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#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
/* * 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;}
static void array_block_prepare_for_write(const 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(const struct dm_block_validator *v, struct dm_block *b, size_t size_of_block){ struct array_block *bh_le = dm_block_data(b); uint32_t nr_entries, max_entries, value_size; __le32 csum_disk;
if (dm_block_location(b) != le64_to_cpu(bh_le->blocknr)) { DMERR_LIMIT("%s failed: blocknr %llu != wanted %llu", __func__, (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("%s failed: csum %u != wanted %u", __func__, (unsigned int) le32_to_cpu(csum_disk), (unsigned int) le32_to_cpu(bh_le->csum)); return -EILSEQ; }
nr_entries = le32_to_cpu(bh_le->nr_entries); max_entries = le32_to_cpu(bh_le->max_entries); value_size = le32_to_cpu(bh_le->value_size);
if (!value_size) { DMERR_LIMIT("%s failed: value_size is zero", __func__); return -EILSEQ; }
if (max_entries != calc_max_entries(value_size, size_of_block)) { DMERR_LIMIT("%s failed: max_entries %u invalid for value_size %u", __func__, max_entries, value_size); return -EILSEQ; }
if (nr_entries > max_entries) { DMERR_LIMIT("%s failed: too many entries", __func__); return -EILSEQ; }
return 0;}
static const 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 int 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 int)){ unsigned int nr_entries = le32_to_cpu(ab->nr_entries);
fn(info->value_type.context, element_at(info, ab, 0), nr_entries);}
/* * 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);}
/* * 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 int new_nr){ uint32_t nr_entries, delta, i; 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); delta = new_nr - nr_entries; if (vt->inc) vt->inc(vt->context, value, delta); for (i = nr_entries; i < new_nr; i++) 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 int new_nr){ uint32_t nr_entries, delta; 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); delta = nr_entries - new_nr; if (vt->dec) vt->dec(vt->context, element_at(info, ab, new_nr - 1), delta); 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); if (le32_to_cpu((*ab)->value_size) != info->value_type.size) { DMERR_LIMIT("%s failed: value_size %u != wanted %u", __func__, le32_to_cpu((*ab)->value_size), info->value_type.size); dm_tm_unlock(info->btree_info.tm, *block); return -EILSEQ; }
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 int 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);}
/*----------------------------------------------------------------*/
static int __shadow_ablock(struct dm_array_info *info, dm_block_t b, struct dm_block **block, struct array_block **ab){ int inc; int r = dm_tm_shadow_block(info->btree_info.tm, b, &array_validator, block, &inc); if (r) return r;
*ab = dm_block_data(*block); if (le32_to_cpu((*ab)->value_size) != info->value_type.size) { DMERR_LIMIT("%s failed: value_size %u != wanted %u", __func__, le32_to_cpu((*ab)->value_size), info->value_type.size); dm_tm_unlock(info->btree_info.tm, *block); return -EILSEQ; }
if (inc) inc_ablock_entries(info, *ab);
return 0;}
/* * The shadow op will often be a noop. Only insert if it really * copied data. */static int __reinsert_ablock(struct dm_array_info *info, unsigned int index, struct dm_block *block, dm_block_t b, dm_block_t *root){ int r = 0;
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;}
/* * 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 int index, struct dm_block **block, struct array_block **ab){ int r; uint64_t key = index; dm_block_t b; __le64 block_le;
r = dm_btree_lookup(&info->btree_info, *root, &key, &block_le); if (r) return r; b = le64_to_cpu(block_le);
r = __shadow_ablock(info, b, block, ab); if (r) return r;
return __reinsert_ablock(info, index, *block, b, root);}
/* * 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 int 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 int begin_block, unsigned int end_block, unsigned int 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 int max_entries;
/* * nr of completely full blocks in the array. * * 'old' refers to before the resize, 'new' after. */ unsigned int old_nr_full_blocks, new_nr_full_blocks;
/* * Number of entries in the final block. 0 iff only full blocks in * the array. */ unsigned int 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 int begin_index, unsigned int 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 int total_nr_blocks_needed(unsigned int nr_full_blocks, unsigned int 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 int 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 int 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, unsigned int count){ const __le64 *block_le = value; struct dm_array_info *info = context; unsigned int i;
for (i = 0; i < count; i++, 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 void block_dec(void *context, const void *value, unsigned int count){ unsigned int i;
for (i = 0; i < count; i++, value += sizeof(__le64)) __block_dec(context, value);}
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);
static int populate_ablock_with_values(struct dm_array_info *info, struct array_block *ab, value_fn fn, void *context, unsigned int base, unsigned int new_nr){ int r; unsigned int i; struct dm_btree_value_type *vt = &info->value_type;
BUG_ON(le32_to_cpu(ab->nr_entries)); BUG_ON(new_nr > le32_to_cpu(ab->max_entries));
for (i = 0; i < new_nr; i++) { r = fn(base + i, element_at(info, ab, i), context); if (r) return r;
if (vt->inc) vt->inc(vt->context, element_at(info, ab, i), 1); }
ab->nr_entries = cpu_to_le32(new_nr); return 0;}
int dm_array_new(struct dm_array_info *info, dm_block_t *root, uint32_t size, value_fn fn, void *context){ int r; struct dm_block *block; struct array_block *ab; unsigned int block_index, end_block, size_of_block, max_entries;
r = dm_array_empty(info, root); if (r) return r;
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); end_block = dm_div_up(size, max_entries);
for (block_index = 0; block_index != end_block; block_index++) { r = alloc_ablock(info, size_of_block, max_entries, &block, &ab); if (r) break;
r = populate_ablock_with_values(info, ab, fn, context, block_index * max_entries, min(max_entries, size)); if (r) { unlock_ablock(info, block); break; }
r = insert_ablock(info, block_index, block, root); unlock_ablock(info, block); if (r) break;
size -= max_entries; }
return r;}EXPORT_SYMBOL_GPL(dm_array_new);
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 int 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 int max_entries; unsigned int 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, 1); if (vt->inc) vt->inc(vt->context, value, 1); }
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 int i; __le64 block_le; unsigned int 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);
/*----------------------------------------------------------------*/
static int load_ablock(struct dm_array_cursor *c){ int r; __le64 value_le; uint64_t key;
if (c->block) unlock_ablock(c->info, c->block);
c->index = 0;
r = dm_btree_cursor_get_value(&c->cursor, &key, &value_le); if (r) { DMERR("dm_btree_cursor_get_value failed"); goto out;
} else { r = get_ablock(c->info, le64_to_cpu(value_le), &c->block, &c->ab); if (r) { DMERR("get_ablock failed"); goto out; } }
return 0;
out: dm_btree_cursor_end(&c->cursor); c->block = NULL; c->ab = NULL; return r;}
int dm_array_cursor_begin(struct dm_array_info *info, dm_block_t root, struct dm_array_cursor *c){ int r;
memset(c, 0, sizeof(*c)); c->info = info; r = dm_btree_cursor_begin(&info->btree_info, root, true, &c->cursor); if (r) { DMERR("couldn't create btree cursor"); return r; }
return load_ablock(c);}EXPORT_SYMBOL_GPL(dm_array_cursor_begin);
void dm_array_cursor_end(struct dm_array_cursor *c){ if (c->block) unlock_ablock(c->info, c->block);
dm_btree_cursor_end(&c->cursor);}EXPORT_SYMBOL_GPL(dm_array_cursor_end);
int dm_array_cursor_next(struct dm_array_cursor *c){ int r;
if (!c->block) return -ENODATA;
c->index++;
if (c->index >= le32_to_cpu(c->ab->nr_entries)) { r = dm_btree_cursor_next(&c->cursor); if (r) return r;
r = load_ablock(c); if (r) return r; }
return 0;}EXPORT_SYMBOL_GPL(dm_array_cursor_next);
int dm_array_cursor_skip(struct dm_array_cursor *c, uint32_t count){ int r;
do { uint32_t remaining = le32_to_cpu(c->ab->nr_entries) - c->index;
if (count < remaining) { c->index += count; return 0; }
count -= remaining; c->index += (remaining - 1); r = dm_array_cursor_next(c);
} while (!r);
return r;}EXPORT_SYMBOL_GPL(dm_array_cursor_skip);
void dm_array_cursor_get_value(struct dm_array_cursor *c, void **value_le){ *value_le = element_at(c->info, c->ab, c->index);}EXPORT_SYMBOL_GPL(dm_array_cursor_get_value);
/*----------------------------------------------------------------*/