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linux/drivers/md/persistent-data/dm-space-map-disk.c
Joe Thornber 65e780667c dm space maps: don't reset space map allocation cursor when committing 
[ Upstream commit 5faafc77f7de69147d1e818026b9a0cbf036a7b2 ]

Current commit code resets the place where the search for free blocks
will begin back to the start of the metadata device.  There are a couple
of repercussions to this:

- The first allocation after the commit is likely to take longer than
  normal as it searches for a free block in an area that is likely to
  have very few free blocks (if any).

- Any free blocks it finds will have been recently freed.  Reusing them
  means we have fewer old copies of the metadata to aid recovery from
  hardware error.

Fix these issues by leaving the cursor alone, only resetting when the
search hits the end of the metadata device.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-07-19 09:44:45 +02:00

328 lines
6.9 KiB
C
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/*
* Copyright (C) 2011 Red Hat, Inc.
*
* This file is released under the GPL.
*/
#include "dm-space-map-common.h"
#include "dm-space-map-disk.h"
#include "dm-space-map.h"
#include "dm-transaction-manager.h"
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <linux/device-mapper.h>
#define DM_MSG_PREFIX "space map disk"
/*----------------------------------------------------------------*/
/*
* Space map interface.
*/
struct sm_disk {
struct dm_space_map sm;
struct ll_disk ll;
struct ll_disk old_ll;
dm_block_t begin;
dm_block_t nr_allocated_this_transaction;
};
static void sm_disk_destroy(struct dm_space_map *sm)
{
struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
kfree(smd);
}
static int sm_disk_extend(struct dm_space_map *sm, dm_block_t extra_blocks)
{
struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
return sm_ll_extend(&smd->ll, extra_blocks);
}
static int sm_disk_get_nr_blocks(struct dm_space_map *sm, dm_block_t *count)
{
struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
*count = smd->old_ll.nr_blocks;
return 0;
}
static int sm_disk_get_nr_free(struct dm_space_map *sm, dm_block_t *count)
{
struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
*count = (smd->old_ll.nr_blocks - smd->old_ll.nr_allocated) - smd->nr_allocated_this_transaction;
return 0;
}
static int sm_disk_get_count(struct dm_space_map *sm, dm_block_t b,
uint32_t *result)
{
struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
return sm_ll_lookup(&smd->ll, b, result);
}
static int sm_disk_count_is_more_than_one(struct dm_space_map *sm, dm_block_t b,
int *result)
{
int r;
uint32_t count;
r = sm_disk_get_count(sm, b, &count);
if (r)
return r;
*result = count > 1;
return 0;
}
static int sm_disk_set_count(struct dm_space_map *sm, dm_block_t b,
uint32_t count)
{
int r;
uint32_t old_count;
enum allocation_event ev;
struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
r = sm_ll_insert(&smd->ll, b, count, &ev);
if (!r) {
switch (ev) {
case SM_NONE:
break;
case SM_ALLOC:
/*
* This _must_ be free in the prior transaction
* otherwise we've lost atomicity.
*/
smd->nr_allocated_this_transaction++;
break;
case SM_FREE:
/*
* It's only free if it's also free in the last
* transaction.
*/
r = sm_ll_lookup(&smd->old_ll, b, &old_count);
if (r)
return r;
if (!old_count)
smd->nr_allocated_this_transaction--;
break;
}
}
return r;
}
static int sm_disk_inc_block(struct dm_space_map *sm, dm_block_t b)
{
int r;
enum allocation_event ev;
struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
r = sm_ll_inc(&smd->ll, b, &ev);
if (!r && (ev == SM_ALLOC))
/*
* This _must_ be free in the prior transaction
* otherwise we've lost atomicity.
*/
smd->nr_allocated_this_transaction++;
return r;
}
static int sm_disk_dec_block(struct dm_space_map *sm, dm_block_t b)
{
int r;
uint32_t old_count;
enum allocation_event ev;
struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
r = sm_ll_dec(&smd->ll, b, &ev);
if (!r && (ev == SM_FREE)) {
/*
* It's only free if it's also free in the last
* transaction.
*/
r = sm_ll_lookup(&smd->old_ll, b, &old_count);
if (!r && !old_count)
smd->nr_allocated_this_transaction--;
}
return r;
}
static int sm_disk_new_block(struct dm_space_map *sm, dm_block_t *b)
{
int r;
enum allocation_event ev;
struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
/*
* Any block we allocate has to be free in both the old and current ll.
*/
r = sm_ll_find_common_free_block(&smd->old_ll, &smd->ll, smd->begin, smd->ll.nr_blocks, b);
if (r == -ENOSPC) {
/*
* There's no free block between smd->begin and the end of the metadata device.
* We search before smd->begin in case something has been freed.
*/
r = sm_ll_find_common_free_block(&smd->old_ll, &smd->ll, 0, smd->begin, b);
}
if (r)
return r;
smd->begin = *b + 1;
r = sm_ll_inc(&smd->ll, *b, &ev);
if (!r) {
BUG_ON(ev != SM_ALLOC);
smd->nr_allocated_this_transaction++;
}
return r;
}
static int sm_disk_commit(struct dm_space_map *sm)
{
int r;
dm_block_t nr_free;
struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
r = sm_disk_get_nr_free(sm, &nr_free);
if (r)
return r;
r = sm_ll_commit(&smd->ll);
if (r)
return r;
memcpy(&smd->old_ll, &smd->ll, sizeof(smd->old_ll));
smd->nr_allocated_this_transaction = 0;
r = sm_disk_get_nr_free(sm, &nr_free);
if (r)
return r;
return 0;
}
static int sm_disk_root_size(struct dm_space_map *sm, size_t *result)
{
*result = sizeof(struct disk_sm_root);
return 0;
}
static int sm_disk_copy_root(struct dm_space_map *sm, void *where_le, size_t max)
{
struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
struct disk_sm_root root_le;
root_le.nr_blocks = cpu_to_le64(smd->ll.nr_blocks);
root_le.nr_allocated = cpu_to_le64(smd->ll.nr_allocated);
root_le.bitmap_root = cpu_to_le64(smd->ll.bitmap_root);
root_le.ref_count_root = cpu_to_le64(smd->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_disk_destroy,
.extend = sm_disk_extend,
.get_nr_blocks = sm_disk_get_nr_blocks,
.get_nr_free = sm_disk_get_nr_free,
.get_count = sm_disk_get_count,
.count_is_more_than_one = sm_disk_count_is_more_than_one,
.set_count = sm_disk_set_count,
.inc_block = sm_disk_inc_block,
.dec_block = sm_disk_dec_block,
.new_block = sm_disk_new_block,
.commit = sm_disk_commit,
.root_size = sm_disk_root_size,
.copy_root = sm_disk_copy_root,
.register_threshold_callback = NULL
};
struct dm_space_map *dm_sm_disk_create(struct dm_transaction_manager *tm,
dm_block_t nr_blocks)
{
int r;
struct sm_disk *smd;
smd = kmalloc(sizeof(*smd), GFP_KERNEL);
if (!smd)
return ERR_PTR(-ENOMEM);
smd->begin = 0;
smd->nr_allocated_this_transaction = 0;
memcpy(&smd->sm, &ops, sizeof(smd->sm));
r = sm_ll_new_disk(&smd->ll, tm);
if (r)
goto bad;
r = sm_ll_extend(&smd->ll, nr_blocks);
if (r)
goto bad;
r = sm_disk_commit(&smd->sm);
if (r)
goto bad;
return &smd->sm;
bad:
kfree(smd);
return ERR_PTR(r);
}
EXPORT_SYMBOL_GPL(dm_sm_disk_create);
struct dm_space_map *dm_sm_disk_open(struct dm_transaction_manager *tm,
void *root_le, size_t len)
{
int r;
struct sm_disk *smd;
smd = kmalloc(sizeof(*smd), GFP_KERNEL);
if (!smd)
return ERR_PTR(-ENOMEM);
smd->begin = 0;
smd->nr_allocated_this_transaction = 0;
memcpy(&smd->sm, &ops, sizeof(smd->sm));
r = sm_ll_open_disk(&smd->ll, tm, root_le, len);
if (r)
goto bad;
r = sm_disk_commit(&smd->sm);
if (r)
goto bad;
return &smd->sm;
bad:
kfree(smd);
return ERR_PTR(r);
}
EXPORT_SYMBOL_GPL(dm_sm_disk_open);
/*----------------------------------------------------------------*/
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