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Go Back   Linux Archive > Redhat > Device-mapper Development

 
 
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Old 03-01-2010, 11:23 PM
Mike Snitzer
 
Default dm-multisnap-mikulas-btree

From: Mikulas Patocka <mpatocka@redhat.com>

B+tree operations.

Adding and deleting entries and walking the whole b+tree.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
---
drivers/md/dm-multisnap-btree.c | 838 +++++++++++++++++++++++++++++++++++++++
1 files changed, 838 insertions(+), 0 deletions(-)
create mode 100644 drivers/md/dm-multisnap-btree.c

diff --git a/drivers/md/dm-multisnap-btree.c b/drivers/md/dm-multisnap-btree.c
new file mode 100644
index 0000000..a7e3b60
--- /dev/null
+++ b/drivers/md/dm-multisnap-btree.c
@@ -0,0 +1,838 @@
+/*
+ * Copyright (C) 2009 Red Hat Czech, s.r.o.
+ *
+ * Mikulas Patocka <mpatocka@redhat.com>
+ *
+ * This file is released under the GPL.
+ */
+
+#include "dm-multisnap-mikulas.h"
+
+/*
+ * Read one btree node and do basic consistency checks.
+ * Any btree access should be done with this function.
+ */
+static struct dm_multisnap_bt_node *
+dm_multisnap_read_btnode(struct dm_exception_store *s, int depth,
+ chunk_t block, unsigned want_entries, struct dm_buffer **bp)
+{
+ struct dm_multisnap_bt_node *node;
+
+ BUG_ON((unsigned)depth >= s->bt_depth);
+
+ node = dm_multisnap_read_block(s, block, bp);
+ if (unlikely(!node))
+ return NULL;
+
+ if (unlikely(node->signature != BT_SIGNATURE)) {
+ dm_bufio_release(*bp);
+ DM_MULTISNAP_SET_ERROR(s->dm, -EFSERROR,
+ ("dm_multisnap_read_btnode: bad signature on btree node %llx",
+ (unsigned long long)block));
+ return NULL;
+ }
+
+ if (unlikely((unsigned)(le32_to_cpu(node->n_entries) - 1) >= s->btree_entries) ||
+ (want_entries && unlikely(le32_to_cpu(node->n_entries) != want_entries))) {
+ dm_bufio_release(*bp);
+ DM_MULTISNAP_SET_ERROR(s->dm, -EFSERROR,
+ ("dm_multisnap_read_btnode: bad number of entries in btree node "
+ "%llx: %x, wanted %x",
+ (unsigned long long)block,
+ le32_to_cpu(node->n_entries),
+ want_entries));
+ return NULL;
+ }
+
+ return node;
+}
+
+/*
+ * Write orig_chunk entry.
+ *
+ * If we are compiled with 32-bit chunk_t, we must write the special fields
+ * with bits 32-47 set, so that the store could be read on a system with
+ * 64-bit chunk_t.
+ */
+static void write_orig_chunk(struct dm_multisnap_bt_entry *be, chunk_t n)
+{
+ write_48(be, orig_chunk, n);
+ if (sizeof(chunk_t) == 4 && unlikely(n > DM_CHUNK_T_MAX))
+ be->orig_chunk2 = cpu_to_le16(0xffff);
+}
+
+/*
+ * Add an entry (key, new_chunk) at an appropriate index to the btree node.
+ * Move the existing entries
+ */
+static void add_at_idx(struct dm_multisnap_bt_node *node, unsigned index,
+ struct bt_key *key, chunk_t new_chunk)
+{
+ memmove(&node->entries[index + 1], &node->entries[index],
+ (le32_to_cpu(node->n_entries) - index) * sizeof(struct dm_multisnap_bt_entry));
+ write_orig_chunk(&node->entries[index], key->chunk);
+ write_48(&node->entries[index], new_chunk, new_chunk);
+ node->entries[index].snap_from = cpu_to_mikulas_snapid(key->snap_from);
+ node->entries[index].snap_to = cpu_to_mikulas_snapid(key->snap_to);
+ node->entries[index].flags = cpu_to_le32(0);
+ node->n_entries = cpu_to_le32(le32_to_cpu(node->n_entries) + 1);
+}
+
+/*
+ * Create an initial btree.
+ * (*writing_block) is updated to point after the btree.
+ */
+void dm_multisnap_create_btree(struct dm_exception_store *s, chunk_t *writing_block)
+{
+ struct dm_buffer *bp;
+ struct dm_multisnap_bt_node *node;
+ struct bt_key new_key;
+
+ while (dm_multisnap_is_commit_block(s, *writing_block))
+ (*writing_block)++;
+
+ if (*writing_block >= s->dev_size) {
+ DM_MULTISNAP_SET_ERROR(s->dm, -ENOSPC,
+ ("dm_multisnap_create_btree: device is too small"));
+ return;
+ }
+
+ node = dm_bufio_new(s->bufio, *writing_block, &bp);
+ if (IS_ERR(node)) {
+ DM_MULTISNAP_SET_ERROR(s->dm, PTR_ERR(node),
+ ("dm_multisnap_create_btree: 't create direct bitmap block at %llx",
+ (unsigned long long)*writing_block));
+ return;
+ }
+ memset(node, 0, s->chunk_size);
+ node->signature = BT_SIGNATURE;
+ node->n_entries = cpu_to_le32(0);
+
+ /*
+ * A btree node must have at least one entry --- so create this empty
+ * one
+ */
+ new_key.snap_from = new_key.snap_to = DM_SNAPID_T_LAST;
+ new_key.chunk = DM_CHUNK_T_LAST;
+ add_at_idx(node, 0, &new_key, 0);
+
+ dm_bufio_mark_buffer_dirty(bp);
+ dm_bufio_release(bp);
+ s->bt_root = *writing_block;
+ s->bt_depth = 1;
+ (*writing_block)++;
+}
+
+/*
+ * Compare btree entry and a search key. Returns:
+ * -1: the entry is lower than the key
+ * 1: the entry is higher than the key
+ * 0: the entry matches the key (both entry and key have ranges, a match
+ * is returned when the ranges overlap)
+ */
+static int compare_key(struct dm_multisnap_bt_entry *e, struct bt_key *key)
+{
+ chunk_t orig_chunk = read_48(e, orig_chunk);
+ if (orig_chunk < key->chunk)
+ return -1;
+ if (orig_chunk > key->chunk)
+ return 1;
+
+ if (mikulas_snapid_to_cpu(e->snap_to) < key->snap_from)
+ return -1;
+ if (mikulas_snapid_to_cpu(e->snap_from) > key->snap_to)
+ return 1;
+
+ return 0;
+}
+
+/*
+ * Perform binary search on the btree node.
+ * Returns: 1 - found, 0 - not found
+ * *result - if found, then the first entry in the requested range
+ * - if not found, then the first entry after the requested range
+ */
+static int binary_search(struct dm_multisnap_bt_node *node, struct bt_key *key,
+ unsigned *result)
+{
+ int c;
+ int first = 0;
+ int last = le32_to_cpu(node->n_entries) - 1;
+
+ while (1) {
+ int middle = (first + last) >> 1;
+ struct dm_multisnap_bt_entry *e = &node->entries[middle];
+
+ c = compare_key(e, key);
+
+ if (first == last)
+ break;
+
+ if (c < 0)
+ first = middle + 1;
+ else
+ last = middle;
+
+ cond_resched();
+ }
+
+ *result = first;
+ return !c;
+}
+
+/*
+ * Find a given key in the btree.
+ *
+ * Returns: 1 - found, 0 - not found, -1 - error
+ * In case of not error (0 or 1 is returned), the node and held buffer for
+ * this node is returned (the buffer must be released with
+ * dm_bufio_release). Also, path with s->bt_depth entries is returned.
+ */
+static int walk_btree(struct dm_exception_store *s, struct bt_key *key,
+ struct dm_multisnap_bt_node **nodep, struct dm_buffer **bp,
+ struct path_element path[MAX_BT_DEPTH])
+{
+#define node (*nodep)
+ int r;
+ chunk_t block = s->bt_root;
+ unsigned d = 0;
+
+ /*
+ * These four are purely to check tree consistency.
+ * They could be commented out. But it's safer to leave them there.
+ */
+ chunk_t want_last_chunk = DM_CHUNK_T_LAST;
+ mikulas_snapid_t want_last_snapid = DM_SNAPID_T_LAST;
+ chunk_t last_chunk;
+ mikulas_snapid_t last_snapid;
+
+ while (1) {
+ path[d].block = block;
+ node = dm_multisnap_read_btnode(s, d, block, 0, bp);
+ if (!node)
+ return -1;
+ path[d].n_entries = le32_to_cpu(node->n_entries);
+
+ /* Check consistency (can be commented out) */
+ last_chunk = read_48(&node->entries[path[d].n_entries - 1], orig_chunk);
+ last_snapid = mikulas_snapid_to_cpu(node->entries[path[d].n_entries - 1].snap_to);
+ if (unlikely(last_chunk != want_last_chunk) ||
+ unlikely(last_snapid != want_last_snapid)) {
+ dm_bufio_release(*bp);
+ DM_MULTISNAP_SET_ERROR(s->dm, -EFSERROR,
+ ("walk_btree: invalid last entry in node %llx/%llx: "
+ "last_chunk %llx, want_last_chunk %llx, last_snapid: %llx, "
+ "want_last_snapid: %llx, searching for %llx, %llx-%llx",
+ (unsigned long long)block,
+ (unsigned long long)dm_multisnap_remap_block(s, block),
+ (unsigned long long)last_chunk,
+ (unsigned long long)want_last_chunk,
+ (unsigned long long)last_snapid,
+ (unsigned long long)want_last_snapid,
+ (unsigned long long)key->chunk,
+ (unsigned long long)key->snap_from,
+ (unsigned long long)key->snap_to));
+ return -1;
+ }
+
+ r = binary_search(node, key, &path[d].idx);
+
+ want_last_chunk = read_48(&node->entries[path[d].idx], orig_chunk);
+ want_last_snapid = mikulas_snapid_to_cpu(node->entries[path[d].idx].snap_to);
+
+ block = read_48(&node->entries[path[d].idx], new_chunk);
+ if (++d == s->bt_depth)
+ break;
+ dm_bufio_release(*bp);
+ }
+ if (unlikely(compare_key(&node->entries[path[s->bt_depth - 1].idx], key) < 0))
+ path[s->bt_depth - 1].idx++;
+ return r;
+#undef node
+}
+
+/*
+ * Find a given key in the btree.
+ *
+ * Returns: 1 - found, 0 - not found, -1 - error
+ * In case the node is found, key contains updated key and result contains
+ * the resulting chunk.
+ */
+int dm_multisnap_find_in_btree(struct dm_exception_store *s, struct bt_key *key,
+ chunk_t *result)
+{
+ struct dm_multisnap_bt_node *node;
+ struct path_element path[MAX_BT_DEPTH];
+ struct dm_buffer *bp;
+
+ int r = walk_btree(s, key, &node, &bp, path);
+ if (unlikely(r < 0))
+ return r;
+
+ if (r) {
+ struct dm_multisnap_bt_entry *entry = &node->entries[path[s->bt_depth - 1].idx];
+ *result = read_48(entry, new_chunk);
+ key->chunk = read_48(entry, orig_chunk);
+ key->snap_from = mikulas_snapid_to_cpu(entry->snap_from);
+ key->snap_to = mikulas_snapid_to_cpu(entry->snap_to);
+ }
+ dm_bufio_release(bp);
+
+ return r;
+}
+
+/*
+ * Scan the btree sequentially.
+ * Start with the given key. Perform "call" on each leaf node. When call returns
+ * nonzero, terminate the scan and return the value returned from call.
+ * When the whole tree is scanned, return 0.
+ * On error, return -1.
+ */
+int dm_multisnap_list_btree(struct dm_exception_store *s, struct bt_key *key,
+ int (*call)(struct dm_exception_store *, struct dm_multisnap_bt_node *,
+ struct dm_multisnap_bt_entry *, void *),
+ void *cookie)
+{
+ struct dm_multisnap_bt_node *node;
+ struct path_element path[MAX_BT_DEPTH];
+ struct dm_buffer *bp;
+ int depth;
+ int i;
+ int r;
+
+ r = walk_btree(s, key, &node, &bp, path);
+ if (unlikely(r < 0))
+ return r;
+
+list_next_node:
+ for (i = path[s->bt_depth - 1].idx; i < le32_to_cpu(node->n_entries); i++) {
+ cond_resched();
+ r = call(s, node, &node->entries[i], cookie);
+ if (unlikely(r)) {
+ dm_bufio_release(bp);
+ return r;
+ }
+ }
+ dm_bufio_release(bp);
+
+ for (depth = s->bt_depth - 2; depth >= 0; depth--) {
+ int idx;
+ node = dm_multisnap_read_btnode(s, depth, path[depth].block,
+ path[depth].n_entries, &bp);
+ if (!node)
+ return -1;
+ idx = path[depth].idx + 1;
+ if (idx < path[depth].n_entries) {
+ r = compare_key(&node->entries[idx], key);
+ if (unlikely(r <= 0)) {
+ dm_bufio_release(bp);
+ DM_MULTISNAP_SET_ERROR(s->dm, -EFSERROR,
+ ("dm_multisnap_list_btree: non-monotonic btree: node "
+ "%llx, index %x",
+ (unsigned long long)path[depth].block, idx));
+ return 0;
+ }
+ path[depth].idx = idx;
+ do {
+ depth++;
+ path[depth].block = read_48(&node->entries[path[depth - 1].idx], new_chunk);
+ path[depth].idx = 0;
+ dm_bufio_release(bp);
+ node = dm_multisnap_read_btnode(s, depth, path[depth].block, 0, &bp);
+ if (!node)
+ return -1;
+ path[depth].n_entries = le32_to_cpu(node->n_entries);
+ } while (depth < s->bt_depth - 1);
+ goto list_next_node;
+ }
+ dm_bufio_release(bp);
+ }
+
+ return 0;
+}
+
+/*
+ * Add a key and chunk to the btree.
+ * The key must not overlap with any existing btree entry.
+ */
+
+void dm_multisnap_add_to_btree(struct dm_exception_store *s, struct bt_key *key, chunk_t new_chunk)
+{
+ struct dm_multisnap_bt_node *node;
+ struct dm_buffer *bp;
+ struct path_element path[MAX_BT_DEPTH];
+ int depth;
+
+ unsigned split_entries, split_index, split_offset, split_size;
+ struct bt_key new_key;
+ struct dm_multisnap_bt_entry *last_one;
+ chunk_t new_root;
+
+ int r = walk_btree(s, key, &node, &bp, path);
+
+ if (unlikely(r)) {
+ if (r > 0) {
+ dm_bufio_release(bp);
+ DM_MULTISNAP_SET_ERROR(s->dm, -EFSERROR,
+ ("dm_multisnap_add_to_btree: adding key that already exists: "
+ "%llx, %llx-%llx",
+ (unsigned long long)key->chunk,
+ (unsigned long long)key->snap_from,
+ (unsigned long long)key->snap_to));
+ }
+ return;
+ }
+
+ depth = s->bt_depth - 1;
+
+go_up:
+ node = dm_multisnap_alloc_duplicate_block(s, path[depth].block, &bp, node);
+ if (unlikely(!node))
+ return;
+
+ if (likely(le32_to_cpu(node->n_entries) < s->btree_entries)) {
+ add_at_idx(node, path[depth].idx, key, new_chunk);
+ dm_bufio_mark_buffer_dirty(bp);
+ dm_bufio_release(bp);
+ return;
+ }
+ cond_resched();
+ memcpy(s->tmp_chunk, node, s->chunk_size);
+ cond_resched();
+ add_at_idx(s->tmp_chunk, path[depth].idx, key, new_chunk);
+
+ split_entries = le32_to_cpu(((struct dm_multisnap_bt_node *)s->tmp_chunk)->n_entries);
+ split_index = split_entries / 2;
+ split_offset = sizeof(struct dm_multisnap_bt_node) + split_index * sizeof(struct dm_multisnap_bt_entry);
+ split_size = sizeof(struct dm_multisnap_bt_node) + split_entries * sizeof(struct dm_multisnap_bt_entry);
+ cond_resched();
+ memcpy(node, s->tmp_chunk, sizeof(struct dm_multisnap_bt_node));
+ cond_resched();
+ memcpy((char *)node + sizeof(struct dm_multisnap_bt_node),
+ (char *)s->tmp_chunk + split_offset, split_size - split_offset);
+ cond_resched();
+ memset((char *)node + sizeof(struct dm_multisnap_bt_node) + split_size - split_offset, 0,
+ s->chunk_size - (sizeof(struct dm_multisnap_bt_node) + split_size - split_offset));
+ cond_resched();
+ node->n_entries = cpu_to_le32(split_entries - split_index);
+
+ dm_bufio_mark_buffer_dirty(bp);
+ dm_bufio_release(bp);
+
+ node = dm_multisnap_alloc_make_block(s, &new_chunk, &bp);
+ if (unlikely(!node))
+ return;
+
+ cond_resched();
+ memcpy(node, s->tmp_chunk, split_offset);
+ cond_resched();
+ memset((char *)node + split_offset, 0, s->chunk_size - split_offset);
+ cond_resched();
+ node->n_entries = cpu_to_le32(split_index);
+
+ last_one = &node->entries[split_index - 1];
+ new_key.chunk = read_48(last_one, orig_chunk);
+ new_key.snap_from = mikulas_snapid_to_cpu(last_one->snap_to);
+ new_key.snap_to = mikulas_snapid_to_cpu(last_one->snap_to);
+
+ key = &new_key;
+
+ dm_bufio_mark_buffer_dirty(bp);
+ dm_bufio_release(bp);
+
+ if (depth--) {
+ node = dm_multisnap_read_btnode(s, depth, path[depth].block,
+ path[depth].n_entries, &bp);
+ if (unlikely(!node))
+ return;
+ goto go_up;
+ }
+
+ if (s->bt_depth >= MAX_BT_DEPTH) {
+ DM_MULTISNAP_SET_ERROR(s->dm, -EFSERROR,
+ ("dm_multisnap_add_to_btree: max b+-tree depth reached"));
+ return;
+ }
+
+ node = dm_multisnap_alloc_make_block(s, &new_root, &bp);
+ if (unlikely(!node))
+ return;
+
+ cond_resched();
+ memset(node, 0, s->chunk_size);
+ cond_resched();
+ node->signature = BT_SIGNATURE;
+ node->n_entries = cpu_to_le32(0);
+ add_at_idx(node, 0, &new_key, new_chunk);
+ new_key.snap_from = new_key.snap_to = DM_SNAPID_T_LAST;
+ new_key.chunk = DM_CHUNK_T_LAST;
+ add_at_idx(node, 1, &new_key, path[0].block);
+
+ dm_bufio_mark_buffer_dirty(bp);
+ dm_bufio_release(bp);
+
+ s->bt_root = new_root;
+ s->bt_depth++;
+}
+
+/*
+ * Change the last entry from old_chunk/old_snapid to new_chunk/new_snapid.
+ * Start at a given depth and go upward to the root.
+ */
+static void dm_multisnap_fixup_backlimits(struct dm_exception_store *s,
+ struct path_element path[MAX_BT_DEPTH], int depth,
+ chunk_t old_chunk, mikulas_snapid_t old_snapid,
+ chunk_t new_chunk, mikulas_snapid_t new_snapid)
+{
+ int idx;
+ struct dm_multisnap_bt_node *node;
+ struct dm_buffer *bp;
+
+ if (old_chunk == new_chunk && old_snapid == new_snapid)
+ return;
+
+ for (depth--; depth >= 0; depth--) {
+ node = dm_multisnap_read_btnode(s, depth, path[depth].block,
+ path[depth].n_entries, &bp);
+ if (unlikely(!node))
+ return;
+
+ node = dm_multisnap_alloc_duplicate_block(s, path[depth].block, &bp, node);
+ if (unlikely(!node))
+ return;
+
+ idx = path[depth].idx;
+
+ if (unlikely(read_48(&node->entries[idx], orig_chunk) != old_chunk) ||
+ unlikely(mikulas_snapid_to_cpu(node->entries[idx].snap_from) != old_snapid) ||
+ unlikely(mikulas_snapid_to_cpu(node->entries[idx].snap_to) != old_snapid)) {
+ dm_bufio_release(bp);
+ DM_MULTISNAP_SET_ERROR(s->dm, -EFSERROR,
+ ("dm_multisnap_fixup_backlimits: btree limit does not match, block "
+ "%llx, idx %x, orig_chunk %llx, snap_from %llx, snap_to "
+ "%llx, want %llx, %llx",
+ (unsigned long long)path[depth].block,
+ idx,
+ (unsigned long long)read_48(&node->entries[idx], orig_chunk),
+ (unsigned long long)mikulas_snapid_to_cpu(node->entries[idx].snap_from),
+ (unsigned long long)mikulas_snapid_to_cpu(node->entries[idx].snap_to),
+ (unsigned long long)old_chunk,
+ (unsigned long long)old_snapid));
+ return;
+ }
+ write_48(&node->entries[idx], orig_chunk, new_chunk);
+ node->entries[idx].snap_from = node->entries[idx].snap_to = cpu_to_mikulas_snapid(new_snapid);
+
+ dm_bufio_mark_buffer_dirty(bp);
+ dm_bufio_release(bp);
+
+ if (path[depth].idx != path[depth].n_entries - 1)
+ return;
+ }
+ DM_MULTISNAP_SET_ERROR(s->dm, -EFSERROR,
+ ("dm_multisnap_fixup_backlimits: the last entry modified, %llx/%llx -> %llx/%llx",
+ (unsigned long long)old_chunk,
+ (unsigned long long)old_snapid,
+ (unsigned long long)new_chunk,
+ (unsigned long long)new_snapid));
+}
+
+/*
+ * Restrict the range of an existing btree entry.
+ * The key must have the same beginning or end as some existing entry (not both)
+ * The range of the key is excluded from the entry.
+ */
+void dm_multisnap_restrict_btree_entry(struct dm_exception_store *s, struct bt_key *key)
+{
+ struct dm_multisnap_bt_node *node;
+ struct path_element path[MAX_BT_DEPTH];
+ struct dm_buffer *bp;
+ int idx;
+ struct dm_multisnap_bt_entry *entry;
+ mikulas_snapid_t from, to, new_to;
+
+ int r = walk_btree(s, key, &node, &bp, path);
+ if (unlikely(r < 0))
+ return;
+
+ if (!r) {
+ dm_bufio_release(bp);
+ DM_MULTISNAP_SET_ERROR(s->dm, -EFSERROR,
+ ("dm_multisnap_restrict_btree_entry: unknown key: %llx, %llx-%llx",
+ (unsigned long long)key->chunk,
+ (unsigned long long)key->snap_from,
+ (unsigned long long)key->snap_to));
+ return;
+ }
+
+ node = dm_multisnap_alloc_duplicate_block(s, path[s->bt_depth - 1].block, &bp, node);
+ if (unlikely(!node))
+ return;
+
+ idx = path[s->bt_depth - 1].idx;
+ entry = &node->entries[idx];
+ from = mikulas_snapid_to_cpu(entry->snap_from);
+ to = new_to = mikulas_snapid_to_cpu(entry->snap_to);
+ if (key->snap_from == from && key->snap_to < to) {
+ entry->snap_from = cpu_to_mikulas_snapid(key->snap_to + 1);
+ } else if (key->snap_from > from && key->snap_to == to) {
+ new_to = key->snap_from - 1;
+ entry->snap_to = cpu_to_mikulas_snapid(new_to);
+ } else {
+ dm_bufio_release(bp);
+ DM_MULTISNAP_SET_ERROR(s->dm, -EFSERROR,
+ ("dm_multisnap_restrict_btree_entry: invali range to restruct: "
+ "%llx, %llx-%llx %llx-%llx",
+ (unsigned long long)key->chunk,
+ (unsigned long long)from,
+ (unsigned long long)to,
+ (unsigned long long)key->snap_from,
+ (unsigned long long)key->snap_to));
+ return;
+ }
+
+ dm_bufio_mark_buffer_dirty(bp);
+ dm_bufio_release(bp);
+
+ if (unlikely(idx == path[s->bt_depth - 1].n_entries - 1))
+ dm_multisnap_fixup_backlimits(s, path, s->bt_depth - 1,
+ key->chunk, to, key->chunk, new_to);
+}
+
+/*
+ * Expand range of an existing btree entry.
+ * The key represents the whole new range (including the old and new part).
+ */
+void dm_multisnap_extend_btree_entry(struct dm_exception_store *s, struct bt_key *key)
+{
+ struct dm_multisnap_bt_node *node;
+ struct path_element path[MAX_BT_DEPTH];
+ struct dm_buffer *bp;
+ int idx;
+ struct dm_multisnap_bt_entry *entry;
+ mikulas_snapid_t from, to, new_to;
+
+ int r = walk_btree(s, key, &node, &bp, path);
+ if (unlikely(r < 0))
+ return;
+
+ if (!r) {
+ dm_bufio_release(bp);
+ DM_MULTISNAP_SET_ERROR(s->dm, -EFSERROR,
+ ("dm_multisnap_extend_btree_entry: unknown key: "
+ "%llx, %llx-%llx",
+ (unsigned long long)key->chunk,
+ (unsigned long long)key->snap_from,
+ (unsigned long long)key->snap_to));
+ return;
+ }
+
+ node = dm_multisnap_alloc_duplicate_block(s, path[s->bt_depth - 1].block,
+ &bp, node);
+ if (unlikely(!node))
+ return;
+
+ idx = path[s->bt_depth - 1].idx;
+ entry = &node->entries[idx];
+ from = mikulas_snapid_to_cpu(entry->snap_from);
+ to = new_to = mikulas_snapid_to_cpu(entry->snap_to);
+ if (key->snap_from < from)
+ entry->snap_from = cpu_to_mikulas_snapid(key->snap_from);
+ if (key->snap_to > to) {
+ new_to = key->snap_to;
+ entry->snap_to = cpu_to_mikulas_snapid(new_to);
+ }
+
+ dm_bufio_mark_buffer_dirty(bp);
+ dm_bufio_release(bp);
+
+ if (unlikely(idx == path[s->bt_depth - 1].n_entries - 1))
+ dm_multisnap_fixup_backlimits(s, path, s->bt_depth - 1,
+ key->chunk, to, key->chunk, new_to);
+}
+
+/*
+ * Delete an entry from the btree.
+ */
+void dm_multisnap_delete_from_btree(struct dm_exception_store *s, struct bt_key *key)
+{
+ struct dm_multisnap_bt_node *node;
+ struct path_element path[MAX_BT_DEPTH];
+ struct dm_buffer *bp;
+ int idx;
+ struct dm_multisnap_bt_entry *entry;
+ mikulas_snapid_t from, to;
+ int depth, n_entries;
+
+ struct dm_multisnap_bt_entry *last_one;
+ chunk_t last_one_chunk;
+ mikulas_snapid_t last_one_snap_to;
+
+ int r = walk_btree(s, key, &node, &bp, path);
+ if (unlikely(r < 0))
+ return;
+
+ if (unlikely(!r)) {
+ dm_bufio_release(bp);
+ DM_MULTISNAP_SET_ERROR(s->dm, -EFSERROR,
+ ("dm_multisnap_delete_from_btree: unknown key: %llx, %llx-%llx",
+ (unsigned long long)key->chunk,
+ (unsigned long long)key->snap_from,
+ (unsigned long long)key->snap_to));
+ return;
+ }
+
+ depth = s->bt_depth - 1;
+
+ idx = path[depth].idx;
+ entry = &node->entries[idx];
+ from = mikulas_snapid_to_cpu(entry->snap_from);
+ to = mikulas_snapid_to_cpu(entry->snap_to);
+ if (unlikely(from != key->snap_from) || unlikely(to != key->snap_to)) {
+ dm_bufio_release(bp);
+ DM_MULTISNAP_SET_ERROR(s->dm, -EFSERROR,
+ ("dm_multisnap_delete_from_btree: invalid range to restrict: "
+ "%llx, %llx-%llx %llx-%llx",
+ (unsigned long long)key->chunk,
+ (unsigned long long)from,
+ (unsigned long long)to,
+ (unsigned long long)key->snap_from,
+ (unsigned long long)key->snap_to));
+ return;
+ }
+
+ while (unlikely((n_entries = le32_to_cpu(node->n_entries)) == 1)) {
+ dm_bufio_release(bp);
+ if (unlikely(!depth)) {
+ DM_MULTISNAP_SET_ERROR(s->dm, -EFSERROR,
+ ("dm_multisnap_delete_from_btree: b-tree is empty"));
+ return;
+ }
+ dm_multisnap_free_block_and_duplicates(s, path[depth].block);
+ depth--;
+ node = dm_multisnap_read_btnode(s, depth, path[depth].block,
+ path[depth].n_entries, &bp);
+ if (!node)
+ return;
+ }
+
+ node = dm_multisnap_alloc_duplicate_block(s, path[depth].block, &bp, node);
+ if (unlikely(!node))
+ return;
+
+ idx = path[depth].idx;
+
+ cond_resched();
+ memmove(node->entries + idx, node->entries + idx + 1,
+ (n_entries - idx - 1) * sizeof(struct dm_multisnap_bt_entry));
+ cond_resched();
+ n_entries--;
+ memset(node->entries + n_entries, 0, sizeof(struct dm_multisnap_bt_entry));
+
+ node->n_entries = cpu_to_le32(n_entries);
+
+ last_one = &node->entries[n_entries - 1];
+ last_one_chunk = read_48(last_one, orig_chunk);
+ last_one_snap_to = mikulas_snapid_to_cpu(last_one->snap_to);
+
+ dm_bufio_mark_buffer_dirty(bp);
+ dm_bufio_release(bp);
+
+ if (unlikely(idx == n_entries))
+ dm_multisnap_fixup_backlimits(s, path, depth, key->chunk,
+ key->snap_to, last_one_chunk,
+ last_one_snap_to);
+}
+
+/*
+ * Process btree tmp remaps.
+ * Find the whole path for tmp_remap and write the path as new entries, from
+ * the root.
+ */
+void dm_multisnap_bt_finalize_tmp_remap(struct dm_exception_store *s,
+ struct tmp_remap *tmp_remap)
+{
+ struct dm_buffer *bp;
+ struct dm_multisnap_bt_node *node;
+ struct bt_key key;
+ struct path_element path[MAX_BT_DEPTH];
+ int results_ptr;
+
+ chunk_t new_blockn;
+ int r;
+ int i;
+
+ if (s->n_preallocated_blocks < s->bt_depth) {
+ if (dm_multisnap_alloc_blocks(s, s->preallocated_blocks + s->n_preallocated_blocks,
+ s->bt_depth - s->n_preallocated_blocks, 0) < 0)
+ return;
+ s->n_preallocated_blocks = s->bt_depth;
+ }
+ results_ptr = 0;
+
+ /*
+ * Read the key from this node --- we'll walk the btree according
+ * to this key to find a path from the root.
+ */
+ node = dm_multisnap_read_btnode(s, s->bt_depth - 1, tmp_remap->new, 0, &bp);
+ if (!node)
+ return;
+ key.chunk = read_48(&node->entries[0], orig_chunk);
+ key.snap_from = key.snap_to = mikulas_snapid_to_cpu(node->entries[0].snap_from);
+ dm_bufio_release(bp);
+
+ r = walk_btree(s, &key, &node, &bp, path);
+ if (r < 0)
+ return;
+
+ dm_bufio_release(bp);
+
+ for (i = s->bt_depth - 1; i >= 0; i--)
+ if (path[i].block == tmp_remap->old)
+ goto found;
+
+ DMERR("block %llx/%llx was not found in btree when searching for %llx/%llx",
+ (unsigned long long)tmp_remap->old,
+ (unsigned long long)tmp_remap->new,
+ (unsigned long long)key.chunk,
+ (unsigned long long)key.snap_from);
+ for (i = 0; i < s->bt_depth; i++)
+ DMERR("path[%d]: %llx/%x", i, (unsigned long long)path[i].block, path[i].idx);
+ dm_multisnap_set_error(s->dm, -EFSERROR);
+ return;
+
+found:
+ dm_multisnap_free_block(s, tmp_remap->old, 0);
+
+ new_blockn = tmp_remap->new;
+ for (i--; i >= 0; i--) {
+ int remapped = 0;
+ node = dm_multisnap_read_btnode(s, i, path[i].block, path[i].n_entries, &bp);
+ if (!node)
+ return;
+ if (!dm_multisnap_block_is_uncommitted(s, path[i].block)) {
+ remapped = 1;
+ dm_bufio_release_move(bp, s->preallocated_blocks[results_ptr]);
+ dm_multisnap_free_block_and_duplicates(s, path[i].block);
+ node = dm_multisnap_read_btnode(s, i, s->preallocated_blocks[results_ptr],
+ path[i].n_entries, &bp);
+ if (!node)
+ return;
+ dm_multisnap_block_set_uncommitted(s, s->preallocated_blocks[results_ptr]);
+ }
+ write_48(&node->entries[path[i].idx], new_chunk, new_blockn);
+ dm_bufio_mark_buffer_dirty(bp);
+ dm_bufio_release(bp);
+
+ if (!remapped)
+ goto skip_it;
+ new_blockn = s->preallocated_blocks[results_ptr];
+ results_ptr++;
+ }
+
+ s->bt_root = new_blockn;
+
+skip_it:
+ memmove(s->preallocated_blocks, s->preallocated_blocks + results_ptr,
+ (s->n_preallocated_blocks -= results_ptr) * sizeof(chunk_t));
+}
--
1.6.5.2

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