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authorJoe Thornber <ejt@redhat.com>2016-09-15 11:11:42 -0400
committerMike Snitzer <snitzer@redhat.com>2016-09-22 11:15:04 -0400
commitfdd1315aa5f022fe6574efdc2d9535f75a0ee255 (patch)
tree769113eca5f6a1594247d62410dbd829e74d8fd3 /drivers/md/persistent-data
parent7d111c81fa29041c730010450618917fb05cab62 (diff)
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dm array: introduce cursor api
More efficient way to iterate an array due to prefetching (makes use of the new dm_btree_cursor_* api). Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md/persistent-data')
-rw-r--r--drivers/md/persistent-data/dm-array.c86
-rw-r--r--drivers/md/persistent-data/dm-array.h33
2 files changed, 119 insertions, 0 deletions
diff --git a/drivers/md/persistent-data/dm-array.c b/drivers/md/persistent-data/dm-array.c
index 155180954cdf..e83047cbb2da 100644
--- a/drivers/md/persistent-data/dm-array.c
+++ b/drivers/md/persistent-data/dm-array.c
@@ -899,3 +899,89 @@ int dm_array_walk(struct dm_array_info *info, dm_block_t root,
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->block = NULL;
+ c->ab = NULL;
+ c->index = 0;
+
+ r = dm_btree_cursor_get_value(&c->cursor, &key, &value_le);
+ if (r) {
+ DMERR("dm_btree_cursor_get_value failed");
+ dm_btree_cursor_end(&c->cursor);
+
+ } else {
+ r = get_ablock(c->info, le64_to_cpu(value_le), &c->block, &c->ab);
+ if (r) {
+ DMERR("get_ablock failed");
+ dm_btree_cursor_end(&c->cursor);
+ }
+ }
+
+ 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);
+
+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);
+
+/*----------------------------------------------------------------*/
diff --git a/drivers/md/persistent-data/dm-array.h b/drivers/md/persistent-data/dm-array.h
index 45ea3f6e1ded..27ee49a55473 100644
--- a/drivers/md/persistent-data/dm-array.h
+++ b/drivers/md/persistent-data/dm-array.h
@@ -182,4 +182,37 @@ int dm_array_walk(struct dm_array_info *info, dm_block_t root,
/*----------------------------------------------------------------*/
+/*
+ * Cursor api.
+ *
+ * This lets you iterate through all the entries in an array efficiently
+ * (it will preload metadata).
+ *
+ * I'm using a cursor, rather than a walk function with a callback because
+ * the cache target needs to iterate both the mapping and hint arrays in
+ * unison.
+ */
+struct dm_array_cursor {
+ struct dm_array_info *info;
+ struct dm_btree_cursor cursor;
+
+ struct dm_block *block;
+ struct array_block *ab;
+ unsigned index;
+};
+
+int dm_array_cursor_begin(struct dm_array_info *info,
+ dm_block_t root, struct dm_array_cursor *c);
+void dm_array_cursor_end(struct dm_array_cursor *c);
+
+uint32_t dm_array_cursor_index(struct dm_array_cursor *c);
+int dm_array_cursor_next(struct dm_array_cursor *c);
+
+/*
+ * value_le is only valid while the cursor points at the current value.
+ */
+void dm_array_cursor_get_value(struct dm_array_cursor *c, void **value_le);
+
+/*----------------------------------------------------------------*/
+
#endif /* _LINUX_DM_ARRAY_H */