diff options
Diffstat (limited to 'kernel/drivers/md/persistent-data/dm-transaction-manager.c')
| -rw-r--r-- | kernel/drivers/md/persistent-data/dm-transaction-manager.c | 455 |
1 files changed, 455 insertions, 0 deletions
diff --git a/kernel/drivers/md/persistent-data/dm-transaction-manager.c b/kernel/drivers/md/persistent-data/dm-transaction-manager.c new file mode 100644 index 000000000..9cb797d80 --- /dev/null +++ b/kernel/drivers/md/persistent-data/dm-transaction-manager.c @@ -0,0 +1,455 @@ +/* + * Copyright (C) 2011 Red Hat, Inc. + * + * This file is released under the GPL. + */ +#include "dm-transaction-manager.h" +#include "dm-space-map.h" +#include "dm-space-map-disk.h" +#include "dm-space-map-metadata.h" +#include "dm-persistent-data-internal.h" + +#include <linux/export.h> +#include <linux/mutex.h> +#include <linux/hash.h> +#include <linux/slab.h> +#include <linux/device-mapper.h> + +#define DM_MSG_PREFIX "transaction manager" + +/*----------------------------------------------------------------*/ + +#define PREFETCH_SIZE 128 +#define PREFETCH_BITS 7 +#define PREFETCH_SENTINEL ((dm_block_t) -1ULL) + +struct prefetch_set { + struct mutex lock; + dm_block_t blocks[PREFETCH_SIZE]; +}; + +static unsigned prefetch_hash(dm_block_t b) +{ + return hash_64(b, PREFETCH_BITS); +} + +static void prefetch_wipe(struct prefetch_set *p) +{ + unsigned i; + for (i = 0; i < PREFETCH_SIZE; i++) + p->blocks[i] = PREFETCH_SENTINEL; +} + +static void prefetch_init(struct prefetch_set *p) +{ + mutex_init(&p->lock); + prefetch_wipe(p); +} + +static void prefetch_add(struct prefetch_set *p, dm_block_t b) +{ + unsigned h = prefetch_hash(b); + + mutex_lock(&p->lock); + if (p->blocks[h] == PREFETCH_SENTINEL) + p->blocks[h] = b; + + mutex_unlock(&p->lock); +} + +static void prefetch_issue(struct prefetch_set *p, struct dm_block_manager *bm) +{ + unsigned i; + + mutex_lock(&p->lock); + + for (i = 0; i < PREFETCH_SIZE; i++) + if (p->blocks[i] != PREFETCH_SENTINEL) { + dm_bm_prefetch(bm, p->blocks[i]); + p->blocks[i] = PREFETCH_SENTINEL; + } + + mutex_unlock(&p->lock); +} + +/*----------------------------------------------------------------*/ + +struct shadow_info { + struct hlist_node hlist; + dm_block_t where; +}; + +/* + * It would be nice if we scaled with the size of transaction. + */ +#define DM_HASH_SIZE 256 +#define DM_HASH_MASK (DM_HASH_SIZE - 1) + +struct dm_transaction_manager { + int is_clone; + struct dm_transaction_manager *real; + + struct dm_block_manager *bm; + struct dm_space_map *sm; + + spinlock_t lock; + struct hlist_head buckets[DM_HASH_SIZE]; + + struct prefetch_set prefetches; +}; + +/*----------------------------------------------------------------*/ + +static int is_shadow(struct dm_transaction_manager *tm, dm_block_t b) +{ + int r = 0; + unsigned bucket = dm_hash_block(b, DM_HASH_MASK); + struct shadow_info *si; + + spin_lock(&tm->lock); + hlist_for_each_entry(si, tm->buckets + bucket, hlist) + if (si->where == b) { + r = 1; + break; + } + spin_unlock(&tm->lock); + + return r; +} + +/* + * This can silently fail if there's no memory. We're ok with this since + * creating redundant shadows causes no harm. + */ +static void insert_shadow(struct dm_transaction_manager *tm, dm_block_t b) +{ + unsigned bucket; + struct shadow_info *si; + + si = kmalloc(sizeof(*si), GFP_NOIO); + if (si) { + si->where = b; + bucket = dm_hash_block(b, DM_HASH_MASK); + spin_lock(&tm->lock); + hlist_add_head(&si->hlist, tm->buckets + bucket); + spin_unlock(&tm->lock); + } +} + +static void wipe_shadow_table(struct dm_transaction_manager *tm) +{ + struct shadow_info *si; + struct hlist_node *tmp; + struct hlist_head *bucket; + int i; + + spin_lock(&tm->lock); + for (i = 0; i < DM_HASH_SIZE; i++) { + bucket = tm->buckets + i; + hlist_for_each_entry_safe(si, tmp, bucket, hlist) + kfree(si); + + INIT_HLIST_HEAD(bucket); + } + + spin_unlock(&tm->lock); +} + +/*----------------------------------------------------------------*/ + +static struct dm_transaction_manager *dm_tm_create(struct dm_block_manager *bm, + struct dm_space_map *sm) +{ + int i; + struct dm_transaction_manager *tm; + + tm = kmalloc(sizeof(*tm), GFP_KERNEL); + if (!tm) + return ERR_PTR(-ENOMEM); + + tm->is_clone = 0; + tm->real = NULL; + tm->bm = bm; + tm->sm = sm; + + spin_lock_init(&tm->lock); + for (i = 0; i < DM_HASH_SIZE; i++) + INIT_HLIST_HEAD(tm->buckets + i); + + prefetch_init(&tm->prefetches); + + return tm; +} + +struct dm_transaction_manager *dm_tm_create_non_blocking_clone(struct dm_transaction_manager *real) +{ + struct dm_transaction_manager *tm; + + tm = kmalloc(sizeof(*tm), GFP_KERNEL); + if (tm) { + tm->is_clone = 1; + tm->real = real; + } + + return tm; +} +EXPORT_SYMBOL_GPL(dm_tm_create_non_blocking_clone); + +void dm_tm_destroy(struct dm_transaction_manager *tm) +{ + if (!tm->is_clone) + wipe_shadow_table(tm); + + kfree(tm); +} +EXPORT_SYMBOL_GPL(dm_tm_destroy); + +int dm_tm_pre_commit(struct dm_transaction_manager *tm) +{ + int r; + + if (tm->is_clone) + return -EWOULDBLOCK; + + r = dm_sm_commit(tm->sm); + if (r < 0) + return r; + + return dm_bm_flush(tm->bm); +} +EXPORT_SYMBOL_GPL(dm_tm_pre_commit); + +int dm_tm_commit(struct dm_transaction_manager *tm, struct dm_block *root) +{ + if (tm->is_clone) + return -EWOULDBLOCK; + + wipe_shadow_table(tm); + dm_bm_unlock(root); + + return dm_bm_flush(tm->bm); +} +EXPORT_SYMBOL_GPL(dm_tm_commit); + +int dm_tm_new_block(struct dm_transaction_manager *tm, + struct dm_block_validator *v, + struct dm_block **result) +{ + int r; + dm_block_t new_block; + + if (tm->is_clone) + return -EWOULDBLOCK; + + r = dm_sm_new_block(tm->sm, &new_block); + if (r < 0) + return r; + + r = dm_bm_write_lock_zero(tm->bm, new_block, v, result); + if (r < 0) { + dm_sm_dec_block(tm->sm, new_block); + return r; + } + + /* + * New blocks count as shadows in that they don't need to be + * shadowed again. + */ + insert_shadow(tm, new_block); + + return 0; +} + +static int __shadow_block(struct dm_transaction_manager *tm, dm_block_t orig, + struct dm_block_validator *v, + struct dm_block **result) +{ + int r; + dm_block_t new; + struct dm_block *orig_block; + + r = dm_sm_new_block(tm->sm, &new); + if (r < 0) + return r; + + r = dm_sm_dec_block(tm->sm, orig); + if (r < 0) + return r; + + r = dm_bm_read_lock(tm->bm, orig, v, &orig_block); + if (r < 0) + return r; + + /* + * It would be tempting to use dm_bm_unlock_move here, but some + * code, such as the space maps, keeps using the old data structures + * secure in the knowledge they won't be changed until the next + * transaction. Using unlock_move would force a synchronous read + * since the old block would no longer be in the cache. + */ + r = dm_bm_write_lock_zero(tm->bm, new, v, result); + if (r) { + dm_bm_unlock(orig_block); + return r; + } + + memcpy(dm_block_data(*result), dm_block_data(orig_block), + dm_bm_block_size(tm->bm)); + + dm_bm_unlock(orig_block); + return r; +} + +int dm_tm_shadow_block(struct dm_transaction_manager *tm, dm_block_t orig, + struct dm_block_validator *v, struct dm_block **result, + int *inc_children) +{ + int r; + + if (tm->is_clone) + return -EWOULDBLOCK; + + r = dm_sm_count_is_more_than_one(tm->sm, orig, inc_children); + if (r < 0) + return r; + + if (is_shadow(tm, orig) && !*inc_children) + return dm_bm_write_lock(tm->bm, orig, v, result); + + r = __shadow_block(tm, orig, v, result); + if (r < 0) + return r; + insert_shadow(tm, dm_block_location(*result)); + + return r; +} +EXPORT_SYMBOL_GPL(dm_tm_shadow_block); + +int dm_tm_read_lock(struct dm_transaction_manager *tm, dm_block_t b, + struct dm_block_validator *v, + struct dm_block **blk) +{ + if (tm->is_clone) { + int r = dm_bm_read_try_lock(tm->real->bm, b, v, blk); + + if (r == -EWOULDBLOCK) + prefetch_add(&tm->real->prefetches, b); + + return r; + } + + return dm_bm_read_lock(tm->bm, b, v, blk); +} +EXPORT_SYMBOL_GPL(dm_tm_read_lock); + +int dm_tm_unlock(struct dm_transaction_manager *tm, struct dm_block *b) +{ + return dm_bm_unlock(b); +} +EXPORT_SYMBOL_GPL(dm_tm_unlock); + +void dm_tm_inc(struct dm_transaction_manager *tm, dm_block_t b) +{ + /* + * The non-blocking clone doesn't support this. + */ + BUG_ON(tm->is_clone); + + dm_sm_inc_block(tm->sm, b); +} +EXPORT_SYMBOL_GPL(dm_tm_inc); + +void dm_tm_dec(struct dm_transaction_manager *tm, dm_block_t b) +{ + /* + * The non-blocking clone doesn't support this. + */ + BUG_ON(tm->is_clone); + + dm_sm_dec_block(tm->sm, b); +} +EXPORT_SYMBOL_GPL(dm_tm_dec); + +int dm_tm_ref(struct dm_transaction_manager *tm, dm_block_t b, + uint32_t *result) +{ + if (tm->is_clone) + return -EWOULDBLOCK; + + return dm_sm_get_count(tm->sm, b, result); +} + +struct dm_block_manager *dm_tm_get_bm(struct dm_transaction_manager *tm) +{ + return tm->bm; +} + +void dm_tm_issue_prefetches(struct dm_transaction_manager *tm) +{ + prefetch_issue(&tm->prefetches, tm->bm); +} +EXPORT_SYMBOL_GPL(dm_tm_issue_prefetches); + +/*----------------------------------------------------------------*/ + +static int dm_tm_create_internal(struct dm_block_manager *bm, + dm_block_t sb_location, + struct dm_transaction_manager **tm, + struct dm_space_map **sm, + int create, + void *sm_root, size_t sm_len) +{ + int r; + + *sm = dm_sm_metadata_init(); + if (IS_ERR(*sm)) + return PTR_ERR(*sm); + + *tm = dm_tm_create(bm, *sm); + if (IS_ERR(*tm)) { + dm_sm_destroy(*sm); + return PTR_ERR(*tm); + } + + if (create) { + r = dm_sm_metadata_create(*sm, *tm, dm_bm_nr_blocks(bm), + sb_location); + if (r) { + DMERR("couldn't create metadata space map"); + goto bad; + } + + } else { + r = dm_sm_metadata_open(*sm, *tm, sm_root, sm_len); + if (r) { + DMERR("couldn't open metadata space map"); + goto bad; + } + } + + return 0; + +bad: + dm_tm_destroy(*tm); + dm_sm_destroy(*sm); + return r; +} + +int dm_tm_create_with_sm(struct dm_block_manager *bm, dm_block_t sb_location, + struct dm_transaction_manager **tm, + struct dm_space_map **sm) +{ + return dm_tm_create_internal(bm, sb_location, tm, sm, 1, NULL, 0); +} +EXPORT_SYMBOL_GPL(dm_tm_create_with_sm); + +int dm_tm_open_with_sm(struct dm_block_manager *bm, dm_block_t sb_location, + void *sm_root, size_t root_len, + struct dm_transaction_manager **tm, + struct dm_space_map **sm) +{ + return dm_tm_create_internal(bm, sb_location, tm, sm, 0, sm_root, root_len); +} +EXPORT_SYMBOL_GPL(dm_tm_open_with_sm); + +/*----------------------------------------------------------------*/ |