linux-stable/drivers/md/persistent-data/dm-array.c
Mikulas Patocka 4c7da06f5a dm persistent data: eliminate unnecessary return values
dm_bm_unlock and dm_tm_unlock return an integer value but the returned
value is always 0.  The calling code sometimes checks the return value
and sometimes doesn't.

Eliminate these unnecessary return values and also the checks for them.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2015-10-31 19:06:02 -04:00

821 lines
20 KiB
C

/*
* Copyright (C) 2012 Red Hat, Inc.
*
* This file is released under the GPL.
*/
#include "dm-array.h"
#include "dm-space-map.h"
#include "dm-transaction-manager.h"
#include <linux/export.h>
#include <linux/device-mapper.h>
#define DM_MSG_PREFIX "array"
/*----------------------------------------------------------------*/
/*
* The array is implemented as a fully populated btree, which points to
* blocks that contain the packed values. This is more space efficient
* than just using a btree since we don't store 1 key per value.
*/
struct array_block {
__le32 csum;
__le32 max_entries;
__le32 nr_entries;
__le32 value_size;
__le64 blocknr; /* Block this node is supposed to live in. */
} __packed;
/*----------------------------------------------------------------*/
/*
* Validator methods. As usual we calculate a checksum, and also write the
* block location into the header (paranoia about ssds remapping areas by
* mistake).
*/
#define CSUM_XOR 595846735
static void array_block_prepare_for_write(struct dm_block_validator *v,
struct dm_block *b,
size_t size_of_block)
{
struct array_block *bh_le = dm_block_data(b);
bh_le->blocknr = cpu_to_le64(dm_block_location(b));
bh_le->csum = cpu_to_le32(dm_bm_checksum(&bh_le->max_entries,
size_of_block - sizeof(__le32),
CSUM_XOR));
}
static int array_block_check(struct dm_block_validator *v,
struct dm_block *b,
size_t size_of_block)
{
struct array_block *bh_le = dm_block_data(b);
__le32 csum_disk;
if (dm_block_location(b) != le64_to_cpu(bh_le->blocknr)) {
DMERR_LIMIT("array_block_check failed: blocknr %llu != wanted %llu",
(unsigned long long) le64_to_cpu(bh_le->blocknr),
(unsigned long long) dm_block_location(b));
return -ENOTBLK;
}
csum_disk = cpu_to_le32(dm_bm_checksum(&bh_le->max_entries,
size_of_block - sizeof(__le32),
CSUM_XOR));
if (csum_disk != bh_le->csum) {
DMERR_LIMIT("array_block_check failed: csum %u != wanted %u",
(unsigned) le32_to_cpu(csum_disk),
(unsigned) le32_to_cpu(bh_le->csum));
return -EILSEQ;
}
return 0;
}
static struct dm_block_validator array_validator = {
.name = "array",
.prepare_for_write = array_block_prepare_for_write,
.check = array_block_check
};
/*----------------------------------------------------------------*/
/*
* Functions for manipulating the array blocks.
*/
/*
* Returns a pointer to a value within an array block.
*
* index - The index into _this_ specific block.
*/
static void *element_at(struct dm_array_info *info, struct array_block *ab,
unsigned index)
{
unsigned char *entry = (unsigned char *) (ab + 1);
entry += index * info->value_type.size;
return entry;
}
/*
* Utility function that calls one of the value_type methods on every value
* in an array block.
*/
static void on_entries(struct dm_array_info *info, struct array_block *ab,
void (*fn)(void *, const void *))
{
unsigned i, nr_entries = le32_to_cpu(ab->nr_entries);
for (i = 0; i < nr_entries; i++)
fn(info->value_type.context, element_at(info, ab, i));
}
/*
* Increment every value in an array block.
*/
static void inc_ablock_entries(struct dm_array_info *info, struct array_block *ab)
{
struct dm_btree_value_type *vt = &info->value_type;
if (vt->inc)
on_entries(info, ab, vt->inc);
}
/*
* Decrement every value in an array block.
*/
static void dec_ablock_entries(struct dm_array_info *info, struct array_block *ab)
{
struct dm_btree_value_type *vt = &info->value_type;
if (vt->dec)
on_entries(info, ab, vt->dec);
}
/*
* Each array block can hold this many values.
*/
static uint32_t calc_max_entries(size_t value_size, size_t size_of_block)
{
return (size_of_block - sizeof(struct array_block)) / value_size;
}
/*
* Allocate a new array block. The caller will need to unlock block.
*/
static int alloc_ablock(struct dm_array_info *info, size_t size_of_block,
uint32_t max_entries,
struct dm_block **block, struct array_block **ab)
{
int r;
r = dm_tm_new_block(info->btree_info.tm, &array_validator, block);
if (r)
return r;
(*ab) = dm_block_data(*block);
(*ab)->max_entries = cpu_to_le32(max_entries);
(*ab)->nr_entries = cpu_to_le32(0);
(*ab)->value_size = cpu_to_le32(info->value_type.size);
return 0;
}
/*
* Pad an array block out with a particular value. Every instance will
* cause an increment of the value_type. new_nr must always be more than
* the current number of entries.
*/
static void fill_ablock(struct dm_array_info *info, struct array_block *ab,
const void *value, unsigned new_nr)
{
unsigned i;
uint32_t nr_entries;
struct dm_btree_value_type *vt = &info->value_type;
BUG_ON(new_nr > le32_to_cpu(ab->max_entries));
BUG_ON(new_nr < le32_to_cpu(ab->nr_entries));
nr_entries = le32_to_cpu(ab->nr_entries);
for (i = nr_entries; i < new_nr; i++) {
if (vt->inc)
vt->inc(vt->context, value);
memcpy(element_at(info, ab, i), value, vt->size);
}
ab->nr_entries = cpu_to_le32(new_nr);
}
/*
* Remove some entries from the back of an array block. Every value
* removed will be decremented. new_nr must be <= the current number of
* entries.
*/
static void trim_ablock(struct dm_array_info *info, struct array_block *ab,
unsigned new_nr)
{
unsigned i;
uint32_t nr_entries;
struct dm_btree_value_type *vt = &info->value_type;
BUG_ON(new_nr > le32_to_cpu(ab->max_entries));
BUG_ON(new_nr > le32_to_cpu(ab->nr_entries));
nr_entries = le32_to_cpu(ab->nr_entries);
for (i = nr_entries; i > new_nr; i--)
if (vt->dec)
vt->dec(vt->context, element_at(info, ab, i - 1));
ab->nr_entries = cpu_to_le32(new_nr);
}
/*
* Read locks a block, and coerces it to an array block. The caller must
* unlock 'block' when finished.
*/
static int get_ablock(struct dm_array_info *info, dm_block_t b,
struct dm_block **block, struct array_block **ab)
{
int r;
r = dm_tm_read_lock(info->btree_info.tm, b, &array_validator, block);
if (r)
return r;
*ab = dm_block_data(*block);
return 0;
}
/*
* Unlocks an array block.
*/
static void unlock_ablock(struct dm_array_info *info, struct dm_block *block)
{
dm_tm_unlock(info->btree_info.tm, block);
}
/*----------------------------------------------------------------*/
/*
* Btree manipulation.
*/
/*
* Looks up an array block in the btree, and then read locks it.
*
* index is the index of the index of the array_block, (ie. the array index
* / max_entries).
*/
static int lookup_ablock(struct dm_array_info *info, dm_block_t root,
unsigned index, struct dm_block **block,
struct array_block **ab)
{
int r;
uint64_t key = index;
__le64 block_le;
r = dm_btree_lookup(&info->btree_info, root, &key, &block_le);
if (r)
return r;
return get_ablock(info, le64_to_cpu(block_le), block, ab);
}
/*
* Insert an array block into the btree. The block is _not_ unlocked.
*/
static int insert_ablock(struct dm_array_info *info, uint64_t index,
struct dm_block *block, dm_block_t *root)
{
__le64 block_le = cpu_to_le64(dm_block_location(block));
__dm_bless_for_disk(block_le);
return dm_btree_insert(&info->btree_info, *root, &index, &block_le, root);
}
/*
* Looks up an array block in the btree. Then shadows it, and updates the
* btree to point to this new shadow. 'root' is an input/output parameter
* for both the current root block, and the new one.
*/
static int shadow_ablock(struct dm_array_info *info, dm_block_t *root,
unsigned index, struct dm_block **block,
struct array_block **ab)
{
int r, inc;
uint64_t key = index;
dm_block_t b;
__le64 block_le;
/*
* lookup
*/
r = dm_btree_lookup(&info->btree_info, *root, &key, &block_le);
if (r)
return r;
b = le64_to_cpu(block_le);
/*
* shadow
*/
r = dm_tm_shadow_block(info->btree_info.tm, b,
&array_validator, block, &inc);
if (r)
return r;
*ab = dm_block_data(*block);
if (inc)
inc_ablock_entries(info, *ab);
/*
* Reinsert.
*
* The shadow op will often be a noop. Only insert if it really
* copied data.
*/
if (dm_block_location(*block) != b) {
/*
* dm_tm_shadow_block will have already decremented the old
* block, but it is still referenced by the btree. We
* increment to stop the insert decrementing it below zero
* when overwriting the old value.
*/
dm_tm_inc(info->btree_info.tm, b);
r = insert_ablock(info, index, *block, root);
}
return r;
}
/*
* Allocate an new array block, and fill it with some values.
*/
static int insert_new_ablock(struct dm_array_info *info, size_t size_of_block,
uint32_t max_entries,
unsigned block_index, uint32_t nr,
const void *value, dm_block_t *root)
{
int r;
struct dm_block *block;
struct array_block *ab;
r = alloc_ablock(info, size_of_block, max_entries, &block, &ab);
if (r)
return r;
fill_ablock(info, ab, value, nr);
r = insert_ablock(info, block_index, block, root);
unlock_ablock(info, block);
return r;
}
static int insert_full_ablocks(struct dm_array_info *info, size_t size_of_block,
unsigned begin_block, unsigned end_block,
unsigned max_entries, const void *value,
dm_block_t *root)
{
int r = 0;
for (; !r && begin_block != end_block; begin_block++)
r = insert_new_ablock(info, size_of_block, max_entries, begin_block, max_entries, value, root);
return r;
}
/*
* There are a bunch of functions involved with resizing an array. This
* structure holds information that commonly needed by them. Purely here
* to reduce parameter count.
*/
struct resize {
/*
* Describes the array.
*/
struct dm_array_info *info;
/*
* The current root of the array. This gets updated.
*/
dm_block_t root;
/*
* Metadata block size. Used to calculate the nr entries in an
* array block.
*/
size_t size_of_block;
/*
* Maximum nr entries in an array block.
*/
unsigned max_entries;
/*
* nr of completely full blocks in the array.
*
* 'old' refers to before the resize, 'new' after.
*/
unsigned old_nr_full_blocks, new_nr_full_blocks;
/*
* Number of entries in the final block. 0 iff only full blocks in
* the array.
*/
unsigned old_nr_entries_in_last_block, new_nr_entries_in_last_block;
/*
* The default value used when growing the array.
*/
const void *value;
};
/*
* Removes a consecutive set of array blocks from the btree. The values
* in block are decremented as a side effect of the btree remove.
*
* begin_index - the index of the first array block to remove.
* end_index - the one-past-the-end value. ie. this block is not removed.
*/
static int drop_blocks(struct resize *resize, unsigned begin_index,
unsigned end_index)
{
int r;
while (begin_index != end_index) {
uint64_t key = begin_index++;
r = dm_btree_remove(&resize->info->btree_info, resize->root,
&key, &resize->root);
if (r)
return r;
}
return 0;
}
/*
* Calculates how many blocks are needed for the array.
*/
static unsigned total_nr_blocks_needed(unsigned nr_full_blocks,
unsigned nr_entries_in_last_block)
{
return nr_full_blocks + (nr_entries_in_last_block ? 1 : 0);
}
/*
* Shrink an array.
*/
static int shrink(struct resize *resize)
{
int r;
unsigned begin, end;
struct dm_block *block;
struct array_block *ab;
/*
* Lose some blocks from the back?
*/
if (resize->new_nr_full_blocks < resize->old_nr_full_blocks) {
begin = total_nr_blocks_needed(resize->new_nr_full_blocks,
resize->new_nr_entries_in_last_block);
end = total_nr_blocks_needed(resize->old_nr_full_blocks,
resize->old_nr_entries_in_last_block);
r = drop_blocks(resize, begin, end);
if (r)
return r;
}
/*
* Trim the new tail block
*/
if (resize->new_nr_entries_in_last_block) {
r = shadow_ablock(resize->info, &resize->root,
resize->new_nr_full_blocks, &block, &ab);
if (r)
return r;
trim_ablock(resize->info, ab, resize->new_nr_entries_in_last_block);
unlock_ablock(resize->info, block);
}
return 0;
}
/*
* Grow an array.
*/
static int grow_extend_tail_block(struct resize *resize, uint32_t new_nr_entries)
{
int r;
struct dm_block *block;
struct array_block *ab;
r = shadow_ablock(resize->info, &resize->root,
resize->old_nr_full_blocks, &block, &ab);
if (r)
return r;
fill_ablock(resize->info, ab, resize->value, new_nr_entries);
unlock_ablock(resize->info, block);
return r;
}
static int grow_add_tail_block(struct resize *resize)
{
return insert_new_ablock(resize->info, resize->size_of_block,
resize->max_entries,
resize->new_nr_full_blocks,
resize->new_nr_entries_in_last_block,
resize->value, &resize->root);
}
static int grow_needs_more_blocks(struct resize *resize)
{
int r;
unsigned old_nr_blocks = resize->old_nr_full_blocks;
if (resize->old_nr_entries_in_last_block > 0) {
old_nr_blocks++;
r = grow_extend_tail_block(resize, resize->max_entries);
if (r)
return r;
}
r = insert_full_ablocks(resize->info, resize->size_of_block,
old_nr_blocks,
resize->new_nr_full_blocks,
resize->max_entries, resize->value,
&resize->root);
if (r)
return r;
if (resize->new_nr_entries_in_last_block)
r = grow_add_tail_block(resize);
return r;
}
static int grow(struct resize *resize)
{
if (resize->new_nr_full_blocks > resize->old_nr_full_blocks)
return grow_needs_more_blocks(resize);
else if (resize->old_nr_entries_in_last_block)
return grow_extend_tail_block(resize, resize->new_nr_entries_in_last_block);
else
return grow_add_tail_block(resize);
}
/*----------------------------------------------------------------*/
/*
* These are the value_type functions for the btree elements, which point
* to array blocks.
*/
static void block_inc(void *context, const void *value)
{
__le64 block_le;
struct dm_array_info *info = context;
memcpy(&block_le, value, sizeof(block_le));
dm_tm_inc(info->btree_info.tm, le64_to_cpu(block_le));
}
static void block_dec(void *context, const void *value)
{
int r;
uint64_t b;
__le64 block_le;
uint32_t ref_count;
struct dm_block *block;
struct array_block *ab;
struct dm_array_info *info = context;
memcpy(&block_le, value, sizeof(block_le));
b = le64_to_cpu(block_le);
r = dm_tm_ref(info->btree_info.tm, b, &ref_count);
if (r) {
DMERR_LIMIT("couldn't get reference count for block %llu",
(unsigned long long) b);
return;
}
if (ref_count == 1) {
/*
* We're about to drop the last reference to this ablock.
* So we need to decrement the ref count of the contents.
*/
r = get_ablock(info, b, &block, &ab);
if (r) {
DMERR_LIMIT("couldn't get array block %llu",
(unsigned long long) b);
return;
}
dec_ablock_entries(info, ab);
unlock_ablock(info, block);
}
dm_tm_dec(info->btree_info.tm, b);
}
static int block_equal(void *context, const void *value1, const void *value2)
{
return !memcmp(value1, value2, sizeof(__le64));
}
/*----------------------------------------------------------------*/
void dm_array_info_init(struct dm_array_info *info,
struct dm_transaction_manager *tm,
struct dm_btree_value_type *vt)
{
struct dm_btree_value_type *bvt = &info->btree_info.value_type;
memcpy(&info->value_type, vt, sizeof(info->value_type));
info->btree_info.tm = tm;
info->btree_info.levels = 1;
bvt->context = info;
bvt->size = sizeof(__le64);
bvt->inc = block_inc;
bvt->dec = block_dec;
bvt->equal = block_equal;
}
EXPORT_SYMBOL_GPL(dm_array_info_init);
int dm_array_empty(struct dm_array_info *info, dm_block_t *root)
{
return dm_btree_empty(&info->btree_info, root);
}
EXPORT_SYMBOL_GPL(dm_array_empty);
static int array_resize(struct dm_array_info *info, dm_block_t root,
uint32_t old_size, uint32_t new_size,
const void *value, dm_block_t *new_root)
{
int r;
struct resize resize;
if (old_size == new_size) {
*new_root = root;
return 0;
}
resize.info = info;
resize.root = root;
resize.size_of_block = dm_bm_block_size(dm_tm_get_bm(info->btree_info.tm));
resize.max_entries = calc_max_entries(info->value_type.size,
resize.size_of_block);
resize.old_nr_full_blocks = old_size / resize.max_entries;
resize.old_nr_entries_in_last_block = old_size % resize.max_entries;
resize.new_nr_full_blocks = new_size / resize.max_entries;
resize.new_nr_entries_in_last_block = new_size % resize.max_entries;
resize.value = value;
r = ((new_size > old_size) ? grow : shrink)(&resize);
if (r)
return r;
*new_root = resize.root;
return 0;
}
int dm_array_resize(struct dm_array_info *info, dm_block_t root,
uint32_t old_size, uint32_t new_size,
const void *value, dm_block_t *new_root)
__dm_written_to_disk(value)
{
int r = array_resize(info, root, old_size, new_size, value, new_root);
__dm_unbless_for_disk(value);
return r;
}
EXPORT_SYMBOL_GPL(dm_array_resize);
int dm_array_del(struct dm_array_info *info, dm_block_t root)
{
return dm_btree_del(&info->btree_info, root);
}
EXPORT_SYMBOL_GPL(dm_array_del);
int dm_array_get_value(struct dm_array_info *info, dm_block_t root,
uint32_t index, void *value_le)
{
int r;
struct dm_block *block;
struct array_block *ab;
size_t size_of_block;
unsigned entry, max_entries;
size_of_block = dm_bm_block_size(dm_tm_get_bm(info->btree_info.tm));
max_entries = calc_max_entries(info->value_type.size, size_of_block);
r = lookup_ablock(info, root, index / max_entries, &block, &ab);
if (r)
return r;
entry = index % max_entries;
if (entry >= le32_to_cpu(ab->nr_entries))
r = -ENODATA;
else
memcpy(value_le, element_at(info, ab, entry),
info->value_type.size);
unlock_ablock(info, block);
return r;
}
EXPORT_SYMBOL_GPL(dm_array_get_value);
static int array_set_value(struct dm_array_info *info, dm_block_t root,
uint32_t index, const void *value, dm_block_t *new_root)
{
int r;
struct dm_block *block;
struct array_block *ab;
size_t size_of_block;
unsigned max_entries;
unsigned entry;
void *old_value;
struct dm_btree_value_type *vt = &info->value_type;
size_of_block = dm_bm_block_size(dm_tm_get_bm(info->btree_info.tm));
max_entries = calc_max_entries(info->value_type.size, size_of_block);
r = shadow_ablock(info, &root, index / max_entries, &block, &ab);
if (r)
return r;
*new_root = root;
entry = index % max_entries;
if (entry >= le32_to_cpu(ab->nr_entries)) {
r = -ENODATA;
goto out;
}
old_value = element_at(info, ab, entry);
if (vt->dec &&
(!vt->equal || !vt->equal(vt->context, old_value, value))) {
vt->dec(vt->context, old_value);
if (vt->inc)
vt->inc(vt->context, value);
}
memcpy(old_value, value, info->value_type.size);
out:
unlock_ablock(info, block);
return r;
}
int dm_array_set_value(struct dm_array_info *info, dm_block_t root,
uint32_t index, const void *value, dm_block_t *new_root)
__dm_written_to_disk(value)
{
int r;
r = array_set_value(info, root, index, value, new_root);
__dm_unbless_for_disk(value);
return r;
}
EXPORT_SYMBOL_GPL(dm_array_set_value);
struct walk_info {
struct dm_array_info *info;
int (*fn)(void *context, uint64_t key, void *leaf);
void *context;
};
static int walk_ablock(void *context, uint64_t *keys, void *leaf)
{
struct walk_info *wi = context;
int r;
unsigned i;
__le64 block_le;
unsigned nr_entries, max_entries;
struct dm_block *block;
struct array_block *ab;
memcpy(&block_le, leaf, sizeof(block_le));
r = get_ablock(wi->info, le64_to_cpu(block_le), &block, &ab);
if (r)
return r;
max_entries = le32_to_cpu(ab->max_entries);
nr_entries = le32_to_cpu(ab->nr_entries);
for (i = 0; i < nr_entries; i++) {
r = wi->fn(wi->context, keys[0] * max_entries + i,
element_at(wi->info, ab, i));
if (r)
break;
}
unlock_ablock(wi->info, block);
return r;
}
int dm_array_walk(struct dm_array_info *info, dm_block_t root,
int (*fn)(void *, uint64_t key, void *leaf),
void *context)
{
struct walk_info wi;
wi.info = info;
wi.fn = fn;
wi.context = context;
return dm_btree_walk(&info->btree_info, root, walk_ablock, &wi);
}
EXPORT_SYMBOL_GPL(dm_array_walk);
/*----------------------------------------------------------------*/