A new btree function, dm_btree_lookup_next(), is introduced which is
more efficiently able to skip over regions of the thin device which
aren't mapped.
---
drivers/md/dm-thin-metadata.c | 66 ++++++++++++++++-----------
drivers/md/persistent-data/dm-btree.c | 84 +++++++++++++++++++++++++++++++++++
drivers/md/persistent-data/dm-btree.h | 7 +++
3 files changed, 132 insertions(+), 25 deletions(-)
diff --git a/drivers/md/dm-thin-metadata.c b/drivers/md/dm-thin-metadata.c
index 7fd8309..2eff2ae 100644
--- a/drivers/md/dm-thin-metadata.c
+++ b/drivers/md/dm-thin-metadata.c
@@ -1381,6 +1381,19 @@ static bool __snapshotted_since(struct dm_thin_device *td, uint32_t time)
return td->snapshotted_time > time;
}
+static void unpack_lookup_result(struct dm_thin_device *td, __le64 value,
+ struct dm_thin_lookup_result *result)
+{
+ uint64_t block_time = 0;
+ dm_block_t exception_block;
+ uint32_t exception_time;
+
+ block_time = le64_to_cpu(value);
+ unpack_block_time(block_time, &exception_block, &exception_time);
+ result->block = exception_block;
+ result->shared = __snapshotted_since(td, exception_time);
+}
+
int dm_thin_find_block(struct dm_thin_device *td, dm_block_t block,
int can_issue_io, struct dm_thin_lookup_result *result)
{
@@ -1402,23 +1415,36 @@ int dm_thin_find_block(struct dm_thin_device *td, dm_block_t block,
info = &pmd->nb_info;
r = dm_btree_lookup(info, pmd->root, keys, &value);
- if (!r) {
- uint64_t block_time = 0;
- dm_block_t exception_block;
- uint32_t exception_time;
-
- block_time = le64_to_cpu(value);
- unpack_block_time(block_time, &exception_block,
- &exception_time);
- result->block = exception_block;
- result->shared = __snapshotted_since(td, exception_time);
+ if (!r)
+ unpack_lookup_result(td, value, result);
+
+ up_read(&pmd->root_lock);
+ return r;
+}
+
+static int dm_thin_find_next_mapped_block(struct dm_thin_device *td, dm_block_t block,
+ dm_block_t *vblock,
+ struct dm_thin_lookup_result *result)
+{
+ int r;
+ __le64 value;
+ struct dm_pool_metadata *pmd = td->pmd;
+ dm_block_t keys[2] = { td->id, block };
+
+ down_read(&pmd->root_lock);
+ if (pmd->fail_io) {
+ up_read(&pmd->root_lock);
+ return -EINVAL;
}
+ r = dm_btree_lookup_next(&pmd->info, pmd->root, keys, vblock, &value);
+ if (!r)
+ unpack_lookup_result(td, value, result);
+
up_read(&pmd->root_lock);
return r;
}
-/* FIXME: write a more efficient one in btree */
int dm_thin_find_mapped_range(struct dm_thin_device *td,
dm_block_t begin, dm_block_t end,
dm_block_t *thin_begin, dm_block_t *thin_end,
@@ -1431,21 +1457,11 @@ int dm_thin_find_mapped_range(struct dm_thin_device *td,
if (end < begin)
return -ENODATA;
- /*
- * Find first mapped block.
- */
- while (begin < end) {
- r = dm_thin_find_block(td, begin, true, &lookup);
- if (r) {
- if (r != -ENODATA)
- return r;
- } else
- break;
-
- begin++;
- }
+ r = dm_thin_find_next_mapped_block(td, begin, &begin, &lookup);
+ if (r)
+ return r;
- if (begin == end)
+ if (begin >= end)
return -ENODATA;
*thin_begin = begin;
diff --git a/drivers/md/persistent-data/dm-btree.c b/drivers/md/persistent-data/dm-btree.c
index a262fbc..ca07ce7 100644
--- a/drivers/md/persistent-data/dm-btree.c
+++ b/drivers/md/persistent-data/dm-btree.c
@@ -63,6 +63,11 @@ int lower_bound(struct btree_node *n, uint64_t key)
return bsearch(n, key, 0);
}
+static int upper_bound(struct btree_node *n, uint64_t key)
+{
+ return bsearch(n, key, 1);
+}
+
void inc_children(struct dm_transaction_manager *tm, struct btree_node *n,
struct dm_btree_value_type *vt)
{
@@ -395,6 +400,85 @@ int dm_btree_lookup(struct dm_btree_info *info, dm_block_t root,
}
EXPORT_SYMBOL_GPL(dm_btree_lookup);
+static int dm_btree_lookup_next_single(struct dm_btree_info *info, dm_block_t root,
+ uint64_t key, uint64_t *rkey, void *value_le)
+{
+ int r, i;
+ uint32_t flags, nr_entries;
+ struct dm_block *node;
+ struct btree_node *n;
+
+ r = bn_read_lock(info, root, &node);
+ if (r)
+ return r;
+
+ n = dm_block_data(node);
+ flags = le32_to_cpu(n->header.flags);
+ nr_entries = le32_to_cpu(n->header.nr_entries);
+
+ if (flags & INTERNAL_NODE) {
+ i = lower_bound(n, key);
+ if (i < 0 || i >= nr_entries) {
+ r = -ENODATA;
+ goto out;
+ }
+
+ r = dm_btree_lookup_next_single(info, value64(n, i), key, rkey, value_le);
+ if (r == -ENODATA && i < nr_entries) {
+ i++;
+ r = dm_btree_lookup_next_single(info, value64(n, i), key, rkey, value_le);
+ }
+
+ } else {
+ i = upper_bound(n, key);
+ if (i < 0 || i >= nr_entries) {
+ r = -ENODATA;
+ goto out;
+ }
+
+ *rkey = le64_to_cpu(n->keys[i]);
+ memcpy(value_le, value_ptr(n, i), info->value_type.size);
+ }
+
+out:
+ dm_tm_unlock(info->tm, node);
+ return r;
+}
+
+int dm_btree_lookup_next(struct dm_btree_info *info, dm_block_t root,
+ uint64_t *keys, uint64_t *rkey, void *value_le)
+{
+ unsigned level;
+ int r = -ENODATA;
+ __le64 internal_value_le;
+ struct ro_spine spine;
+
+ init_ro_spine(&spine, info);
+ for (level = 0; level < info->levels - 1u; level++) {
+ r = btree_lookup_raw(&spine, root, keys[level],
+ lower_bound, rkey,
+ &internal_value_le, sizeof(uint64_t));
+
+ if (r)
+ goto out;
+
+ if (*rkey != keys[level]) {
+ r = -ENODATA;
+ goto out;
+ }
+
+ root = le64_to_cpu(internal_value_le);
+ }
+
+ r = dm_btree_lookup_next_single(info, root, keys[level], rkey, value_le);
+
+out:
+ exit_ro_spine(&spine);
+ return r;
+}
+
+EXPORT_SYMBOL_GPL(dm_btree_lookup_next);
+
/*
* 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
diff --git a/drivers/md/persistent-data/dm-btree.h b/drivers/md/persistent-data/dm-btree.h
index 11d8cf7..bf1f3db 100644
--- a/drivers/md/persistent-data/dm-btree.h
+++ b/drivers/md/persistent-data/dm-btree.h
@@ -110,6 +110,13 @@ int dm_btree_lookup(struct dm_btree_info *info, dm_block_t root,
uint64_t *keys, void *value_le);
/*
+ * Tries to find the first key where the bottom level key is >= to that
+ * given. Useful for skipping empty sections of the btree.
+ */
+int dm_btree_lookup_next(struct dm_btree_info *info, dm_block_t root,
+ uint64_t *keys, uint64_t *rkey, void *value_le);
+
+/*
* Insertion (or overwrite an existing value). O(ln(n))
*/
int dm_btree_insert(struct dm_btree_info *info, dm_block_t root,
--
2.5.0
--
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