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linux-hardened/drivers/md/persistent-data/dm-space-map-metadata.c
Joe Thornber 3241b1d3e0 dm: add persistent data library 
The persistent-data library offers a re-usable framework for the storage
and management of on-disk metadata in device-mapper targets.

It's used by the thin-provisioning target in the next patch and in an
upcoming hierarchical storage target.

For further information, please read
Documentation/device-mapper/persistent-data.txt

Signed-off-by: Joe Thornber <thornber@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2011-10-31 20:19:11 +00:00

596 lines
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/*
* Copyright (C) 2011 Red Hat, Inc.
*
* This file is released under the GPL.
*/
#include "dm-space-map.h"
#include "dm-space-map-common.h"
#include "dm-space-map-metadata.h"
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/device-mapper.h>
#define DM_MSG_PREFIX "space map metadata"
/*----------------------------------------------------------------*/
/*
* Space map interface.
*
* The low level disk format is written using the standard btree and
* transaction manager. This means that performing disk operations may
* cause us to recurse into the space map in order to allocate new blocks.
* For this reason we have a pool of pre-allocated blocks large enough to
* service any metadata_ll_disk operation.
*/
/*
* FIXME: we should calculate this based on the size of the device.
* Only the metadata space map needs this functionality.
*/
#define MAX_RECURSIVE_ALLOCATIONS 1024
enum block_op_type {
BOP_INC,
BOP_DEC
};
struct block_op {
enum block_op_type type;
dm_block_t block;
};
struct sm_metadata {
struct dm_space_map sm;
struct ll_disk ll;
struct ll_disk old_ll;
dm_block_t begin;
unsigned recursion_count;
unsigned allocated_this_transaction;
unsigned nr_uncommitted;
struct block_op uncommitted[MAX_RECURSIVE_ALLOCATIONS];
};
static int add_bop(struct sm_metadata *smm, enum block_op_type type, dm_block_t b)
{
struct block_op *op;
if (smm->nr_uncommitted == MAX_RECURSIVE_ALLOCATIONS) {
DMERR("too many recursive allocations");
return -ENOMEM;
}
op = smm->uncommitted + smm->nr_uncommitted++;
op->type = type;
op->block = b;
return 0;
}
static int commit_bop(struct sm_metadata *smm, struct block_op *op)
{
int r = 0;
enum allocation_event ev;
switch (op->type) {
case BOP_INC:
r = sm_ll_inc(&smm->ll, op->block, &ev);
break;
case BOP_DEC:
r = sm_ll_dec(&smm->ll, op->block, &ev);
break;
}
return r;
}
static void in(struct sm_metadata *smm)
{
smm->recursion_count++;
}
static int out(struct sm_metadata *smm)
{
int r = 0;
/*
* If we're not recursing then very bad things are happening.
*/
if (!smm->recursion_count) {
DMERR("lost track of recursion depth");
return -ENOMEM;
}
if (smm->recursion_count == 1 && smm->nr_uncommitted) {
while (smm->nr_uncommitted && !r) {
smm->nr_uncommitted--;
r = commit_bop(smm, smm->uncommitted +
smm->nr_uncommitted);
if (r)
break;
}
}
smm->recursion_count--;
return r;
}
/*
* When using the out() function above, we often want to combine an error
* code for the operation run in the recursive context with that from
* out().
*/
static int combine_errors(int r1, int r2)
{
return r1 ? r1 : r2;
}
static int recursing(struct sm_metadata *smm)
{
return smm->recursion_count;
}
static void sm_metadata_destroy(struct dm_space_map *sm)
{
struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
kfree(smm);
}
static int sm_metadata_extend(struct dm_space_map *sm, dm_block_t extra_blocks)
{
DMERR("doesn't support extend");
return -EINVAL;
}
static int sm_metadata_get_nr_blocks(struct dm_space_map *sm, dm_block_t *count)
{
struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
*count = smm->ll.nr_blocks;
return 0;
}
static int sm_metadata_get_nr_free(struct dm_space_map *sm, dm_block_t *count)
{
struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
*count = smm->old_ll.nr_blocks - smm->old_ll.nr_allocated -
smm->allocated_this_transaction;
return 0;
}
static int sm_metadata_get_count(struct dm_space_map *sm, dm_block_t b,
uint32_t *result)
{
int r, i;
struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
unsigned adjustment = 0;
/*
* We may have some uncommitted adjustments to add. This list
* should always be really short.
*/
for (i = 0; i < smm->nr_uncommitted; i++) {
struct block_op *op = smm->uncommitted + i;
if (op->block != b)
continue;
switch (op->type) {
case BOP_INC:
adjustment++;
break;
case BOP_DEC:
adjustment--;
break;
}
}
r = sm_ll_lookup(&smm->ll, b, result);
if (r)
return r;
*result += adjustment;
return 0;
}
static int sm_metadata_count_is_more_than_one(struct dm_space_map *sm,
dm_block_t b, int *result)
{
int r, i, adjustment = 0;
struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
uint32_t rc;
/*
* We may have some uncommitted adjustments to add. This list
* should always be really short.
*/
for (i = 0; i < smm->nr_uncommitted; i++) {
struct block_op *op = smm->uncommitted + i;
if (op->block != b)
continue;
switch (op->type) {
case BOP_INC:
adjustment++;
break;
case BOP_DEC:
adjustment--;
break;
}
}
if (adjustment > 1) {
*result = 1;
return 0;
}
r = sm_ll_lookup_bitmap(&smm->ll, b, &rc);
if (r)
return r;
if (rc == 3)
/*
* We err on the side of caution, and always return true.
*/
*result = 1;
else
*result = rc + adjustment > 1;
return 0;
}
static int sm_metadata_set_count(struct dm_space_map *sm, dm_block_t b,
uint32_t count)
{
int r, r2;
enum allocation_event ev;
struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
if (smm->recursion_count) {
DMERR("cannot recurse set_count()");
return -EINVAL;
}
in(smm);
r = sm_ll_insert(&smm->ll, b, count, &ev);
r2 = out(smm);
return combine_errors(r, r2);
}
static int sm_metadata_inc_block(struct dm_space_map *sm, dm_block_t b)
{
int r, r2 = 0;
enum allocation_event ev;
struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
if (recursing(smm))
r = add_bop(smm, BOP_INC, b);
else {
in(smm);
r = sm_ll_inc(&smm->ll, b, &ev);
r2 = out(smm);
}
return combine_errors(r, r2);
}
static int sm_metadata_dec_block(struct dm_space_map *sm, dm_block_t b)
{
int r, r2 = 0;
enum allocation_event ev;
struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
if (recursing(smm))
r = add_bop(smm, BOP_DEC, b);
else {
in(smm);
r = sm_ll_dec(&smm->ll, b, &ev);
r2 = out(smm);
}
return combine_errors(r, r2);
}
static int sm_metadata_new_block_(struct dm_space_map *sm, dm_block_t *b)
{
int r, r2 = 0;
enum allocation_event ev;
struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
r = sm_ll_find_free_block(&smm->old_ll, smm->begin, smm->old_ll.nr_blocks, b);
if (r)
return r;
smm->begin = *b + 1;
if (recursing(smm))
r = add_bop(smm, BOP_INC, *b);
else {
in(smm);
r = sm_ll_inc(&smm->ll, *b, &ev);
r2 = out(smm);
}
if (!r)
smm->allocated_this_transaction++;
return combine_errors(r, r2);
}
static int sm_metadata_new_block(struct dm_space_map *sm, dm_block_t *b)
{
int r = sm_metadata_new_block_(sm, b);
if (r)
DMERR("out of metadata space");
return r;
}
static int sm_metadata_commit(struct dm_space_map *sm)
{
int r;
struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
r = sm_ll_commit(&smm->ll);
if (r)
return r;
memcpy(&smm->old_ll, &smm->ll, sizeof(smm->old_ll));
smm->begin = 0;
smm->allocated_this_transaction = 0;
return 0;
}
static int sm_metadata_root_size(struct dm_space_map *sm, size_t *result)
{
*result = sizeof(struct disk_sm_root);
return 0;
}
static int sm_metadata_copy_root(struct dm_space_map *sm, void *where_le, size_t max)
{
struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
struct disk_sm_root root_le;
root_le.nr_blocks = cpu_to_le64(smm->ll.nr_blocks);
root_le.nr_allocated = cpu_to_le64(smm->ll.nr_allocated);
root_le.bitmap_root = cpu_to_le64(smm->ll.bitmap_root);
root_le.ref_count_root = cpu_to_le64(smm->ll.ref_count_root);
if (max < sizeof(root_le))
return -ENOSPC;
memcpy(where_le, &root_le, sizeof(root_le));
return 0;
}
static struct dm_space_map ops = {
.destroy = sm_metadata_destroy,
.extend = sm_metadata_extend,
.get_nr_blocks = sm_metadata_get_nr_blocks,
.get_nr_free = sm_metadata_get_nr_free,
.get_count = sm_metadata_get_count,
.count_is_more_than_one = sm_metadata_count_is_more_than_one,
.set_count = sm_metadata_set_count,
.inc_block = sm_metadata_inc_block,
.dec_block = sm_metadata_dec_block,
.new_block = sm_metadata_new_block,
.commit = sm_metadata_commit,
.root_size = sm_metadata_root_size,
.copy_root = sm_metadata_copy_root
};
/*----------------------------------------------------------------*/
/*
* When a new space map is created that manages its own space. We use
* this tiny bootstrap allocator.
*/
static void sm_bootstrap_destroy(struct dm_space_map *sm)
{
}
static int sm_bootstrap_extend(struct dm_space_map *sm, dm_block_t extra_blocks)
{
DMERR("boostrap doesn't support extend");
return -EINVAL;
}
static int sm_bootstrap_get_nr_blocks(struct dm_space_map *sm, dm_block_t *count)
{
struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
return smm->ll.nr_blocks;
}
static int sm_bootstrap_get_nr_free(struct dm_space_map *sm, dm_block_t *count)
{
struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
*count = smm->ll.nr_blocks - smm->begin;
return 0;
}
static int sm_bootstrap_get_count(struct dm_space_map *sm, dm_block_t b,
uint32_t *result)
{
struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
return b < smm->begin ? 1 : 0;
}
static int sm_bootstrap_count_is_more_than_one(struct dm_space_map *sm,
dm_block_t b, int *result)
{
*result = 0;
return 0;
}
static int sm_bootstrap_set_count(struct dm_space_map *sm, dm_block_t b,
uint32_t count)
{
DMERR("boostrap doesn't support set_count");
return -EINVAL;
}
static int sm_bootstrap_new_block(struct dm_space_map *sm, dm_block_t *b)
{
struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
/*
* We know the entire device is unused.
*/
if (smm->begin == smm->ll.nr_blocks)
return -ENOSPC;
*b = smm->begin++;
return 0;
}
static int sm_bootstrap_inc_block(struct dm_space_map *sm, dm_block_t b)
{
struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
return add_bop(smm, BOP_INC, b);
}
static int sm_bootstrap_dec_block(struct dm_space_map *sm, dm_block_t b)
{
struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
return add_bop(smm, BOP_DEC, b);
}
static int sm_bootstrap_commit(struct dm_space_map *sm)
{
return 0;
}
static int sm_bootstrap_root_size(struct dm_space_map *sm, size_t *result)
{
DMERR("boostrap doesn't support root_size");
return -EINVAL;
}
static int sm_bootstrap_copy_root(struct dm_space_map *sm, void *where,
size_t max)
{
DMERR("boostrap doesn't support copy_root");
return -EINVAL;
}
static struct dm_space_map bootstrap_ops = {
.destroy = sm_bootstrap_destroy,
.extend = sm_bootstrap_extend,
.get_nr_blocks = sm_bootstrap_get_nr_blocks,
.get_nr_free = sm_bootstrap_get_nr_free,
.get_count = sm_bootstrap_get_count,
.count_is_more_than_one = sm_bootstrap_count_is_more_than_one,
.set_count = sm_bootstrap_set_count,
.inc_block = sm_bootstrap_inc_block,
.dec_block = sm_bootstrap_dec_block,
.new_block = sm_bootstrap_new_block,
.commit = sm_bootstrap_commit,
.root_size = sm_bootstrap_root_size,
.copy_root = sm_bootstrap_copy_root
};
/*----------------------------------------------------------------*/
struct dm_space_map *dm_sm_metadata_init(void)
{
struct sm_metadata *smm;
smm = kmalloc(sizeof(*smm), GFP_KERNEL);
if (!smm)
return ERR_PTR(-ENOMEM);
memcpy(&smm->sm, &ops, sizeof(smm->sm));
return &smm->sm;
}
int dm_sm_metadata_create(struct dm_space_map *sm,
struct dm_transaction_manager *tm,
dm_block_t nr_blocks,
dm_block_t superblock)
{
int r;
dm_block_t i;
enum allocation_event ev;
struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
smm->begin = superblock + 1;
smm->recursion_count = 0;
smm->allocated_this_transaction = 0;
smm->nr_uncommitted = 0;
memcpy(&smm->sm, &bootstrap_ops, sizeof(smm->sm));
r = sm_ll_new_metadata(&smm->ll, tm);
if (r)
return r;
r = sm_ll_extend(&smm->ll, nr_blocks);
if (r)
return r;
memcpy(&smm->sm, &ops, sizeof(smm->sm));
/*
* Now we need to update the newly created data structures with the
* allocated blocks that they were built from.
*/
for (i = superblock; !r && i < smm->begin; i++)
r = sm_ll_inc(&smm->ll, i, &ev);
if (r)
return r;
return sm_metadata_commit(sm);
}
int dm_sm_metadata_open(struct dm_space_map *sm,
struct dm_transaction_manager *tm,
void *root_le, size_t len)
{
int r;
struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
r = sm_ll_open_metadata(&smm->ll, tm, root_le, len);
if (r)
return r;
smm->begin = 0;
smm->recursion_count = 0;
smm->allocated_this_transaction = 0;
smm->nr_uncommitted = 0;
memcpy(&smm->old_ll, &smm->ll, sizeof(smm->old_ll));
return 0;
}
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