diff options
Diffstat (limited to 'drivers/md/persistent-data/dm-btree.c')
| -rw-r--r-- | drivers/md/persistent-data/dm-btree.c | 804 |
1 files changed, 804 insertions, 0 deletions
diff --git a/drivers/md/persistent-data/dm-btree.c b/drivers/md/persistent-data/dm-btree.c new file mode 100644 index 00000000..d12b2cc5 --- /dev/null +++ b/drivers/md/persistent-data/dm-btree.c @@ -0,0 +1,804 @@ +/* + * Copyright (C) 2011 Red Hat, Inc. + * + * This file is released under the GPL. + */ + +#include "dm-btree-internal.h" +#include "dm-space-map.h" +#include "dm-transaction-manager.h" + +#include <linux/export.h> +#include <linux/device-mapper.h> + +#define DM_MSG_PREFIX "btree" + +/*---------------------------------------------------------------- + * Array manipulation + *--------------------------------------------------------------*/ +static void memcpy_disk(void *dest, const void *src, size_t len) + __dm_written_to_disk(src) +{ + memcpy(dest, src, len); + __dm_unbless_for_disk(src); +} + +static void array_insert(void *base, size_t elt_size, unsigned nr_elts, + unsigned index, void *elt) + __dm_written_to_disk(elt) +{ + if (index < nr_elts) + memmove(base + (elt_size * (index + 1)), + base + (elt_size * index), + (nr_elts - index) * elt_size); + + memcpy_disk(base + (elt_size * index), elt, elt_size); +} + +/*----------------------------------------------------------------*/ + +/* makes the assumption that no two keys are the same. */ +static int bsearch(struct node *n, uint64_t key, int want_hi) +{ + int lo = -1, hi = le32_to_cpu(n->header.nr_entries); + + while (hi - lo > 1) { + int mid = lo + ((hi - lo) / 2); + uint64_t mid_key = le64_to_cpu(n->keys[mid]); + + if (mid_key == key) + return mid; + + if (mid_key < key) + lo = mid; + else + hi = mid; + } + + return want_hi ? hi : lo; +} + +int lower_bound(struct node *n, uint64_t key) +{ + return bsearch(n, key, 0); +} + +void inc_children(struct dm_transaction_manager *tm, struct node *n, + struct dm_btree_value_type *vt) +{ + unsigned i; + uint32_t nr_entries = le32_to_cpu(n->header.nr_entries); + + if (le32_to_cpu(n->header.flags) & INTERNAL_NODE) + for (i = 0; i < nr_entries; i++) + dm_tm_inc(tm, value64(n, i)); + else if (vt->inc) + for (i = 0; i < nr_entries; i++) + vt->inc(vt->context, value_ptr(n, i)); +} + +static int insert_at(size_t value_size, struct node *node, unsigned index, + uint64_t key, void *value) + __dm_written_to_disk(value) +{ + uint32_t nr_entries = le32_to_cpu(node->header.nr_entries); + __le64 key_le = cpu_to_le64(key); + + if (index > nr_entries || + index >= le32_to_cpu(node->header.max_entries)) { + DMERR("too many entries in btree node for insert"); + __dm_unbless_for_disk(value); + return -ENOMEM; + } + + __dm_bless_for_disk(&key_le); + + array_insert(node->keys, sizeof(*node->keys), nr_entries, index, &key_le); + array_insert(value_base(node), value_size, nr_entries, index, value); + node->header.nr_entries = cpu_to_le32(nr_entries + 1); + + return 0; +} + +/*----------------------------------------------------------------*/ + +/* + * We want 3n entries (for some n). This works more nicely for repeated + * insert remove loops than (2n + 1). + */ +static uint32_t calc_max_entries(size_t value_size, size_t block_size) +{ + uint32_t total, n; + size_t elt_size = sizeof(uint64_t) + value_size; /* key + value */ + + block_size -= sizeof(struct node_header); + total = block_size / elt_size; + n = total / 3; /* rounds down */ + + return 3 * n; +} + +int dm_btree_empty(struct dm_btree_info *info, dm_block_t *root) +{ + int r; + struct dm_block *b; + struct node *n; + size_t block_size; + uint32_t max_entries; + + r = new_block(info, &b); + if (r < 0) + return r; + + block_size = dm_bm_block_size(dm_tm_get_bm(info->tm)); + max_entries = calc_max_entries(info->value_type.size, block_size); + + n = dm_block_data(b); + memset(n, 0, block_size); + n->header.flags = cpu_to_le32(LEAF_NODE); + n->header.nr_entries = cpu_to_le32(0); + n->header.max_entries = cpu_to_le32(max_entries); + n->header.value_size = cpu_to_le32(info->value_type.size); + + *root = dm_block_location(b); + return unlock_block(info, b); +} +EXPORT_SYMBOL_GPL(dm_btree_empty); + +/*----------------------------------------------------------------*/ + +/* + * Deletion uses a recursive algorithm, since we have limited stack space + * we explicitly manage our own stack on the heap. + */ +#define MAX_SPINE_DEPTH 64 +struct frame { + struct dm_block *b; + struct node *n; + unsigned level; + unsigned nr_children; + unsigned current_child; +}; + +struct del_stack { + struct dm_transaction_manager *tm; + int top; + struct frame spine[MAX_SPINE_DEPTH]; +}; + +static int top_frame(struct del_stack *s, struct frame **f) +{ + if (s->top < 0) { + DMERR("btree deletion stack empty"); + return -EINVAL; + } + + *f = s->spine + s->top; + + return 0; +} + +static int unprocessed_frames(struct del_stack *s) +{ + return s->top >= 0; +} + +static int push_frame(struct del_stack *s, dm_block_t b, unsigned level) +{ + int r; + uint32_t ref_count; + + if (s->top >= MAX_SPINE_DEPTH - 1) { + DMERR("btree deletion stack out of memory"); + return -ENOMEM; + } + + r = dm_tm_ref(s->tm, b, &ref_count); + if (r) + return r; + + if (ref_count > 1) + /* + * This is a shared node, so we can just decrement it's + * reference counter and leave the children. + */ + dm_tm_dec(s->tm, b); + + else { + struct frame *f = s->spine + ++s->top; + + r = dm_tm_read_lock(s->tm, b, &btree_node_validator, &f->b); + if (r) { + s->top--; + return r; + } + + f->n = dm_block_data(f->b); + f->level = level; + f->nr_children = le32_to_cpu(f->n->header.nr_entries); + f->current_child = 0; + } + + return 0; +} + +static void pop_frame(struct del_stack *s) +{ + struct frame *f = s->spine + s->top--; + + dm_tm_dec(s->tm, dm_block_location(f->b)); + dm_tm_unlock(s->tm, f->b); +} + +int dm_btree_del(struct dm_btree_info *info, dm_block_t root) +{ + int r; + struct del_stack *s; + + s = kmalloc(sizeof(*s), GFP_KERNEL); + if (!s) + return -ENOMEM; + s->tm = info->tm; + s->top = -1; + + r = push_frame(s, root, 1); + if (r) + goto out; + + while (unprocessed_frames(s)) { + uint32_t flags; + struct frame *f; + dm_block_t b; + + r = top_frame(s, &f); + if (r) + goto out; + + if (f->current_child >= f->nr_children) { + pop_frame(s); + continue; + } + + flags = le32_to_cpu(f->n->header.flags); + if (flags & INTERNAL_NODE) { + b = value64(f->n, f->current_child); + f->current_child++; + r = push_frame(s, b, f->level); + if (r) + goto out; + + } else if (f->level != (info->levels - 1)) { + b = value64(f->n, f->current_child); + f->current_child++; + r = push_frame(s, b, f->level + 1); + if (r) + goto out; + + } else { + if (info->value_type.dec) { + unsigned i; + + for (i = 0; i < f->nr_children; i++) + info->value_type.dec(info->value_type.context, + value_ptr(f->n, i)); + } + f->current_child = f->nr_children; + } + } + +out: + kfree(s); + return r; +} +EXPORT_SYMBOL_GPL(dm_btree_del); + +/*----------------------------------------------------------------*/ + +static int btree_lookup_raw(struct ro_spine *s, dm_block_t block, uint64_t key, + int (*search_fn)(struct node *, uint64_t), + uint64_t *result_key, void *v, size_t value_size) +{ + int i, r; + uint32_t flags, nr_entries; + + do { + r = ro_step(s, block); + if (r < 0) + return r; + + i = search_fn(ro_node(s), key); + + flags = le32_to_cpu(ro_node(s)->header.flags); + nr_entries = le32_to_cpu(ro_node(s)->header.nr_entries); + if (i < 0 || i >= nr_entries) + return -ENODATA; + + if (flags & INTERNAL_NODE) + block = value64(ro_node(s), i); + + } while (!(flags & LEAF_NODE)); + + *result_key = le64_to_cpu(ro_node(s)->keys[i]); + memcpy(v, value_ptr(ro_node(s), i), value_size); + + return 0; +} + +int dm_btree_lookup(struct dm_btree_info *info, dm_block_t root, + uint64_t *keys, void *value_le) +{ + unsigned level, last_level = info->levels - 1; + int r = -ENODATA; + uint64_t rkey; + __le64 internal_value_le; + struct ro_spine spine; + + init_ro_spine(&spine, info); + for (level = 0; level < info->levels; level++) { + size_t size; + void *value_p; + + if (level == last_level) { + value_p = value_le; + size = info->value_type.size; + + } else { + value_p = &internal_value_le; + size = sizeof(uint64_t); + } + + r = btree_lookup_raw(&spine, root, keys[level], + lower_bound, &rkey, + value_p, size); + + if (!r) { + if (rkey != keys[level]) { + exit_ro_spine(&spine); + return -ENODATA; + } + } else { + exit_ro_spine(&spine); + return r; + } + + root = le64_to_cpu(internal_value_le); + } + exit_ro_spine(&spine); + + return r; +} +EXPORT_SYMBOL_GPL(dm_btree_lookup); + +/* + * Splits a node by creating a sibling node and shifting half the nodes + * contents across. Assumes there is a parent node, and it has room for + * another child. + * + * Before: + * +--------+ + * | Parent | + * +--------+ + * | + * v + * +----------+ + * | A ++++++ | + * +----------+ + * + * + * After: + * +--------+ + * | Parent | + * +--------+ + * | | + * v +------+ + * +---------+ | + * | A* +++ | v + * +---------+ +-------+ + * | B +++ | + * +-------+ + * + * Where A* is a shadow of A. + */ +static int btree_split_sibling(struct shadow_spine *s, dm_block_t root, + unsigned parent_index, uint64_t key) +{ + int r; + size_t size; + unsigned nr_left, nr_right; + struct dm_block *left, *right, *parent; + struct node *ln, *rn, *pn; + __le64 location; + + left = shadow_current(s); + + r = new_block(s->info, &right); + if (r < 0) + return r; + + ln = dm_block_data(left); + rn = dm_block_data(right); + + nr_left = le32_to_cpu(ln->header.nr_entries) / 2; + nr_right = le32_to_cpu(ln->header.nr_entries) - nr_left; + + ln->header.nr_entries = cpu_to_le32(nr_left); + + rn->header.flags = ln->header.flags; + rn->header.nr_entries = cpu_to_le32(nr_right); + rn->header.max_entries = ln->header.max_entries; + rn->header.value_size = ln->header.value_size; + memcpy(rn->keys, ln->keys + nr_left, nr_right * sizeof(rn->keys[0])); + + size = le32_to_cpu(ln->header.flags) & INTERNAL_NODE ? + sizeof(uint64_t) : s->info->value_type.size; + memcpy(value_ptr(rn, 0), value_ptr(ln, nr_left), + size * nr_right); + + /* + * Patch up the parent + */ + parent = shadow_parent(s); + + pn = dm_block_data(parent); + location = cpu_to_le64(dm_block_location(left)); + __dm_bless_for_disk(&location); + memcpy_disk(value_ptr(pn, parent_index), + &location, sizeof(__le64)); + + location = cpu_to_le64(dm_block_location(right)); + __dm_bless_for_disk(&location); + + r = insert_at(sizeof(__le64), pn, parent_index + 1, + le64_to_cpu(rn->keys[0]), &location); + if (r) + return r; + + if (key < le64_to_cpu(rn->keys[0])) { + unlock_block(s->info, right); + s->nodes[1] = left; + } else { + unlock_block(s->info, left); + s->nodes[1] = right; + } + + return 0; +} + +/* + * Splits a node by creating two new children beneath the given node. + * + * Before: + * +----------+ + * | A ++++++ | + * +----------+ + * + * + * After: + * +------------+ + * | A (shadow) | + * +------------+ + * | | + * +------+ +----+ + * | | + * v v + * +-------+ +-------+ + * | B +++ | | C +++ | + * +-------+ +-------+ + */ +static int btree_split_beneath(struct shadow_spine *s, uint64_t key) +{ + int r; + size_t size; + unsigned nr_left, nr_right; + struct dm_block *left, *right, *new_parent; + struct node *pn, *ln, *rn; + __le64 val; + + new_parent = shadow_current(s); + + r = new_block(s->info, &left); + if (r < 0) + return r; + + r = new_block(s->info, &right); + if (r < 0) { + /* FIXME: put left */ + return r; + } + + pn = dm_block_data(new_parent); + ln = dm_block_data(left); + rn = dm_block_data(right); + + nr_left = le32_to_cpu(pn->header.nr_entries) / 2; + nr_right = le32_to_cpu(pn->header.nr_entries) - nr_left; + + ln->header.flags = pn->header.flags; + ln->header.nr_entries = cpu_to_le32(nr_left); + ln->header.max_entries = pn->header.max_entries; + ln->header.value_size = pn->header.value_size; + + rn->header.flags = pn->header.flags; + rn->header.nr_entries = cpu_to_le32(nr_right); + rn->header.max_entries = pn->header.max_entries; + rn->header.value_size = pn->header.value_size; + + memcpy(ln->keys, pn->keys, nr_left * sizeof(pn->keys[0])); + memcpy(rn->keys, pn->keys + nr_left, nr_right * sizeof(pn->keys[0])); + + size = le32_to_cpu(pn->header.flags) & INTERNAL_NODE ? + sizeof(__le64) : s->info->value_type.size; + memcpy(value_ptr(ln, 0), value_ptr(pn, 0), nr_left * size); + memcpy(value_ptr(rn, 0), value_ptr(pn, nr_left), + nr_right * size); + + /* new_parent should just point to l and r now */ + pn->header.flags = cpu_to_le32(INTERNAL_NODE); + pn->header.nr_entries = cpu_to_le32(2); + pn->header.max_entries = cpu_to_le32( + calc_max_entries(sizeof(__le64), + dm_bm_block_size( + dm_tm_get_bm(s->info->tm)))); + pn->header.value_size = cpu_to_le32(sizeof(__le64)); + + val = cpu_to_le64(dm_block_location(left)); + __dm_bless_for_disk(&val); + pn->keys[0] = ln->keys[0]; + memcpy_disk(value_ptr(pn, 0), &val, sizeof(__le64)); + + val = cpu_to_le64(dm_block_location(right)); + __dm_bless_for_disk(&val); + pn->keys[1] = rn->keys[0]; + memcpy_disk(value_ptr(pn, 1), &val, sizeof(__le64)); + + /* + * rejig the spine. This is ugly, since it knows too + * much about the spine + */ + if (s->nodes[0] != new_parent) { + unlock_block(s->info, s->nodes[0]); + s->nodes[0] = new_parent; + } + if (key < le64_to_cpu(rn->keys[0])) { + unlock_block(s->info, right); + s->nodes[1] = left; + } else { + unlock_block(s->info, left); + s->nodes[1] = right; + } + s->count = 2; + + return 0; +} + +static int btree_insert_raw(struct shadow_spine *s, dm_block_t root, + struct dm_btree_value_type *vt, + uint64_t key, unsigned *index) +{ + int r, i = *index, top = 1; + struct node *node; + + for (;;) { + r = shadow_step(s, root, vt); + if (r < 0) + return r; + + node = dm_block_data(shadow_current(s)); + + /* + * We have to patch up the parent node, ugly, but I don't + * see a way to do this automatically as part of the spine + * op. + */ + if (shadow_has_parent(s) && i >= 0) { /* FIXME: second clause unness. */ + __le64 location = cpu_to_le64(dm_block_location(shadow_current(s))); + + __dm_bless_for_disk(&location); + memcpy_disk(value_ptr(dm_block_data(shadow_parent(s)), i), + &location, sizeof(__le64)); + } + + node = dm_block_data(shadow_current(s)); + + if (node->header.nr_entries == node->header.max_entries) { + if (top) + r = btree_split_beneath(s, key); + else + r = btree_split_sibling(s, root, i, key); + + if (r < 0) + return r; + } + + node = dm_block_data(shadow_current(s)); + + i = lower_bound(node, key); + + if (le32_to_cpu(node->header.flags) & LEAF_NODE) + break; + + if (i < 0) { + /* change the bounds on the lowest key */ + node->keys[0] = cpu_to_le64(key); + i = 0; + } + + root = value64(node, i); + top = 0; + } + + if (i < 0 || le64_to_cpu(node->keys[i]) != key) + i++; + + *index = i; + return 0; +} + +static int insert(struct dm_btree_info *info, dm_block_t root, + uint64_t *keys, void *value, dm_block_t *new_root, + int *inserted) + __dm_written_to_disk(value) +{ + int r, need_insert; + unsigned level, index = -1, last_level = info->levels - 1; + dm_block_t block = root; + struct shadow_spine spine; + struct node *n; + struct dm_btree_value_type le64_type; + + le64_type.context = NULL; + le64_type.size = sizeof(__le64); + le64_type.inc = NULL; + le64_type.dec = NULL; + le64_type.equal = NULL; + + init_shadow_spine(&spine, info); + + for (level = 0; level < (info->levels - 1); level++) { + r = btree_insert_raw(&spine, block, &le64_type, keys[level], &index); + if (r < 0) + goto bad; + + n = dm_block_data(shadow_current(&spine)); + need_insert = ((index >= le32_to_cpu(n->header.nr_entries)) || + (le64_to_cpu(n->keys[index]) != keys[level])); + + if (need_insert) { + dm_block_t new_tree; + __le64 new_le; + + r = dm_btree_empty(info, &new_tree); + if (r < 0) + goto bad; + + new_le = cpu_to_le64(new_tree); + __dm_bless_for_disk(&new_le); + + r = insert_at(sizeof(uint64_t), n, index, + keys[level], &new_le); + if (r) + goto bad; + } + + if (level < last_level) + block = value64(n, index); + } + + r = btree_insert_raw(&spine, block, &info->value_type, + keys[level], &index); + if (r < 0) + goto bad; + + n = dm_block_data(shadow_current(&spine)); + need_insert = ((index >= le32_to_cpu(n->header.nr_entries)) || + (le64_to_cpu(n->keys[index]) != keys[level])); + + if (need_insert) { + if (inserted) + *inserted = 1; + + r = insert_at(info->value_type.size, n, index, + keys[level], value); + if (r) + goto bad_unblessed; + } else { + if (inserted) + *inserted = 0; + + if (info->value_type.dec && + (!info->value_type.equal || + !info->value_type.equal( + info->value_type.context, + value_ptr(n, index), + value))) { + info->value_type.dec(info->value_type.context, + value_ptr(n, index)); + } + memcpy_disk(value_ptr(n, index), + value, info->value_type.size); + } + + *new_root = shadow_root(&spine); + exit_shadow_spine(&spine); + + return 0; + +bad: + __dm_unbless_for_disk(value); +bad_unblessed: + exit_shadow_spine(&spine); + return r; +} + +int dm_btree_insert(struct dm_btree_info *info, dm_block_t root, + uint64_t *keys, void *value, dm_block_t *new_root) + __dm_written_to_disk(value) +{ + return insert(info, root, keys, value, new_root, NULL); +} +EXPORT_SYMBOL_GPL(dm_btree_insert); + +int dm_btree_insert_notify(struct dm_btree_info *info, dm_block_t root, + uint64_t *keys, void *value, dm_block_t *new_root, + int *inserted) + __dm_written_to_disk(value) +{ + return insert(info, root, keys, value, new_root, inserted); +} +EXPORT_SYMBOL_GPL(dm_btree_insert_notify); + +/*----------------------------------------------------------------*/ + +static int find_highest_key(struct ro_spine *s, dm_block_t block, + uint64_t *result_key, dm_block_t *next_block) +{ + int i, r; + uint32_t flags; + + do { + r = ro_step(s, block); + if (r < 0) + return r; + + flags = le32_to_cpu(ro_node(s)->header.flags); + i = le32_to_cpu(ro_node(s)->header.nr_entries); + if (!i) + return -ENODATA; + else + i--; + + *result_key = le64_to_cpu(ro_node(s)->keys[i]); + if (next_block || flags & INTERNAL_NODE) + block = value64(ro_node(s), i); + + } while (flags & INTERNAL_NODE); + + if (next_block) + *next_block = block; + return 0; +} + +int dm_btree_find_highest_key(struct dm_btree_info *info, dm_block_t root, + uint64_t *result_keys) +{ + int r = 0, count = 0, level; + struct ro_spine spine; + + init_ro_spine(&spine, info); + for (level = 0; level < info->levels; level++) { + r = find_highest_key(&spine, root, result_keys + level, + level == info->levels - 1 ? NULL : &root); + if (r == -ENODATA) { + r = 0; + break; + + } else if (r) + break; + + count++; + } + exit_ro_spine(&spine); + + return r ? r : count; +} +EXPORT_SYMBOL_GPL(dm_btree_find_highest_key); |