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