlocked the bios become available.
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*/
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struct dm_bio_prison;
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struct dm_cell_key {
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int virtual;
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dm_thin_id dev;
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dm_block_t block;
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};
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struct dm_bio_prison_cell {
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struct hlist_node list;
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struct dm_bio_prison *prison;
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struct dm_cell_key key;
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struct bio *holder;
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struct bio_list bios;
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};
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struct dm_bio_prison {
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spinlock_t lock;
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mempool_t *cell_pool;
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unsigned nr_buckets;
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unsigned hash_mask;
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struct hlist_head *cells;
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};
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static uint32_t calc_nr_buckets(unsigned nr_cells)
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{
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uint32_t n = 128;
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nr_cells /= 4;
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nr_cells = min(nr_cells, 8192u);
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while (n < nr_cells)
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n <<= 1;
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return n;
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}
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static struct kmem_cache *_cell_cache;
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/*
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* @nr_cells should be the number of cells you want in use _concurrently_.
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* Don't confuse it with the number of distinct keys.
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*/
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static struct dm_bio_prison *dm_bio_prison_create(unsigned nr_cells)
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{
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unsigned i;
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uint32_t nr_buckets = calc_nr_buckets(nr_cells);
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size_t len = sizeof(struct dm_bio_prison) +
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(sizeof(struct hlist_head) * nr_buckets);
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struct dm_bio_prison *prison = kmalloc(len, GFP_KERNEL);
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if (!prison)
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return NULL;
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spin_lock_init(&prison->lock);
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prison->cell_pool = mempool_create_slab_pool(nr_cells, _cell_cache);
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if (!prison->cell_pool) {
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kfree(prison);
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return NULL;
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}
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prison->nr_buckets = nr_buckets;
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prison->hash_mask = nr_buckets - 1;
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prison->cells = (struct hlist_head *) (prison + 1);
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for (i = 0; i < nr_buckets; i++)
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INIT_HLIST_HEAD(prison->cells + i);
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return prison;
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}
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static void dm_bio_prison_destroy(struct dm_bio_prison *prison)
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{
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mempool_destroy(prison->cell_pool);
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kfree(prison);
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}
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static uint32_t hash_key(struct dm_bio_prison *prison, struct dm_cell_key *key)
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{
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const unsigned long BIG_PRIME = 4294967291UL;
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uint64_t hash = key->block * BIG_PRIME;
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return (uint32_t) (hash & prison->hash_mask);
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}
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static int keys_equal(struct dm_cell_key *lhs, struct dm_cell_key *rhs)
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{
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return (lhs->virtual == rhs->virtual) &&
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(lhs->dev == rhs->dev) &&
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(lhs->block == rhs->block);
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}
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static struct dm_bio_prison_cell *__search_bucket(struct hlist_head *bucket,
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struct dm_cell_key *key)
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{
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struct dm_bio_prison_cell *cell;
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struct hlist_node *tmp;
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hlist_for_each_entry(cell, tmp, bucket, list)
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if (keys_equal(&cell->key, key))
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return cell;
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return NULL;
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}
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/*
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* This may block if a new cell needs allocating. You must ensure that
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* cells will be unlocked even if the calling thread is blocked.
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*
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* Returns 1 if the cell was already held, 0 if @inmate is the new holder.
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*/
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static int dm_bio_detain(struct dm_bio_prison *prison, struct dm_cell_key *key,
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struct bio *inmate, struct dm_bio_prison_cell **ref)
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{
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int r = 1;
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unsigned long flags;
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uint32_t hash = hash_key(prison, key);
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struct dm_bio_prison_cell *cell, *cell2;
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BUG_ON(hash > prison->nr_buckets);
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spin_lock_irqsave(&prison->lock, flags);
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cell = __search_bucket(prison->cells + hash, key);
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if (cell) {
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bio_list_add(&cell->bios, inmate);
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goto out;
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}
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/*
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* Allocate a new cell
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*/
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spin_unlock_irqrestore(&prison->lock, flags);
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cell2 = mempool_alloc(prison->cell_pool, GFP_NOIO);
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spin_lock_irqsave(&prison->lock, flags);
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/*
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* We've been unlocked, so we have to double check that
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* nobody else has inserted this cell in the meantime.
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*/
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cell = __search_bucket(prison->cells + hash, key);
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if (cell) {
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mempool_free(cell2, prison->cell_pool);
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bio_list_add(&cell->bios, inmate);
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goto out;
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}
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/*
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* Use new cell.
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*/
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cell = cell2;
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cell->prison = prison;
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memcpy(&cell->key, key, sizeof(cell->key));
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cell->holder = inmate;
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bio_list_init(&cell->bios);
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hlist_add_head(&cell->list, prison->cells + hash);
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r = 0;
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out:
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spin_unlock_irqrestore(&prison->lock, flags);
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*ref = cell;
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return r;
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}
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/*
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* @inmates must have been initialised prior to this call
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*/
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static void __cell_release(struct dm_bio_prison_cell *cell, struct bio_list *inmates)
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{
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struct dm_bio_prison *prison = cell->prison;
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hlist_del(&cell->list);
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if (inmates) {
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bio_list_add(inmates, cell->holder);
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bio_list_merge(inmates, &cell->bios);
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}
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mempool_free(cell, prison->cell_pool);
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}
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static void dm_cell_release(struct dm_bio_prison_cell *cell, struct bio_list *bios)
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{
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unsigned long flags;
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struct dm_bio_prison *prison = cell->prison;
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spin_lock_irqsave(&prison->lock, flags);
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__cell_release(cell, bios);
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spin_unlock_irqrestore(&prison->lock, flags);
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}
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/*
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* There are a couple of places where we put a bio into a cell briefly
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* before taking it out again. In these situations we know that no other
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* bio may be in the cell. This function releases the cell, and also does
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* a sanity check.
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*/
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static void __cell_release_singleton(struct dm_bio_prison_cell *cell, struct bio *bio)
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{
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BUG_ON(cell->holder != bio);
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BUG_ON(!bio_list_empty(&cell->bios));
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__cell_release(cell, NULL);
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}
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static void dm_cell_release_singleton(struct dm_bio_prison_cell *cell, struct bio *bio)
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{
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unsigned long flags;
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struct dm_bio_prison *prison = cell->prison;
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spin_lock_irqsave(&prison->lock, flags);
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__cell_release_singleton(cell, bio);
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spin_unlock_irqrestore(&prison->lock, flags);
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}
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/*
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* Sometimes we don't want the holder, just the additional bios.
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*/
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static void __cell_release_no_holder(struct dm_bio_prison_cell *cell,
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struct bio_list *inmates)
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{
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struct dm_bio_prison *prison = cell->prison;
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hlist_del(&cell->list);
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bio_list_merge(inmates, &cell->bios);
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mempool_free(cell, prison->cell_pool);
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}
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static void dm_cell_release_no_holder(struct dm_bio_prison_cell *cell,
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struct bio_list *inmates)
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{
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unsigned long flags;
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struct dm_bio_prison *prison = cell->prison;
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spin_lock_irqsave(&prison->lock, flags);
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__cell_release_no_holder(cell, inmates);
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spin_unlock_irqrestore(&prison->lock, flags);
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}
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static void dm_cell_error(struct dm_bio_prison_cell *cell)
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{
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struct dm_bio_prison *prison = cell->prison;
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struct bio_list bios;
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struct bio *bio;
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unsigned long flags;
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bio_list_init(&bios);
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spin_lock_irqsave(&prison->lock, flags);
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__cell_release(cell, &bios);
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spin_unlock_irqrestore(&prison->lock, flags);
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while ((bio = bio_list_pop(&bios)))
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bio_io_error(bio);
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}
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/*----------------------------------------------------------------*/
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/*
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* We use the deferred set to keep track of pending reads to shared blocks.
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* We do this to ensure the new mapping caused by a write isn't performed
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* until these prior reads have completed. Otherwise the insertion of the
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* new mapping could free the old block that the read bios are mapped to.
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*/
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struct dm_deferred_set;
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struct dm_deferred_entry {
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struct dm_deferred_set *ds;
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unsigned count;
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struct list_head work_items;
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};
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struct dm_deferred_set {
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spinlock_t lock;
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unsigned current_entry;
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unsigned sweeper;
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struct dm_deferred_entry entries[DEFERRED_SET_SIZE];
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};
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static struct dm_deferred_set *dm_deferred_set_create(void)
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{
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int i;
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struct dm_deferred_set *ds;
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ds = kmalloc(sizeof(*ds), GFP_KERNEL);
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if (!ds)
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return NULL;
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spin_lock_init(&ds->lock);
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ds->current_entry = 0;
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ds->sweeper = 0;
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for (i = 0; i < DEFERRED_SET_SIZE; i++) {
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ds->entries[i].ds = ds;
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ds->entries[i].count = 0;
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INIT_LIST_HEAD(&ds->entries[i].work_items);
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}
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return ds;
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}
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static void dm_deferred_set_destroy(struct dm_deferred_set *ds)
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{
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kfree(ds);
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}
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static struct dm_deferred_entry *dm_deferred_entry_inc(struct dm_deferred_set *ds)
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{
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unsigned long flags;
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struct dm_deferred_entry *entry;
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spin_lock_irqsave(&ds->lock, flags);
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entry = ds->entries + ds->current_entry;
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entry->count++;
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spin_unlock_irqrestore(&ds->lock, flags);
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return entry;
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}
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static unsigned ds_next(unsigned index)
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{
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return (index + 1) % DEFERRED_SET_SIZE;
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}
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static void __sweep(struct dm_deferred_set *ds, struct list_head *head)
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{
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while ((ds->sweeper != ds->current_entry) &&
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!ds->entries[ds->sweeper].count) {
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list_splice_init(&ds->entries[ds->sweeper].work_items, head);
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ds->sweeper = ds_next(ds->sweeper);
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}
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if ((ds->sweeper == ds->current_entry) && !ds->entries[ds->sweeper].count)
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list_splice_init(&ds->entries[ds->sweeper].work_items, head);
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}
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static void dm_deferred_entry_dec(struct dm_deferred_entry *entry, struct list_head *head)
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{
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unsigned long flags;
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spin_lock_irqsave(&entry->ds->lock, flags);
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BUG_ON(!entry->count);
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--entry->count;
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__sweep(entry->ds, head);
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spin_unlock_irqrestore(&entry->ds->lock, flags);
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}
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/*
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* Returns 1 if deferred or 0 if no pending items to delay job.
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*/
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static int dm_deferred_set_add_work(struct dm_deferred_set *ds, struct list_head *work)
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{
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int r = 1;
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unsigned long flags;
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unsigned next_entry;
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spin_lock_irqsave(&ds->lock, flags);
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if ((ds->sweeper == ds->current_entry) &&
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!ds->entries[ds->current_entry].count)
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r = 0;
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else {
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list_add(work, &ds->entries[ds->current_entry].work_items);
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next_entry = ds_next(ds->current_entry);
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if (!ds->entries[next_entry].count)
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ds->current_entry = next_entry;
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}
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spin_unlock_irqrestore(&ds->lock, flags);
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return r;
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}
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static int __init dm_bio_prison_init(void)
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{
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_cell_cache = KMEM_CACHE(dm_bio_prison_cell, 0);
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if (!_cell_cache)
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return -ENOMEM;
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return 0;
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}
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static void __exit dm_bio_prison_exit(void)
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{
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kmem_cache_destroy(_cell_cache);
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_cell_cache = NULL;
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}
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/*----------------------------------------------------------------*/
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/*
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* Key building.
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*/
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@@ -2852,7 +2454,7 @@ static struct target_type pool_target = {
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.name = "thin-pool",
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.features = DM_TARGET_SINGLETON | DM_TARGET_ALWAYS_WRITEABLE |
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DM_TARGET_IMMUTABLE,
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.version = {1, 4, 0},
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.version = {1, 5, 0},
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.module = THIS_MODULE,
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.ctr = pool_ctr,
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.dtr = pool_dtr,
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@@ -3143,7 +2745,7 @@ static void thin_io_hints(struct dm_target *ti, struct queue_limits *limits)
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static struct target_type thin_target = {
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.name = "thin",
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.version = {1, 4, 0},
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.version = {1, 5, 0},
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.module = THIS_MODULE,
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.ctr = thin_ctr,
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.dtr = thin_dtr,
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@@ -3173,8 +2775,6 @@ static int __init dm_thin_init(void)
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r = -ENOMEM;
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dm_bio_prison_init();
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_new_mapping_cache = KMEM_CACHE(dm_thin_new_mapping, 0);
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if (!_new_mapping_cache)
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goto bad_new_mapping_cache;
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@@ -3200,7 +2800,6 @@ static void dm_thin_exit(void)
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dm_unregister_target(&thin_target);
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dm_unregister_target(&pool_target);
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dm_bio_prison_exit();
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kmem_cache_destroy(_new_mapping_cache);
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kmem_cache_destroy(_endio_hook_cache);
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}
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Referencia en una nueva incidencia
Block a user