https://github.com/torvalds/linux
Tip revision: 569dbb88e80deb68974ef6fdd6a13edb9d686261 authored by Linus Torvalds on 03 September 2017, 20:56:17 UTC
Linux 4.13
Linux 4.13
Tip revision: 569dbb8
dm-space-map-metadata.c
/*
* 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"
/*----------------------------------------------------------------*/
/*
* An edge triggered threshold.
*/
struct threshold {
bool threshold_set;
bool value_set;
dm_block_t threshold;
dm_block_t current_value;
dm_sm_threshold_fn fn;
void *context;
};
static void threshold_init(struct threshold *t)
{
t->threshold_set = false;
t->value_set = false;
}
static void set_threshold(struct threshold *t, dm_block_t value,
dm_sm_threshold_fn fn, void *context)
{
t->threshold_set = true;
t->threshold = value;
t->fn = fn;
t->context = context;
}
static bool below_threshold(struct threshold *t, dm_block_t value)
{
return t->threshold_set && value <= t->threshold;
}
static bool threshold_already_triggered(struct threshold *t)
{
return t->value_set && below_threshold(t, t->current_value);
}
static void check_threshold(struct threshold *t, dm_block_t value)
{
if (below_threshold(t, value) &&
!threshold_already_triggered(t))
t->fn(t->context);
t->value_set = true;
t->current_value = value;
}
/*----------------------------------------------------------------*/
/*
* 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 bop_ring_buffer {
unsigned begin;
unsigned end;
struct block_op bops[MAX_RECURSIVE_ALLOCATIONS + 1];
};
static void brb_init(struct bop_ring_buffer *brb)
{
brb->begin = 0;
brb->end = 0;
}
static bool brb_empty(struct bop_ring_buffer *brb)
{
return brb->begin == brb->end;
}
static unsigned brb_next(struct bop_ring_buffer *brb, unsigned old)
{
unsigned r = old + 1;
return (r >= (sizeof(brb->bops) / sizeof(*brb->bops))) ? 0 : r;
}
static int brb_push(struct bop_ring_buffer *brb,
enum block_op_type type, dm_block_t b)
{
struct block_op *bop;
unsigned next = brb_next(brb, brb->end);
/*
* We don't allow the last bop to be filled, this way we can
* differentiate between full and empty.
*/
if (next == brb->begin)
return -ENOMEM;
bop = brb->bops + brb->end;
bop->type = type;
bop->block = b;
brb->end = next;
return 0;
}
static int brb_peek(struct bop_ring_buffer *brb, struct block_op *result)
{
struct block_op *bop;
if (brb_empty(brb))
return -ENODATA;
bop = brb->bops + brb->begin;
result->type = bop->type;
result->block = bop->block;
return 0;
}
static int brb_pop(struct bop_ring_buffer *brb)
{
if (brb_empty(brb))
return -ENODATA;
brb->begin = brb_next(brb, brb->begin);
return 0;
}
/*----------------------------------------------------------------*/
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;
struct bop_ring_buffer uncommitted;
struct threshold threshold;
};
static int add_bop(struct sm_metadata *smm, enum block_op_type type, dm_block_t b)
{
int r = brb_push(&smm->uncommitted, type, b);
if (r) {
DMERR("too many recursive allocations");
return -ENOMEM;
}
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 apply_bops(struct sm_metadata *smm)
{
int r = 0;
while (!brb_empty(&smm->uncommitted)) {
struct block_op bop;
r = brb_peek(&smm->uncommitted, &bop);
if (r) {
DMERR("bug in bop ring buffer");
break;
}
r = commit_bop(smm, &bop);
if (r)
break;
brb_pop(&smm->uncommitted);
}
return r;
}
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)
apply_bops(smm);
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_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;
unsigned 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 = smm->uncommitted.begin;
i != smm->uncommitted.end;
i = brb_next(&smm->uncommitted, i)) {
struct block_op *op = smm->uncommitted.bops + 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, adjustment = 0;
unsigned i;
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 = smm->uncommitted.begin;
i != smm->uncommitted.end;
i = brb_next(&smm->uncommitted, i)) {
struct block_op *op = smm->uncommitted.bops + 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)
{
dm_block_t count;
struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
int r = sm_metadata_new_block_(sm, b);
if (r) {
DMERR_LIMIT("unable to allocate new metadata block");
return r;
}
r = sm_metadata_get_nr_free(sm, &count);
if (r) {
DMERR_LIMIT("couldn't get free block count");
return r;
}
check_threshold(&smm->threshold, count);
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_register_threshold_callback(struct dm_space_map *sm,
dm_block_t threshold,
dm_sm_threshold_fn fn,
void *context)
{
struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
set_threshold(&smm->threshold, threshold, fn, context);
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 int sm_metadata_extend(struct dm_space_map *sm, dm_block_t extra_blocks);
static const 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,
.register_threshold_callback = sm_metadata_register_threshold_callback
};
/*----------------------------------------------------------------*/
/*
* 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("bootstrap 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);
*count = smm->ll.nr_blocks;
return 0;
}
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);
*result = (b < smm->begin) ? 1 : 0;
return 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("bootstrap 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("bootstrap doesn't support root_size");
return -EINVAL;
}
static int sm_bootstrap_copy_root(struct dm_space_map *sm, void *where,
size_t max)
{
DMERR("bootstrap doesn't support copy_root");
return -EINVAL;
}
static const 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,
.register_threshold_callback = NULL
};
/*----------------------------------------------------------------*/
static int sm_metadata_extend(struct dm_space_map *sm, dm_block_t extra_blocks)
{
int r, i;
struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
dm_block_t old_len = smm->ll.nr_blocks;
/*
* Flick into a mode where all blocks get allocated in the new area.
*/
smm->begin = old_len;
memcpy(sm, &bootstrap_ops, sizeof(*sm));
/*
* Extend.
*/
r = sm_ll_extend(&smm->ll, extra_blocks);
if (r)
goto out;
/*
* We repeatedly increment then commit until the commit doesn't
* allocate any new blocks.
*/
do {
for (i = old_len; !r && i < smm->begin; i++)
r = add_bop(smm, BOP_INC, i);
if (r)
goto out;
old_len = smm->begin;
r = apply_bops(smm);
if (r) {
DMERR("%s: apply_bops failed", __func__);
goto out;
}
r = sm_ll_commit(&smm->ll);
if (r)
goto out;
} while (old_len != smm->begin);
out:
/*
* Switch back to normal behaviour.
*/
memcpy(sm, &ops, sizeof(*sm));
return r;
}
/*----------------------------------------------------------------*/
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;
struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
smm->begin = superblock + 1;
smm->recursion_count = 0;
smm->allocated_this_transaction = 0;
brb_init(&smm->uncommitted);
threshold_init(&smm->threshold);
memcpy(&smm->sm, &bootstrap_ops, sizeof(smm->sm));
r = sm_ll_new_metadata(&smm->ll, tm);
if (!r) {
if (nr_blocks > DM_SM_METADATA_MAX_BLOCKS)
nr_blocks = DM_SM_METADATA_MAX_BLOCKS;
r = sm_ll_extend(&smm->ll, nr_blocks);
}
memcpy(&smm->sm, &ops, sizeof(smm->sm));
if (r)
return r;
/*
* 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 = add_bop(smm, BOP_INC, i);
if (r)
return r;
r = apply_bops(smm);
if (r) {
DMERR("%s: apply_bops failed", __func__);
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;
brb_init(&smm->uncommitted);
threshold_init(&smm->threshold);
memcpy(&smm->old_ll, &smm->ll, sizeof(smm->old_ll));
return 0;
}