- 根目录:
- drivers
- md
- persistent-data
- dm-transaction-manager.c
/*
* 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-checker.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/slab.h>
#include <linux/device-mapper.h>
#define DM_MSG_PREFIX "transaction manager"
/*----------------------------------------------------------------*/
struct shadow_info {
struct hlist_node hlist;
dm_block_t where;
};
/*
* It would be nice if we scaled with the size of transaction.
*/
#define HASH_SIZE 256
#define HASH_MASK (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[HASH_SIZE];
};
/*----------------------------------------------------------------*/
static int is_shadow(struct dm_transaction_manager *tm, dm_block_t b)
{
int r = 0;
unsigned bucket = dm_hash_block(b, HASH_MASK);
struct shadow_info *si;
struct hlist_node *n;
spin_lock(&tm->lock);
hlist_for_each_entry(si, n, 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, 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 *n, *tmp;
struct hlist_head *bucket;
int i;
spin_lock(&tm->lock);
for (i = 0; i < HASH_SIZE; i++) {
bucket = tm->buckets + i;
hlist_for_each_entry_safe(si, n, 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 < HASH_SIZE; i++)
INIT_HLIST_HEAD(tm->buckets + i);
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 0;
}
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);
return dm_bm_flush_and_unlock(tm->bm, root);
}
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;
r = dm_bm_unlock_move(orig_block, new);
if (r < 0) {
dm_bm_unlock(orig_block);
return r;
}
return dm_bm_write_lock(tm->bm, new, v, result);
}
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;
}
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)
return dm_bm_read_try_lock(tm->real->bm, b, v, blk);
return dm_bm_read_lock(tm->bm, b, v, blk);
}
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;
}
/*----------------------------------------------------------------*/
static int dm_tm_create_internal(struct dm_block_manager *bm,
dm_block_t sb_location,
struct dm_block_validator *sb_validator,
size_t root_offset, size_t root_max_len,
struct dm_transaction_manager **tm,
struct dm_space_map **sm,
struct dm_block **sblock,
int create)
{
int r;
struct dm_space_map *inner;
inner = dm_sm_metadata_init();
if (IS_ERR(inner))
return PTR_ERR(inner);
*tm = dm_tm_create(bm, inner);
if (IS_ERR(*tm)) {
dm_sm_destroy(inner);
return PTR_ERR(*tm);
}
if (create) {
r = dm_bm_write_lock_zero(dm_tm_get_bm(*tm), sb_location,
sb_validator, sblock);
if (r < 0) {
DMERR("couldn't lock superblock");
goto bad1;
}
r = dm_sm_metadata_create(inner, *tm, dm_bm_nr_blocks(bm),
sb_location);
if (r) {
DMERR("couldn't create metadata space map");
goto bad2;
}
*sm = dm_sm_checker_create(inner);
if (IS_ERR(*sm)) {
r = PTR_ERR(*sm);
goto bad2;
}
} else {
r = dm_bm_write_lock(dm_tm_get_bm(*tm), sb_location,
sb_validator, sblock);
if (r < 0) {
DMERR("couldn't lock superblock");
goto bad1;
}
r = dm_sm_metadata_open(inner, *tm,
dm_block_data(*sblock) + root_offset,
root_max_len);
if (r) {
DMERR("couldn't open metadata space map");
goto bad2;
}
*sm = dm_sm_checker_create(inner);
if (IS_ERR(*sm)) {
r = PTR_ERR(*sm);
goto bad2;
}
}
return 0;
bad2:
dm_tm_unlock(*tm, *sblock);
bad1:
dm_tm_destroy(*tm);
dm_sm_destroy(inner);
return r;
}
int dm_tm_create_with_sm(struct dm_block_manager *bm, dm_block_t sb_location,
struct dm_block_validator *sb_validator,
struct dm_transaction_manager **tm,
struct dm_space_map **sm, struct dm_block **sblock)
{
return dm_tm_create_internal(bm, sb_location, sb_validator,
0, 0, tm, sm, sblock, 1);
}
EXPORT_SYMBOL_GPL(dm_tm_create_with_sm);
int dm_tm_open_with_sm(struct dm_block_manager *bm, dm_block_t sb_location,
struct dm_block_validator *sb_validator,
size_t root_offset, size_t root_max_len,
struct dm_transaction_manager **tm,
struct dm_space_map **sm, struct dm_block **sblock)
{
return dm_tm_create_internal(bm, sb_location, sb_validator, root_offset,
root_max_len, tm, sm, sblock, 0);
}
EXPORT_SYMBOL_GPL(dm_tm_open_with_sm);
/*----------------------------------------------------------------*/